diff --git "a/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" "b/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" --- "a/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" +++ "b/raw_rss_feeds/https___arxiv_org_rss_quant_ph.xml" @@ -7,1617 +7,3079 @@ http://www.rssboard.org/rss-specification en-us - Mon, 22 Dec 2025 05:00:05 +0000 + Tue, 23 Dec 2025 05:00:23 +0000 rss-help@arxiv.org - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 - Saturday Sunday + Saturday - Bundling of bipartite entanglement - https://arxiv.org/abs/2512.16979 - arXiv:2512.16979v1 Announce Type: new -Abstract: We investigate bipartite entanglement and prove that in constrained energy subspaces, the entanglement spectra of multiple bipartitions are the same across the whole subspace. We show that in quantum many-body systems the bipartite entanglement entropy is affected in such a way that it forms "bundles" under unitary time evolution. Leveraging the structure of the subspace, we present methods to verify whether the entanglement spectrum of two bipartitions is identical throughout the entire subspace. For the subspace defined by the parity embedding, we further provide an algorithm that can determine this in polynomial time. - oai:arXiv.org:2512.16979v1 + A Polylogarithmic-Time Quantum Algorithm for the Laplace Transform + https://arxiv.org/abs/2512.17980 + arXiv:2512.17980v1 Announce Type: new +Abstract: We introduce a quantum algorithm to perform the Laplace transform on quantum computers. Already, the quantum Fourier transform (QFT) is the cornerstone of many quantum algorithms, but the Laplace transform or its discrete version has not seen any efficient implementation on quantum computers due to its dissipative nature and hence non-unitary dynamics. However, a recent work has shown an efficient implementation for certain cases on quantum computers using the Taylor series. Unlike previous work, our work provides a completely different algorithm for doing Laplace Transform using Quantum Eigenvalue Transformation and Lap-LCHS, very efficiently at points which form an arithmetic progression. Our algorithm can implement $N \times N$ discrete Laplace transform in gate complexity that grows as $O((log\,N)^3)$, ignoring the state preparation cost, where $N=2^n$ and $n$ is the number of qubits, which is a superpolynomial speedup in number of gates over the best classical counterpart that has complexity $O(N\cdot log\,N)$ for the same cases. Also, the circuit width grows as $O(log\,N)$. Quantum Laplace Transform (QLT) may enable new Quantum algorithms for cases like solving differential equations in the Laplace domain, developing an inverse Laplace transform algorithm on quantum computers, imaginary time evolution in the resolvent domain for calculating ground state energy, and spectral estimation of non-Hermitian matrices. + oai:arXiv.org:2512.17980v1 quant-ph - math-ph - math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Maike Drieb-Schoen, Florian Dreier, Wolfgang Lechner + http://creativecommons.org/licenses/by/4.0/ + Akash Kumar Singh, Ashish Kumar Patra, Anurag K. S. V., Sai Shankar P., Ruchika Bhat, Jaiganesh G - Subsystems (in)dependence in GIE proposals - https://arxiv.org/abs/2512.17024 - arXiv:2512.17024v1 Announce Type: new -Abstract: Recent proposals suggest that detecting entanglement between two spatially superposed masses would establish the quantum nature of gravity. However, these gravitationally induced entanglement (GIE) experiments rely on assumptions about subsystem independence. We sharpen the theoretical underpinnings of such proposals by examining them through the lens of algebraic quantum field theory (AQFT), distinguishing distinct operational and algebraic notions of independence. We argue that state and measurement independence of subsystems, essential to the experimental logic, is nontrivial in the presence of gauge constraints and gravitational dressing. Using gravitationally dressed fields, we recall that commutation relations between spacelike separated observables are nontrivial, undermining strict Hilbert space factorization. We further explore the implications for entanglement witnesses, investigating the Tsirelson bound when subsystem algebras fail to commute, and showing that the Tsirelson bound persists for a suitably symmetrized CHSH observable even though the operational status of such "joint" observables becomes delicate when commensurability fails. Our analysis highlights how even within linearized covariant quantum gravity, violations of microcausality may affect both the interpretation, modelling, and design of proposed laboratory tests of quantum gravity, despite remaining negligible for current experimental regimes. Although we consider GIE-style protocols as a concrete case study, the subsystem-independence issues we highlight are generic to low-energy (perturbative) quantum gravity. Finally, we derive estimates for dressing-induced microcausality violations, which suggest a complementary avenue to current proposals: in principle, bounding dressing-induced microcausality violations themselves as a probe of the quantum nature of gravity. - oai:arXiv.org:2512.17024v1 + Recasting Schr\"odinger's Cat Thought Experiment as a Remote Measurement Problem + https://arxiv.org/abs/2512.17991 + arXiv:2512.17991v1 Announce Type: new +Abstract: With 2025 being declared the Year of Quantum Science and Technology, our contribution seeks to provide a fresh perspective on Schr\"odinger's cat thought experiment. We reinterpret this experiment by viewing it through the lens of quantum theory as a generalisation of classical probability, rooted in a Bayesian subjectivist framework. In this revised approach, we treat the experiment as a remote measurement problem. Specifically, we explore how the beliefs of two agents, Alice and Bob, who are spatially separated yet share a quantum state, are updated when local measurements are conducted on their respective systems. Through this reinterpretation of the well-known experiment, we also aim to offer an educational perspective that will be beneficial for young scientists interested in the field of quantum theory. + oai:arXiv.org:2512.17991v1 quant-ph - hep-th - math-ph - math.MP - physics.hist-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Nicolas Boulle, Guilherme Franzmann + Lucas L. Brugger, Cristhiano Duarte, Bruno F. Rizzuti - Comparing Homodyne and Heterodyne Tomography of Quantum States of Light - https://arxiv.org/abs/2512.17031 - arXiv:2512.17031v1 Announce Type: new -Abstract: Non-Gaussian quantum states are critical resources in photonic quantum information processing, rendering their generation and characterization of increasing importance in quantum optics. In this work, we theoretically and numerically analyze the relative efficiency of homodyne versus heterodyne measurements for reconstructing non-Gaussian states, a major outstanding question in continuous-variable tomography. Combining a Fisher information-based formalism with simulated experiments, we find homodyne tomography to outperform heterodyne measurements for all non-Gaussian states tested, although the separation between the two modalities proves significantly narrower than suggested by the asymptotic Cramer-Rao lower bound. Our results should find use for optimizing measurement strategies in practical continuous-variable quantum systems. - oai:arXiv.org:2512.17031v1 + Logical gates on Floquet codes via folds and twists + https://arxiv.org/abs/2512.17999 + arXiv:2512.17999v1 Announce Type: new +Abstract: Floquet codes have recently emerged as a new family of error-correcting codes, and have drawn significant interest across both theoretical and practical quantum computing. A central open question has been how to implement logical operations on these codes. In this work, we show how two techniques from static quantum error-correcting codes can also be implemented on Floquet codes. First, we present a way of implementing fold-transversal operations on Floquet codes in order to yield logical Hadamard and S gates. And second, we present a way of implementing logical CNOT gates on Floquet codes via Dehn twists. We discuss the requirements for these techniques, and show that they are applicable to a wide family of Floquet codes defined on colour code lattices. Through numerical benchmarking of the logical operations on the CCS Floquet code, we establish a logical-gate threshold of 0.25-0.35% and verify sub-threshold exponential error suppression. Our results show that these logical operations are robust, featuring a performance that is close to the baseline set by a quantum memory benchmark. Finally, we explain in detail how to implement logical gates on Floquet codes by operating on the embedded codes. + oai:arXiv.org:2512.17999v1 quant-ph - physics.optics - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Rhea P. Fernandes, Andrew J. Pizzimenti, Christos N. Gagatsos, Joseph M. Lukens + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Alexandra E. Moylett, Bhargavi Jonnadula - Attosecond Control of Squeezed Light - https://arxiv.org/abs/2512.17046 - arXiv:2512.17046v1 Announce Type: new -Abstract: Squeezed light has revolutionized quantum metrology by enhancing interferometry for sensitive applications such as the detection of gravitational waves. Squeezed light has also played a pivotal role in quantum information science with numerous applications in quantum computing and communication. Previously, squeezed light has been primarily generated using nonlinear optical interactions, where control of the degree of squeezing was possible by tuning the nonlinearity of the generating medium using suitable material engineering. Here, we modulate the third-order nonlinear response in dielectrics with strong ultrafast laser fields to control the degree of squeezing on attosecond time scales. We demonstrate the ability to change the ultrafast squeezed light generated in the nonlinear process from amplitude-squeezed to phase-squeezed by controlling the strong-field-driven nonlinear response of the material through a sub-cycle phase delay between the input femtosecond laser pulses. The squeezing of quantum noise is measured using a frequency-resolved balanced homodyne detection scheme capable of extracting the field quadratures in different frequency modes simultaneously. Using this frequency-resolved measurement we extract the complete coherency matrix containing the quantum correlations between field quadratures across different frequency modes of the femtosecond squeezed light pulse. These results have major implications for the development of quantum light sources with unprecedented levels of control over quadrature squeezing, for applications in multimode quantum information processing, and for measuring transient quantum matter correlations via transduction to quantum field correlations in an ultrafast light-matter interaction. - oai:arXiv.org:2512.17046v1 + Systematizing the Interpretation of Quantum Theory via Reconstruction + https://arxiv.org/abs/2512.18002 + arXiv:2512.18002v1 Announce Type: new +Abstract: For a century, quantum theory has posed a fundamental challenge to philosophical thinking. On its face, it repudiates many of the key features of the mechanical conception of physical reality. However, the challenge of developing a precise, coherent alternative to that conception has yet to be met. Here, I argue that a major hindrance to the project of quantum interpretation is its existing interpretative methodologies, which suffer from a lack of systematicity in their judgements about what aspects of the theory are interpretational relevant. In particular, I argue that current interpretations tend to marginalize the informal part of the theory in favour of its formal part, and place inappropriate emphasis on the natural language component of the formalism over its detailed mathematical structure. To counterbalance these biases, I propose that an interpretation-free zone be constructed around the theory, wherein an interpreter initially adopt a descriptive stance which considers all parts of the theory, and that the results of this deliberation~(and the judgements about what facts are interpretationally relevant) are reported as part of their interpretation. + I argue that the interpretation of quantum theory poses special challenges and difficulties which necessitate this interpretation-free zone, and that existing interpretative methodologies are insufficient to address them. Further, I argue that a reconstructive interpretative methodology, which harnesses the recent results of the quantum reconstruction program, provides a powerful means to identify almost all facts that could be interpretationally relevant, and naturally meets these challenges and difficulties. Moreover, I argue that the quantum reconstruction program offers a powerful way to discover new physical principles, and offers a systematic pathway to build a rich, coherent conception of quantum reality. + oai:arXiv.org:2512.18002v1 quant-ph - physics.optics - Mon, 22 Dec 2025 00:00:00 -0500 + physics.hist-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Philip Goyal + + + Shuttling Compiler for Trapped-Ion Quantum Computers Based on Large Language Models + https://arxiv.org/abs/2512.18021 + arXiv:2512.18021v1 Announce Type: new +Abstract: Trapped-ion quantum computers based on segmented traps rely on shuttling operations to establish connectivity between multiple sub-registers within a quantum processing unit. Several architectures of increasing complexity have already been realized, including linear arrays, racetrack loops, and junction-based layouts. As hardware capabilities advance, the need arises for flexible software layers within the control stack to manage qubit routing$\unicode{x2014}$the process of dynamically reconfiguring qubit positions so that all qubits involved in a gate operation are co-located within the same segment. Existing approaches typically employ architecture-specific heuristics, which become impractical as system complexity grows. To address this challenge, we propose a layout-independent compilation strategy based on large language models (LLMs). Specifically, we fine-tune pretrained LLMs to generate the required shuttling operations. We evaluate this approach on both linear and branched one-dimensional architectures, demonstrating that it provides a foundation for developing LLM-based shuttling compilers for trapped-ion quantum computers. + oai:arXiv.org:2512.18021v1 + quant-ph + cs.ET + cs.LG + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Russell Zimmerman, Shashank Kumar, Shiva Kant Tiwari, Eric Liu, Francis Walz, Siddhant Pandey, George J. Economou II, Hadiseh Alaeian, Chen-Ting Liao, Valentin Walther, Niranjan Shivaram + Fabian Kreppel, Reza Salkhordeh, Ferdinand Schmidt-Kaler, Andr\'e Brinkmann - Molecular Quantum Computations on a Protein - https://arxiv.org/abs/2512.17130 - arXiv:2512.17130v1 Announce Type: new -Abstract: This work presents the implementation of a fragment-based, quantum-centric supercomputing workflow for computing molecular electronic structure using quantum hardware. The workflow is applied to predict the relative energies of two conformers of the 300-atom Trp-cage miniprotein. The methodology employs wave function-based embedding (EWF) as the underlying fragmentation framework, in which all atoms in the system are explicitly included in the CI treatment. CI calculations for individual fragments are performed using either sample-based quantum diagonalization (SQD) for challenging fragments or full configuration interaction (FCI) for trivial fragments. To assess the accuracy of SQD for fragment CI calculations, EWF-(FCI,SQD) results are compared against EWF-MP2 and EWF-CCSD benchmarks. Overall, the results demonstrate that large-scale electronic configuration interaction (CI) simulations of protein systems containing hundreds or even thousands of atoms can be realized through the combined use of quantum and classical computing resources. - oai:arXiv.org:2512.17130v1 + Stability studies on subtractively-fabricated CMOS-compatible superconducting transmon qubits + https://arxiv.org/abs/2512.18037 + arXiv:2512.18037v1 Announce Type: new +Abstract: Developing fault-tolerant quantum processors with error correction demands large arrays of physical qubits whose key performance metrics (coherence times, control fidelities) must remain within specifications over both short and long timescales. Here we investigated the temporal stability of subtractively fabricated CMOS-compatible superconducting transmon qubits. During a single cooldown and over a period of 95 hours, we monitored several parameters for 8 qubits, including coherence times $T_1$ and $T_2^*$, which exhibit fluctuations originating primarily from the interaction between two-level system (TLS) defects and the host qubit. We also demonstrate that subtractively-fabricated superconducting quantum devices align with the theoretical predictions that higher mean lifetimes $T_1$ correspond to larger fluctuations. To assess long-term stability, we tracked two representative qubits over 10 cooldown cycles spanning more than one year. We observed an average total downward shift in both qubit transition frequencies of approximately 61 MHz within the thermal cycles considered. In contrast, readout resonator frequencies decreased only marginally. Meanwhile, $T_1$ exhibits fluctuations from cycle to cycle, but maintains a stable baseline value. + oai:arXiv.org:2512.18037v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.supr-con + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Akhil Shajan, Danil Kaliakin, Fangchun Liang, Thaddeus Pellegrini, Hakan Doga, Subhamoy Bhowmik, Susanta Das, Antonio Mezzacapo, Mario Motta, Kenneth M. Merz Jr + Chawki Dhieb, Johannes Weber, Samuel Taubenberger, Carla Moran Guizan, Simon J. K. Lang, Zhen Luo, Emir Music, Alwin Maiwald, Wilfried Lerch, Lars Nebrich, Marc Tornow, Thomas Mayer, Daniela Zahn, Rui N. Pereira, Christoph Kutter - Evaluating Sample-Based Krylov Quantum Diagonalization for Heisenberg Models with Applications to Materials Science - https://arxiv.org/abs/2512.17141 - arXiv:2512.17141v1 Announce Type: new -Abstract: We evaluate the Sample-based Krylov Quantum Diagonalization (SKQD) algorithm on one- and two-dimensional Heisenberg models, including strongly correlated regimes in which the ground state is dense. Using problem-informed initial states and magnetization-sector sweeps, SKQD accurately reproduces ground-state energies and field-dependent magnetization across a range of anisotropies. Benchmarks against DMRG and exact diagonalization show consistent qualitative agreement, with accuracy improving systematically in more anisotropic regimes. We further demonstrate SKQD on quantum hardware by implementing 18- and 30-qubit Heisenberg chains, obtaining magnetization curves that match theoretical expectations. Simulations on small 2D square-lattice systems further demonstrate that the method applies effectively beyond 1D geometries. - oai:arXiv.org:2512.17141v1 + Real 3-qubit gate decompositions via triality + https://arxiv.org/abs/2512.18049 + arXiv:2512.18049v1 Announce Type: new +Abstract: We show that any unimodular real 3-qubit gate can be expressed as the product of at most 14 CNOT gates plus single-qubit gates, improving on the bound of 16 CNOTs due to Wei and Di. Our method uses the exotic triality symmetry of $\operatorname{PSO}(8)$, and we explore some of the useful properties of this map in relation to the study of real 3-qubit gates. + oai:arXiv.org:2512.18049v1 quant-ph - cond-mat.mtrl-sci - Mon, 22 Dec 2025 00:00:00 -0500 + math.GR + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Roman Firt, Neel Misciasci, Jonathan E. Mueller, Triet Friedhoff, Chinonso Onah, Aaron Schulze, Sarah Mostame + Brendan Pawlowski - fractional-time deformation of quantum coherence in open systems: a non-markovian framework beyond lindblad dynamics - https://arxiv.org/abs/2512.17144 - arXiv:2512.17144v1 Announce Type: new -Abstract: In this paper, we propose a fractional time extension of the Quan tum Master Equation. We introduce a Caputo-type fractional derivative in time as an extension of the exponential decay of the Lindblad framework through the incorporation of fractional derivatives into the Lindblad framework. We show that the analytical and numerical results of our analytical and numerical models, demonstrate that fractional dynamics produces long-memory coherence decay naturally and provides an interpretable and flexible model of non-Markovianity. - oai:arXiv.org:2512.17144v1 + Correcting quantum errors one gradient step at a time + https://arxiv.org/abs/2512.18061 + arXiv:2512.18061v1 Announce Type: new +Abstract: In this work, we introduce a general, gradient-based method that optimises codewords for a given noise channel and fixed recovery. We do so by differentiating fidelity and descending on the complex coefficients using finite-difference Wirtinger gradients with soft penalties to promote orthonormalisation. We validate the gradients on symmetry checks (XXX/ZZZ repetition codes) and the $[[5, 1, 3]]$ code, then demonstrate substantial gains under isotropic Pauli noise with Petz recovery: fidelity improves from 0.783 to 0.915 in 100 steps for an isotropic Pauli noise of strength 0.05. The procedure is deterministic, highly parallelisable, and highly scalable. + oai:arXiv.org:2512.18061v1 quant-ph - math-ph - math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + cs.NA + math.NA + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Taylan Demir + Manav Seksaria, Anil Prabhakar - Zero-added-loss entanglement multiplexing using time-bin spectral shearing - https://arxiv.org/abs/2512.17148 - arXiv:2512.17148v1 Announce Type: new -Abstract: High-quality quantum communications that enable important capabilities, such as distributed quantum computing and sensing, will require quantum repeaters for providing high-quality entanglement. To realize high-rate heralded entanglement for quantum repeaters, Chen et al. [Phys. Rev. Appl. 19, 054209 (2023)] proposed a scheme for heralded-multiplexed generation of quasi-deterministic entangled photon pairs, called zero-added-loss multiplexing (ZALM). Here, we propose a design of ZALM source using time-bin entanglement and spectral shearing. Additionally, we provide an analysis of experimentally relevant spectral-shearing parameters to optimize the spectral multiplexing. Moreover, we experimentally verify the compatibility of time-bin pulses and spectral shearing, as supported by observation of no phase shift when the same shearing is applied to both time bins. These results expand the benefits of applying a ZALM source to time-bin entanglement use cases. Moreover, more fully demonstrating time-bin and spectral shearing compatibility clears a path towards a broader use of spectral shearing that provides a deterministic frequency shift of high utility. - oai:arXiv.org:2512.17148v1 + Simulation of depolarizing channel exploring maximally non separable spin-orbit mode + https://arxiv.org/abs/2512.18065 + arXiv:2512.18065v1 Announce Type: new +Abstract: Depolaring Channel is one of the most important noise model and constitute a reliable benchmark quantum information field. In this work we present a simple way to emulate depolaring channel exploring a vector beam in a compact linear optical circuit. The evolution of different states are successfully reproduced. Our results are in excellent agreement compared with the results obtained by the spin-orbit Solovay-Kitaiev decomposiotion for Depolarizing Channel, also presented here for the first time. + oai:arXiv.org:2512.18065v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Joseph C. Chapman, Muneer Alshowkan, Jack Postlewaite, Saikat Guha, Nageswara Rao + http://creativecommons.org/licenses/by/4.0/ + G. Tiago, V. S. Lamego, M. H. M. Passos, W. F. Balthazar, J. A. O. Huguenin - On-Demand Millisecond Storage of Spectro-Temporal Multimode Telecom Photons - https://arxiv.org/abs/2512.17181 - arXiv:2512.17181v1 Announce Type: new -Abstract: The realization of scalable quantum networks for distribution of entanglement over long distances hinges on quantum repeaters. To outperform the exponential transmission loss in optical fibers, quantum repeaters must employ multiplexing schemes in the temporal, spectral, or spatial domain. The performance of such a multiplexed scheme is contingent on efficient quantum memories offering both extended storage times and large multimode capacities. In this work, we experimentally demonstrate such a memory operating at telecom wavelength using an Er$^{3+}$:Y$_{2}$SiO$_{5}$ crystal. Using single-photon detectors, we record on-demand storage and recall of weak coherent pulses for up to $1$ ms, exceeding that of previously reported quantum memories based on Er$^{3+}$. The memory exhibits an efficiency of 10.36\% at 300 $\mu$s storage time with a signal-to-noise ratio of $10.9$. We further showcase its multimode capacity by storing 20 temporal and 3 spectral modes simultaneously with on-demand and selective recall capabilities, essential for a scalable quantum repeater architecture. - oai:arXiv.org:2512.17181v1 + Loschmidt Echo and Classicality of the Gamma Model + https://arxiv.org/abs/2512.18085 + arXiv:2512.18085v1 Announce Type: new +Abstract: The classicality of the Gamma Model, an analytically solvable quantum oscillator with non-linear dynamics, is investigated using the overlap dynamics, also known as the Loschmidt Echo, and roughness, a classicality measure based on the Wigner representation of a state. Though the overlap dynamics would indicate a chaotic regime, here the model is integrable. The time mean of the overlap function decays inversely with the effective Hilbert space occupied by the initial state for the non-periodic case. Two different stationary regimes were found for the overlap mean and overlap variance. The state non-classicality was investigated using the roughness measure, and its mean also has two stationary regimes. For large effective Hilbert space, the roughness time mean depends more on the effective space than the initial state. While the Wigner function is dominated by the non-diagonal terms, the overlap operator has some contribution on each part, but it is more affected by the diagonal terms than the density matrix. + oai:arXiv.org:2512.18085v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Anuj Sethia, Nasser Gohari Kamel, Daniel Oblak + Gilson V. Soares, Mauricio Reis, Adelcio C. Oliveira - Quantum-enhanced Information Retrieval from Reflective Intelligent Surfaces - https://arxiv.org/abs/2512.17199 - arXiv:2512.17199v1 Announce Type: new -Abstract: Information retrieval from passive backscatter systems is widely used in digital applications with tight energy budgets, short communication distances, and low data rates. Due to the fundamental limits of classical wireless receivers, the achievable data rate cannot be increased without compromising either energy efficiency or communication range, thereby hindering the broader adoption of this technology. In this work, we present a novel time-resolving quantum receiver combined with a multi-mode probing signal to extract large-alphabet information modulated by a passive reconfigurable intelligent surface (RIS). The adaptive nature of the proposed receiver yields significant quantum advantages over classical receivers without relying on complex or fragile quantum resources such as entanglement. Simulation results show that the proposed technique surpasses the classical standard quantum limit (SQL) for modulation sizes up to M = 2^8, meanwhile halving the probing energy or increasing the communication distance by a factor of 1.41. - oai:arXiv.org:2512.17199v1 + The CHSH Game, Tsirelson's Bound, and Causal Locality + https://arxiv.org/abs/2512.18105 + arXiv:2512.18105v1 Announce Type: new +Abstract: We reformulate the CHSH game in terms of indivisible stochastic processes. Using Barandes's stochastic-quantum correspondence and its associated definition of causal locality, we present a novel proof of the Tsirelson bound. In particular, we show that unlike the no-signaling principle alone, the postulates defining causally local, indivisible stochastic processes are precisely strong enough to allow for violations of the Bell inequality up to, but not beyond, the Tsirelson bound. + oai:arXiv.org:2512.18105v1 quant-ph - cs.NI - Mon, 22 Dec 2025 00:00:00 -0500 + physics.hist-ph + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by-nc-nd/4.0/ - Shiqian Guo, Tingxiang Ji, Jianqing Liu + Jacob A. Barandes, Mahmudul Hasan, David Kagan - Bound states and decay dynamics in $N$-level Friedrichs model with factorizable interactions - https://arxiv.org/abs/2512.17207 - arXiv:2512.17207v1 Announce Type: new -Abstract: Considering an $N$-level system interacting factorizably with a continuous spectrum, we derive analytical expressions for the bound states and the dynamical evolution within this single-excitation Friedrichs model by using the projection operator formalism. First, we establish explicit criteria to determine the number of bound states, whose existence suppresses the complete spontaneous decay of the system. Second, we derive the open system's dissipative dynamics, which is naturally described by an energy-independent non-Hermitian Hamiltonian in the Markovian limit. As an example, we apply our framework to an atomic chain embedded in a photonic crystal waveguide, uncovering a rich variety of decay dynamics and realizing an anti-$\mathcal{PT}$-symmetric Hamiltonian in the system's evolution. - oai:arXiv.org:2512.17207v1 + Quantum thermodynamics, quantum correlations and quantum coherence in accelerating Unruh-DeWitt detectors in both steady and dynamical state + https://arxiv.org/abs/2512.18123 + arXiv:2512.18123v1 Announce Type: new +Abstract: We investigate the interplay between quantum thermodynamics, quantum correlations, and quantum coherence within the framework of the Unruh-DeWitt (UdW) detector model. By analyzing both the steady and dynamical states of various quantum resources (including steerability, entanglement, quantum discord, and coherence), we study how these resources evolve under Markovian and non-Markovian environments. Furthermore, we investigate the impact of both the Unruh temperature and the energy levels on three key quantum phenomena: thermodynamic evolution, quantum correlations, and quantum coherence, considering different initial state preparations. The hierarchical structure relating quantum correlations and quantum coherence is determined. We further examine the thermodynamic performance of a quantum heat engine, highlighting the influence of memory effects and classical correlations on heat exchange, work extraction, and efficiency. Our results reveal that non-Markovian dynamics can enhance the preservation of quantum correlations and improve the engine's efficiency compared to purely Markovian regime. These findings provide insights into the role of quantum correlations and quantum coherence in quantum thermodynamic processes and open avenues for optimizing quantum devices operating in relativistic or open-system settings. + oai:arXiv.org:2512.18123v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jia-Ming Zhang, Yu Xin, Bing Chen + Omar Bachain, Mohamed Amazioug, Rachid Ahl Laamara - Emergent Universality Class in Dissipative Quantum Systems with Dipole Moment Conservation - https://arxiv.org/abs/2512.17210 - arXiv:2512.17210v1 Announce Type: new -Abstract: Understanding the non-equilibrium dynamics of quantum many-body systems remains one of the grand challenges of modern physics. In particular, increasing attention has been devoted to the emergence of non-equilibrium universality classes that have no equilibrium counterparts. A prominent example is the Kardar-Parisi-Zhang universality class realized in dissipative Bose-Einstein condensates. In this Letter, motivated by recent experimental advances, we investigate the universal dynamics of dissipative quantum systems with dipole moment conservation. We develop an effective field theory description, supported by a concrete quantum spin model, to capture the resulting universal behaviors. Our analysis unveils a novel strongly interacting non-equilibrium fixed point that governs the equal-time phase fluctuations in systems with either strong or weak dipole symmetries. Moreover, charge transport becomes subdiffusive in the presence of strong dipole symmetry, while it remains diffusive in the weakly symmetric case. Our results reveal the intricate interplay between kinetic constraints and dissipation in quantum many-body systems. - oai:arXiv.org:2512.17210v1 + Exploring polymer classification with a hybrid single-photon quantum approach + https://arxiv.org/abs/2512.18125 + arXiv:2512.18125v1 Announce Type: new +Abstract: Polymers exhibit complex architectures and diverse properties that place them at the center of contemporary research in chemistry and materials science. As conventional computational techniques, even multi-scale ones, struggle to capture this complexity, quantum computing offers a promising alternative framework for extracting structure-property relationships. Noisy Intermediate-Scale Quantum (NISQ) devices are commonly used to explore the implementation of algorithms, including quantum neural networks for classification tasks, despite ongoing debate regarding their practical impact. + We present a hybrid classical-quantum formalism that couples a classical deep neural network for polymer featurization with a single-photon-based quantum classifier native to photonic quantum computing. This pipeline successfully classifies polymer species by their optical gap, with performance in line between CPU-based noisy simulations and a proof-of-principle run on Quandela's Ascella quantum processor. These findings demonstrate the effectiveness of the proposed computational workflow and indicate that chemistryfrelated classification tasks can already be tackled under the constraints of today's NISQ devices. + oai:arXiv.org:2512.18125v1 quant-ph - cond-mat.quant-gas - Mon, 22 Dec 2025 00:00:00 -0500 + cs.LG + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Wenbo Zhou, Yuke Zhang, Pengfei Zhang + Alexandrina Stoyanova, Bogdan Penkovsky - An edge-based and subspace reduction encoding scheme to solve the traveling salesman problem in quantum computers - https://arxiv.org/abs/2512.17291 - arXiv:2512.17291v1 Announce Type: new -Abstract: This paper introduces a novel edge-based encoding technique for solving the Traveling Salesman Problem (TSP) on a quantum computer, reducing the required number of qubits. For implementation in real quantum devices, we applied the subspace reduction encoding to further reduce the dimension of the TSP solution space. We attack the TSP for 4-, 5-, and 6-city instances in both simulators and real quantum computers across different encoding frameworks. Optimal solutions of the 4-city TSP instance are obtained on state-of-the art IQM quantum computer. Our study presents a comparative analysis between edge-based encoding scheme and the node-based encoding methodology in the literature. Our findings indicate that the proposed encoding scheme outperforms conventional methods in terms of statistical measures, quantum resource utilization, and computational efficiency when applied to smaller TSP instances. - oai:arXiv.org:2512.17291v1 + Optimizing Epsilon Security Parameters in QKD + https://arxiv.org/abs/2512.18130 + arXiv:2512.18130v1 Announce Type: new +Abstract: We investigate the optimization of epsilon-security parameters in quantum key distribution (QKD), aiming to improve the achievable secure key rate under a fixed overall composable security level. For this purpose, we employ a continuous genetic algorithm (CGA) to optimize the epsilon-security components of two representative protocols: the homodyne protocol from the continuous-variable (CV) family and the BB84 protocol from the discrete-variable (DV) family. We detail the CGA configuration, summarize the derivation of the composable key rate, and emphasize the role of the epsilon-parameters in both protocols. We then compare key rates obtained with optimized epsilon-values against those derived from standard and randomized choices. Our results demonstrate substantial key rate improvements at high security levels, where the key rate typically vanishes, and uncover positive-rate regimes that are inaccessible without optimization. + oai:arXiv.org:2512.18130v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + physics.optics + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Anandu Kalleri Madhu, Chi-Kwong Li, Jami R\"onkk\"o, Mikio Nakahara, Ray-Kuang Lee + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Alexander G. Mountogiannakis, Stefano Pirandola - Towards Quantum Advantage in Sparsified Bosonic SYK Models - https://arxiv.org/abs/2512.17294 - arXiv:2512.17294v1 Announce Type: new -Abstract: We advocate the sparsification of bosonic SYK models as a promising arena for the exploration of quantum advantage. We initiate the study of quantum simulations of the models, both in classical simulators and on quantum devices implemented using superconducting qubits. We point out subtleties in the quantum simulations of highly chaotic systems, which should be addressed in the future search for quantum advantage. - oai:arXiv.org:2512.17294v1 + Crosstalk Dispersion and Spatial Scaling in Superconducting Qubit Arrays + https://arxiv.org/abs/2512.18148 + arXiv:2512.18148v1 Announce Type: new +Abstract: Crosstalk between qubits fundamentally limits the scalability of quantum processors, necessitating physics-based models that can handle the complexity of large qubit arrays. Here, we develop a comprehensive theoretical and experimental framework that captures residual interactions between both adjacent and non-adjacent qubits in fixed-frequency transmon lattices. The model integrates the combined effects of exponential localization in banded capacitance matrices, suppression of virtual couplings through detuning products across intermediate modes, and evanescent decay of below-cutoff electromagnetic fields, yielding predictive scaling relations for coupling strength as a function of spatial separation and spectral detuning. Experimental characterization of a $4 \times 4$ superconducting-qubit lattice with inductive shunt pillars reveals exponential spatial decay and frequency-dependent suppression consistent with theoretical predictions, achieving quantitative agreement for all nearest-neighbor couplings across the \qtyrange[range-phrase = --, range-units = single]{4}{6}{\giga\hertz} operating range. Our results show that standard dispersive Hamiltonian approximations systematically overestimate long-range coupling when spatial and spectral dependencies are neglected; these errors propagate into circuit simulation and design strategies. Our framework provides design guidance for crosstalk mitigation in larger-scale quantum processors under realistic fabrication constraints, addressing a bottleneck in scalability. + oai:arXiv.org:2512.18148v1 quant-ph - hep-th - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Vaibhav Gautam, Atsushi Matsuo, Masahito Yamazaki + http://creativecommons.org/licenses/by/4.0/ + Mohammed Alghadeer, Simon Pettersson Fors, Shuxiang Cao, Simone D. Fasciati, Haru Ishizaka, Anton Frisk Kockum, Peter Leek, Mustafa Bakr - Spin minimum uncertainty states for refined uncertainty relations - https://arxiv.org/abs/2512.17307 - arXiv:2512.17307v1 Announce Type: new -Abstract: Minimum uncertainty states of the conventional Heisenberg uncertainty relation have been extensively studied and are often regarded as the most classical quantum states from the perspective of uncertainty, providing valuable insight into the nature of quantumness and its potential applications. In this work, we investigate the minimum uncertainty states associated with an information-theoretic refinement of the Heisenberg uncertainty relation in general spin systems. Using two different approaches, the matrix formulation and the Wick symbol representation, we derive explicit expressions for the states that saturate the uncertainty bound. We show that spin coherent states indeed achieve minimum uncertainty, consistent with their conventional identification as the classical states of spin systems. Moreover, we also identify additional classes of minimum uncertainty states beyond the coherent family. Finally, we compare the spin-system results with the previously studied bosonic case and elucidate the origin of the differences between the two settings. - oai:arXiv.org:2512.17307v1 + Lattice-Renormalized Tunneling Models for Superconducting Qubit Materials + https://arxiv.org/abs/2512.18156 + arXiv:2512.18156v1 Announce Type: new +Abstract: We present a lattice-renormalized formalism for configurational tunneling two-level systems (TLS) that overcomes limitations of minimum-energy-path and light-particle models. Derived from the nuclear Hamiltonian, our formulation introduces composite phonon coordinates to capture lattice distortions between degenerate potential wells. This approach resolves deficiencies in prior models and enables accurate computation of tunnel splittings and excitation spectra for hydrogen-based TLS in bcc Nb. Our results bound experimental tunnel splittings and reveal strong anharmonic couplings between tunneling atoms and lattice phonons, establishing a direct link between TLS dynamics and phonon-mediated strain interactions. The formalism further generalizes to multi-level systems (MLS), providing insight into defect-induced decoherence in superconducting qubits and guiding strategies for materials design to suppress TLS-related loss. + oai:arXiv.org:2512.18156v1 quant-ph - math-ph - math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.mtrl-sci + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hao Dai, Yue Zhang + P. G. Pritchard, James M. Rondinelli - Microcomb-driven large-scale fully connected quantum network - https://arxiv.org/abs/2512.17318 - arXiv:2512.17318v1 Announce Type: new -Abstract: Fully connected quantum networks enable simultaneously connecting every user to every other user and are the most versatile and robust networking architecture. However, the scalability of such networks remains great challenge for practical applications. Here we construct a large-scale fully connected quantum network founded on two-photon Hong-Ou-Mandel (HOM) interference, where user-to-user security is guaranteed even with untrusted network provider. Using integrated soliton microcomb (SMC) and photonic encoding chips, we realize precise massive parallel frequency generation and locking, high-visibility HOM interferences and measurement-device-independent (MDI) quantum key distribution. The proposed architecture enables a 200-user fully connected quantum network over 200 kilometers with strict information-theoretic security via untrusted network provider. The implemented networking architecture paves the way for realizing large-scale fully connected MDI quantum networks across metropolitan and intercity regions. - oai:arXiv.org:2512.17318v1 + Superconducting qubit decoherence correlated with detected radiation events + https://arxiv.org/abs/2512.18171 + arXiv:2512.18171v1 Announce Type: new +Abstract: Most quantum error correction (QEC) protocols for superconducting qubits assume spatially and temporally uncorrelated decoherence events; however, recent evidence suggests that cosmic radiation induces spatially correlated errors. We present a platform that sandwiches a superconducting transmon qubit between two microwave kinetic inductance detector (MKID) arrays, enabling real-time detection of radiation-induced phonon bursts. By synchronizing MKID event detection with single-shot measurements of qubit energy relaxation ($T_1$) and phase coherence ($T_2$), we observe statistically significant reductions in both $T_1$ and $T_2$-up to 30.5%-immediately following dual MKID events attributed to penetrating muons. Our findings directly link radiating events to correlated qubit decoherence. Furthermore, our experimental platform provides a foundation for systematic studies of radiation effects, the development of shielding and mitigation techniques, and the refinement of error-correction algorithms tailored to correlated noise sources. + oai:arXiv.org:2512.18171v1 quant-ph - physics.optics - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.supr-con + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Fang-Xiang Wang, Sheng-Teng Zheng, Long Huang, Guo-We Zhang, Guang-Shu Wang, Wen-Jing Ding, Ze-Hao Wang, Shuang Wang, Zhen-Qiang Yin, Chang-Ling Zou, Brent E. Little, Guochao Wang, Lingxiao Zhu, Guang-Can Guo, Weiqiang Wang, Wenfu Zhang, Wei Chen, Zheng-Fu Han + A. R. Castelli, K. M. Beck, L. D. H. Alegria, L. A. Martinez, K. R. Chaves, S. R. O'Kelley, N. Materise, J. L DuBois, Y. J. Rosen - The Standard Model Symmetry and Qubit Entanglement - https://arxiv.org/abs/2512.17328 - arXiv:2512.17328v1 Announce Type: new -Abstract: Research at the intersection of quantum gravity and quantum information theory has seen significant success in describing the emergence of spacetime and gravity from quantum states whose entanglement entropy approximately obeys an area law. In a different direction, the Kaluza-Klein proposal aims to recover gauge symmetries by means of dimensional reduction of higher-dimensional gravitational theories. Integrating both, gravitational and gauge degrees of freedom in $3+1$ dimensions may be obtained upon dimensional reduction of higher-dimensional emergent gravity. To this end, we show that entangled systems of two and three qubits can be associated with $5+1$ and $9+1$ dimensional spacetimes respectively, which are reduced to $3+1$ dimensions upon singling out a preferred complex direction. In the latter case, this reduction is invariant under a residual $SU(3) \times SU(2) \times U(1) /\mathbb{Z}_6$ symmetry, the Standard Model gauge group. This motivates a picture in which spacetime emerges from the area law-contribution to the entanglement entropy, while gauge and matter degrees of freedom are due to area law-violating terms. We remark on a possible natural origin of the chirality of the weak force in the given construction. Furthermore, we highlight the possibility of using this construction in quantum simulations of Standard Model fields. - oai:arXiv.org:2512.17328v1 + High-Throughput Microwave Package for Precise Superconducting Device Measurement + https://arxiv.org/abs/2512.18198 + arXiv:2512.18198v1 Announce Type: new +Abstract: Cryogenic microwave measurement of superconducting quantum devices is complicated by the packaging required to connect devices to control and readout circuitry. In this work, we outline the design and experimental demonstration of a wirebond-free, PCB-free, drop-in microwave package for on-chip superconducting quantum devices. The package is composed of a superconducting aluminum cavity with a suspended tungsten transmission pin. The fundamental package cavity mode is far detuned from the 4 GHz to 8 GHz band of interest, and the pin transmission exhibits less than 3 dB of ripple across this range. We demonstrate the use of this package to extract the loss tangent of superconducting ring resonators, measuring a value of (1.10 +- 0.09) x 10^-6, which agrees with measurements of lambda/4 resonators in wirebond-based packaging. This high-throughput measurement system will allow the rapid generation of large datasets for improving superconducting qubit performance, and facilitate time-sensitive surface passivation and oxide regrowth studies. + oai:arXiv.org:2512.18198v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.3390/e27060569 - Jochen Szangolies + http://creativecommons.org/licenses/by/4.0/ + Wei-Ren Syong, Allie Miller, Emma Davis, John R. Pitten, Jorge Ramirez, Nathan Ortiz, Michael Vissers, Doug Bennett, Corey Rae Harrington McRae - Validating the calibrated creation of heralded single photons - https://arxiv.org/abs/2512.17336 - arXiv:2512.17336v1 Announce Type: new -Abstract: Coincidence-count discrimination have turned utterly practical in the characterization of photon-pair processes and heralded single photons. Here, we implement a heralded single photon source based on parametric down-conversion (PDC) in a PP-KTP waveguide in the telecom wavelength range involving a low number of optical modes. We extend the toolbox for the loss-tolerant state characterization by combining conventional figures-of-merit in order to access the heralded state's mean photon number and its photon-number parity. Our experiment demonstrates that an accurate determination of these characteristics is possible just through simple photon-correlation measurements. We believe that our results can find usage in the calibrated creation of heralded single photons and in determining the expectation values of observables that are crucial for denoting a single quantum. - oai:arXiv.org:2512.17336v1 + Hermitian Matrix Function Synthesis without Block-Encoding + https://arxiv.org/abs/2512.18249 + arXiv:2512.18249v1 Announce Type: new +Abstract: Implementing arbitrary functions of Hermitian matrices on quantum hardware is a foundational task in quantum computing, critical for accurate Hamiltonian simulation, quantum linear system solving, high-fidelity state preparation, machine learning kernels, and other advance quantum algorithms. Existing state-of-the-art techniques, including Qubitization, Quantum Singular Value Transformation (QSVT), and Quantum Signal Processing (QSP), rely heavily on block-encoding the Hermitian matrix. These methods are often constrained by the complexity of preparing the block-encoded state, the overhead associated with the required ancillary qubits, or the challenging problem of angle synthesis for the polynomial's phase factors, which limits the achievable circuit depth and overall efficiency. + In this work, we propose a novel and resource-efficient approach to implement arbitrary polynomials of a Hermitian matrix, by leveraging the Generalized Quantum Signal Processing (GQSP) framework. Our method circumvents the need for block-encoding by expressing the target Hermitian matrix as a symmetric combination of unitary conjugates, enabling polynomial synthesis via GQSP circuits applied to each unitary component. We derive closed-form expressions for symmetric polynomial expansions and demonstrate how linear combinations of GQSP circuits can realize the desired transformation. This approach reduces resource overhead, and opens new pathways for quantum algorithm design for functions of Hermitian matrices. + oai:arXiv.org:2512.18249v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Daniel Borrero Landazabal, Kaisa Laiho + http://creativecommons.org/licenses/by/4.0/ + Anuradha Mahasinghe, Kaushika De Silva, Xavier Cadet, Peter Chin, Frederic Cadet, Jingbo Wang - Rydberg Atomic RF Sensor-based Quantum Radar - https://arxiv.org/abs/2512.17421 - arXiv:2512.17421v1 Announce Type: new -Abstract: Rydberg atom-based RF sensors offer distinct advantages over conventional dipole antennas for electric field detection. This paper presents a system model and performance analysis of a Rydberg atom-based quantum radar, which employs optical readout via lasers and photon detectors instead of circuit-based receivers. We derive the signal-to-noise ratio (SNR), compare it with classical radar, and estimate Doppler frequency using an invariant function-based method. Simulations show that the quantum radar achieves higher SNR and lower RMSE in velocity estimation than conventional radar. - oai:arXiv.org:2512.17421v1 + Casimir operators for the relativistic quantum phase space symmetry group + https://arxiv.org/abs/2512.18262 + arXiv:2512.18262v1 Announce Type: new +Abstract: Recent developments in the unification of quantum mechanics and relativity have emphasized the necessity of generalizing classical phase space into a relativistic quantum phase space which is a framework that inherently incorporates the uncertainty principle and relativistic covariance. In this context, the present work considers the derivation of linear and quadratic Casimir operators corresponding to representations of the Linear Canonical Transformations (LCT) group associated with a five-dimensional spacetime of signature (1,4). This LCT group, which emerges naturally as the symmetry group of the relativistic quantum phase space, is isomorphic to the symplectic group Sp(2,8). The latter notably contains the de Sitter group SO(1,4) as a subgroup. This geometric setting provides a unified framework for extending the Standard Model of particle physics while incorporating cosmological features. Previous studies have shown that the LCT group admits both fermionic-like and bosonic-like representations. Within this framework, a novel classification of quarks and leptons, including sterile neutrinos, has also been proposed. In this work, we present a systematic derivation of the linear and quadratic Casimir operators associated with these representations, motivated by their fundamental role in the characterization of symmetry groups in physics. The construction is based on the relations between the LCT group and the pseudo-unitary group U(1,4). Three linears and three quadratics Casimir operators are identified: two corresponding to the fermionic-like representation, two to the bosonic-like representation, and two hybrid operators linking the two representations. The complete eigenvalue spectra and corresponding eigenstates for each operator are subsequently computed and identified + oai:arXiv.org:2512.18262v1 quant-ph - eess.SP - Mon, 22 Dec 2025 00:00:00 -0500 + hep-th + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Sourav Banerjee, Neel Kanth Kundu + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Philippe Manjakasoa Randriantsoa, Ravo Tokiniaina Ranaivoson, Raoelina Andriambololona, Roland Raboanary, Wilfrid Chrysante Solofoarisina, Anjary Feno Hasina Rasamimanana - Single-Photon Scattering in a Waveguide Coupled to a Lossy or Gain Giant Atom - https://arxiv.org/abs/2512.17456 - arXiv:2512.17456v1 Announce Type: new -Abstract: This work investigates single-photon scattering in a one-dimensional coupled-resonator waveguide coupled to a giant atom with a complex on-site energy. Within the generalized projection operator formalism, we derive analytical expressions for the scattering coefficients. We find that a lossy giant atom absorbs the incident wave, whereas a gain giant atom not only amplifies the incident wave but also leads to scattering divergence at certain energies, corresponding to spectral singularities. We explore the critical scattering dynamics associated with these singularities, and attribute the persistent wave emission to the existence of a stationary bound state in the continuum. Due to the presence of this bound state, the conventional time-independent scattering theory proves inadequate for such a non-Hermitian system. Furthermore, we show that the system with gain always features at least one time-growing bound state, which dominates the long-time dynamics, and we verify our time-dependent theoretical predictions via numerical simulations of Gaussian wave packet scattering. - oai:arXiv.org:2512.17456v1 + Quantum hash function using discrete-time quantum walk on Hanoi network + https://arxiv.org/abs/2512.18271 + arXiv:2512.18271v1 Announce Type: new +Abstract: Quantum walk based hash functions have attracted a lot of attention in recent years because of its faster execution time and robust resistance against attacks compared to classical hash functions. It has been observed that the underlying graph and the way message controls the quantum walk iteration steps play a crucial role for the robustness of the hash function. We propose a quantum hash function based on the discrete-time quantum walk on a Hanoi network--a one dimensional periodic lattice with extra long-range edges of a specific form--which is highly collision resistant. The message bits of our scheme control the flow of probability amplitude through the extra long-range edges and the conditional shift operators. Our method even works for messages with small bit-lengths, contrary to most of the quantum walk based hash functions defined on a cycle, which usually work for messages with bit-lengths more than the length of the cycle. + oai:arXiv.org:2512.18271v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yu Xin, Jia-Ming Zhang, Bing Chen + Pulak Ranjan Giri - Probing an electron spin ensemble with squeezed microwave signals - https://arxiv.org/abs/2512.17490 - arXiv:2512.17490v1 Announce Type: new -Abstract: The efficient transfer of quantum states into a long-lived storage unit such as solid-state spin ensembles is widely recognized as a critical challenge with significant implications for quantum communication, sensing and computing applications. Here, we experimentally investigate the interaction of propagating squeezed microwaves with an electron spin resonance transition in order to evaluate the use of spin ensembles as quantum memories for GHz signals. We generate continuous variable microwave states with a squeezing of up to 5dB below the vacuum level and let this signal interrogate a spin ensemble, which is inductively coupled to a lumped element superconducting microwave resonator with a cooperativity of C=0.3. Analyzing this signal using Wigner tomography, we observe a transfer efficiency of around 61% between the squeezed microwaves and the spin excitation. We successfully model our experimental results with a dedicated steady-state model based on the quantum input-output formalism and provide guidance for design parameters required to enable spin-based quantum memories. - oai:arXiv.org:2512.17490v1 + Evolutionary BP+OSD Decoding for Low-Latency Quantum Error Correction + https://arxiv.org/abs/2512.18273 + arXiv:2512.18273v1 Announce Type: new +Abstract: We propose an evolutionary belief propagation (EBP) decoder for quantum error correction, which incorporates trainable weights into the BP algorithm and optimizes them via the differential evolution algorithm. This approach enables end-to-end optimization of the EBP combined with ordered statistics decoding (OSD). Experimental results on surface codes and quantum low-density parity-check codes show that EBP+OSD achieves better decoding performance and lower computational complexity than BP+OSD, particularly under strict low latency constraints (within 5 BP iterations). + oai:arXiv.org:2512.18273v1 quant-ph - cond-mat.mes-hall - Mon, 22 Dec 2025 00:00:00 -0500 + cs.AI + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - P. Oehrl, F. Fesquet, K. E. Honasoge, M. Handschuh, A. Marx, R. Gross, K. G. Fedorov, H. Huebl + Hee-Youl Kwak, Seong-Joon Park, Hyunwoo Jung, Jeongseok Ha, Jae-Won Kim - Bias-Class Discrimination of Universal QRAM Boolean Memories - https://arxiv.org/abs/2512.17503 - arXiv:2512.17503v1 Announce Type: new -Abstract: We study the discrimination of Boolean memory configurations via a fixed Universal QRAM (U-QRAM) interface. Given query access to a quantum memory storing an unknown Boolean function $f:[N]\to\{0,1\}$, we ask: what can be inferred about the bias class of $f$ (its imbalance from $1/2$, up to complement symmetry) using coherent, addressable queries? We show that for exact-weight bias classes, the induced single-query ensemble state on the address register has a two-eigenspace structure that yields closed-form expressions for the single-copy Helstrom-optimal measurement and success probability. Because complementing $f$ changes the state $|\psi\rangle$ only by a global phase, hypotheses $p$ and $1-p$ are information-theoretically identical in this model; thus the natural discriminand is the phase-bias magnitude $|\mu|$ (equivalently $\mu^2$). This goes beyond the perfect-discrimination case of Deutsch-Jozsa and complements exact-identification settings such as Bernstein-Vazirani. - oai:arXiv.org:2512.17503v1 + Cyber Risk Scoring with QUBO: A Quantum and Hybrid Benchmark Study + https://arxiv.org/abs/2512.18305 + arXiv:2512.18305v1 Announce Type: new +Abstract: Assessing cyber risk in complex IT infrastructures poses significant challenges due to the dynamic, interconnected nature of digital systems. Traditional methods often fall short, relying on static and largely qualitative models that do not scale with system complexity and fail to capture systemic interdependencies. In this work, we introduce a novel quantitative approach to cyber risk assessment based on Quadratic Unconstrained Binary Optimization (QUBO), a formulation compatible with both classical computing and quantum annealing. We demonstrate the capabilities of our approach using a realistic 255-nodes layered infrastructure, showing how risk spreads in non-trivial patterns that are difficult to identify through visual inspection alone. To assess scalability, we further conduct extensive experiments on networks up to 1000 nodes comparing classical, quantum, and hybrid classical-quantum workflows. Our results reveal that although quantum annealing produces solutions comparable to classical heuristics, its potential advantages are significantly hindered by the embedding overhead required to map the densely connected cyber-risk QUBO onto the limited connectivity of current quantum hardware. By contrast, hybrid quantum-classical solvers avoid this bottleneck and therefore emerge as a promising option, combining competitive scaling with an improved ability to explore the solution space and identify more stable risk configurations. Overall, this work delivers two main advances. First, we present a rigorous, tunable, and generalizable mathematical model for cyber risk that can be adapted to diverse infrastructures and domains through flexible parameterization. Second, we provide the first comparative study of classical, quantum, and hybrid approaches for cyber risk scoring at scale, highlighting the emerging potential of hybrid quantum-classical methods for large-scale infrastructures. + oai:arXiv.org:2512.18305v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cs.CR + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Leonardo Bohac + Remo Marini, Riccardo Arpe - Autonomous Picosecond-Precision Synchronization in Measurement-Device-Independent Quantum Key Distribution - https://arxiv.org/abs/2512.17510 - arXiv:2512.17510v1 Announce Type: new -Abstract: Measurement-device-independent quantum key distribution (MDI-QKD) eliminates detector side-channel attacks by relocating all measurements to an untrusted intermediate node. However, its practical implementation critically relies on picosecond-level temporal synchronization between spatially separated users. In this work, we present a physically motivated autonomous synchronization algorithm for fiber-based MDI-QKD networks that does not require auxiliary optical channels or shared clock references. The method exploits round-trip optical pulse propagation and statistical signal detection in the presence of Gaussian noise. We derive analytical expressions for false-alarm probabilities, quantify detection reliability, and demonstrate through numerical modeling that synchronization accuracy better than 10~ps is achievable for channel lengths up to 100~km with realistic optical power levels. The proposed approach improves the scalability and robustness of MDI-QKD architectures and is directly applicable to metropolitan and backbone quantum networks. - oai:arXiv.org:2512.17510v1 + Experimental Efficient Source-Independent Quantum Secret Sharing against Coherent Attacks + https://arxiv.org/abs/2512.18325 + arXiv:2512.18325v1 Announce Type: new +Abstract: Source-independent quantum secret sharing (SI QSS), while essential for secure multiuser cryptographic operations in quantum networks, faces significant implementation challenges stemming from the inherent complexity of generating and distributing multipartite entangled states. Recently, a resource-efficient SI QSS protocol utilizing entangled photon pairs combined with a postmatching method has been proposed to address this limitation. In this Letter, we report an experimental demonstration of this protocol using high-fidelity polarization-entangled photon pairs in a star topology. For a three-user network, we obtain secure key rates of 21.18, 4.69, and 1.71 kbps under single-user channel losses of 7.6, 10.9, and 12.9 dB respectively. Furthermore, under conditions of equal channel loss per user, we achieve secure key rates of 6.97, 6.46, and 5.88 kbps for three-, four-, and five-user scenarios respectively. These results demonstrate the advantageous independence of the key rate from the number of users. Our work paves the way for large-scale deployment of SI QSS in multiuser quantum networks. + oai:arXiv.org:2512.18325v1 quant-ph - physics.optics - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - A. P. Pljonkin + http://creativecommons.org/licenses/by/4.0/ + 10.1103/7wrk-p6gl + Phys. Rev. Lett. 135, 150801 (2025) + Yi-Ran Xiao, Hua-Lei Yin, Wen-Ji Hua, Xiao-Yu Cao, Zeng-Bing Chen - Refrigeration of a 1D gas of microwave photons - https://arxiv.org/abs/2512.17530 - arXiv:2512.17530v1 Announce Type: new -Abstract: We discuss a conceptually simple scheme for cooling a one dimensional gas of microwave photons in a superconducting transmission line. By shunting one end of the transmission line by a nonlinear Josephson element, we show how a cooling mechanism can be engineered that transfers photons from high- into low-frequency modes, while preserving their total number. We evaluate the resulting nonequilibrium steady state of the photon gas, which arises from a competition between this engineered cooling process and the natural, number non-conserving thermalization with the surrounding bath. Our analysis predicts that for realistic experimental parameters, this mechanism can be used to prepare photonic gases at sub-millikelvin temperatures, considerably below the typical base temperature of a dilution refrigerator. In addition, the system exhibits a new type of condensation transition that does not occur in the corresponding equilibrium scenario. As an outlook, we discuss potential applications of this cooling approach for quantum simulation schemes with interacting microwave photons. - oai:arXiv.org:2512.17530v1 + Full Quantum Work Statistics for Non-Homogeneous Many-Body Systems + https://arxiv.org/abs/2512.18338 + arXiv:2512.18338v1 Announce Type: new +Abstract: The nonequilibrium thermodynamics of interacting quantum many-body systems is investigated within the framework of thermal time-dependent density functional theory using a generalized linear-response formulation for the full quantum work statistics. A first-principles route is established to reconstruct the relaxation function that underlies linear-response theory, thereby moving beyond phenomenological descriptions and enabling a consistent evaluation of all moments of the dissipated-work distribution in interacting systems. The predictive power of the approach is demonstrated for the Hubbard model subject to a staggered external potential, where the evolution of the relaxation dynamics across the Mott-to-band-insulator crossover reveals how distinct many-body phases shape the out-of-equilibrium thermodynamic response. These results provide a microscopic and transferable framework for quantum thermodynamics in correlated systems, bridging thermal density functional theory and nonequilibrium work statistics. + oai:arXiv.org:2512.18338v1 quant-ph cond-mat.mes-hall - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.quant-gas + cond-mat.stat-mech + cond-mat.str-el + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Lukas Schamri{\ss}, Louis Garbe, Peter Rabl + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Antonio Palamara, Francesco Plastina, Antonello Sindona, Irene D'Amico - Coherent phase control of orbital-angular-momentum light-induced torque in a double-tripod atom-light coupling scheme - https://arxiv.org/abs/2512.17537 - arXiv:2512.17537v1 Announce Type: new -Abstract: We investigate a phase-controllable mechanism for generating optical torque in a five-level double-tripod (DT) atom-light coupling scheme interacting with four strong coherent control fields as well as two weak optical vortex probe beams carrying orbital angular momentum (OAM). The spatial phase gradients of the OAM-carrying probes induce a quantized torque that is transferred to the atoms, rotating them and generating a directed atomic flow within an annular geometry. Analytical solutions of the optical Bloch equations under steady-state conditions show that the induced torque and resulting rotational motion exhibit high sensitivity to phase variations. We show that the DT system coherently reconfigures into either coupled {\Lambda} or double-{\Lambda} schemes depending on the relative phases, with each configuration exhibiting distinct quantized torque characteristics. This enables precise phase control of the atomic current flow, with potential applications in quantum control, precision measurement, and quantum information processing. - oai:arXiv.org:2512.17537v1 + Triple measurements uncertainty and the distinguishment between the separable and entangled states + https://arxiv.org/abs/2512.18374 + arXiv:2512.18374v1 Announce Type: new +Abstract: Uncertainty and entanglement are both profound and key concepts in quantum theory. For three observables, the tightest uncertainty constants for both product and summation forms are revealed. In this work, we give an alternative proof for three observables, also with a physical interpretation of the uncertainty constants. Our results show that such constants are intimately connected with the distinguishment between separable and entangled states. + oai:arXiv.org:2512.18374v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/nbx8-l3v4 - Phys. Rev. A 112, 063720 (2025) - Hamid R. Hamedi, Via\v{c}eslav Kudria\v{s}ov, Ma\v{z}ena Mackoit-Sinkevi\v{c}ien\.e, Julius Ruseckas + Minyi Huang, Ray-Kuang Lee - Bloch Motions and Spinning Tops - https://arxiv.org/abs/2512.17549 - arXiv:2512.17549v1 Announce Type: new -Abstract: This work investigates the dynamics of closed quantum systems in the Bloch vector representation using methods from rigid body dynamics and the theory of integrable systems. To this end, equations of motion for Bloch components are derived from the von Neumann equation, which are mathematically equivalent to equations of motion for a distribution of point masses from classical mechanics. Furthermore, using the Heisenberg equation, another system of Bloch vector equations is derived, which forms an Euler-Poinsot system, as is commonly encountered in the theory of torque-free spinning tops. This is used to prove the Liouville integrability of the corresponding Hamilton equations of motion, whereby formal connections to the Neumann model of classical Hamiltonian dynamics and the Hamiltonian Euler-Poinsot model are drawn to identify the first integrals of motion. Within the same framework, stability criteria for quantum dynamics are then derived which correspond to the Routh-Hurwitz criterion resp. other criteria following from the Energy-Casimir method of classical Newtonian mechanics. Following that, specific solutions to the equations of motion are constructed that encode the complex dynamics of composite quantum systems. Eventually, to show that this formalism provides concrete physical predictions, an analogue of the intermediate axis theorem is derived and the effect of oscillating entanglement is discussed. As a basis for this, special types of solutions to the equations of motion are derived that constitute oscillating entangled states, i.e., dynamical quantum states that change their entanglement structure from maximally entangled to separable and vice versa. - oai:arXiv.org:2512.17549v1 + Size-Consistent Quantum Chemistry on Quantum Computers + https://arxiv.org/abs/2512.18395 + arXiv:2512.18395v1 Announce Type: new +Abstract: Hybrid quantum-classical algorithms have begun to leverage quantum devices to efficiently represent many-electron wavefunctions, enabling early demonstrations of molecular simulations on real hardware. A key prerequisite for scalable quantum chemistry, however, is size consistency: the energy of non-interacting subsystems must scale linearly with system size. While many algorithms are theoretically size-consistent, noise on quantum devices may couple nominally independent subsystems and degrade this fundamental property. Here, we systematically evaluate size consistency on quantum hardware by simulating systems composed of increasing numbers of non-interacting H$_{2}$ molecules using optimally shallow unitary circuits. We find that molecular energies remain size-consistent within chemical accuracy for an estimated 118 and 71 H$_{2}$ subsystems for one- and two-qubit unitary designs, respectively, demonstrating that current quantum devices preserve size consistency over chemically relevant system sizes and supporting the feasibility of scalable, noise-resilient simulation of strongly correlated molecules and materials. + oai:arXiv.org:2512.18395v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + physics.chem-ph + physics.comp-ph + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Albert Huber, Paul Schreivogl + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Noah Garrett, Michael Rose, David A. Mazziotti - Group-theoretical analysis of quantum complexity: the oscillator group case - https://arxiv.org/abs/2512.17552 - arXiv:2512.17552v1 Announce Type: new -Abstract: Motivated by the recent rapid development of complexity theory applied to quantum mechanical processes we present the complete derivation of Nielsen's complexity of unitaries belonging to the representations of oscillator group. Our approach is based on the observation that the whole problem refers to the structure of the underlying group. The questions concerning the complexity of particular unitaries are solved by lifting the abstract structure to the operator level by considering the relevant unitary representation. For the class of right-invariant metrics obeying natural invariance condition we solve the geodesic equations on oscillator group. The solution is given explicitly in terms of elementary functions. Imposing the boundary conditions yield a transcendental equation and the length of the geodesic is given in terms of the solutions to the latter. Since the unitary irreducible representations of oscillator group are classified this allows us to compute, at least in principle, the complexity of any unitary operator belonging to the representation. - oai:arXiv.org:2512.17552v1 + There is No Quantum World + https://arxiv.org/abs/2512.18400 + arXiv:2512.18400v1 Announce Type: new +Abstract: I outline a neo-Bohrian interpretation of quantum mechanics -- a view of quantum mechanics that accords with the core insights in Bohr's thinking, with a twist that justifies the prefix `neo.' In a second part of the paper, I show how von Neumann's work on infinite direct products provides a theoretical framework that deflates the measurement problem and justifies Bohr's insistence on the primacy of classical concepts. + oai:arXiv.org:2512.18400v1 quant-ph - hep-th - math-ph - math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - K. Andrzejewski, K. Bolonek-Laso\'n, P. Kosi\'nski + Jeffrey Bub - Quantum Mechanics in a Spherical Wedge: Complete Solution and Implications for Angular Momentum Theory - https://arxiv.org/abs/2512.17558 - arXiv:2512.17558v1 Announce Type: new -Abstract: We solve the stationary Schr\"odinger equation for a particle confined to a 3D spherical wedge -- the region $\{(r,\theta,\phi): 0 \leq r \leq R,\, 0 \leq \theta \leq \pi,\, 0 \leq \phi \leq \Phi\}$ with Dirichlet BCs on all surfaces. This exactly solvable constrained-domain model exhibits spectral reorganisation under symmetry-breaking BCs and provides an operator-domain viewpoint on angular momentum quantisation. We obtain three main results. First, the stationary states are standing waves in the azimuthal coordinate and consequently are \emph{not} eigenstates of $\hat{L}_z$; we prove $\langle L_z \rangle = 0$ with $\Delta L_z = \hbar n_\phi\pi/\Phi \neq 0$, demonstrating that angular momentum projection becomes an observable with genuine quantum uncertainty rather than a good quantum number. Second, the effective azimuthal quantum number $\mu = n_\phi\pi/\Phi$ is generically non-integer, and square-integrability of the polar wavefunctions at both poles requires the angular eigenvalue parameter $\nu$ to satisfy $\nu - \mu \in \mathbb{Z}_{\geq 0}$. This regularity constraint yields a hierarchy: sectoral solutions ($\nu = \mu$, satisfying the first-order highest-weight condition) exist for any real $\mu > 0$, while tesseral and zonal solutions require integer steps, appearing only when $\mu$ itself is integer. Third, application to a Coulomb potential shows that the familiar integer angular momentum spectrum of hydrogen arises from the periodic identification $\phi \sim \phi + 2\pi$ that defines the full-sphere Hilbert space domain; modified boundary conditions yield a reorganised spectrum with non-integer effective angular momentum. The model clarifies the distinct roles of single-valuedness (selecting integer $m$ via azimuthal topology) and polar regularity (selecting integer $\ell \geq |m|$ via analytic constraints) in the standard quantisation of orbital angular momentum. - oai:arXiv.org:2512.17558v1 + Partner-mode overlap as a symplectic-invariant measure of correlations in Gaussian Systems + https://arxiv.org/abs/2512.18410 + arXiv:2512.18410v1 Announce Type: new +Abstract: We introduce a locally symplectic-invariant quantifier of correlations between two different arbitrary modes in bosonic Gaussian systems, denoted by $\mathcal{D}^{\mathrm{sym}}$. This quantity admits a simple geometric interpretation as an overlap between each mode and the purification partner of the other, formulated using the complex-structure description of Gaussian states. The construction builds on the partner-mode framework of Ref.~\cite{agullo_correlation_2025} and can be viewed as a symmetrized extension of earlier overlap-based measures~\cite{osawa2025entanglement}. We formulate a simple necessary and sufficient criterion for two-mode entanglement in Gaussian states in terms of $\mathcal{D}^{\mathrm{sym}}$, placing on firm quantitative footing the intuition that entanglement with a given localized mode `lives' on the spatial support of its partner mode. We illustrate the framework with a numerical analysis of a scalar field in Minkowski spacetime and discuss its extension to multimode systems and mixed Gaussian states. + oai:arXiv.org:2512.18410v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + gr-qc + hep-th + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Mustafa Bakr, Smain Amari + Ivan Agullo, Eduardo Mart\'in-Mart\'inez, Sergi Nadal-Gisbert, Koji Yamaguchi - Investigating methods to solve large windfarm optimization problems with a minimum number of qubits using circuit-based quantum computers - https://arxiv.org/abs/2512.17582 - arXiv:2512.17582v1 Announce Type: new -Abstract: This study investigates quantum computing approaches for solving the windfarm layout optimization (WFLO) problems formulated as a quadratic unconstrained binary optimization (QUBO) problem. We investigate two encoding methods that require fewer than one qubit per grid point: the previously developed Pauli correlation encoding (PCE) and a novel single-qubit operator encoding (SQOE). These methods are tested on three windfarm configurations - two from prior WFLO scaling studies and a new real-world model based on an existing windfarm in Wales. The improved encoding methods allow us to solve WFLO problems on $9\times 9$ grids using up to 20 qubits on a quantum computer simulator. The results show that both encoding methods perform competitively and demonstrate favorable scaling characteristics across the tested systems. - oai:arXiv.org:2512.17582v1 + Analog Quantum Image Representation with Qubit-Frugal Encoding + https://arxiv.org/abs/2512.18451 + arXiv:2512.18451v1 Announce Type: new +Abstract: In this work, we introduce a fundamentally new paradigm for quantum image representation tailored for neutral-atom quantum devices. The proposed method constructs a qubit-efficient image representation by first applying a cartographic generalization algorithm to a classical edge-extracted input image, yielding a highly optimized sparse-dot based geometric description. While ensuring the structural integrity of the image, this sparse representation is then embedded into the atomic configuration of Aquila (QuEra Computing Inc.), modeled through the Bloqade simulation software stack. By encoding visual information through physical atom placement rather than digital basis-state coding, the approach avoids the costly state-preparation overhead inherent to digital quantum image processing circuits. Additionally, pruning sparse dot images, akin to map feature reduction, compresses representations without fidelity loss, thereby substantially reducing qubit requirements when implemented on an analog neutral-atom quantum device. The resulting quantum-native images have been successfully evaluated through matching tasks against an image database, thus illustrating the feasibility of this approach for image matching applications. Since sparse-dot image representations enable seamless generation of synthetic datasets, this work constitutes an initial step towards fully quantum-native machine-learning pipelines for visual data and highlights the potential of scalable analog quantum computing to enable resource-efficient alternatives to energy-intensive classical AI-based image processing frameworks. + oai:arXiv.org:2512.18451v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + eess.IV + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - James Hancock, Matthew Craven, Craig McNeile + Vikrant Sharma, Neel Kanth Kundu - Frequency-Multiplexed Millimeter-Wave Fault-Tolerant Superconducting Qubits Enabled by an On-Chip Nonreciprocal Control Bus - https://arxiv.org/abs/2512.17588 - arXiv:2512.17588v1 Announce Type: new -Abstract: Scaling superconducting quantum processors is fundamentally limited by the escalating complexity of cryogenic wiring and the debilitating effects of microwave crosstalk and Purcell decay. This paper proposes the concept of frequency-multiplexed millimeter-wave superconducting qubits and demonstrates a novel architecture that integrates an on-chip cryogenic nonreciprocal space-time-periodic superconducting frequency multiplier as a universal control bus for a frequency-multiplexed qubit array. The bus replaces multiple high-frequency XY drive lines with a single low-frequency input tone, which the multiplier converts into a comb of high-order harmonics, each resonantly addressing a distinct qubit. Crucially, the dynamic and nonreciprocal nature of the bus provides signal gain and intrinsic isolation that simultaneously suppresses Purcell decay, enhancing T1 times across all distinct-frequency qubits, and reduces coherent crosstalk by more than two orders of magnitude. The spatiotemporal modulation enables parametric frequency multiplication and creates wave-propagation dynamics analogous to cosmological expansion, with observed redshift-like broadening and deceleration of magnetic-field wavepackets. Theoretical modeling based on a non-Markovian master equation confirms that the engineered memory kernel extends coherence while reshaping the noise spectrum. Full error-budget analysis shows that the architecture maintains gate errors below the fault-tolerance threshold for arrays exceeding 25 qubits, converting a crosstalk-dominated error budget into one limited by intrinsic material coherence. This integrated, frequency-multiplexed, and nonreciprocal control bus therefore offers a path toward unprecedented I/O simplification, noise resilience, and scalable high-coherence quantum processin - oai:arXiv.org:2512.17588v1 + Hierarchical divide and conquer quantum approach to combinatorial optimization problems with tunable reduction + https://arxiv.org/abs/2512.18464 + arXiv:2512.18464v1 Announce Type: new +Abstract: Combinatorial optimization is considered a promising class of problems in which quantum computers can show significant advantages. However, problems of practical relevance typically have more variables than current or foreseeable quantum computers have qubits. Here we introduce a divide and conquer approach that partitions the optimization problem into subgraphs that can be represented on smaller quantum processors. We then find all states of the subgraphs that can possibly be part of the solution to the entire problem by determining the cost or energy ranges in which the local subgraph energies of these states must be contained. This allows us to reduce the problem by only considering the subspace spanned by these states. We then recombine the system using a binary encoding for each subgraph with a local energy ordering. This process can be iterated until no further reduction is possible. We also find that the number of necessary qubits can be reduced further when only retaining states in a fraction of the relevant energy range at very little expense in terms of approximation ratio to the global ground state. In numerical simulations, we find that our approach allows us to solve combinatorial optimization problems on weighted random 3-regular graphs with $|\mathcal{V}|=40$ discrete variables on $\sim |\mathcal{V}| / 4$ qubits while retaining a possible approximation ratio of $\sim99.9\%$. We also observe an increasing reduction with larger system sizes. + oai:arXiv.org:2512.18464v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Sajjad Taravati + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Mathias Schmid, Naeimeh Mohseni, Michael J. Hartmann - The threshold for quantum-classical correspondence is $D \sim \hbar^{\frac43}$ - https://arxiv.org/abs/2512.17623 - arXiv:2512.17623v1 Announce Type: new -Abstract: In chaotic quantum systems, an initially localized quantum state can deviate strongly from the corresponding classical phase-space distribution after the Ehrenfest time $t_{\mathrm{E}} \sim \log(\hbar^{-1})$, even in the limit $\hbar \to 0$. Decoherence by the environment is often invoked to explain the persistence of the quantum-classical correspondence at longer timescales. Recent rigorous results for Lindblad dynamics with phase-space diffusion strength $D$ show that quantum and classical evolutions remain close for times that are exponentially longer than the Ehrenfest time whenever $D \gg \hbar^{\frac43}$, in units set by the classical Hamiltonian. At the same time, some heuristic arguments have suggested the weaker condition $D \gg \hbar^{2}$ always suffices. Here we construct an explicit Lindbladian that demonstrates that the scaling $D \sim \hbar^{\frac43}$ is indeed the threshold for quantum-classical correspondence beyond the Ehrenfest time. Our example uses a smooth time-dependent Hamiltonian and linear Lindblad operators generating homogeneous isotropic diffusion. It exhibits an $\hbar$-independent quantum-classical discrepancy at the Ehrenfest time whenever $D \ll \hbar^{\frac43}$, even for $\hbar$-independent "macroscopic" smooth observables. - oai:arXiv.org:2512.17623v1 + Position-Resolved Resonance Quantization for Lossy Cavities + https://arxiv.org/abs/2512.18478 + arXiv:2512.18478v1 Announce Type: new +Abstract: Modern experiments in resonators are moving to ever more extreme quantum regimes, posing major challenges to established theoretical approaches, such as so-called few-mode models. While these models have driven major insights for traditional regimes, they are now hitting their limitations for highly open cavities and extended systems, as encountered in cavity experiments with molecules and solid-state systems. Here, we present a novel method that significantly extends the conceptual underpinning of these discrete-mode models, promoting them to a systematic treatment. We develop an ansatz which allows to quantize the resonator's resonances with position-resolved discrete modes, thus naturally incorporating losses in the formalism. Such a construction effectively unifies key ideas from pseudomodes and quantized quasi-normal modes theory. We further present a criterion for construction of the ansatz parameters at every point in space, and semi-analytically benchmark the resulting solution for a paradigmatic one-dimensional example resonator. + oai:arXiv.org:2512.18478v1 quant-ph - math-ph - math.AP - math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Lucas Weitzel, Andreas Buchleitner, Dominik Lentrodt + + + Collective Dissipation and Parameter Sensitivity in Trapped Ions Coupled to a Common Thermal Reservoir + https://arxiv.org/abs/2512.18481 + arXiv:2512.18481v1 Announce Type: new +Abstract: We investigate the dynamics of two trapped ions interacting with a common thermal reservoir, focusing on how cross-correlated dissipation influences heating, steady-state behavior, and parameter sensitivity. Starting from a microscopic system--reservoir model, we derive the corresponding Heisenberg--Langevin equations and show that reservoir-induced correlations generate collective decay channels and, when the cross-damping rate matches the local damping, a decoherence-free normal mode that preserves memory of the initial excitations. Using the Fisher information associated with motional population measurements, we identify the parameter regimes in which cross-damping enhances the estimability of both system and reservoir properties. For nonclassical initial states, we also show that reservoir-mediated correlations can generate or maintain entanglement, with the strongest effects occurring near the decoherence-free condition. + oai:arXiv.org:2512.18481v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Felipe Hern\'andez, Daniel Ranard, C. Jess Riedel + C. F. P. Avalos, G. A. Prataviera, M. C. de Oliveira - Fraud detection in credit card transactions using Quantum-Assisted Restricted Boltzmann Machines - https://arxiv.org/abs/2512.17660 - arXiv:2512.17660v1 Announce Type: new -Abstract: Use cases for emerging quantum computing platforms become economically relevant as the efficiency of processing and availability of quantum computers increase. We assess the performance of Restricted Boltzmann Machines (RBM) assisted by quantum computing, running on real quantum hardware and simulators, using a real dataset containing 145 million transactions provided by Stone, a leading Brazilian fintech, for credit card fraud detection. The results suggest that the quantum-assisted RBM method is able to achieve superior performance in most figures of merit in comparison to classical approaches, even using current noisy quantum annealers. Our study paves the way for implementing quantum-assisted RBMs for general fault detection in financial systems. - oai:arXiv.org:2512.17660v1 + Multifractality Analysis of Single Qubit Quantum Circuit Outcomes for a Superconducting Quantum Computer + https://arxiv.org/abs/2512.18491 + arXiv:2512.18491v1 Announce Type: new +Abstract: We present a multifractal analysis of time series data obtained by repeatedly running a single-qubit quantum circuit on IBM superconducting quantum computers, in which the measurement outcomes are recorded as the number of zeros. By applying advanced signal processing techniques, including the wavelet leader method and multifractal detrended fluctuation analysis, we uncover strong multifractal behavior in the output data. This finding indicates that the temporal fluctuations inherent to quantum circuit outputs are not purely random but exhibit complex scaling properties across multiple time scales. The multifractal nature of the signal suggests the possibility of tailoring filtering strategies that specifically target these scaling features to effectively mitigate noise in quantum computations. Our results not only contribute to a deeper understanding of the dynamical properties of quantum systems under repeated measurement but also provide a promising avenue for improving noise reduction techniques in near-term quantum devices. + oai:arXiv.org:2512.18491v1 quant-ph - cs.LG - Mon, 22 Dec 2025 00:00:00 -0500 + cs.ET + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Jo\~ao Marcos Cavalcanti de Albuquerque Neto, Gustavo Castro do Amaral, Guilherme Penello Tempor\~ao + Mohammadreza Saghafi, Lamine Mili, Karlton Wirsing - Quantum heat current in Terahertz-driven phonon systems - https://arxiv.org/abs/2512.17669 - arXiv:2512.17669v1 Announce Type: new -Abstract: The advent of high-intensity ultrafast laser pulses has opened new opportunities for controlling and designing quantum materials. In particular, terahertz (THz) pulses can resonantly drive optical phonon modes, enabling dynamic manipulation of lattice degrees of freedom. In this work, we investigate the ultrafast quantum thermodynamics of optical phonon mode driven by a THz pulse by treating the phonon as an open quantum system coupled to a thermal environment within a Caldeira-Leggett-type framework. We derive the quantum heat current between the phonon and the bath and analyze its behavior under realistic pulse protocols. Our results demonstrate that ultrafast laser driving can reveal and even induce significant deviations from the commonly adopted Markovian approximation, thereby providing a pathway to probe and control non-Markovian dissipation in driven solid-state systems. - oai:arXiv.org:2512.17669v1 + Cyber Threat Detection Enabled by Quantum Computing + https://arxiv.org/abs/2512.18493 + arXiv:2512.18493v1 Announce Type: new +Abstract: Threat detection models in cybersecurity must keep up with shifting traffic, strict feature budgets, and noisy hardware, yet even strong classical systems still miss rare or borderline attacks when the data distribution drifts. Small, near-term quantum processors are now available, but existing work rarely shows whether quantum components can improve end-to-end detection under these unstable, resource constrained conditions rather than just adding complexity. We address this gap with a hybrid architecture that uses a compact multilayer perceptron to compress security data and then routes a few features to 2-4 qubit quantum heads implemented as quantum support vector machines and variational circuits. Under matched preprocessing and training budgets, we benchmark these hybrids against tuned classical baselines on two security tasks, network intrusion detection on NSL-KDD and spam filtering on Ling-Spam datasets, and then deploy the best 4-qubit quantum SVM to an IBM Quantum device with noise-aware execution (readout mitigation and dynamical decoupling). Across both datasets, shallow quantum heads consistently match, and on difficult near-boundary cases modestly reduce, missed attacks and false alarms relative to classical models using the same features. Hardware results track simulator behavior closely enough that the remaining gap is dominated by device noise rather than model design. Taken together, the study shows that even on small, noisy chips, carefully engineered quantum components can already function as competitive, budget-aware elements in practical threat detection pipelines. + oai:arXiv.org:2512.18493v1 quant-ph - cond-mat.mtrl-sci - Mon, 22 Dec 2025 00:00:00 -0500 + cs.CR + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Yulong Qiao, Richard. Matthias Geilhufe + Zisheng Chen, Zirui Zhu, Xiangyang Li - Detecting non-Gaussian entanglement beyond Gaussian criteria - https://arxiv.org/abs/2512.17681 - arXiv:2512.17681v1 Announce Type: new -Abstract: Entanglement is central to quantum theory, yet detecting it reliably in non-Gaussian systems remains a long-standing challenge. In continuous-variable platforms, inseparability tests based on Gaussian statistics - such as those of Duan and Simon - fail when quantum correlations are encoded in higher moments of the field quadratures. Here we introduce an inseparability criterion that exposes non-Gaussian entanglement that escapes covariance-based criteria by incorporating higher-order quadrature cumulants. The criterion extends Gaussian theory without requiring full state tomography and can be evaluated directly from homodyne and heterodyne data and is possible to extend to arbitrary superpositions of Fock states in two modes. This provides an experimentally viable approach for identifying non-Gaussian resources in continuous-variable platforms. - oai:arXiv.org:2512.17681v1 + Quantum Nonlocality and Device-Independent Randomness Robust to Relaxations of Bell Assumptions + https://arxiv.org/abs/2512.18513 + arXiv:2512.18513v1 Announce Type: new +Abstract: The question of certifying quantum nonlocality under a relaxation of the assumptions in the Bell theorem has gained traction, with potential for device-independent applications under weak seeds and cross-talk. Recently, it was shown that quantum nonlocality can be certified even under a simultaneous arbitrary (but not full) relaxation of the assumptions of Measurement Independence (MI) and Parameter Independence (PI), using states of local dimension $d = poly((1-\epsilon)^{-1})$ for an $\epsilon \in [0,1)$-relaxation. Here, we derive three results strengthening the state-of-art. Firstly, we show that states of constant local dimension $d$ are already sufficient to certify quantum nonlocality under arbitrary MI and PI relaxation, albeit in a non-robust manner. Secondly, and as a theoretical paradigm to derive the above, we introduce the notion of \textit{measurement-dependent parameter-dependent locality} as the set of input-output behaviors under simultaneous relaxations of measurement and parameter independence. We provide a rigorous characterisation of the vertices of the polytope of joint input-output behaviors that obey a $\mu$-relaxation of MI and $\epsilon$-relaxation of PI. We highlight a relation between nonlocality certification under PI relaxation and that under detection inefficiencies by pointing out alternative extremal correlations to the Eberhard correlations that also allow to achieve detection efficiency of $\eta = 2/3$ in the two-input scenario. Finally, we study the implication of the relaxed assumptions for device-independent randomness certification. We analytically derive the quantum guessing probability for one player's outcomes in the CHSH Bell test, as a function of the noise in the test as well as of a leakage of an average amount of $I(X:B) < 1$ bits of input information per measurement round. + oai:arXiv.org:2512.18513v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Abhinav Verma, Olga Solodovnikova, Jonas S. Neergaard-Nielsen, Ulrik L. Andersen + Ravishankar Ramanathan, Yuan Liu - Digital-Analog Quantum Computing with Qudits - https://arxiv.org/abs/2512.17697 - arXiv:2512.17697v1 Announce Type: new -Abstract: Digital-analog quantum computing with two-level systems is a computational paradigm that combines an analog Hamiltonian with single-qubit gates to achieve universality. We extend this framework to $d$-level systems by conjugating an analog Hamiltonian block with single-qudit gates drawn from the Weyl-Heisenberg basis, which provides a natural set of operations for qudit architectures. More specifically, we propose a protocol to simulate arbitrary two-body Hamiltonians with at most $O(d^4 n^2)$ analog blocks. The power of this approach is illustrated by the simulation of many-body qudit spin Hamiltonians including magnetic quadrupolar terms. - oai:arXiv.org:2512.17697v1 + Two Photon Tripartite Entanglement Transfer via Time-Multiplexed Quantum Walks + https://arxiv.org/abs/2512.18523 + arXiv:2512.18523v1 Announce Type: new +Abstract: Photonic multidimensional quantum networks (MDQN), where individual subsystems are encoded using multiple degrees of freedom and photons, are an emerging platform for quantum algorithms because they offer high scalability. The distribution of non-classical and non-local correlations between the individual subsystems in an MDQN is of fundamental interest for many quantum protocols. Interestingly in an MDQN, the inseparability of two subsystems underlying entanglement can occur both between multiple distinct photons as well as between individual degrees of freedom associated with a single photon. In this work, we investigate the entanglement transfer enabled by the interplay of both entanglement between two distinct photons as well as inseparability between multiple degrees of freedom. For this purpose, we subject one photon of a polarization entangled two-photon pair to a discrete-time quantum walk introducing the position subsystem of the quantum walk as a third subsystem with qudit encoding. Here we study the resulting transfer of entanglement from the polarization degree of freedom, representing qubit encoding, towards the position degree of freedom, representing quidt encoding, via partial state tomography and correlation measurements. + oai:arXiv.org:2512.18523v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Alatz Alvarez-Ahedo, Mikel Garcia de Andoin, Mikel Sanz + Jonas Lammers, Federico Pegoraro, Philip Held, Nidhin Prasannan, Benjamin Brecht, Christine Silberhorn - Inclusion constants for free spectrahedra with applications to quantum incompatibility - https://arxiv.org/abs/2512.17706 - arXiv:2512.17706v1 Announce Type: new -Abstract: Building on the matrix cube problem, inclusions of free spectrahedra have been used successfully to obtain relaxations of hard spectrahedral inclusion problems. The quality of such a relaxation is quantified by the inclusion constant associated with each free spectrahedron. While optimal values of inclusion constants were known in certain highly symmetric cases, no general method for computing them was available. In this work, we show that inclusion constants for Cartesian products of free simplices can be computed using methods from non-commutative polynomial optimization, together with a detailed analysis of the extreme points of the associated free spectrahedra. This analysis also yields new closed-form analytic expressions for these constants. As an application to quantum information theory, we prove new bounds on the amount of white noise that incompatible measurements can tolerate before they become compatible. In particular, we study the case of one dichotomic and one $k$-outcome measurement, as well as the case of four dichotomic qubit measurements. - oai:arXiv.org:2512.17706v1 + Read-Only Opacity and Restricted-Access Inference on Quantum Memories via U-QRAM + https://arxiv.org/abs/2512.18526 + arXiv:2512.18526v1 Announce Type: new +Abstract: Universal QRAM (U-QRAM) is a fixed, data-independent unitary interface that implements coherent random-access reads relative to a designated computational "truth-table" basis on the memory register. This work studies restricted-access inference: the memory register is persistent but inaccessible, while an experimenter may prepare and measure only accessible registers and may invoke the fixed read interaction. + Allowing the memory to be in an arbitrary quantum state (pure or mixed, possibly entangled with an inaccessible reference system, or a coherent superposition of truth tables), we establish a sharp, protocol-independent limitation of read-only access. For any finite-query protocol -- including arbitrary accessible ancillas, intermediate measurements, adaptivity, and general CPTP processing between queries -- the induced output state on the accessible registers depends on the memory state only through its diagonal in the truth-table basis. Equivalently, read-only access factors through dephasing (pinching) in that basis; coherences between distinct truth tables are operationally invisible. + Consequently, every memory-hypothesis testing task reduces to a standard state-discrimination problem on the accessible registers, and the minimum-error optimal measurement is characterized by Helstrom theory. We illustrate the framework with three explicit examples: (i) the phase-kickback reduction recovering the one-query Bernstein-Vazirani/Deutsch-Jozsa geometry, (ii) a minimal Helstrom instance with optimal success probability 3/4, and (iii) perfect indistinguishability of relative phases in entangled truth-table superpositions. + oai:arXiv.org:2512.18526v1 quant-ph - math-ph - math.FA - math.MP - math.OC - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Andreas Bluhm, Eric Evert, Igor Klep, Victor Magron, Ion Nechita + http://creativecommons.org/licenses/by/4.0/ + Leonardo Bohac - Certified bounds on optimization problems in quantum theory - https://arxiv.org/abs/2512.17713 - arXiv:2512.17713v1 Announce Type: new -Abstract: Semidefinite relaxations of polynomial optimization have become a central tool for addressing the non-convex optimization problems over non-commutative operators that are ubiquitous in quantum information theory and, more in general, quantum physics. Yet, as these global relaxation methods rely on floating-point methods, the bounds issued by the semidefinite solver can - and often do - exceed the global optimum, undermining their certifiability. To counter this issue, we introduce a rigorous framework for extracting exact rational bounds on non-commutative optimization problems from numerical data, and apply it to several paradigmatic problems in quantum information theory. An extension to sparsity and symmetry-adapted semidefinite relaxations is also provided and compared to the general dense scheme. Our results establish rational post-processing as a practical route to reliable certification, pushing semidefinite optimization toward a certifiable standard for quantum information science. - oai:arXiv.org:2512.17713v1 + A regularisation method to obtain analytical solutions to de Broglie-Bohm wave equation + https://arxiv.org/abs/2512.18555 + arXiv:2512.18555v1 Announce Type: new +Abstract: We present an analytical method to solve de Broglie Bohm equation for the wave function by combining concepts from the Hamilton Jacobi equations of mechanics, continuity equations, and information theory. From a statistical point of view, the probabilistic description of particle motion provides a middle ground for transitioning from classical to quantum mechanics. An action functional obtained by coupling a Fisher information term produces a parametrically equivalent form of the de Broglie Bohm dBB equations. Next, we show that generalized Euler Lagrange equations can provide analytical solutions of dBB equations for certain simple stationary systems. One- and two-dimensional examples are provided to illustrate the similarities and differences between regular QM and the wave functions obtained from our generalization. To retain the generality of the method, we do not use hbar apriori but instead introduce a parametric information-error coupling term, mu. Our emphasis is strictly limited to the regularization method and its implications for energy states. We defer formal interpretations of the foundational aspects of this subject to a separate communication. + oai:arXiv.org:2512.18555v1 quant-ph - cs.SC - math.OC - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Younes Naceur, Jie Wang, Victor Magron, Antonio Ac\'in + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Anand Aruna Kumar, S. K. Srivatsa, Rajesh Tengli - Continuum Limits of Lazy Open Quantum Walks - https://arxiv.org/abs/2512.17755 - arXiv:2512.17755v1 Announce Type: new -Abstract: We derive the continuous spacetime limit of the one dimensional lazy discrete time quantum walk, obtaining explicit macroscopic evolution equations for a three state model in the presence of decoherence. While continuum limits of two state quantum walks are well established, an explicit continuous spacetime formulation for the lazy three state walk, particularly including noise, has not previously been constructed. Using an SU(3) representation of a Grover type coin together with a Lindblad formulation of decoherence acting either on the coin or the spatial subspace, we systematically expand the discrete dynamics in both space and time to obtain continuum master equations governing the coarse grained evolution. The resulting generators yield a genuine partial differential equation description of the walk, going beyond purely probabilistic or spectral correspondences. We show that the unitary limit is governed by a Dirac-type SU(3) Hamiltonian describing ballistic advection of left and right moving modes coupled by local symmetric mixing, with the rest state acting as an additional internal degree of freedom. Coin dephasing selectively damps internal coherences while preserving coherent spatial transport, whereas spatial dephasing suppresses long range spatial interference and rapidly drives the dynamics toward classical behaviour. This continuum framework clarifies how internal symmetry, rest state coupling, and distinct decoherence channels shape large scale transport in lazy open quantum walks, and provides a foundation for future extensions toward multichannel quantum transport models and quantum-inspired algorithms. - oai:arXiv.org:2512.17755v1 + Image Denoising via Quantum Reservoir Computing + https://arxiv.org/abs/2512.18612 + arXiv:2512.18612v1 Announce Type: new +Abstract: Quantum Reservoir Computing (QRC) leverages the natural dynamics of quantum systems for information processing, without requiring a fault-tolerant quantum computer. In this work, we apply QRC within a hybrid quantum classical framework for image denoising. The quantum reservoir is implemented using a Rydberg atom array, while a classical neural network serves as the readout layer. To prepare the input, images are first compressed using Principal Component Analysis (PCA), reducing their dimensionality to match the size of the atom array. Each feature vector is encoded into local detuning parameters of a time-dependent Hamiltonian governing the Rydberg system. As the system evolves, it generates nonlinear embeddings through the measurement of observables across multiple time steps. These temporal embeddings capture complex correlations, which are fed into a classical neural network to reconstruct the denoised images. To evaluate performance, we compare this QRC-assisted model against a baseline architecture consisting of PCA followed by a dense neural network, trained under identical conditions. Our results show that the QRC-based approach achieves improved image sharpness and similar structural recovery compared to the PCA-based model. We demonstrate the practical viability of this framework through experiments on QuEra's Aquila neutral-atom processor, leveraging its programmable atom arrays to physically realize the reservoir dynamics. + oai:arXiv.org:2512.18612v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Lara Janiurek, Viv Kendon + Soumyadip Das, Luke Antoncich, Jingbo B. Wang - Demonstration of a quantum comparator on an ion-trap quantum device - https://arxiv.org/abs/2512.17779 - arXiv:2512.17779v1 Announce Type: new -Abstract: Quantum computers are believed to solve a class of computational problems that are based on modular arithmetic faster than classical computers. Among the arithmetic building blocks, comparison of integer pairs is a primitive. Here we report its demonstration in the Reimei quantum computer at RIKEN, whose trapped-ion architecture provides all-to-all qubit connectivity together with high gate fidelities. We observe high success probabilities for bit widths n = 3, 5, 7, and 9: Under a conventional output-only success criterion we obtain 95% at n=9; under a stricter criterion additionally requiring the ancilla to be correct, the success is 69% at n=9. These results demonstrate reliable quantum comparison at scales far beyond those previously achieved experimentally, not only for comparators but also in the broader context of quantum arithmetic circuits. - oai:arXiv.org:2512.17779v1 + A Hidden Quantum Markov model framework for Entanglement and Topological Order in the AKLT Chain + https://arxiv.org/abs/2512.18642 + arXiv:2512.18642v1 Announce Type: new +Abstract: This paper introduces a hidden quantum Markov models (HQMMs) framework to the Affleck-Kennedy-Lieb-Tasaki (AKLT) state-a cornerstone example of a symmetry-protected topological (SPT) phase. The model's observation system is the physical spin-1 chain, which emerges from a hidden spin-1/2 layer through well-defined quantum emission operation. We show that the underlying Markov dynamics caputure maximal entanglement through the use of significant channels relevant to the AKLT state. We also show that SPT order induces a covariance on the observation decoding channels. This establishes an additional bridge between the quantum Machine learning and many-body physics, with promising implication in topological order and quantum information. + oai:arXiv.org:2512.18642v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tatsuhiko N. Ikeda, Riku Nakama, Shunsuke Saeki, Hiroki Kuwata, Shuhei M. Yoshida, Akira Shimizu, Sho Sugiura + http://creativecommons.org/licenses/by/4.0/ + Abdessatar Souissi, Amenallah Andolsi - Adiabatic preparation of many-body quantum states: getting the beginning and ending right - https://arxiv.org/abs/2512.17780 - arXiv:2512.17780v1 Announce Type: new -Abstract: We present numerical calculations, and simulations performed on a Rydberg atom quantum simulator, of the adiabatic evolution of many-body quantum systems around a quantum phase transition. We demonstrate that the end-to-end transfer error, for a given process duration and dissipative losses, can be suppressed by adopting smooth initial and final scheduling functions for the Hamiltonian. We consider a one-dimensional mixed-field Ising model, as well as a chain of Rydberg atoms, and compare numerical calculations and experimental results for the end-to-end transfer error with different schedule functions. We show, in particular, that if the time dependent Hamiltonian is $n$ times differentiable with vanishing $1^{st}$ to $n^{th}$ order derivatives in the beginning and in the end, the infidelity with respect to the final adiabatic eigenstate scales as $1/T^{n+1}$ when evolving for time $T$. - oai:arXiv.org:2512.17780v1 + Kicked fluxonium with quantum strange attractor + https://arxiv.org/abs/2512.18644 + arXiv:2512.18644v1 Announce Type: new +Abstract: The quantum dissipative time evolution of a fluxonium under a pulsed field (kicks) is studied numerically and analytically. In the classical limit the system dynamics is converged to a strange chaotic attractor. The quantum properties of this system are studied for the density matrix in the frame of Lindblad equation. In the case of dissipative quantum evolution the steady-state density matrix is converged to a quantum strange attractor being similar to the classical one. It is shown that depending on the dissipation strength there is a regime when the eigenstates of density matrix are localized at a strong or moderate dissipation. At a weak dissipation the eigenstates are argued to be delocalized being linked to the Ehrenfest explosion of quantum wave packet. This phenomenon is related with the Lyapunov exponent and Ehrenfest time for the quantum strange attractor. Possible experimental realisations of this quantum strange attractor with fluxonium are discussed. + oai:arXiv.org:2512.18644v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + nlin.CD + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Emil T. M. Pedersen, Freek Witteveen, Klaus M{\o}lmer, Matthias Christandl + http://creativecommons.org/publicdomain/zero/1.0/ + Alexei D. Chepelianskii, Dima L. Shepelyansky - Kerr-induced non-Gaussianity of ultrafast bright squeezed vacuum - https://arxiv.org/abs/2512.17797 - arXiv:2512.17797v1 Announce Type: new -Abstract: Non-Gaussian states of light are a critical resource for fault-tolerant quantum computing and enhanced metrology, but are typically faint and often obtained via post-selection. Here, we demonstrate the deterministic generation of a bright non-Gaussian state by introducing a Kerr nonlinearity to a macroscopic state of light called bright squeezed vacuum (BSV). To characterize the resulting state, we use a single-shot f-2f interferometer to sample its Husimi function. We observe a clear transformation from a 2D Gaussian distribution to an 'S'-shaped non-Gaussian profile, which is the direct statistical evidence of the intensity-dependent nonlinear phase. The negativity of the Wigner function, which is an intrinsic property of any pure non-Gaussian state, cannot be observed because BSV is a mixed state even under minute optical loss. However, we show that BSV can be considered as a mixture of pure squeezed coherent states, for some of which Kerr-induced Wigner-function negativity is quite tolerant to loss. This work bridges the gap between quantum optics and ultrafast nonlinear optics, opening a path to quantum applications that require high photon flux. - oai:arXiv.org:2512.17797v1 + Toward Live Noise Fingerprinting in Quantum Software Engineering + https://arxiv.org/abs/2512.18667 + arXiv:2512.18667v1 Announce Type: new +Abstract: Noise is a major bottleneck in today's quantum computing, stemming from decoherence, gate imperfections and other hardware limitations. Accurate noise fingerprints are essential, yet undocumented noise model differences between Quantum Ecosystems undermine core functionality, such as compilation, development and debugging, offering limited transferability and support for quantum software engineering (QSE) tasks. We propose a new research direction: live empirical noise fingerprinting as a lightweight QSE-oriented "noise fingerprinting". Though explored in physics as device-level diagnostics, we reposition them as a QSE paradigm: we propose leveraging classical shadow tomography to enable a new generation of techniques. As a first step, we introduce SimShadow, which prepares reference states, applies shadow-tomography-inspired estimation and constructs deviation fingerprints. Initial experiments uncover systematic discrepancies between platforms (e.g. Frobenius distances up to 7.39) at up to 2.5x10^6 lower cost than traditional methods. SimShadow opens new directions for noise-aware compilation, transpilation, cross-platform validation, error mitigation, and formal methods in QSE. + oai:arXiv.org:2512.18667v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cs.SE + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Andrei Rasputnyi, Ilya Karuseichyk, Gerd Leuchs, Denis Seletskiy, Maria Chekhova + Avner Bensoussan, Elena Chachkarova, Karine Even-Mendoza, Sophie Fortz, Vasileios Klimis - Domain-Aware Quantum Circuit for QML - https://arxiv.org/abs/2512.17800 - arXiv:2512.17800v1 Announce Type: new -Abstract: Designing parameterized quantum circuits (PQCs) that are expressive, trainable, and robust to hardware noise is a central challenge for quantum machine learning (QML) on noisy intermediate-scale quantum (NISQ) devices. We present a Domain-Aware Quantum Circuit (DAQC) that leverages image priors to guide locality-preserving encoding and entanglement via non-overlapping DCT-style zigzag windows. The design employs interleaved encode-entangle-train cycles, where entanglement is applied among qubits hosting neighboring pixels, aligned to device connectivity. This staged, locality-preserving information flow expands the effective receptive field without deep global mixing, enabling efficient use of limited depth and qubits. The design concentrates representational capacity on short-range correlations, reduces long-range two-qubit operations, and encourages stable optimization, thereby mitigating depth-induced and globally entangled barren-plateau effects. We evaluate DAQC on MNIST, FashionMNIST, and PneumoniaMNIST datasets. On quantum hardware, DAQC achieves performance competitive with strong classical baselines (e.g., ResNet-18/50, DenseNet-121, EfficientNet-B0) and substantially outperforming Quantum Circuit Search (QCS) baselines. To the best of our knowledge, DAQC, which uses a quantum feature extractor with only a linear classical readout (no deep classical backbone), currently achieves the best reported performance on real quantum hardware for QML-based image classification tasks. Code and pretrained models are available at: https://github.com/gurinder-hub/DAQC. - oai:arXiv.org:2512.17800v1 + Temperature-enhanced quantum sensing for the cutoff frequency of Ohmic environments + https://arxiv.org/abs/2512.18686 + arXiv:2512.18686v1 Announce Type: new +Abstract: We investigate the quantum sensing performance of a dephasing qubit as a probe in Ohmic environments, characterized by the coupling strength $\eta$, the Ohmicity parameter $s$, and the cutoff frequency $\omega_c$ to be estimated. The performance is quantified by the dimensionless quantum signal-to-noise ratio $\mathcal{Q}$. We show that the evolution of $\mathcal{Q}$ with the scaled time $\omega_c t$ is independent of $\omega_c$, and peaks at an optimal time $t_{\text{opt}}$, yielding optimal sensitivity $\mathcal{Q}_{\text{opt}}$. We analyze how $\mathcal{Q}_{\text{opt}}$ depends on $\eta$, $s$ and the temperature $T$. Our results demonstrate that, for any Ohmic environment, provided that $\omega_c t_{\text{opt}} \ll 1$, $\mathcal{Q}_{\text{opt}}$ always reaches the upper bound: $\mathcal{Q}_{\text{max}} = 0.648$ at zero temperature, and consistently attains $\mathcal{Q}_{\text{max}}/4$ at high temperatures. Remarkably, we find that increasing the scaled temperature $T/\omega_c$ can enhance $\mathcal{Q}_{\text{opt}}$ by nearly two orders of magnitude compared to its zero-temperature counterpart for certain Ohmic environments. Our work reveals that temperature can serve as a resource to enhance sensing precision, as it accelerates the encoding of the cutoff frequency information into the probe state, thereby enabling optimal measurement within a short time window. + oai:arXiv.org:2512.18686v1 quant-ph - cs.LG - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by/4.0/ - Gurinder Singh, Thaddeus Pellegrini, Kenneth M. Merz, Jr + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yuan Ji-Bing, Song Ya-Ju, Tang Shi-Qing, Wang Xin-Wen, Kuang Le-Man - Quantum Wasserstein distance for Gaussian states - https://arxiv.org/abs/2512.17809 - arXiv:2512.17809v1 Announce Type: new -Abstract: Optimal transport between classical probability distributions has been proven useful in areas such as machine learning and random combinatorial optimization. Quantum optimal transport, and the quantum Wasserstein distance as the minimal cost associated with transforming one quantum state to another, is expected to have implications in quantum state discrimination and quantum metrology. In this work, following the formalism introduced in [De Palma, G. and Trevisan, D. Ann. Henri Poincar\'e, {\bf 22} (2021), 3199-3234] to compute the optimal transport plan between two quantum states, we give a general formula for the Wasserstein distance of order 2 between any two one-mode Gaussian states. We discuss how the Wasserstein distance between classical Gaussian distributions and the quantum Wasserstein distance by De Palma and Trevisan for thermal states can be recovered from our general formula for Gaussian states. This opens the path to directly compare various known distance measures with the Wasserstein distance through their closed-form solutions. - oai:arXiv.org:2512.17809v1 + A graphical framework for proving holographic entanglement entropy inequalities in multipartite systems + https://arxiv.org/abs/2512.18726 + arXiv:2512.18726v1 Announce Type: new +Abstract: We present a graphical method for proving holographic entanglement entropy inequalities (HEIs) in general multipartite systems. By introducing a geometric representation of the entanglement structure, we develop a systematic approach that enables one to visualize and verify the validity of HEIs for any number of subsystems $n$. Several theorems are established to formalize this method, and explicit examples are provided for systems with $n = 4$ to $7$ entangled regions. + oai:arXiv.org:2512.18726v1 quant-ph - math-ph - math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + hep-th + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Anaelle Hertz, Mohammad Ahmadpoor, Oleksandr Dzhenzherov, Augusto Gerolin, Khabat Heshami + Chia-Jui Chou, Hans B. Lao, Yi Yang - Low-loss frequency-tunable Josephson junction array cavities on Ge/SiGe heterostructures with a tapered etching approach - https://arxiv.org/abs/2512.17812 - arXiv:2512.17812v1 Announce Type: new -Abstract: Ge/SiGe heterostructures represent a promising platform for hosting various quantum devices such as hole spin qubits and Andreev spin qubits. However, the compatibility of such heterostructures with high-quality-factor microwave superconducting cavities remains a challenge due to defects in the material stack. In this work, we present an approach to enhance the coherence of cavity modes on a reverse-graded Ge/SiGe heterostructure, which consists of etching the full $\sim 1.6~\mathrm{\mu m}$-thick Ge/SiGe stack down to its starting high-resistivity Si substrate, in order to pattern superconducting cavities directly on it. We engineer the mesa step to be tapered, so that it can be easily climbed by the superconducting cavities to reach the quantum devices potentially hosted in the Ge quantum well. Using this approach, we observe internal quality factors of $Q_\mathrm{i} \approx 10000-20000$ for high-impedance frequency-tunable Josephson junction array resonators, limited by the junctions' fabrication, and $Q_\mathrm{i} \approx 100000$ for $50~\mathrm{\Omega}$ coplanar waveguide Nb lift-off resonators. These $Q_\mathrm{i}$ are preserved despite the overlap with the mesa structure in the climbing region, and are comparable to the ones obtained for identical resonators fabricated on a high-resistivity Si wafer reference. Thereby, this work paves a practical path toward superconductor-semiconductor hybrid devices, immediately applicable to emerging technologies on planar Ge. - oai:arXiv.org:2512.17812v1 + Interplay of Confinement and Localization in a Programmable Rydberg Atom Chain + https://arxiv.org/abs/2512.18765 + arXiv:2512.18765v1 Announce Type: new +Abstract: Analog quantum simulators promise access to complex many-body dynamics, yet their performance is ultimately set by how device imperfections compete with intrinsic physical mechanisms. Here we present an end-to-end study of correlation spreading in a programmable Rydberg-atom chain realizing a longitudinal-field transverse-field Ising model, focusing on the joint impact of confinement and effective disorder. Experiments performed on QuEra's Aquila quantum processor are benchmarked against large-scale coherent emulations using the Juelich Quantum Annealing Simulator (JUQAS), enabling the controlled inclusion of realistic hardware imperfections. In the ideal coherent limit, a tunable longitudinal field induces confinement of domain-wall excitations into mesonic bound states, leading to a progressive truncation of the correlation light cone. When experimentally relevant inhomogeneities and fluctuations are included, correlations instead saturate at finite distance even in the nominally deconfined regime, revealing localization driven by emergent disorder. The close quantitative agreement between noisy emulations and experimental data allows us to attribute the observed saturation to specific hardware error channels and to identify the dominant contribution. Our results establish a practical framework for diagnosing and modeling error-induced localization in Rydberg quantum processors, while demonstrating that confinement remains a robust and programmable mechanism for engineering non-ergodic dynamics on near-term quantum hardware. + oai:arXiv.org:2512.18765v1 quant-ph - cond-mat.mes-hall - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Franco De Palma, Elena Acinapura, Wonjin Jang, Fabian Oppliger, Radha Krishnan, Arianna Nigro, Ilaria Zardo, Pasquale Scarlino + http://creativecommons.org/licenses/by/4.0/ + Andrea B. Rava, Jhon A. Montanez-Barrera, Kristel Michielsen, Jaka Vodeb - Witnessing Entanglement in Mixed-Particle Quantum Systems - https://arxiv.org/abs/2512.17860 - arXiv:2512.17860v1 Announce Type: new -Abstract: We introduce an entanglement witness that identifies off-diagonal long-range order (ODLRO) -- a distinctive form of entanglement -- in systems containing both fermionic and bosonic particles. By analyzing the particle-hole reduced density matrices of each subsystem, the approach detects ODLRO independently in both fermionic and bosonic sectors and identifies when long-range order develops across the entire mixed-particle system. The witness also quantifies the magnitude of ODLRO within each particle type, revealing how fermionic and bosonic correlations combine to form the total entanglement of the system, including a bosonic condensation of particle-hole pairs driven by many-body correlations rather than particle statistics. Using the Lipkin-Meshkov-Glick spin model, we show how the transition from ODLRO localized to one particle type to ODLRO shared by both particle types captures the onset of collective entanglement in a mixed-particle environment, providing new insight into systems where fermionic and bosonic correlations coexist. - oai:arXiv.org:2512.17860v1 + Long-distance quantum communication sending single photons and keeping many + https://arxiv.org/abs/2512.18767 + arXiv:2512.18767v1 Announce Type: new +Abstract: Fiber-based classical communication is all-optical and uses light pulses reamplified and reshaped every 50-100 km in classical repeaters. Most compatible with this would be a quantum communication system which is also all-optical with quantum processing units placed in similar intervals. However, existing all-optical quantum communication protocols either require complicated quantum error correction steps for logical-qubit recoveries at every few kilometers or, over larger quantum repeater segments, they would at least depend on sharing complex multi-photon entangled states. Here we propose an all-optical memory-based quantum repeater for long-distance quantum communication, with quantum memories at each repeater station realized in the form of fiber loops combined with suitable quantum error correction codes for photon-loss protection. By sending only single-photon states through the fibers connecting the stations, such repeaters can operate in the classical infrastructure's long-segment regime. We analyze the performance of our scheme for the Gottesman-Kitaev-Preskill code, including a concatenation with the Steane code, as well as the single-photon quantum parity code for total distances up to 10000 km. + oai:arXiv.org:2512.18767v1 quant-ph - physics.chem-ph - physics.comp-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Irma Avdic, David A. Mazziotti + Stefan H\"aussler, Peter van Loock - Simulation of topological superconductors and their competing orders using photon-mediated interactions - https://arxiv.org/abs/2512.17889 - arXiv:2512.17889v1 Announce Type: new -Abstract: Realizing and controlling the unconventional pairing featured by topological superconductors remains a central challenge. We introduce a cavity QED quantum simulator that engineers competing chiral $p_x+ip_y$ and $d_{x^2-y^2}+id_{xy}$ orders by tailoring cavity-mediated couplings between atomic pseudospins that emulate momentum-dependent pairing channels. The desired spatially inhomogeneous cavity-mediated couplings can be engineered in a 2D optical lattice using incommensurate cavity-lattice wavelengths naturally occurring in cavity QED systems. This minimal and fully tunable platform enables controlled state preparation and continuous measurement of superconducting order parameters, revealing phases in both equilibrium and sudden-quench settings with a single dominant pairing channel, as well as coexistence regimes with competing pairing channels. Crucially, our implementation allows direct observation of topological transitions in and out of equilibrium, providing a powerful route to the quantum simulation of competing topological superconducting phases that remain elusive in solid-state and ultracold-atom systems. - oai:arXiv.org:2512.17889v1 + Chaos-controlled switching between entanglement and coherence + https://arxiv.org/abs/2512.18777 + arXiv:2512.18777v1 Announce Type: new +Abstract: Controlling entanglement and coherence is central to quantum information, yet the two resources often exhibit antagonistic trends and are difficult to optimize within a single platform. Here we show that chaos enables switchable eigenstate resources: avoided crossings in soft- versus strong- chaos windows selectively realize an entanglement-peak mode or a coherence-peak mode within the same system. Crucially, this chaos-controlled inversion is not tied to a particular notion of subsystems, appearing both in single-wave settings and in genuine many-body settings. From the quantum-chaos perspective, conventional diagnostics based on avoided-crossing phenomenology and eigenmode delocalization are insufficient; eigenfunction entanglement and basis coherence provide the missing discriminants. Using two wave-chaotic billiards and a tilted-field Ising chain, we track the information-theoretic response of eigenstates across localized hybridization windows. Even when avoided-crossing phenomenology and delocalization are comparable, the entanglement and coherence responses invert between soft- and strong-chaos regimes. In the Ising chain, a single microscopic knob, the global field tilt, toggles between the two operating modes and reveals a trade-off in which off-diagonal correlations grow as diagonal populations dip. Our diagnostics require only reduced states (or their spectra) and are compatible with mode imaging in wave-chaos resonators and randomized measurements in programmable spin simulators. + oai:arXiv.org:2512.18777v1 quant-ph - cond-mat.quant-gas - physics.atom-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Anjun Chu, Joyce Kwan, Eric Yilun Song, Seth Hew Peng Chew, James K. Thompson, Ana Maria Rey + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Kyu-Won Park, Soojoon Lee, Kabgyun Jeong - Exploring the Effect of Basis Rotation on NQS Performance - https://arxiv.org/abs/2512.17893 - arXiv:2512.17893v1 Announce Type: new -Abstract: Neural Quantum States (NQS) use neural networks to represent wavefunctions of quantum many-body systems, but their performance depends on the choice of basis, yet the underlying mechanism remains poorly understood. We use a fully solvable one-dimensional Ising model to show that local basis rotations leave the loss landscape unchanged while relocating the exact wavefunction in parameter space, effectively increasing its geometric distance from typical initializations. By sweeping a rotation angle, we compute quantum Fisher information and Fubini-Study distances to quantify how the rotated wavefunction moves within the loss landscape. Shallow architectures (with focus on Restricted Boltzmann Machines (RBMs)) trained with quantum natural gradient are more likely to fall into saddle-point regions depending on the rotation angle: they achieve low energy error but fail to reproduce correct coefficient distributions. In the ferromagnetic case, near-degenerate eigenstates create high-curvature barriers that trap optimization at intermediate fidelities. We introduce a framework based on an analytically solvable rotated Ising model to investigate how relocating the target wavefunction within a fixed loss landscape exposes information-geometric barriers,such as saddle points and high-curvature regions,that hinder shallow NQS optimization, underscoring the need for landscape-aware model design in variational training. - oai:arXiv.org:2512.17893v1 + Noisy Monitored Quantum Circuits + https://arxiv.org/abs/2512.18783 + arXiv:2512.18783v1 Announce Type: new +Abstract: Noisy monitored quantum circuits have emerged as a versatile and unifying framework connecting quantum many-body physics, quantum information, and quantum computation. In this review, we provide a comprehensive overview of recent advances in understanding the dynamics of such circuits, with an emphasis on their entanglement structure, information-protection capabilities, and noise-induced phase transitions. A central theme is the mapping to classical statistical models, which reveals how quantum noise reshapes dominant spin configurations. This framework elucidates universal scaling behaviors, including the characteristic $q^{-1/3}$ entanglement scaling with noise probability $q$ and distinct timescales for information protection. We further highlight a broad range of constructions and applications inspired by noisy monitored circuits, spanning variational quantum algorithms, classical simulation methods, mixed-state phases of matter, and emerging approaches to quantum error mitigation and quantum error correction. These developments collectively establish noisy monitored circuits as a powerful platform for probing and controlling quantum dynamics in realistic, decohering environments. + oai:arXiv.org:2512.18783v1 quant-ph - cs.AI - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.dis-nn + cond-mat.stat-mech + Tue, 23 Dec 2025 00:00:00 -0500 new http://creativecommons.org/licenses/by/4.0/ - Sven Benjamin Ko\v{z}i\'c, Vinko Zlati\'c, Fabio Franchini, Salvatore Marco Giampaolo + Shuo Liu, Shao-Kai Jian, Shi-Xin Zhang - Visualizing Detection Efficiency in Optomechanical Scattering - https://arxiv.org/abs/2512.17894 - arXiv:2512.17894v1 Announce Type: new -Abstract: Many optical measurement techniques, such as light scattering from wavelength-scale particles or detecting motion from a surface with an optical lever, encode information in a complex radiation pattern. Extracting all available information is essential for many quantum-enhanced sensing protocols but is often impractical, as it requires many channels to spatially resolve the scattered signal. We present a new method to visualize how efficiently a practical measurement scheme captures the information available in the scattered light by mapping out the local contribution to the detection efficiency on the detector surface. We use this tool to experimentally optimize the free space measurement of the amplitude of motion of an optomechanical resonator with a quadrant photodiode. We show that blocking sections of the photodetector enhances sensitivity, counterintuitively yielding a significant improvement in detecting higher-order mechanical modes in the system. We also show how our method can be applied to light scattering measurements of small particles. - oai:arXiv.org:2512.17894v1 + Singularity Selector: Topological Chirality via Non-Abelian Loops around Exceptional Points + https://arxiv.org/abs/2512.18789 + arXiv:2512.18789v1 Announce Type: new +Abstract: Chirality is more than a geometric curiosity; it governs measurable asymmetries across nature, from enantiomer-selective drugs and left-handed fermions in particle physics to handed charge transport in Weyl semimetals. We extend this universal concept to non-Hermitian systems by defining topological chirality, an invariant that emerges whenever an exceptional-points (EP) pair is present. Built from the non-commutative fundamental group and its braid representation, topological chirality acts as a singularity selector: clockwise EP loops occupy a homotopy class that avoids EPs, whereas counter-clockwise mirrors are equivalent only if they cross the EPs themselves. We confirm this binary rule in an optical microcavity and a non-Hermitian topological band. The same two-sheeted topology governs EP pairs in spin systems, photonic crystals and hybrid light-matter structures, where EP encirclements have already been demonstrated, so the framework transfers without alteration and confirms its experimental viability. Our findings lay the cornerstone for interpreting loop-sensitive observables such as spectral vorticity, the complex Berry phase and the non-Abelian holonomy. Finally, a gluing-of-planes construction extends the invariant to an n-sheeted surface hosting 2m EPs, unifying higher-order EP pairs. + oai:arXiv.org:2512.18789v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 new - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Youssef Tawfik, Shan Hao, Thomas P. Purdy + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Kyu-Won Park, KyeongRo Kim, Kabgyun Jeong - Quantum Alternating Direction Method of Multipliers for Semidefinite Programming - https://arxiv.org/abs/2510.10056 - arXiv:2510.10056v3 Announce Type: cross -Abstract: Semidefinite programming (SDP) is a fundamental convex optimization problem with wide-ranging applications. However, solving large-scale instances remains computationally challenging due to the high cost of solving linear systems and performing eigenvalue decompositions. In this paper, we present a quantum alternating direction method of multipliers (QADMM) for SDPs, building on recent advances in quantum computing. An inexact ADMM framework is developed, which tolerates errors in the iterates arising from block-encoding approximation and quantum measurement. Within this robust scheme, we design a polynomial proximal operator to address the semidefinite conic constraints and apply the quantum singular value transformation to accelerate the most costly projection updates. We prove that the scheme converges to an $\epsilon$-optimal solution of the SDP problem under the strong duality assumption. A detailed complexity analysis shows that the QADMM algorithm achieves favorable scaling with respect to dimension compared to the classical ADMM algorithm and quantum interior point methods, highlighting its potential for solving large-scale SDPs. - oai:arXiv.org:2510.10056v3 - math.OC + Foundation Model for Unified Characterization of Optical Quantum States + https://arxiv.org/abs/2512.18801 + arXiv:2512.18801v1 Announce Type: new +Abstract: Machine learning methods have been used to infer specific properties of limited families of optical quantum states, but a unified model that predicts a broad range of properties for practically relevant-especially multimode non-Gaussian-states without full tomography is still lacking. Here we introduce the first foundation model for the characterization of optical quantum states across a wide range of complexity, defined by three key factors: non-Gaussianity, number of modes, and degree of squeezing. We show that a single model pretrained on low-complexity states can be directly applied to characterize states of higher complexity. With limited fine-tuning, the model adapts to downstream tasks such as predicting quantum fidelity and Wigner negativity over a broad class of experimentally relevant states, including strongly non-Gaussian Schr\"odinger cat states, multimode systems with up to ten modes, and highly squeezed states with squeezing levels up to 10.4dB. Our results establish a unified framework for characterizing optical quantum states from limited measurement data, enabling efficient certification of quantum states relevant to optical quantum information computation, communication and metrology. + oai:arXiv.org:2512.18801v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + Tue, 23 Dec 2025 00:00:00 -0500 + new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hantao Nie, Dong An, Zaiwen Wen + Xiaoting Gao, Yan Zhu, Feng-Xiao Sun, Ya-Dong Wu, Qiongyi He - Women in Theoretical Quantum Physics in Brazil:demographics, career profiles, recognition, and leadership - https://arxiv.org/abs/2512.16946 - arXiv:2512.16946v1 Announce Type: cross -Abstract: Gender imbalance in Physics remains a persistent global challenge, and Brazil is no exception. While women account for only 24% of Physics faculty in the country, their representation in Quantum Physics is even smaller. In this work, we provide the first comprehensive overview of women working in Theoretical Quantum Physics in Brazil, here referred to as the SheQ (She + Quantum) community. Using data from the CNPq Lattes platform, we identify 93 researchers and analyze their geographic distribution, academic trajectories, scientific productivity, international experience, recognition through awards and fellowships, and engagement with initiatives promoting gender equity. Our results reveal both progress and persistent disparities: SheQ researchers have a strong scientific output, leadership roles, and international training; yet, their recognition through productivity fellowships remains modest, and their involvement in gender-related initiatives, although increasing among younger generations, remains limited. By combining quantitative indicators with institutional perspectives, we highlight structural barriers as well as opportunities for fostering a more inclusive environment in Quantum Physics. his study thus contributes to a broader reflection on how diversity not only promotes fairness but also strengthens creativity, innovation, and scientific progress. - oai:arXiv.org:2512.16946v1 - physics.soc-ph - physics.ed-ph + Families of $k$-positive maps and Schmidt number witnesses from generalized equiangular measurements + https://arxiv.org/abs/2512.18807 + arXiv:2512.18807v1 Announce Type: new +Abstract: Quantum entanglement is an important resource in many modern technologies, like quantum computation or quantum communication and information processing. Therefore, most interest is given to detect and quantify entangled states. Entanglement degree of bipartite mixed quantum states can be quantified using the Schmidt number. Witnesses of the Schmidt numbers are closely related to $k$-positive linear maps, for which there is no general construction. Here, we use the generalized equiangular measurements to define a family of $k$-positive maps and the corresponding Schmidt number witnesses. + oai:arXiv.org:2512.18807v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 + new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tatiana Pauletti, Paula Homem de Mello, Thereza Paiva, Vivian V. Fran\c{c}a + Katarzyna Siudzi\'nska - QSMOTE-PGM/kPGM: QSMOTE Based PGM and kPGM for Imbalanced Dataset Classification - https://arxiv.org/abs/2512.16960 - arXiv:2512.16960v1 Announce Type: cross -Abstract: Quantum-inspired machine learning (QiML) leverages mathematical frameworks from quantum theory to enhance classical algorithms, with particular emphasis on inner product structures in high-dimensional feature spaces. Among the prominent approaches, the Kernel Trick, widely used in support vector machines, provides efficient similarity computation, while the Pretty Good Measurement (PGM), originating from quantum state discrimination, enables classification grounded in Hilbert space geometry. Building on recent developments in kernelized PGM (KPGM) and direct PGM-based classifiers, this work presents a unified theoretical and empirical comparison of these paradigms. We analyze their performance across synthetic oversampling scenarios using Quantum SMOTE (QSMOTE) variants. Experimental results show that both PGM and KPGM classifiers consistently outperform a classical random forest baseline, particularly when multiple quantum copies are employed. Notably, PGM with stereo encoding and n_copies=2 achieves the highest overall accuracy (0.8512) and F1-score (0.8234), while KPGM demonstrates competitive and more stable behavior across QSMOTE variants, with top scores of 0.8511 (stereo) and 0.8483 (amplitude). These findings highlight that quantum-inspired classifiers not only provide tangible gains in recall and balanced performance but also offer complementary strengths: PGM benefits from encoding-specific enhancements, whereas KPGM ensures robustness across sampling strategies. Our results advance the understanding of kernel-based and measurement-based QiML methods, offering practical guidance on their applicability under varying data characteristics and computational constraints. - oai:arXiv.org:2512.16960v1 - cs.LG + El Agente Cu\'antico: Automating quantum simulations + https://arxiv.org/abs/2512.18847 + arXiv:2512.18847v1 Announce Type: new +Abstract: Quantum simulation is central to understanding and designing quantum systems across physics and chemistry. Yet it has barriers to access from both computational complexity and computational perspectives, due to the exponential growth of Hilbert space and the complexity of modern software tools. Here we introduce{\cinzel El Agente Cu\'antico}, a multi-agent AI system that automates quantum-simulation workflows by translating natural-language scientific intent into executed and validated computations across heterogeneous quantum-software frameworks. By reasoning directly over library documentation and APIs, our agentic system dynamically assembles end-to-end simulations spanning state preparation, closed- and open-system dynamics, tensor-network methods, quantum control, quantum error correction, and quantum resource estimation. The developed system unifies traditionally distinct simulation paradigms behind a single natural-language interface. Beyond reducing technical barriers, this approach opens a path toward scalable, adaptive, and increasingly autonomous quantum simulation, enabling faster exploration of physical models, rapid hypothesis testing, and closer integration between theory, simulation, and emerging quantum hardware. + oai:arXiv.org:2512.18847v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + physics.comp-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Ignacio Gustin, Luis Mantilla Calder\'on, Juan B. P\'erez-S\'anchez, J\'er\^ome F. Gonthier, Yuma Nakamura, Karthik Panicker, Manav Ramprasad, Zijian Zhang, Yunheng Zou, Varinia Bernales, Al\'an Aspuru-Guzik + + + Correlated Entropic Uncertainty as a Signature of Exceptional Points + https://arxiv.org/abs/2512.18856 + arXiv:2512.18856v1 Announce Type: new +Abstract: Non-Hermitian physics has become a fundamental framework for understanding open systems where gain and loss play essential roles, with impact across photonics, quantum science, and condensed matter. While the role of complex eigenvalues is well established, the nature of the corresponding eigenfunctions has remained a long-standing problem. Here we show that it arises from a fundamental entropic uncertainty trade-off between phase entropy and its Fourier representation. This trade-off enforces a correlated behavior of phase and Fourier entropies near avoided crossings and exceptional points, precisely where the Petermann factor diverges and phase rigidity collapses. Our results establish biorthogonality is not as an anomaly but an intrinsic property of eigenfunctions, arising universal manifestation of uncertainty relation in non-Hermitian systems. Beyond resolving this foundational question, our framework provides a unifying and testable principle that advances the fundamentals of non-Hermitian physics and can be directly verified with existing interferometric techniques. + oai:arXiv.org:2512.18856v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by-nc-nd/4.0/ - Bikash K. Behera, Giuseppe Sergioli, Robert Giuntini + Kyu-Won Park, Soojoon Lee, Kabgyun Jeong - Irrelevant carrots and non-existent sticks: trust, governance, and security in the transition to quantum-safe systems - https://arxiv.org/abs/2512.16974 - arXiv:2512.16974v1 Announce Type: cross -Abstract: Quantum computing poses an urgent and widely recognised threat to global cybersecurity, enabling encrypted government, financial, and healthcare data harvested today to be decrypted in the near future. Transitioning to quantum-safe cryptography is therefore essential, demanding coordinated action across a complex, multi-actor innovation system. Drawing on insights from an expert workshop in Amsterdam, this study develops a socially informed vision for a quantum-safe future and analyses the current innovation landscape to identify critical gaps and the actions needed to address them. We map twelve key actor groups involved in the migration process, finding that regulators exert the strongest direct influence, while standardisation bodies play a crucial indirect role. This research provides one of the first system-level mappings of actors, influence pathways and governance responsibilities shaping the quantum-safe transition, revealing several responsibilities with unclear ownership. Although centred on the Netherlands, our findings are applicable to other national contexts navigating quantum-safe transitions. - oai:arXiv.org:2512.16974v1 - physics.soc-ph - cs.CY + Temporal nonclassicality in continuous-time quantum walks + https://arxiv.org/abs/2512.18873 + arXiv:2512.18873v1 Announce Type: new +Abstract: We investigate the genuinely quantum features of continuous-time quantum walks by combining a single-time and a multi-time quantifier of nonclassicality. On the one hand, we consider the quantum-classical dynamical distance $D_{\mathrm{QC}}(t)$, which measures the departure of the time-evolved quantum state of a continuous-time quantum walk from the classical state of a random walk on the same graph. On the other, we analyse the joint probability distributions associated with sequential measurements of the walker's position, assessing their violation of the classical Kolmogorov consistency conditions via a dedicated quantifier $\bar{K}(t)$. We demonstrate a quadratic short-time scaling of $\bar{K}(t)$, which differs from the known linear scaling of $D_{\mathrm{QC}}(t)$, but, as the latter, is fully determined by the degree of the initially occupied node and is independent of the global graph topology. At longer times, instead, $\bar{K}(t)$ exhibits a pronounced topology-driven behavior: it is strongly suppressed on complete graphs while remaining finite and oscillatory on cycles, in contrast with the almost topology-independent asymptotics of $D_{\mathrm{QC}}(t)$. We then extend the analysis to Markovian open-system dynamics, focusing on dephasing in the position basis (Haken-Strobl model) and in the energy basis (intrinsic decoherence). Site dephasing drives both quantifiers to zero, with the decay of $\bar{K}(t)$ controlled by the spectral gap of the corresponding Lindblad generator. By contrast, energy-basis dephasing preserves a finite asymptotic value of $\bar{K}(t)$, depending on the overlap structure of the Laplacian eigenspaces with the site basis. + oai:arXiv.org:2512.18873v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Ailsa Robertson, Si\^an Brooke, Sebastian De Haro, Christian Schaffner + Paolo Luppi, Claudia Benedetti, Andrea Smirne - Continuum canonical purifications - https://arxiv.org/abs/2512.17014 - arXiv:2512.17014v1 Announce Type: cross -Abstract: We construct and characterize canonical purifications for general algebraic states, extending prior constructions by Woronowicz and by Dutta/Faulkner to general quantum field theories. Given a quantum state on a *-algebra, the canonical purification is a state on a "doubled" algebra that admits an interpretation in terms of CRT reflection. We study the conditions under which these enlarged states are "pure" in the technical sense, compute their modular conjugations, and relate them to GNS and natural-cone purifications in certain settings. In a forthcoming paper with Caminiti and Capeccia, we provide an application of this general theory to the problem of excitability in quantum field theory. - oai:arXiv.org:2512.17014v1 - hep-th + Structure-Preserving Optimal Control of Open Quantum Systems via a Discrete Contact PMP + https://arxiv.org/abs/2512.18879 + arXiv:2512.18879v1 Announce Type: new +Abstract: We develop a discrete Pontryagin Maximum Principle (PMP) for controlled open quantum systems governed by Lindblad dynamics, and introduce a second--order \emph{contact Lie--group variational integrator} (contact LGVI) that preserves both the CPTP (completely positive and trace--preserving) structure of the Lindblad flow and the contact geometry underlying the discrete PMP. A type--II discrete contact generating function produces a strict discrete contactomorphism under which the state, costate, and cost propagate in exact agreement with the variational structure of the discrete contact PMP. + We apply this framework to the optimal control of a dissipative qubit and compare it with a non--geometric explicit RK2 discretization of the Lindblad equation. Although both schemes have the same formal order, the RK2 method accumulates geometric drift (loss of trace, positivity violations, and breakdown of the discrete contact form) that destabilizes PMP shooting iterations, especially under strong dissipation or long horizons. In contrast, the contact LGVI maintains exact CPTP structure and discrete contact geometry step by step, yielding stable, physically consistent, and geometrically faithful optimal control trajectories. + oai:arXiv.org:2512.18879v1 + quant-ph + cs.NA math-ph math.MP + math.NA + math.OC + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Leonardo Colombo + + + Characterizing Kadison--Schwarz maps on $M_3$ + https://arxiv.org/abs/2512.18900 + arXiv:2512.18900v1 Announce Type: new +Abstract: Kadison--Schwarz (KS) maps form a natural class of positive linear maps lying between positivity and complete positivity. Despite their relevance in quantum dynamics and operator algebras, a detailed characterization of KS maps beyond low dimensions remains largely open. In this work we analyze unital linear maps on $M_3$ using the Bloch--Gell--Mann representation. Exploiting unitary equivalence and structural properties of the $\mathfrak{su}(3)$ algebra, we derive analytic conditions ensuring the Kadison--Schwarz property. Our approach clarifies the relation between KS maps and completely positive maps on $M_3$. + oai:arXiv.org:2512.18900v1 + quant-ph math.OA + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Adam Rutkowski + + + Optical perspective on the time-dependent Dirac oscillator + https://arxiv.org/abs/2512.18904 + arXiv:2512.18904v1 Announce Type: new +Abstract: The Dirac oscillator is a relativistic quantum system, characterized by its linearity in both position and momentum. Moreover, considering $(1{+}1)$ and $(2{+}1)$ dimensions, the system can be mapped onto the Jaynes-Cummings and anti-Jaynes-Cummings models, as illustrated in an exact manner by Bermudez \emph{et al.} [\href{ https://doi.org/10.1103/PhysRevA.76.041801}{Phys. Rev. A 76, 041801(R)}]. Using the optical counterparts of the Dirac oscillator, we analyze an extension of the model that incorporates a time-dependent frequency. We focus on the consequences of these time modulations on the angular momentum observables and spin-orbit entanglement. Noticeable changes in the \emph{Zitterbewegung} are found. We show that a specific choice of time dependence yields aperiodic evolution of the observables, whereas an alternative choice allows analytical solutions. + oai:arXiv.org:2512.18904v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 + new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jonathan Sorce + Thiago T. Tsutsui, Alison A. Silva, Antonio S. M. de Castro, Fabiano M. Andrade - Chronicle: "Foot of the iceberg" of Nobel Prize in Physics 2025: ILTPE and LTP contribution - https://arxiv.org/abs/2512.17050 - arXiv:2512.17050v1 Announce Type: cross -Abstract: The Nobel Prize in Physics 2025 has been awarded to John Clarke, John Martinis, and Michel Devoret for "the discovery of macroscopic quantum mechanical tunnelling and energy quantisation in an electric circuit". The paper explains the essence of their studies and shows in a historical context the importance of earlier research in superconductivity and quantum physics of macroscopic systems by other physicists, particularly, Ukrainian scientists, including employees of the B. Verkin Institute for Low Temperature Physics and Engineering of the NAS of Ukraine (ILTPE). The role of the Fizyka Nyzkykh Temperatur (FNT) journal issued by ILTPE in Kharkiv and its translation as AIP Low Temperature Physics (LTP) in dissemination of results of the theoretical and experimental studies in the field is emphasized as well. - oai:arXiv.org:2512.17050v1 - cond-mat.supr-con - physics.hist-ph + Interactions of pre- and postselected quantum particles + https://arxiv.org/abs/2512.18907 + arXiv:2512.18907v1 Announce Type: new +Abstract: An approach for analysis of effective interaction between pre- and postselected quantum particles is developed. It is argued that the cases of complete pre- and postselection of particles are more profound than the cases of partial pre- and postselection, since the former goes beyond modification of the average of interactions on an ensemble of experiments. Recently discussed paradoxical phenomena such as the pigeonhole paradox and the modification of the interaction from repulsion to attraction are analyzed within the introduced formalism, and a few new surprising examples are presented. + oai:arXiv.org:2512.18907v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - 10.1063/10.0039961 - Low Temp. Phys. 51, 1522-1524 (2025) - O. G. Turutanov + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Gregory Reznik, Jan Dziewior, Shrobona Bagchi, Lev Vaidman - Cryogenic Dielectric Metasurface-Integrated Superconducting Nanowire Single-Photon Detectors - https://arxiv.org/abs/2512.17115 - arXiv:2512.17115v1 Announce Type: cross -Abstract: Over the past decade, multi-element superconducting nanowire single-photon detectors (SNSPDs) have emerged as the leading single-photon detection technology due to their exceptional system detection efficiency (SDE), ultrahigh timing precision, negligible dark counts, etc. However, achieving these performances with a \textit{single-element} SNSPD has been an outstanding challenge due to a fundamental trade-off: a large active area is necessary for high SDE, while a smaller area is crucial for higher photon count rates, lower dark counts, and lower jitter. Here, we introduce an all-dielectric cryogenic metalens integrated with a single-element SNSPD to achieve high SDE with a smaller active area. Furthermore, we leverage a bifunctional metalens to demonstrate polarization-resolved photodetection at the telecommunication wavelength theoretically. Integrating multifunctional cryogenic metaurfaces with the state-of-the-art SNSPDs may enable novel capabilities with reduced size, weight, power, cost, and cooling (SWaP-C$^{2}$) requirements. - oai:arXiv.org:2512.17115v1 - physics.optics + Quantum correlations curvature, memory functions, and fundamental bounds + https://arxiv.org/abs/2512.18942 + arXiv:2512.18942v1 Announce Type: new +Abstract: We investigate fundamental bounds on the curvature of quantum correlation functions in imaginary time. Focusing first on topological phases, we show that quantum geometry can qualitatively modify the imaginary-time decay of correlations, leading to nontrivial curvature behavior beyond simple exponential scaling. More generally, we show a universal bound on correlation curvature that holds for interacting systems in thermal equilibrium, and establish connection to leading invariants of the memory-function formalism. Our results identify imaginary-time curvature as a robust probe of intrinsic quantum timescales. + oai:arXiv.org:2512.18942v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Amir Targholizadeh, Grigoriy Y. Nikulin, Pankaj K. Jha + Alexander Kruchkov - Realism and Ontology in Quantum Mechanics and String Theory - https://arxiv.org/abs/2512.17124 - arXiv:2512.17124v1 Announce Type: cross -Abstract: Dualities in physics have challenged traditional forms of scientific realism by undermining the idea that theories describe a unique underlying ontology. In this paper, we develop a new perspective on scientific realism that responds to this challenge. We argue that while realist commitment remains appropriate at the level of a theory's full formal structure, ontological commitment should be treated as tied to specific empirical contexts rather than to a fixed, real ontology. Our proposal draws inspiration from Dennett's notion of a "compression algorithm" as a defining criterion of a scientific theory. On this basis, we separate realism from ontological commitment. To clarify the stakes of this distinction, we contrast our approach with common core realism, which locates ontology in the invariant structure shared by dual models. Focusing on dualities in quantum mechanics and string theory, we show how our view accommodates ontological pluralism while preserving a robust form of structural realism. - oai:arXiv.org:2512.17124v1 - physics.hist-ph - hep-th + Photonic variational quantum eigensolver for NISQ-compatible quantum technology + https://arxiv.org/abs/2512.18952 + arXiv:2512.18952v1 Announce Type: new +Abstract: Quantum computers have the potential to deliver speed-ups for solving certain important problems that are intractable for classical counterparts, making them a promising avenue for advancing modern computation. However, many quantum algorithms require deep quantum circuits, which are challenging to implement on current noisy devices. To address this limitation, variational quantum algorithms (VQAs) have been actively developed, enabling practical quantum computing in the noisy intermediate-scale quantum (NISQ) era. Among them, the variational quantum eigensolver (VQE) stands out as a leading approach for solving problems in quantum chemistry, many-body physics, and even integer factorization. The VQE algorithm can be implemented on various quantum hardware platforms, including photonic systems, quantum dots, trapped ions, neutral atoms, and superconducting circuits. In particular, photonic platforms offer several advantages: they operate at room temperature, exhibit low decoherence, and support multiple degrees of freedom, making them suitable for scalable, high-dimensional quantum computation. Here we present methodologies for realizing VQE on photonic systems, highlighting their potential for practical quantum computing. We first provide a theoretical overview of the VQE framework, focusing on the procedure for variationally estimating ground state energies. We then explore how photonic systems can implement these processes, showing that a wide variety of problems can be addressed using either multiple qubit states or a single qudit state. + oai:arXiv.org:2512.18952v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Richard Dawid, Guilherme Franzmann + 10.1186/s40580-025-00525-x + Nano Convergence, 12, 60 (2025) + Kang-Min Hu, Min Namkung, Hyang-Tag Lim - A Lindblad-Pauli Framework for Coarse-Grained Chaotic Binary-State Dynamics - https://arxiv.org/abs/2512.17200 - arXiv:2512.17200v1 Announce Type: cross -Abstract: Coarse-graining a chaotic bistable oscillator into a binary symbol sequence is a standard reduction, but it often obscures the geometry of the reduced state space and structural constraints of physically meaningful stochastic evolution. We develop a two-state framework that embeds coarse-grained left/right statistics of the driven Duffing oscillator into a $2\times2$ density-matrix representation and models inter-well switching by a two-rate Gorini--Kossakowski--Sudarshan--Lindblad (GKSL) generator. For diagonal states the GKSL dynamics reduces to the classical two-state master equation.The density-matrix language permits an operational ``Bloch half-disk'' embedding with overlap parameter $c(\varepsilon)$ quantifying partition fuzziness; the GKSL model is fitted to diagonal marginals treating $c(\varepsilon)$ as diagnostic. We derive closed-form solutions, an explicit Kraus representation (generalized amplitude damping with dephasing and rotation), and practical diagnostics for the time-homogeneous first-order Markov assumption (order tests, Chapman--Kolmogorov consistency, run-length statistics, stationarity checks). When higher-order memory appears, we extend the framework via augmented Markov models, constructing CPTP maps through discrete-time Kraus representations; continuous-time GKSL generators may not exist for all empirical transition matrices. We provide a numerical pipeline with templates for validating the framework on Duffing simulations. The density-matrix formalism is an organizational convenience rather than claiming quantum-classical equivalence. - oai:arXiv.org:2512.17200v1 - nlin.CD + Integrated Ring-based Quantum Key Distribution with Weak Measurement Enhanced Fiber-Optic Sensing Disturbance Magnitude and Location + https://arxiv.org/abs/2512.18961 + arXiv:2512.18961v1 Announce Type: new +Abstract: The deep integration of quantum communication and fiber-optic sensing is pivotal for the development of next-generation multifunctional and highly reliable secure information infrastructure. Here, we present a Sagnac-loop integrated system (SLIS) that, for the first time, combines ring-based quantum key distribution (QKD) with fiber-based weak measurement (WM) enhanced sensing and disturbance localization capabilities. In the event of communication interruption due to external disturbances, the SLIS seamlessly switches to perception system, employing interference measurement and WM techniques to monitor channel disturbances. By integrating null-frequencies localization (NFL) mode, the system precisely determines the disturbance location, enabling rapid identification of security vulnerabilities along the link. Experimental results demonstrate that, over a 30 km Sagnac loop channel, the SLIS achieves a raw key generation rate of 22.4 kbps with stable operation and clear scalability toward network expansion. In terms of perception performance, the SLIS exhibits strong capability for both dynamic and quasi-static disturbances. For dynamic perturbations, the system detects transient impacts and PZT-driven frequency variations down to 100 Hz, and enables long-distance localization via NFL alignment, with improved localization performance as the disturbance position moves farther away along the loop. For quasi-static disturbances, gravitational changes as small as 100 g are resolved, corresponding to a time-delay variation of 9.81 as. This work provides a novel technical pathway toward self-diagnosing, robust quantum networks through integrated communication and sensing functionalities. + oai:arXiv.org:2512.18961v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Yicong Qiu, Qiye Zheng + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Weiqian Zhao, Wenzhao Huang, Zifu Su, Fangyuan Li, Qirong Jiang, Cheng Yuan, Yafei Yu, Jindong Wang - Detecting Axion Dark Matter with an Organic Molecular Maser - https://arxiv.org/abs/2512.17271 - arXiv:2512.17271v1 Announce Type: cross -Abstract: We present a novel quantum sensing approach to search for axion-electron interactions around the axion mass of 6 \mueV. In this region, laboratory searches are relatively scarce, and our direct experiment measuring the axion-electron coupling constant reaches the sensitivity of 8 \times 10^{-6} GeV^{-1}. The method, based on an organic molecular maser establishes a proof-of-principle for quantum-enhanced detection, with a corresponding magnetic field sensitivity of 0.85 fT/\sqrt{\rm{Hz}}. The methodology is generic and can be readily extended to other physical systems, further broadening its applicability in quantum sensing and dark matter searches. - oai:arXiv.org:2512.17271v1 - hep-ph + DeepQuantum: A PyTorch-based Software Platform for Quantum Machine Learning and Photonic Quantum Computing + https://arxiv.org/abs/2512.18995 + arXiv:2512.18995v1 Announce Type: new +Abstract: We introduce DeepQuantum, an open-source, PyTorch-based software platform for quantum machine learning and photonic quantum computing. This AI-enhanced framework enables efficient design and execution of hybrid quantum-classical models and variational quantum algorithms on both CPUs and GPUs. For photonic quantum computing, DeepQuantum implements Fock, Gaussian, and Bosonic backends, catering to different simulation needs. Notably, it is the first framework to realize closed-loop integration of three paradigms of quantum computing, namely quantum circuits, photonic quantum circuits, and measurement-based quantum computing, thereby enabling robust support for both specialized and universal photonic quantum algorithm design. Furthermore, DeepQuantum supports large-scale simulations based on tensor network techniques and a distributed parallel computing architecture. We demonstrate these capabilities through comprehensive benchmarks and illustrative examples. With its unique features, DeepQuantum is intended to be a powerful platform for both AI for Quantum and Quantum for AI. + oai:arXiv.org:2512.18995v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Hongliang Wu, Yuchen Han, Zhengtao Wang, Dezhi Zheng, Yeliang Wang, Liu Yang, Zhiwei Wang, Bo Zhang, Dmitry Budker, Jun Zhang + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Jun-Jie He, Ke-Ming Hu, Yu-Ze Zhu, Guan-Ju Yan, Shu-Yi Liang, Xiang Zhao, Ding Wang, Fei-Xiang Guo, Ze-Feng Lan, Xiao-Wen Shang, Zi-Ming Yin, Xin-Yang Jiang, Lin Yang, Hao Tang, Xian-Min Jin - Quantum quenches across continuous and first-order quantum transitions in one-dimensional quantum Ising models - https://arxiv.org/abs/2512.17333 - arXiv:2512.17333v1 Announce Type: cross -Abstract: We investigate the quantum dynamics generated by quantum quenches (QQs) of the Hamiltonian parameters in many-body systems, focusing on protocols that cross first-order and continuous quantum transitions, both in finite-size systems and in the thermodynamic limit. As a paradigmatic example, we consider the quantum Ising chain in the presence of homogeneous transverse ($g$) and longitudinal ($h$) magnetic fields. This model exhibits a continuous quantum transition (CQT) at $g=g_c$ and $h=0$, and first-order quantum transitions (FOQTs) driven by $h$ along the line $h=0$ ($g<g_c$). In the integrable limit $h=0$, the system can be mapped onto a quadratic fermionic theory; however, any nonvanishing longitudinal field breaks integrability and the spectrum of the resulting Hamiltonian is generally expected to enter a chaotic regime. We analyze QQs in which the longitudinal field is suddenly changed from a negative value $h_i < 0$ to a positive value $h_f>0$. We focus on values of $h_f$ such that the spectrum of the post-QQ Hamiltonian ${\hat H}(g,h_f)$ lies in the chaotic regime, where thermalization may emerge at asymptotically long times. We study the out-of-equilibrium dynamics for different values of $g$, finding qualitatively distinct behaviors for $g > g_c$ (where the chain is in the disordered phase), for $g = g_c$ (QQ across the CQT), and for $g<g_c$ (QQ across the FOQT line). - oai:arXiv.org:2512.17333v1 - cond-mat.stat-mech + Classical and Quantum Algorithms for Topological Invariants of Torus Bundles + https://arxiv.org/abs/2512.19028 + arXiv:2512.19028v1 Announce Type: new +Abstract: Computing topological invariants of 3-manifolds is generally intractable, yet specialized algebraic structures can enable efficient algorithms. For Witten-Reshetikhin-Turaev (WRT) invariants of torus bundles, we exploit the non-commutative torus structure to embed the skein algebra of the closed torus into its symmetric subalgebra at roots of unity. This yields a fixed $N^2$-dimensional representation that supports polynomial-time classical computation with $O(N^2)$ space, and a quantum algorithm using only $O(\log N)$ qubits -- an exponential space advantage. We further prove that extracting individual expansion coefficients is #P-complete, yet there is a quantum algorithm that can efficiently approximate these coefficients for a non-negligible fraction of configurations. + oai:arXiv.org:2512.19028v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + math.GT + math.QA + Tue, 23 Dec 2025 00:00:00 -0500 + new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Andrea Pelissetto, Davide Rossini, Ettore Vicari + Nelson Abdiel Col\'on Vargas, Carlos Ortiz Marrero - The crossover from classical to quantum transport in a weakly-interacting Fermi gas - https://arxiv.org/abs/2512.17379 - arXiv:2512.17379v1 Announce Type: cross -Abstract: We present an exact solution of the quantum kinetic equation of a weakly interacting Fermi gas in the crossover from the degenerate Fermi-liquid regime to the classical Boltzmann gas. We construct families of orthogonal polynomials tailored to each angular momentum channel, enabling a fast and systematically improvable decomposition of the phase-space distribution. This approach yields accurate, non-variational predictions for the shear viscosity, thermal diffusivity, and spin diffusivity to leading order in the scattering length. We demonstrate that the commonly used relaxation-time approximation fails dramatically at low temperature--by up to 25%. Our method provides a numerically efficient framework for benchmarking transport in strongly correlated regimes and for simulating the kinetics of quantum gases beyond hydrodynamics. - oai:arXiv.org:2512.17379v1 - cond-mat.quant-gas + The energy-speed relationship of quantum particles challenges Bohmian mechanics? + https://arxiv.org/abs/2512.19051 + arXiv:2512.19051v1 Announce Type: new +Abstract: Recently, Sharoglazova et al. claimed to have proven a violation of the basic tenet of Bohmian mechanics, namely the phase-speed relation $\vec{v}(\vec{r},t)=\frac{\hbar}{m}\vec{\nabla}S(\vec{r},t)$. Here, $S(\vec{r},t)$ is the (real) phase of the wave function $\psi(\vec{r},t)=\rho^{\frac{1}{2}}(\vec{r},t)e^{iS(\vec{r},t)}$. In a nutshell, they have measured the speed of a claimed evanescent wave, which is real and therefore must have $\vec{\nabla}S=\vec{0}$. However, Fig. 2 clearly shows a density motion from one waveguide to the other, implying a nonzero density current, $\vec{j}(\vec{r},t)=\frac{\hbar}{2mi}\Im(\psi^*\vec{\nabla}\psi)$. If we combine this evidence with the mathematical identity $\vec{\nabla}S=\frac{m}{\rho}\vec{j}$, we should instead conclude that $\vec{\nabla}S\neq\vec{0}$. So, where does this apparent inconsistency come from? + oai:arXiv.org:2512.19051v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + physics.optics + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Hadrien Kurkjian + S. Di Matteo, C. Mazzoli - Advantages and disadvantages of maximally entangled states in dilaton black hole background - https://arxiv.org/abs/2512.17535 - arXiv:2512.17535v1 Announce Type: cross -Abstract: We investigate quantum entanglement and coherence for four classes of Bell-like fermionic states in the vicinity of the event horizon of a Garfinkle-Horowitz-Strominger (GHS) dilaton black hole. Contrary to the common expectation that maximally entangled states always provide superior quantum resources, our results show that their entanglement can be lower than that of suitably chosen non-maximally entangled states in this curved spacetime background. This reveals that non-maximally entangled states may offer operational advantages for entanglement-based tasks under gravitational effects. In contrast, quantum coherence exhibits monotonic behavior: larger initial coherence leads to systematically enhanced robustness against the dilaton induced degradation. These results indicate that the optimal choice of initial quantum states depends sensitively on the specific quantum resource, either quantum entanglement or quantum coherence, required for quantum information processing near a dilaton black hole. - oai:arXiv.org:2512.17535v1 - gr-qc + Reactive near-field subwavelength microwave imaging with a non-invasive Rydberg probe + https://arxiv.org/abs/2512.19116 + arXiv:2512.19116v1 Announce Type: new +Abstract: Non-invasive microwave field imaging--accurately mapping field distributions without perturbing them--is essential in areas such as aerospace engineering, biomedical imaging and integrated-circuit diagnostics. Conventional metal probes, however, inevitably perturb reactive near fields: they act as strong scatterers that drive induced currents and secondary radiation, remap evanescent components and thereby degrade both accuracy and spatial resolution, particularly in the reactive near-field regime that is most relevant to these applications. Here we demonstrate, to our knowledge for the first time, reactive near-field subwavelength imaging of microwave fields using the quantum non-demolition properties of Rydberg atoms, realized with a compact, non-invasive single-ended fibre-integrated Rydberg probe engineered to minimize field disturbance. The probe achieves an imaging resolution of {\unboldmath$\lambda/56$}, and the measured field distributions agree with full-wave simulations with structural similarity approaching unity, confirming both its subwavelength spatial resolution and its genuinely non-invasive character compared with conventional metal-based probes. Because the atomic sensor is intrinsically isotropic, the same device can faithfully image multi-dimensional field structures without orientation-dependent calibration. Our results therefore establish a general, non-invasive route to high-accuracy, subwavelength reactive near-field microwave imaging, with particular promise for applications such as chip-defect detection and integrated-circuit diagnostics, where even small perturbations by the probe can mask the underlying physics of interest. + oai:arXiv.org:2512.19116v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + physics.app-ph + physics.atom-ph + physics.ins-det + physics.optics + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Zhen Yang, He Cheng, Si-Han Li + Chaoyang Hu, Mingyong Jing, Zongkai Liu, Shaoxin Yuan, Bin Wu, Yan Peng, Tingting Li, Wenguang Yang, Junyao Xie, Hao Zhang, Liantuan Xiao, Suotang Jia, Linjie Zhang - Quantum state of interacting primordial inhomogeneities: de-squeezing and decoherence - https://arxiv.org/abs/2512.17622 - arXiv:2512.17622v1 Announce Type: cross -Abstract: We investigate how interactions affect the quantum state of scalar perturbations during inflation and the quantum correlations they may exhibit. Focusing on the case of scalar perturbations in single-field inflation, we model interactions using a Lindblad equation with a non-unitary contribution quadratic in the scalar perturbations, and of parametrisable amplitude and time dependence. We compute the quantum state of these interacting perturbations, which is fully described by its purity and squeezing parameters. First, we show that, in most of the parameter space, not only the purity but also the squeezing parameter is significantly reduced by interactions. Second, we show that this de-squeezing induced by the interactions, on top of the purity loss, causes a further suppression of quantum correlations. We thus emphasise that the quantum or classical character of the correlations exhibited by the perturbations cannot be correctly determined by computing the effect of interactions on the purity alone. Since the phenomenological framework adopted in this paper encompasses a wide class of possible interactions, our results provide general insights into the nature of decoherence processes in primordial fluctuations. - oai:arXiv.org:2512.17622v1 - hep-th - astro-ph.CO - gr-qc - hep-ph + Narrowband Frequency-Entangled Photon Source for Hong-Ou-Mandel Interferometry + https://arxiv.org/abs/2512.19129 + arXiv:2512.19129v1 Announce Type: new +Abstract: Hong-Ou-Mandel (HOM) interferometry with entangled photons exhibits distinctive quantum features. By introducing frequency entanglement (discrete-color entangled states) into HOM interference, the characteristic HOM dip is modulated by sinusoidal fringes, which significantly enhance the sensitivity of HOM sensors. The frequency-entangled photon sources demonstrated to date rely on non-resonant parametric down-conversion (PDC), which limits the photon coherence length and, consequently, restricts the sensing dynamic range to the sub-millimeter scale. In this work, we demonstrate narrowband frequency-entangled photon source based on resonant PDC in a crystalline whispering gallery mode resonator. The MHz-level spectral bandwidth of photons enables a meter-scale dynamic range. With highly nondegenerate frequency-entangled photon pairs featuring a 96 THz frequency detuning, we observe high-contrast quantum beating with sub-picosecond resolution in the HOM experiment. Our WGMR-based frequency-entangled photon source has potential applications in quantum metrology and quantum information processing. + oai:arXiv.org:2512.19129v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Amaury Micheli, Yuto Oshima, Tomo Takahashi + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Yen-Ju Chen, Sheng-Hsuan Huang, Thomas Dirmeier, Kaisa Laiho, Dmitry V. Strekalov, Andrea Aiello, Gerd Leuchs, Christoph Marquardt - $\Lambda$-Enhanced Gray Molasses Cooling of $^{85}$Rb Atoms in Tweezers Using the D$_2$ Line - https://arxiv.org/abs/2512.17653 - arXiv:2512.17653v1 Announce Type: cross -Abstract: We demonstrate the implementation of $\Lambda$-enhanced gray molasses cooling on the D$_2$ line of $^{85}$Rb atoms in an optical tweezer array. This technique yields lower atomic temperatures of 4.0(2) $\mu$K compared to red-detuned polarization gradient cooling, and consequently extends the $T_2^*$ coherence time of the hyperfine clock qubit by a factor of 1.5. The method is alignment-free and can be readily implemented on laser beams used for magneto-optical trapping, as it only requires frequency and phase modulation control. Our experimental observations are corroborated by a numerical model based on a semi-classical force approach extended to a four-level system, including two hyperfine states of the upper manifold that are 120 MHz apart. - oai:arXiv.org:2512.17653v1 - physics.atom-ph + Learning Hamiltonians for $O(1)$ Oracle-Query Quantum State Preparation + https://arxiv.org/abs/2512.19181 + arXiv:2512.19181v1 Announce Type: new +Abstract: We propose a Hamiltonian-based quantum state preparation method implemented via a shallow parametrized quantum circuit. The approach learns the parameters of a diagonal Hamiltonian through a classical training phase, while the quantum circuit itself performs only fixed-depth Hamiltonian evolution and mixing operations. With oracle access to the learned Hamiltonian parameters, $N$ classical data values can be encoded into $n=\log_2{N}$ qubits using $O(1)$ quantum queries, shifting the overall computational cost to an $O(N\log{N})$ classical preprocessing stage. For structured datasets generated by an underlying function, oracle access can be avoided by expressing the Hamiltonian in the Walsh basis and retaining only a polynomial number of significant terms. In this regime, quantum state preparation is achieved in $\text{poly}(n)$ time using $\text{poly}(n)$ parameters, reaching infidelities on the order of $10^{-5}$. By restricting the Hamiltonian to one-local and two-local terms, the method naturally yields hardware-efficient circuits suitable for near-term quantum devices. + oai:arXiv.org:2512.19181v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-sa/4.0/ - Deon Janse van Rensburg, Rogier Venderbosch, Yuri van der Werf, Jesus del Pozo Mellado, Marijn Venderbosch, Rianne Lous, Edgar Vredenbregt, Servaas Kokkelmans + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Mehdi Ramezani, Sina Asadiyan Zargar, Sadegh Salami, Abolfazl Bahrampour, Alireza Bahrampour - Signatures of coherent energy transfer and exciton delocalization in time-resolved optical cross correlations - https://arxiv.org/abs/2512.17741 - arXiv:2512.17741v1 Announce Type: cross -Abstract: We investigate how optical second-order cross correlations witness the quantum features of a prototype donor-acceptor light-harvesting unit. By considering a pair of detuned two-level emitters electronically coupled and incoherently driven to a non-equilibrium steady-state, we gain insight into how electronic quantum properties such as exciton eigenstate delocalization, coherent energy transfer and steady-state electronic coherence, are manifested in the joint probability of emission or optical second-order cross correlation. Specifically, we show that the frequency associated with oscillations present in time-resolved second-order cross correlation functions quantifies not only the time scale of coherent energy transfer but also the degree of delocalization of the exciton eigenstates. Furthermore, we show that time-resolved cross correlations directly witness steady-state electronic coherence. Our work strengthens the idea that measurements of the intensity quantum cross correlations can provide distinctive signatures of the quantum behavior of biophysical emitters. - oai:arXiv.org:2512.17741v1 - physics.chem-ph - physics.bio-ph + Quantifying superluminal signalling in Schr\"odinger-Newton model + https://arxiv.org/abs/2512.19260 + arXiv:2512.19260v1 Announce Type: new +Abstract: The Schr\"odinger-Newton equation aims at describing the dynamics of massive quantum systems subject to the gravitational self-interaction. As a deterministic nonlinear quantum wave equation, it is generally believed to conflict with the relativistic no-signalling principle. Here we challenge this viewpoint and show that it is of key importance to study the quantitative and operational character of the superluminal effects. To this end we employ a rigorous formalism of probability measures on spacetime and quantify the probability of a successful superluminal bit transfer via the single-particle Schr\"odinger-Newton equation. We demonstrate that such a quantity decreases with the increasing size and mass of the system. Furthermore, we prove that the Einstein-Dirac system, which yields the Schr\"odinger-Newton equation in the non-relativistic limit, is perfectly compatible with the relativistic causal structure. Our study demonstrates that the Schr\"odinger-Newton equation, which is by construction non-relativistic, is in fact `more compatible' with the no-signalling principle than the ordinary free Schr\"odinger equation. + oai:arXiv.org:2512.19260v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + gr-qc + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Julia Os\k{e}ka-Lenart, Marcin P{\l}odzie\'n, Maciej Lewenstein, Micha{\l} Eckstein + + + Limitations of Entangled Two-Photon Absorption detection + https://arxiv.org/abs/2512.19261 + arXiv:2512.19261v1 Announce Type: new +Abstract: We introduce a method for determining the sensitivity of any given Entangled Two-Photon Absorption (ETPA) measurement. By modeling all signal and noise contributions to the measurement, we derive a single numerical value that describes the sensitivity of the ETPA measurement in G\"oppert-Mayer units. This allows us to directly compare vastly different experimental approaches and, determine whether ETPA will be detectable under the given conditions. Therefore, we can quantify the effect of any change to a given experimental apparatus and identify the ideal optimization pathway. + oai:arXiv.org:2512.19261v1 + quant-ph + physics.optics + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Hallmann \'Oskar Gestsson, Alexandra Olaya-Castro + Ren\'e Pollmann, Franz Roeder, Christine Silberhorn, Benjamin Brecht - Methods and Tools for Secure Quantum Clouds with a specific Case Study on Homomorphic Encryption - https://arxiv.org/abs/2512.17748 - arXiv:2512.17748v1 Announce Type: cross -Abstract: The rise of quantum computing/technology potentially introduces significant security challenges to cloud computing, necessitating quantum-resistant encryption strategies as well as protection schemes and methods for cloud infrastructures offering quantum computing time and services (i.e. quantum clouds). This research explores various options for securing quantum clouds and ensuring privacy, especially focussing on the integration of homomorphic encryption (HE) into Eclipse Qrisp, a high-level quantum computing framework, to enhance the security of quantum cloud platforms. The study addresses the technical feasibility of integrating HE with Qrisp, evaluates performance trade-offs, and assesses the potential impact on future quantum cloud architectures.The successful implementation and Qrisp integration of three post-quantum cryptographic (PQC) algorithms demonstrates the feasibility of integrating HE with quantum computing frameworks. The findings indicate that while the Quantum One-Time Pad (QOTP) offers simplicity and low overhead, other algorithms like Chen and Gentry-Sahai-Waters (GSW) present performance trade-offs in terms of runtime and memory consumption. The study results in an overall set of recommendations for securing quantum clouds, e.g. implementing HE at data storage and processing levels, developing Quantum Key Distribution (QKD), and enforcing stringent access control and authentication mechanisms as well as participating in PQC standardization efforts. - oai:arXiv.org:2512.17748v1 - cs.CR + Sonified Quantum Seizures. Sonification of time series in epileptic seizures and simulation of seizures via quantum modelling + https://arxiv.org/abs/2512.19272 + arXiv:2512.19272v1 Announce Type: new +Abstract: We apply sonification strategies and quantum computing to the analysis of an episode of seizure. We first sonify the signal from a selection of channels (from real ECoG data), obtaining a polyphonic sequence. Then, we propose two quantum approaches to simulate a similar episode of seizure, and we sonify the results. The comparison of sonifications can give hints on similarities and discrepancies between real data and simulations, helping refine the \textit{in silico} model. This is a pioneering approach, showing how the combination of quantum computing and sonification can broaden the perspective of real-data investigation, and helping define a new test bench for analysis and prediction of seizures. + oai:arXiv.org:2512.19272v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + cs.ET + cs.SD + Tue, 23 Dec 2025 00:00:00 -0500 + new http://creativecommons.org/licenses/by/4.0/ - Aurelia Kusumastuti, Nikolay Tcholtchev, Philipp L\"ammel, Sebastian Bock, Manfred Hauswirth + Maria Mannone, Paulo Vitor Itaborai, Omar Costa Hamido, Miriam Goldack, Norbert Marwan, Peppino Fazio, Patrizia Ribino - Proximity effect in asymmetric-gap superconducting bilayers and regularization of transition rates - https://arxiv.org/abs/2512.17765 - arXiv:2512.17765v1 Announce Type: cross -Abstract: The standard mean-field treatment of low-temperature superconductors leads to a square-root divergent density of states at the gap value. This feature can lead to unphysical logarithmic divergences in various quantities, such as currents and qubit transition rates. We revisit their possible regularization based on the proximity effect between two superconducting films with different gaps. We derive analytical approximations for the density of states in each superconducting film. We find that the smearing of the density of states grows with the gap asymmetry. As a concrete example, we discuss the regularization of transition rates in qubits with frequency close to resonance with the gap asymmetry between the two films, and the consequent smoothening of the jump discontinuity in the qubit frequency shift. - oai:arXiv.org:2512.17765v1 - cond-mat.supr-con - cond-mat.mes-hall + Spectral Gap Estimation via Adiabatic Preparation + https://arxiv.org/abs/2512.19288 + arXiv:2512.19288v1 Announce Type: new +Abstract: Estimating energy gaps, i.e. the energy difference between two different states, in quantum systems is crucial for understanding their properties. Conventionally, spectral gap estimation relies on independently computing the ground-state and first-excited-state energies and then taking their difference. This work introduces an alternative procedure for estimating spectral gaps on digital quantum devices using the Adiabatic Preparation technique to create a specific superposition state. The expectation values of observables measured on such a state exhibit time-dependent fluctuations which, through a fitting process, can be used to estimate the energy gap. We successfully test our method on the 1D and 2D Ising models, and H2 and He2 molecules, implementing relatively shallow circuits both on noiseless and noisy simulators. The robustness of the approach is corroborated by additional experiments on the real IonQ Aria device for the 1D Ising model up to 20 qubits, demonstrating the applicability of the proposed method for currently available digital quantum devices and paving the way for more complex energy gap calculation requiring deeper circuits in the fault-tolerant era to come. + oai:arXiv.org:2512.19288v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - G. Marchegiani, G. Catelani + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Davide Cugini, Francesco Ghisoni, Angela Rosy Morgillo, Francesco Scala - Momentum correlations of the Hawking effect in a quantum fluid - https://arxiv.org/abs/2512.17807 - arXiv:2512.17807v1 Announce Type: cross -Abstract: The Hawking effect -- the spontaneous emission of correlated quanta from horizons -- can be observed in laboratory systems where an acoustic horizon forms when a fluid transitions from subcritical to supercritical flow. Although most theoretical and experimental studies have relied on real-space observables, the frequency-dependent nature of the Hawking process motivates a momentum-space analysis to access its spectral structure and entanglement features. Here, we numerically compute the momentum-space two-point correlation function in a quantum fluid using the truncated Wigner approximation, a general method applicable to both conservative and driven-dissipative systems. We consider a polaritonic fluid of light in a realistic configuration known to yield strong real-space correlations between Hawking, partner, and witness modes. We find signatures that are directly accessible in state-of-the-art experiments and offer a robust diagnostic of spontaneous emission. Our results form the basis for a new theoretical framework to assess a variety of effects, such as quasi-normal mode emission or modifications of the horizon structure on the Hawking spectrum. - oai:arXiv.org:2512.17807v1 - cond-mat.quant-gas - gr-qc + Quantum and classical algorithms for daily railway rolling stock circulation plans + https://arxiv.org/abs/2512.19340 + arXiv:2512.19340v1 Announce Type: new +Abstract: We study daily rolling stock circulation planning for electric multiple units (EMUs) on a regional passenger network, focusing on services where identical EMUs may be coupled in pairs on selected routes. Motivated by the operational needs of the regional operator Silesian Railways in Poland, we formulate an acyclic mixed-integer linear program on a one-day horizon that incorporates depot balance constraints, demand-driven seat and bicycle capacity limits (which is a new aspect requested by the regional operator and local society of passengers), and simple crew availability constraints. The model is designed to support both baseline planning and disruption management under increased passenger demand. Using a graph-hypergraph representation of trips and single or coupled EMU movements, we first solve the problem with a classical ILP solver. We then derive a Quadratic Unconstrained Binary Optimization (QUBO) reformulation - which is frequently used as the input for quantum optimization - and evaluate its solution by quantum annealing on D-Wave Advantage systems and by the classical quantum-inspired VeloxQ solver. Computational experiments on real-world instances from the Silesian network, with up to 404 train trips and 11 EMU types, show that the ILP approach can obtain high-quality daily circulation plans within at most about 40 minutes, whereas current quantum and quantum-inspired solvers are restricted to substantially smaller sub-instances (up to 51 and 78 train trips, respectively) due to embedding and QUBO size limitations. These results quantify the present frontier of QUBO-based methods for rolling stock circulation and point towards hybrid decision-support architectures in which quantum or quantum-inspired optimizers address only local subproblems within a broader classical planning framework. + oai:arXiv.org:2512.19340v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Marcos Gil de Olivera, Malo Joly, Antonio Z. Khoury, Alberto Bramati, Maxime J. Jacquet + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Ewa K\k{e}dziera, Wojciech Gamon, M\'aty\'as Koniorczyk, Zakaria Mzaouali, Andrea Galad\'ikov\'a, Krzysztof Domino - Effective Mass in Dissipative Coupled Polaritons - https://arxiv.org/abs/2512.17833 - arXiv:2512.17833v1 Announce Type: cross -Abstract: Dissipative coupling refers to the effect where two systems interact with each other mediated by dissipation channels. Recent advances in controlling light-matter systems have opened new avenues to explore non-Hermitian effects arising from dissipative coupling, such as level attraction and anomalous dispersions. In this work, we perform a parametric study of these effects in a polariton system, i.e., a light-matter superposition, under both dissipative and coherent coupling. We characterize the effects of different sources of non-Hermitian behavior and analytically identify the conditions for the emergence of negative effective mass, exceptional points, and bound states in the continuum as a function of the light-matter detuning, the coherent-to-dissipative coupling ratio, and the relative decay rate of the non-interacting subsystems. We also analyze the classical limit of the polariton system within a non-Hermitian framework, employing coherent states. - oai:arXiv.org:2512.17833v1 - cond-mat.mes-hall + The Perspectives of Non-Ideal Quantum Reference Frames + https://arxiv.org/abs/2512.19343 + arXiv:2512.19343v1 Announce Type: new +Abstract: We define the perspective of any quantum reference frame (QRF) and construct reversible transformations between different perspectives. This extends the framework of [arXiv:2110.13199] to non-ideal QRFs with finite resources such as energy or angular momentum. We derive a QRF's perspective starting from two physically motivated principles, leading to an incoherent group averaging approach. The perspective of a non-ideal QRF deviates significantly from that of a more intuitive ideal frame with infinite resources: Firstly, systems described relative to the QRF appear superselected. Secondly, the structure of the QRF perspective attests that successive operations on a system relative to the QRF leads to back-reaction onto the QRF due to its non-ideality. + oai:arXiv.org:2512.19343v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross + gr-qc + Tue, 23 Dec 2025 00:00:00 -0500 + new http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Diego A. Mendoza, Areli J. Vega-Carmona, Arturo Camacho-Guardian, Miguel A. Bastarrachea-Magnani + S\'ebastien Christophe Garmier, Ladina Hausmann, Esteban Castro-Ruiz - A Concept of Two-Point Propagation Field of a Single Photon: A Way to Picometer X-ray Displacement Sensing and Nanometer Resolution 3D X-ray Micro-Tomography - https://arxiv.org/abs/2512.17863 - arXiv:2512.17863v1 Announce Type: cross -Abstract: We introduce the two-point propagation field (TPPF), a real-valued, phase-sensitive quantity defined as the functional derivative of the single-photon detection probability with respect to an infinitesimal opaque perturbation placed between source and detection slits. The TPPF is analytically derived and shown to exhibit a stable, high-frequency sinusoidal structure (6.7 nm period) near the detection slit. This structure enables shot-noise-limited displacement sensing at ~15 pm precision using routinely available synchrotron fluxes and practical nanofabricated slit/comb geometries, requiring mechanical stability only over the final 0.5 mm. The same principle provides a foundation for future nanometer-resolution 3D X-ray microtomography of bulk samples, potentially resulting in a reduced radiation dose. Two conceptual strategies, a central blocker and off-axis multi-slit arrays, are estimated to lower the required incident fluence by more than one order of magnitude each, yielding combined reductions of two to three orders of magnitude with near-term detector development. The TPPF concept, originally developed in a perturbative study of single-particle propagation, thus bridges fundamental quantum measurement questions with practical high-resolution X-ray metrology and imaging. - oai:arXiv.org:2512.17863v1 - physics.optics + Lorentz Invariant Master Equation for Quantum Systems + https://arxiv.org/abs/2512.19346 + arXiv:2512.19346v1 Announce Type: new +Abstract: Irreversibility implies a preferred flow of time, yet special relativity denies the existence of a preferred clock. This tension has long obstructed the formulation of a relativistic master equation: standard Markovian approximations either break Lorentz covariance, trigger catastrophic vacuum heating, or depend arbitrarily on the observer's foliation. In this work, we derive a Lorentz-invariant description of irreversibility for quantum fields. We take an approach that explicitly models the measurements required to observe irreversible dynamics. Instead of evolving the system along an abstract geometric time parameter, we anchor the dynamics to a physical, relational scalar clock field. Using a relational Tomonaga-Schwinger framework, we derive a local, non-Markovian master equation that is manifestly covariant and completely positive. We show that the finite resolution of the physical clock acts as a covariant regulator, preventing the vacuum instability that plagues white-noise models. This framework demonstrates that a consistent relativistic theory of decay exists, provided the reference frame is treated as a dynamical quantum resource rather than a gauge choice. In a gravitating context, the resulting dynamics is described by a hybrid classical-quantum (CQ) evolution that remains completely positive and trace preserving (CPTP). + oai:arXiv.org:2512.19346v1 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Li Hua Yu + gr-qc + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Pranav Vaidhyanathan, Gerard J. Milburn + + + Clifford Volume and Free Fermion Volume: Complementary Scalable Benchmarks for Quantum Computers + https://arxiv.org/abs/2512.19413 + arXiv:2512.19413v1 Announce Type: new +Abstract: As quantum computing advances toward the late-NISQ and early fault-tolerant eras, scalable and platform-independent benchmarks are essential for quantifying computational capacity in a classically verifiable manner. We introduce two volumetric benchmarks, Clifford Volume and Free Fermion Volume, that assess quantum hardware by testing the execution of random Clifford and free fermion operations. These two groups of unitaries possess a combination of properties that make them ideal for benchmarking: (i) each is individually efficient to simulate classically, enabling verification at scale; (ii) together they form a universal gate set; (iii) they serve as essential algorithmic primitives in practical applications (including shadow tomography and quantum chemistry); and (iv) their definitions are formulated abstractly, without explicit reference to hardware-specific features such as qubit connectivity or native gate sets. This framework thus enables scalable and fair cross-platform comparisons and tracks meaningful computational advancement. We demonstrate the practical feasibility of these benchmarks through extensive numerical simulations across realistic noise parameters and through experimental validation on Quantinuum's H2-1 trapped-ion quantum computer, which achieves a Clifford Volume of 34. + oai:arXiv.org:2512.19413v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Attila Portik, Orsolya K\'alm\'an, Thomas Monz, Zolt\'an Zimbor\'as + + + Generative Krylov Subspace Representations for Scalable Quantum Eigensolvers + https://arxiv.org/abs/2512.19420 + arXiv:2512.19420v1 Announce Type: new +Abstract: Predicting ground state energies of quantum many-body systems is one of the central computational challenges in quantum chemistry, physics, and materials science. Krylov subspace methods, such as Krylov Quantum Diagonalization and Sample-based Krylov Quantum Diagonalization, are promising approaches for this task on near-term quantum computers. However, both require repeated quantum circuit executions for each Krylov subspace and for every new Hamiltonian, posing a major bottleneck under noisy hardware constraints. We introduce Generative Krylov Subspace Representations (GenKSR), a framework that learns a classical generative representation of the entire Krylov diagonalization process. To enable effective modeling of quantum systems, GenKSR leverages a conditional generative model framework. We investigate two representative backbone architectures, the standard Transformer and the Mamba state-space model. By learning the distribution of measurement outcomes conditioned on Hamiltonian parameters and evolution time, GenKSR generates Krylov subspace samples for unseen Hamiltonians and for larger subspace dimensions than those used in training. This enables full energy reconstruction purely from the classical model, without additional quantum experiments. We validate our approach through simulations of 15-qubit 1D and 16-qubit 2D Heisenberg models, as well as a hardware experiment on a 20-qubit XXZ chain executed on an IBM quantum processor. Our model successfully learns the distribution from experimental data and generates a high-fidelity representation of the quantum process. This representation enables classical reproduction of experimental outcomes, supports reliable energy estimates for unseen Hamiltonians, and significantly reduces the need for further quantum computation. + oai:arXiv.org:2512.19420v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Changwon Lee, Daniel K. Park + + + Harnessing non-Hermiticity for efficient quantum state transfer + https://arxiv.org/abs/2512.19490 + arXiv:2512.19490v1 Announce Type: new +Abstract: The non-Hermitian Hamiltonian describes the effective dynamics of a system coupled to a continuously measured bath, and can exhibit anti-unitary symmetries that give rise to exceptional points and broken phases with complex eigenvalues, features unique to non-Hermitian systems. Going beyond conventional Hermitian physics, we analyze the impact of non-Hermiticity in the quantum state transmission by employing a non-Hermitian spin chain that functions as a quantum data bus. By deriving a general expression for the fidelity of quantum state transfer for a U(1)-symmetric non-Hermitian Hamiltonian, we analyze PT-symmetric XX and SSH models, complemented by a numerical study of the RT-symmetric iXY model. We demonstrate that, in several parameter regimes, the transfer fidelity in the non-Hermitian setting exceeds the classical threshold and can even exceed the performance of the corresponding Hermitian models. In particular, for the SSH model with dominant inter-cell coupling, the broken phase supports near-unit-fidelity quantum state transfer, a level of performance that the corresponding Hermitian model fails to attain. Moreover, we establish a correspondence between the non-Hermitian and Hermitian descriptions by identifying related parameter regions in which the fidelity fails to surpass the classical bound. + oai:arXiv.org:2512.19490v1 + quant-ph + cond-mat.str-el + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Sejal Ahuja, Keshav Das Agarwal, Aditi Sen De + + + $W$- and Dicke-state engineering using optimal global control in nearest-neighbor coupled ring-shaped qubit arrays + https://arxiv.org/abs/2512.19545 + arXiv:2512.19545v1 Announce Type: new +Abstract: Motivated by a compelling need for time-efficient and robust schemes for quantum-state engineering in systems of neutral atoms in optical tweezers, we consider a ring-shaped array of qubits with nearest-neighbor Ising-type ($zz$) coupling and transverse ($x$ and $y$) global control fields. This system to a large extent mimics -- outside of the Rydberg-blockade regime -- a circular array of neutral atoms interacting through van-der-Waals type interaction. We investigate the preparation of $W$ and Dicke states in this system starting from the default initial state $|00\ldots 0\rangle$ using two different optimal-control approaches: (i) NMR-like pulse sequence, which consists of instantaneous (delta-shaped) control- and Ising-interaction pulses, and (ii) time-dependent control scheme, which entails shaped control pulses in the presence of always-on Ising interaction between adjacent qubits. By making use of the underlying dihedral symmetry of this system -- which allows one to use a symmetry-adapted computational basis with $\mathcal{O}(2^N / N)$ states in an $N$-qubit system -- and utilizing advanced global-optimization methods, we find optimal sequences of pulses for realizing $W$ and Dicke states within both approaches. In addition, we demonstrate robustness of these sequences against unavoidable control errors. Finally, using typical values of parameters in realistic Rydberg-atom systems, we show that our control schemes enable the preparation of the desired multiqubit states on time scales much shorter than the relevant coherence times of those systems. + oai:arXiv.org:2512.19545v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Andrea Muratori, Vladimir M. Stojanovic, Eloisa Cuestas, Tommaso Calarco, Felix Motzoi + + + A Spin-Photon Interface in the Telecom C-Band with Long Hole Spin Dephasing Time + https://arxiv.org/abs/2512.19561 + arXiv:2512.19561v1 Announce Type: new +Abstract: Matter qubits that maintain coherence over extended timescales are essential for many pursued applications in quantum communication and quantum computing. Significant progress has already been made on extending coherence times of spins in semiconductor quantum dots while interfacing them with photons in the near-infrared wavelength range. However, similar results for quantum dots emitting at the telecom range, crucial for many applications, have so far lagged behind. Here, we report on InAs/InAlGaAs quantum dots integrated in a deterministically placed circular Bragg grating emitting at $1.55\,\mu\mathrm{m}$. We quantify the g-factors of electrons and holes from polarization-resolved measurements of a positive trion in an in-plane magnetic field and study the dynamics of the ground-state hole spin qubit. We then herald the hole spin in a pulsed two-photon correlation measurement and determine its inhomogeneous dephasing time to $T_{2}^{*}=(15.9 \pm 1.7)$ ns. + oai:arXiv.org:2512.19561v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Johannes M. Michl, Reza Hekmati, Mohamed Helal, Giora Peniakov, Yorick Reum, Jochen Kaupp, Quirin Buchinger, Jaewon Kim, Andreas T. Pfenning, Yong-Hoon Cho, Sven H\"ofling, Tobias Huber-Loyola + + + Trigonometric continuous-variable gates and hybrid quantum simulations + https://arxiv.org/abs/2512.19582 + arXiv:2512.19582v1 Announce Type: new +Abstract: Hybrid qubit-qumode quantum computing platforms provide a natural setting for simulating interacting bosonic quantum field theories. However, existing continuous-variable gate constructions rely predominantly on polynomial functions of canonical quadratures. In this work, we introduce a complementary universality paradigm based on trigonometric continuous-variable gates, which enable a Fourier-like representation of bosonic operators and are particularly well suited for periodic and non-perturbative interactions. We present a deterministic ancilla-based method for implementing unitary and non-unitary trigonometric gates whose arguments are arbitrary Hermitian functions of qumode quadratures. As a concrete application, we develop a hybrid qubit-qumode quantum simulation of the lattice sine-Gordon model. Using these gates, we prepare ground states via quantum imaginary-time evolution, simulate real-time dynamics, compute time-dependent vertex two-point correlation functions, and extract quantum kink profiles under topological boundary conditions. Our results demonstrate that trigonometric continuous-variable gates provide a physically natural framework for simulating interacting field theories on near-term hybrid quantum hardware, while establishing a parallel route to universality beyond polynomial gate constructions. We expect that the trigonometric gates introduced here to find broader applications, including quantum simulations of condensed matter systems, quantum chemistry, and biological models. + oai:arXiv.org:2512.19582v1 + quant-ph + hep-lat + hep-ph + nucl-th + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Tommaso Rainaldi, Victor Ale, Matt Grau, Dmitri Kharzeev, Enrique Rico, Felix Ringer, Pubasha Shome, George Siopsis + + + Extracting quantum field theory dynamics from an approximate ground state + https://arxiv.org/abs/2512.19594 + arXiv:2512.19594v1 Announce Type: new +Abstract: We develop a linear-programming method to extract dynamical information from static ground-state correlators in quantum field theory. We recast the K\"all\'en-Lehmann inversion as a convex optimization problem, in a spirit similar to the recent approach of Lawrence [arXiv:2408.11766]. This produces robust estimates of the smeared spectral density, the real-time propagator, and the mass gap directly from an approximate equal-time two-point function, and simultaneously yields an \emph{a posteriori} lower bound on the correlation-function error. We test the method on the $1+1$-dimensional $\phi^4$ model, using a variational approximation to the vacuum -- relativistic continuous matrix product states -- that provides accurate correlators in the continuum and thermodynamic limits. The resulting mass gaps agree with renormalized Hamiltonian truncation and Borel-resummed perturbation theory across a wide range of couplings, demonstrating that accurate dynamical data can be recovered from a single equal-time slice. + oai:arXiv.org:2512.19594v1 + quant-ph + hep-lat + hep-th + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Sophie Mutzel, Antoine Tilloy + + + Input phase noise in Gaussian Boson sampling + https://arxiv.org/abs/2512.19596 + arXiv:2512.19596v1 Announce Type: new +Abstract: Gaussian boson sampling is an important protocol for testing the performance of photonic quantum simulators. As such, various noise sources have been investigated that degrade the operation of such devices. In this paper, we examine a situation with phase noise between different modes of the input state leading to dephasing of the system. This models the phase fluctuations which remain even when the mean phase is controlled. We aim to determine whether these phase-noisy input states still form a computationally difficult problem. To do this, we use Matrix Product Operators to model the system, a technique recently used to model boson sampling scenarios. Our investigation finds that the Entanglement entropy grows linearly with the number of input states even for noisy input states. This implies that, unlike boson loss, this form of experimentally relevant noise remains difficult to simulate with tensor networks and may allow for the demonstration of quantum advantage without the need for implementing the challenging task of input-state phase stabilisation. + oai:arXiv.org:2512.19596v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Magdalena Par\'yzkov\'a (FNSPE, Czech Technical University in Prague, B\v{r}ehov\'a 7, 119 15, Praha 1, Czech Republic), Craig S. Hamilton (FNSPE, Czech Technical University in Prague, B\v{r}ehov\'a 7, 119 15, Praha 1, Czech Republic), Igor Jex (FNSPE, Czech Technical University in Prague, B\v{r}ehov\'a 7, 119 15, Praha 1, Czech Republic), Michael Stefszky (Integrated Quantum Optics, Universit\"at Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany), Christine Silberhorn (Integrated Quantum Optics, Universit\"at Paderborn, Warburger Strasse 100, 33098 Paderborn, Germany) + + + Nonequilibrium quantum thermometry with noncommutative system-bath couplings + https://arxiv.org/abs/2512.19607 + arXiv:2512.19607v1 Announce Type: new +Abstract: Accurate temperature estimation in the quantum and cryogenic regimes remains a fundamental challenge. Here, we investigate nonequilibrium quantum thermometry using a single-qubit probe coupled to a bosonic bath through noncommuting interaction operators, which unify pure dephasing and dissipative dynamics within a spin-boson model. We show that the interference between these two coupling channels induces strong non-Markovian feedback between populations and coherences, leading to coherence trapping and enhanced thermal sensitivity. Remarkably, by tuning the coupling structure, the probe's temperature sensitivity exhibits a quadratic low-temperature scaling, even under weak coupling. Moreover, while coherence-based measurements are formally suboptimal, they become the most informative in the early nonequilibrium regime, where memory effects dominate. Our findings identify noncommutative system-bath couplings as a practical and tunable resource for achieving high-precision quantum thermometry in realistic open-system architectures. + oai:arXiv.org:2512.19607v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + 10.1103/prs2-jcxj + Phys. Rev. A 112, 062229 (2025) + Youssef Aiache, Abderrahim El Allati, \.Ilkay Demir, Khadija El Anouz + + + Quantum circuit algorithm for topological invariants of second order topological many-body quantum magnets + https://arxiv.org/abs/2512.19615 + arXiv:2512.19615v1 Announce Type: new +Abstract: Topological quantum matter represents a flexible playground to engineer unconventional excitations. While non-interacting topological single-particle systems have been studied in detail, topology in quantum many-body systems remains an open problem. Specifically, in the quantum many-body limit, one of the challenges lies in the computational complexity of obtaining the many-body ground state and its many-body topological invariant. While algorithms to compute ground states with quantum computers have been heavily investigated, algorithms to compute topological invariants in a quantum computer are still under active development. Here we demonstrate a quantum circuit to compute the many-body topological invariant of a second-order topological quantum magnet encoded in qubits. Our algorithm relies on a quantum circuit adiabatic evolution in transverse paths in parameter space, and we uncover hidden topological invariants depending on the traversed path. Our work puts forward an algorithm to leverage quantum computers to characterize many-body topological quantum matter. + oai:arXiv.org:2512.19615v1 + quant-ph + cond-mat.mes-hall + cond-mat.str-el + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Sebasti\'an Dom\'inguez-Calder\'on, Marcel Niedermeier, Jose L. Lado, Pascal M. Vecsei + + + Quantifying Decoherence + https://arxiv.org/abs/2512.19617 + arXiv:2512.19617v1 Announce Type: new +Abstract: Quantum decoherence refers to the phenomenon when the interaction of a quantum system with its environment results in the degradation of quantum coherence. Decoherence is considered to be the most popular mechanism responsible for the emergence of classicality from quantum mechanics. The issue of formulating a measure of decoherence is addressed here. The approach taken here is that decoherence results from the entanglement of a quantum system with certain environment degrees of freedom, and quantifying this entanglement should yield the most natural measure of decoherence. A simple measure of decoherence is presented based on this notion, and it is examined for various example systems. The measure proves to be effective and is relatively straightforward to compute. In addition, a method has been proposed to measure decoherence in a Mach-Zehnder interferometer. + oai:arXiv.org:2512.19617v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Mohd Shoaib Qureshi, Tabish Qureshi + + + Exponential-to-polynomial scaling of measurement overhead in circuit knitting via quantum tomography + https://arxiv.org/abs/2512.19623 + arXiv:2512.19623v1 Announce Type: new +Abstract: Circuit knitting is a family of techniques that enables large quantum computations on limited-size quantum devices by decomposing a target circuit into smaller subcircuits. However, it typically incurs a measurement overhead exponential in the number of cut locations, and it remains open whether this scaling is fundamentally unavoidable. In conventional circuit-cutting approaches based on the quasiprobability decomposition (QPD), for example, rescaling factors lead to an exponential dependence on the number of cuts. In this work, we show that such an exponential scaling is not universal: it can be circumvented for tree-structured quantum circuits via concatenated quantum tomography protocols. We first consider estimating the expectation value of an observable within additive error $\epsilon$ for a tree-structured circuit with tree depth 1 (two layers), maximum branching factor $R$, and bond dimension at most $d$ on each edge. Our approach uses quantum tomography to construct, for each cut edge, a local decomposition that eliminates the rescaling factors in conventional QPD, instead introducing a controllable bias set by the tomography sample size. After cutting $R$ edges, we show that $\mathcal{O}(d^3R^3\ln(dR)/\epsilon^2)$ total measurements suffice, including tomography cost. Next, we extend the tree-depth-1 case to general trees of depth $L\geq2$, and give an algorithm whose total measurement cost $\tilde{\mathcal{O}}(d^3K^{5}/\epsilon^2)$ scales polynomially with the number of cuts for complete $R$-ary trees. Finally, we perform an information-theoretic analysis to show that, in a comparable tree-depth-1 setting, conventional QPD-based wire-cutting methods require at least $\Omega((d+1)^R/\epsilon^2)$ measurements. This exponential separation highlights the significance of tomography-based construction for reducing measurement overhead in hybrid quantum-classical computations. + oai:arXiv.org:2512.19623v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Hiroyuki Harada, Kaito Wada, Naoki Yamamoto, Suguru Endo + + + Quantum Imaging of Birefringent Samples using Hong-Ou-Mandel Interference + https://arxiv.org/abs/2512.19637 + arXiv:2512.19637v1 Announce Type: new +Abstract: Two-photon interference in a Hong-Ou-Mandel (HOM) interferometer can be used as a quantum sensing mechanism due to the sensitivity of the interference dip to perturbations of the photon indistinguishability. In particular, recent works have generalized this concept to microscopy setups, but the sensitivity to optical path differences constrains its application to samples with thickness variation typically below a few micrometers if tracking changes in the coincidences at a fixed delay. Extending the concept to polarization microscopy and circumventing this limitation, this manuscript explores the use of a narrowband photon pair source with coherence length >1 mm to broaden the HOM dip. Thus, realistic sample-thickness variations introduce negligible temporal distinguishability, and changes in coincidence rate at the dip centre are then dominated by sample-induced polarization effects. To compute the polarization rotation, we develop a statistical model for the interferometer, derive the Fisher information, and establish a maximum-likelihood estimator for the local fast-axis angle. Recording dip and baseline frames at each sample position via raster scanning, the experimental results validate the framework, agreeing with classical polarized-intensity images while demonstrating operation at a maximum-precision regime and insensitiveness to layer thickness. Overall, the approach enclosed provides a quantum-based quantitative imaging of birefringent structures, which can motivate further advantageous applications, including enhanced signal-to-noise ratio and lower damage imaging of photosensitive samples. + oai:arXiv.org:2512.19637v1 + quant-ph + physics.optics + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://creativecommons.org/licenses/by/4.0/ + Carolina Gon\c{c}alves, Tiago D. Ferreira, Catarina S. Monteiro, Nuno A. Silva + + + The EU Quantum Flagship's Key Performance Indicators for Quantum Computing + https://arxiv.org/abs/2512.19653 + arXiv:2512.19653v1 Announce Type: new +Abstract: As quantum processors continue to scale in size and complexity, the need for well-defined, reproducible, and technology-agnostic performance metrics becomes increasingly critical. Here we present a suite of scalable quantum computing benchmarks developed as key performance indicators (KPIs) within the EU Quantum Flagship. These proposed benchmarks are designed to assess holistic system performance rather than isolated components, and to remain applicable across both noisy intermediate-scale quantum (NISQ) devices and future fault-tolerant architectures. We introduce four core benchmarks addressing complementary aspects of quantum computing capability: large multi-qubit circuit execution via a Clifford Volume benchmark, scalable multipartite entanglement generation through GHZ-state preparation, a benchmark based on the application of Shor's period-finding subroutine to simple functions, and a protocol quantifying the benefit of quantum error correction using Bell states. Each benchmark is accompanied by clearly specified protocols, reporting standards, and scalable evaluation methods. Together, these KPIs provide a coherent framework for transparent and fair performance assessment across quantum hardware platforms and for tracking progress late-NISQ toward early fault-tolerant quantum computation. + oai:arXiv.org:2512.19653v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Zolt\'an Zimbor\'as, Attila Portik, David Aguirre, Rub\'en Pe\~na, Domonkos Svastits, Andr\'as P\'alyi, \'Aron M\'arton, J\'anos K. Asb\'oth, Anton Frisk Kockum, Mikel Sanz, Orsolya K\'alm\'an, Thomas Monz, Frank Wilhelm-Mauch + + + Extremizing Measures of Magic on Pure States by Clifford-stabilizer States + https://arxiv.org/abs/2512.19657 + arXiv:2512.19657v1 Announce Type: new +Abstract: Magic states are essential resources enabling universal, fault-tolerant quantum computation within the stabilizer framework. Their non-stabilizerness provides the additional resource required to overcome the constraints of stabilizer codes, as formalized by the Eastin-Knill theorem, while still permitting fault-tolerant distillation. Although numerous measures of magic have been introduced, not every state with nonzero magic has been shown to be distillable by a stabilizer code, and all currently known distillable states arise as special cases of Clifford-stabilizer states, defined as pure states uniquely stabilized by finite subgroups of the Clifford group. In this work, we develop a general framework for group-covariant functionals on the real manifold of Hermitian operators. We formalize the notions of $G$-stabilizer spaces, states, and codes for arbitrary finite subgroups $G \subset \mathrm{U}(\mathcal{H})$, and introduce analytic families of $G$-covariant functionals. Our main theorem shows that any $G$-invariant pure state is an extremal point of a broad class of derived functionals, including symmetric, max-type, and R\'enyi-type functionals, provided the underlying family is $G$-covariant. This extremality holds for variations restricted to directions orthogonal to the stabilized subspace while preserving purity. Specializing to the Pauli and Clifford groups, our framework unifies the extremality structure of several canonical magic measures, including mana, stabilizer R\'enyi entropies, and stabilizer fidelity. In particular, Clifford-stabilizer states extremize these measures. We classify such states for qubits, qutrits, ququints, and two-qubit systems, identifying new candidates for magic distillation protocols. We further propose an inefficient distillation protocol for a two-qubit magic state with stabilizer fidelity exceeding that of standard benchmark states. + oai:arXiv.org:2512.19657v1 + quant-ph + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Muhammad Erew, Moshe Goldstein + + + QuSquare: Scalable Quality-Oriented Benchmark Suite for Pre-Fault-Tolerant Quantum Devices + https://arxiv.org/abs/2512.19665 + arXiv:2512.19665v1 Announce Type: new +Abstract: As quantum technologies continue to advance, the proliferation of hardware architectures with diverse capabilities and limitations has underscored the importance of benchmarking as a tool to compare performance across platforms. Achieving fair, scalable and consistent evaluations is a key open problem in quantum computing, particularly in the pre-fault-tolerant era. To address this challenge, we introduce QuSquare, a quality-oriented benchmark suite designed to provide a scalable, fair, reproducible, and well-defined framework for assessing the performance of quantum devices across hardware architectures. QuSquare consists of four benchmark tests that evaluate quantum hardware performance at both the system and application levels: Partial Clifford Randomized, Multipartite Entanglement, Transverse Field Ising Model (TFIM) Hamiltonian Simulation, and Data Re-Uploading Quantum Neural Network (QNN). Together, these benchmarks offer an integral, hardware-agnostic, and impartial methodology to quantify the quality and capabilities of current quantum computers, supporting fair cross-platform comparisons and fostering the development of future performance standards. + oai:arXiv.org:2512.19665v1 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + David Aguirre, Rub\'en Pe\~na, Mikel Sanz + + + Partition Function Estimation Using Analog Quantum Processors + https://arxiv.org/abs/2512.19685 + arXiv:2512.19685v1 Announce Type: new +Abstract: We evaluate using programmable superconducting flux qubit D-Wave quantum annealers to approximate the partition function of Ising models. We propose the use of two distinct quantum annealer sampling methods: chains of Monte Carlo-like reverse quantum anneals, and standard linear-ramp quantum annealing. The control parameters used to attenuate the quality of the simulations are the effective analog energy scale of the J coupling, the total annealing time, and for the case of reverse annealing the anneal-pause. The core estimation technique is to sample across the energy spectrum of the classical Hamiltonian of interest, and therefore obtain a density of states estimate for each energy level, which in turn can be used to compute an estimate of the partition function with some sampling error. This estimation technique is powerful because once the distribution is sampled it allows thermodynamic quantity computation at arbitrary temperatures. On a $25$ spin $\pm J$ hardware graph native Ising model we find parameter regimes of the D-Wave processors that provide comparable result quality to two standard classical Monte Carlo methods, Multiple Histogram Reweighting and Wang-Landau. Remarkably, we find that fast quench-like anneals can quickly generate ensemble distributions that are very good estimates of the true partition function of the classical Ising model; on a Pegasus graph-structured QPU we report a logarithmic relative error of $7.6 \times 10^{-6}$, from $171,000$ samples generated using $0.2$ seconds of QPU time with an anneal time of $8$ nanoseconds per sample which is interestingly within the closed system dynamics timescale of the superconducting qubits. + oai:arXiv.org:2512.19685v1 + quant-ph + cond-mat.dis-nn + cond-mat.stat-mech + physics.comp-ph + Tue, 23 Dec 2025 00:00:00 -0500 + new + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Thinh Le, Elijah Pelofske + + + A proof-of-principle experiment on the spontaneous symmetry breaking machine and numerical estimation of its performance on the $K_{2000}$ benchmark problem + https://arxiv.org/abs/2512.17922 + arXiv:2512.17922v1 Announce Type: cross +Abstract: In a previous paper, we proposed a unique physically implemented type simulator for combinatorial optimization problems, called the spontaneous symmetry breaking machine (SSBM). In this paper, we first report the results of experimental verification of SSBM using a small-scale benchmark system, and then describe numerical simulations using the benchmark problems (K2000) conducted to confirm its usefulness for large-scale problems. From 1000 samples with different initial fluctuations, it became clear that SSBM can explore a single extremely stable state. This is based on the principle of a phenomenon used in SSBM, and could be a notable advantage over other simulators. + oai:arXiv.org:2512.17922v1 + math.OC + nlin.AO + physics.optics + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Toshiya Sato, Takashi Goh + + + Subcellular Metabolic Tracking Using Fluorescent Nanodiamonds Relaxometry + https://arxiv.org/abs/2512.17931 + arXiv:2512.17931v1 Announce Type: cross +Abstract: Fluorescent nanodiamonds (FNDs) relaxometry holds promising future for advancement of high spatiotemporal resolution metabolic imaging technology. In this study, we demonstrate a simultaneous integration of spatial position tracking with FND relaxometry to characterize the temporal dynamics of metabolic processes, thereby enhancing the capability to monitor cellular activities over time. To enable targeted metabolic probing in living cells, FNDs were surface-functionalized to achieve specific localization within key organelles, including the nucleus and mitochondria. This strategy not only facilitates subcellular-level metabolic monitoring but also allows for direct comparison between intra- and extranuclear microenvironments within the same living cell, offering substantial potential for elucidating the spatial and functional heterogeneity of cellular metabolism. + oai:arXiv.org:2512.17931v1 + physics.bio-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1002/adfm.202527416 + Advanced Functional Materials 2025 + Jia Su, Linyu Zeng, Pengyu Chen, Zenghao Kong, Fazhan Shi + + + Quantum simulation of deep inelastic scattering in the Schwinger model + https://arxiv.org/abs/2512.18062 + arXiv:2512.18062v1 Announce Type: cross +Abstract: Hadronic tensors encode the nonperturbative structure of hadrons probed in deep inelastic scattering (DIS), yet their direct evaluation requires real-time evolution that presents a challenge for traditional Euclidean lattice approaches. In this work, we present the first study of the hadronic tensors in DIS using quantum simulation in the Schwinger model, i.e (1+1)-dimensional QED. Using two complementary quantum-simulation strategies -- quantum-circuit and tensor-network methods -- we compute the real-time current-current correlator directly on the lattice and validate our results against exact diagonalization where applicable. From this correlator, we compute the hadronic tensor and determine the longitudinal structure function, the sole nonvanishing DIS observable in two space-time dimensions. Our study demonstrates that quantum simulation offers a viable complementary pathway towards the evaluation of real-time observables relevant for hadronic structure. It also provides a foundation for extending the calculations from Schwinger model to other gauge theories. + oai:arXiv.org:2512.18062v1 + hep-ph + hep-lat + nucl-th + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Kazuki Ikeda, Zhong-Bo Kang, Dmitri E. Kharzeev, Wenyang Qian + + + Optimization of Si/SiGe Heterostructures for Large and Robust Valley Splitting in Silicon Qubits + https://arxiv.org/abs/2512.18064 + arXiv:2512.18064v1 Announce Type: cross +Abstract: The notoriously low and fluctuating valley splitting is one of the key challenges for electron spin qubits in silicon (Si), limiting the scalability of Si-based quantum processors. In silicon-germanium (SiGe) heterostructures, the problem can be addressed by the design of the epitaxial layer stack. Several heuristic strategies have been proposed to enhance the energy gap between the two nearly degenerate valley states in strained Si/SiGe quantum wells (QWs), e.g., sharp Si/SiGe interfaces, Ge spikes or oscillating Ge concentrations within the QW. In this work, we develop a systematic variational optimization approach to compute optimal Ge concentration profiles that boost selected properties of the intervalley coupling matrix element. Our free-shape optimization approach is augmented by a number of technological constraints to ensure feasibility of the resulting epitaxial profiles. The method is based on an effective-mass-type envelope-function theory accounting for the effects of strain and compositional alloy disorder. Various previously proposed heterostructure designs are recovered as special cases of the constrained optimization problem. Our main result is a novel heterostructure design we refer to as the "modulated wiggle well," which provides a large deterministic enhancement of the valley splitting along with a reliable suppression of the disorder-induced volatility. In addition, our new design offers a wide-range tunability of the valley splitting ranging from about 200 $\mu$eV to above 1 meV controlled by the vertical electric field, which offers new perspectives to engineer switchable qubits with on-demand adjustable valley splitting. + oai:arXiv.org:2512.18064v1 + cond-mat.mes-hall + math.OC + physics.app-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Abel Thayil, Lasse Ermoneit, Lars R. Schreiber, Thomas Koprucki, Markus Kantner + + + Benchmarking the Impact of Active Space Selection on the VQE Pipeline for Quantum Drug Discovery + https://arxiv.org/abs/2512.18203 + arXiv:2512.18203v1 Announce Type: cross +Abstract: Quantum computers promise scalable treatments of electronic structure, yet applying variational quantum eigensolvers (VQE) on realistic drug-like molecules remains constrained by the performance limitations of near-term quantum hardwares. A key strategy for addressing this challenge which effectively leverages current Noisy Intermediate-Scale Quantum (NISQ) hardwares yet remains under-benchmarked is active space selection. We introduce a benchmark that heuristically proposes criteria based on chemically grounded metrics to classify the suitability of a molecule for using quantum computing and then quantifies the impact of active space choices across the VQE pipeline for quantum drug discovery. The suite covers several representative drug-like molecules (e.g., lovastatin, oseltamivir, morphine) and uses chemically motivated active spaces. Our VQE evaluations employ both simulation and quantum processing unit (QPU) execution using unitary coupled-cluster with singles and doubles (UCCSD) and hardware-efficient ansatz (HEA). We adopt a more comprehensive evaluation, including chemistry metrics and architecture-centric metrics. For accuracy, we compare them with classical quantum chemistry methods. This work establishes the first systematic benchmark for active space driven VQE and lays the groundwork for future hardware-algorithm co-design studies in quantum drug discovery. + oai:arXiv.org:2512.18203v1 + physics.chem-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Zhi Yin, Xiaoran Li, Zhupeng Han, Shengyu Zhang, Xin Li, Zhihong Zhang, Runqing Zhang, Anbang Wang, Xiaojin Zhang + + + Symmetry breaking transforms strong to normal correlation and false metals to true insulators + https://arxiv.org/abs/2512.18236 + arXiv:2512.18236v1 Announce Type: cross +Abstract: Material scientists and condensed matter physicists have long been divided on the issue of choosing the conceptual framework for explaining why open-shell transition-metal oxides tend to be insulators, whereas otherwise successful theories such as DFT often predict them to be (false) metals. Strong correlation becomes the recommended medicine. We point out that strong correlation can be mitigated by allowing DFT to lower the energy by breaking structural, magnetic or dipolar symmetries. Such local motifs are observed experimentally by local probes beyond the 'average structure' determined by X-Ray diffraction. Observed broken symmetries can arise from slow fluctuations that persist over the observation time or longer. The surprising fact is that when symmetry breaking motifs are used as input to electronic structure calculations, false metals are converted into real insulators without the recommended medicine of strong correlation. Consistently, DFT calculations that show energy lowering symmetry breaking correct most cases where DFT, even with advanced exchange-correlation functionals, previously missed the correct metal vs insulator designation. Total energy calculations distinguish systems that support energy-lowering symmetry breaking from those that do not. This approach distinguishes between paramagnetic insulating and metallic phases and shows mass enhancement in Mott metals. The reason is that symmetry breaking removes many of the degeneracies that exist in a symmetry-unbroken system, reducing significantly the need for strong correlation. If one chooses to ignore symmetry breaking, the persistent degeneracies often call for strong correlation treatment. Thus, symmetry breaking transforms strong to normal correlation and false metals to true insulators. This view sheds light on the historic controversy between Mott and Slater that still reverberates today. + oai:arXiv.org:2512.18236v1 + cond-mat.mtrl-sci + cond-mat.str-el + physics.comp-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Alex Zunger, Jia-Xin Xiong, John P. Perdew + + + Super-Poissonian Squeezed Light in the Ground State of Strongly Coupled Light-matter Systems + https://arxiv.org/abs/2512.18242 + arXiv:2512.18242v1 Announce Type: cross +Abstract: Strong light-matter coupling enables hybrid states in which photonic and electronic degrees of freedom become correlated even in the ground state. While many-body effects in long-range dispersion interactions are known to reshape electronic properties under such conditions, their impact on quantum-optical observables remains largely unexplored. Here, we address this problem using quantum electrodynamical density-functional theory (QEDFT) combined with the recently developed photon-many-body dispersion (pMBD) functional, which can capture higher-order electron-photon correlations and multi-photon processes. We compute ground-state photonic observables including photon number fluctuations, second-order correlations, and quadrature variances, and find squeezing and super-Poissonian photon statistics emerging from light-matter interactions in the strong coupling regime. Our results demonstrate that capturing the full hierarchy of many-body, electron-photon and multi-photon correlations is essential for a consistent description of quantum-optical properties in strongly coupled molecular systems, establishing QEDFT as a first-principles framework for predicting nonclassical photonic features in the ground state of complex systems. + oai:arXiv.org:2512.18242v1 + physics.chem-ph + cond-mat.mtrl-sci + physics.comp-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Cankut Tasci, Mohammad Hassan, Leon Orlov-Sullivan, Leonardo A. Cunha, Johannes Flick + + + What is Stochastic Supervenience? + https://arxiv.org/abs/2512.18257 + arXiv:2512.18257v1 Announce Type: cross +Abstract: Standard formulations of supervenience typically treat higher level properties as point valued facts strictly fixed by underlying base states. However, in many scientific domains, from statistical mechanics to machine learning, basal structures more naturally determine families of probability measures than single outcomes. This paper develops a general framework for stochastic supervenience, in which the dependence of higher level structures on a physical base is represented by Markov kernels that map base states to distributions over macro level configurations. I formulate axioms that secure law like fixation, nondegeneracy, and directional asymmetry, and show that classical deterministic supervenience appears as a limiting Dirac case within the resulting topological space of dependence relations. To connect these metaphysical claims with empirical practice, the framework incorporates information theoretic diagnostics, including normalized mutual information, divergence based spectra, and measures of tail sensitivity. These indices are used to distinguish genuine structural stochasticity from merely epistemic uncertainty, to articulate degrees of distributional multiple realization, and to identify macro level organizations that are salient for intervention. The overall project offers a conservative extension of physicalist dependence that accommodates pervasive structured uncertainty in the special sciences without abandoning the priority of the base level. + oai:arXiv.org:2512.18257v1 + physics.hist-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Youheng Zhang + + + Controlling Ultrafast Excitations in Germanium:The Role of Pump-Pulse Parameters and Multi-Photon Resonances + https://arxiv.org/abs/2512.18299 + arXiv:2512.18299v1 Announce Type: cross +Abstract: We employ the Dynamical Projective Operatorial Approach (DPOA) to investigate the ultrafast optical excitations of germanium under intense, ultrashort pump pulses. The method has very low resource demand relative to many other available approaches and enables detailed calculation of the residual electron and hole populations induced by the pump pulse. It provides direct access to the energy distribution of excited carriers and to the total energy transferred to the system. By decomposing the response into contributions from different multi-photon resonant processes, we systematically study the dependence of excited-carrier density and absorbed energy on key pump-pulse parameters: duration, amplitude, and photon energy. Our results reveal a complex interplay between these parameters, governed by resonant Rabi-like dynamics and competition between different multi-photon absorption channels. For the studied germanium setup, we find that two-photon processes are generally dominant, while one- and three-photon channels become significant under specific conditions of pump-pulse frequency, duration, and intensity. This comprehensive analysis offers practical insights for optimizing ultrafast optical control in semiconductors by targeting specific multi-photon pathways. + oai:arXiv.org:2512.18299v1 + physics.optics + cond-mat.mtrl-sci + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Amir Eskandari-asl (Dipartimento di Fisica 'E.R. Caianiello', Universit\`a degli Studi di Salerno, I-84084 Fisciano), Adolfo Avella (Dipartimento di Fisica 'E.R. Caianiello', Universit\`a degli Studi di Salerno, I-84084 Fisciano) + + + Momentum-resolved spectral functions of super-moir\'e systems using tensor networks + https://arxiv.org/abs/2512.18397 + arXiv:2512.18397v1 Announce Type: cross +Abstract: Computing spectral functions in large, non-periodic super-moir\'e systems remains an open problem due to the exceptionally large system size that must be considered. Here, we establish a tensor network methodology that allows computing momentum-resolved spectral functions of non-interacting and interacting super-moir\'e systems at an atomistic level. Our methodology relies on encoding an exponentially large tight-binding problem as an auxiliary quantum many-body problem, solved with a many-body kernel polynomial tensor network algorithm combined with a quantum Fourier transform tensor network. We demonstrate the method for one and two-dimensional super-moir\'e systems, including super-moir\'e with non-uniform strain, interactions treated at the mean-field level, and quasicrystalline super-moir\'e patterns. Furthermore, we demonstrate that our methodology allows us to compute momentum-resolved spectral functions restricted to selected regions of a super-moir\'e, enabling direct imaging of position-dependent electronic structure and minigaps in super-moir\'e systems with non-uniform strain. Our results establish a powerful methodology to compute momentum-resolved spectral functions in exceptionally large super-moir\'e systems, providing a tool to directly model scanning twisting microscope tunneling experiments in twisted van der Waals heterostructures. + oai:arXiv.org:2512.18397v1 + cond-mat.str-el + cond-mat.mes-hall + cond-mat.mtrl-sci + physics.comp-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Anouar Moustaj, Yitao Sun, Tiago V. C. Antao, Jose L. Lado + + + A Phase Space Representation of the Metaplectic Group + https://arxiv.org/abs/2512.18415 + arXiv:2512.18415v1 Announce Type: cross +Abstract: The symplectic group Sp(n) acts on phase space while the unitary representation of its double cover, Mp(n), the metaplectic group, acts on functions defined on configuration space. We will construct an extension Mp(n) of Mp(n) acting on square integrable functions on phase space. This is performed using previous results of ours involving explicit expressions of the twisted Weyl symbols of metaplectic operators and Bopp pseudodifferential operators, which are phase space extensions of the usual Weyl operators. + oai:arXiv.org:2512.18415v1 + math-ph + math.AP + math.MP + math.SG + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Maurice de Gosson + + + Beyond spin-1/2: Multipolar spin-orbit coupling in noncentrosymmetric crystals with time-reversal symmetry + https://arxiv.org/abs/2512.18449 + arXiv:2512.18449v1 Announce Type: cross +Abstract: We develop a general multipolar theory of strong spin-orbit coupling for large total angular momentum $j$ in time-reversal-symmetric, noncentrosymmetric crystals. Using a $j\in\{1/2,3/2,5/2\}$ multiplet basis appropriate for heavy-element \textit{p}- and \textit{d}-bands, we systematically construct all symmetry-allowed spin-orbit coupling terms up to fifth order in momentum and generalize the usual spin texture to a total-angular-momentum texture. For $j>1/2$, multipolar spin-orbit coupling qualitatively reshapes Fermi surfaces and makes the topology of Bloch states band dependent. This leads to anisotropic high-$j$ textures that go beyond a single Rashba helix. We classify these textures by their total-angular-momentum vorticity $W_{n}$ for every energy band and identify distinct $|W_{n}|=1,2,5$ phases. We show that their crossovers generate enhanced and nonmonotonic current-induced spin-polarization responses, namely the Edelstein effect, upon tuning the chemical potential. Our results provide a symmetry-based framework for analyzing and predicting multipolar spin-orbit coupling, total-angular-momentum textures, and spintronic responses in heavy-element materials without an inversion center. + oai:arXiv.org:2512.18449v1 + cond-mat.mes-hall + cond-mat.mtrl-sci + cond-mat.str-el + cond-mat.supr-con + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Masoud Bahari, Kristian M{\ae}land, Carsten Timm, Bj\"orn Trauzettel + + + Global approximations to correlation functions of strongly interacting quantum field theories + https://arxiv.org/abs/2512.18532 + arXiv:2512.18532v1 Announce Type: cross +Abstract: We introduce a method for constructing global approximations to correlation functions of strongly interacting quantum field theories, starting from perturbative results. The key idea is to employ interpolation method, such as the two-point Pad\'e expansion, to interpolate the weak and strong coupling expansions of correlation function. We benchmark this many-body interpolation approach on two prototypical models: the lattice $\phi^4$ field theory and the 2D Hubbard model. For the $\phi^4$ theory, the resulting two point Pad\'e approximants exhibit uniform and global convergence to the exact correlation function. For the Hubbard model, we show that even at second order, the Pad\'e appproximant already provides reasonable characterization of the Matsubara Green's function for a wide range of parameters. Finally, we offer a heuristic explanation for these convergence properties based on analytic function theory. + oai:arXiv.org:2512.18532v1 + cond-mat.str-el + hep-th + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yuanran Zhu, Yang Yu, Efekan K\"okc\"u, Emanuel Gull, Chao Yang + + + Bell Nonlocality as a Covariance Obstruction in Locally Covariant Quantum Field Theory + https://arxiv.org/abs/2512.18603 + arXiv:2512.18603v1 Announce Type: cross +Abstract: Locally covariant algebraic quantum field theory (LCQFT) satisfies Einstein causality through microcausality and operational no-signalling, yet Bell-type correlations persist in entangled field states across spacelike regions. We demonstrate that this apparent tension reflects a fundamental covariance obstruction: no assignment of classical past variables can simultaneously be covariant under spacetime embeddings, screen off quantum correlations, and reproduce AQFT statistics. This obstruction is distinct from dynamical nonlocality or signalling violations. We formalize this as a no-go theorem in the category-theoretic framework of LCQFT, showing that Bell's notion of local causality -- requiring factorization conditioned on a common past -- is structurally incompatible with diffeomorphism covariance. The failure of Bell locality thus reflects not a breakdown of relativistic causality but the impossibility of embedding quantum correlations into a classical causal framework without introducing preferred foliations or non-covariant beables. This clarifies the conceptual status of nonlocality in relativistic quantum theory. + oai:arXiv.org:2512.18603v1 + gr-qc + physics.hist-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Joseph Samper Finberg + + + Post-Newtonian Constraints on Semiclassical Gravity with Quantum Superpositions + https://arxiv.org/abs/2512.18617 + arXiv:2512.18617v1 Announce Type: cross +Abstract: Semiclassical gravity, in which a classical spacetime is sourced by the quantum expectation value of the stress-energy tensor, is a standard framework for describing the gravitational interaction of quantum matter. In the nonrelativistic limit this approach leads to the Schr\"odinger-Newton equation, which is often assumed to be consistent at least in the weak-field regime. In this work, we reexamine this assumption for spatial quantum superpositions of massive particles. We show that, when the quantum state is properly normalized, no modification of the Newtonian gravitational potential arises at leading order. However, at first post-Newtonian order the semiclassical coupling generically produces state-dependent contributions involving the mass density and the mass current of the superposition. These terms have a parametric scaling which is different from that of the corresponding relativistic corrections and which does not have Planck mass suppression. Our results therefore impose a strong post-Newtonian consistency constraint on deterministic semiclassical gravity, indicating that sourcing the metric solely by expectation values is insufficient to recover a consistent relativistic weak-field expansion. + oai:arXiv.org:2512.18617v1 + gr-qc + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Hollis Williams + + + Identification and Optimization of Accurate Spin Models for Open-Shell Carbon Ladders with Matrix Product States + https://arxiv.org/abs/2512.18695 + arXiv:2512.18695v1 Announce Type: cross +Abstract: Open-shell nanographenes offer a controlled setting to study correlated magnetism emerging from $\pi$-electron systems. We analyze oligo(indenoindene) molecules, non-bipartite carbon ladders whose tight-binding spectra feature a gapped, weakly dispersing manifold of quasi-zero modes, and show that their low-energy properties can be effectively mapped onto an interacting set of spin-1/2 degrees of freedom. Using Density Matrix Renormalization Group simulations of the full Fermi-Hubbard model, we obtain their excitation spectra, entanglement profiles, and spin-spin correlations. We then construct optimized delocalized fermionic modes that act as emergent spins and show that their interactions are well described by a frustrated $J_1$-$J_2$ Heisenberg chain. This effective description clarifies how spin degrees of freedom arise and interact in non-bipartite nanographene ladders, providing a compact and accurate representation of their correlated behavior. + oai:arXiv.org:2512.18695v1 + cond-mat.mes-hall + cond-mat.str-el + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Andoni Agirre, Thomas Frederiksen, Geza Giedke, Tobias Grass + + + On the construction of graph models realizing given entropy vectors + https://arxiv.org/abs/2512.18702 + arXiv:2512.18702v1 Announce Type: cross +Abstract: We present an efficient algorithm for the construction of a holographic simple tree graph model that realizes a given entropy vector, subject to a specific ``chordality'' condition first introduced in arXiv:2412.18018. We further develop the toolkit of the correlation hypergraph, particularly in relation to coarse-graining and fine-graining of subsystems. We then use these techniques to take the first steps towards the generalization of this new algorithm to arbitrary (not necessarily simple) holographic tree graph models, and the ``detection'' of unrealizability of an entropy vector independently from the knowledge of holographic entropy inequalities. + oai:arXiv.org:2512.18702v1 + hep-th + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Veronika E. Hubeny, Massimiliano Rota + + + Density of scattering resonances in a disordered system + https://arxiv.org/abs/2512.18717 + arXiv:2512.18717v1 Announce Type: cross +Abstract: Reflection of particles from a disordered or chaotic medium is characterized by a scattering matrix that can be represented as a superposition of resonances. Each resonance corresponds to an eigenstate inside the medium and has a width related to the decay time of this eigenstate. We develop a general approach to study the distribution function of these resonance widths based on the nonlinear sigma model. We derive an integral representation of the distribution function that works equally well for systems of any symmetry and for any type of coupling to the measuring device. From this integral representation we find explicit analytic expressions for the distribution function in the case of disordered metallic grains. We also compare the analytic results to large-scale numerical simulations and observe their perfect agreement. + oai:arXiv.org:2512.18717v1 + cond-mat.dis-nn + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + M. S. Kurilov, P. M. Ostrovsky + + + Entanglement Dynamics by (Non-)Unitary Local Operator Quenches in a 2D Holographic CFT + https://arxiv.org/abs/2512.18781 + arXiv:2512.18781v1 Announce Type: cross +Abstract: In this paper, we investigate the time evolution of entanglement entropy and mutual information for the spatially-infinite systems where we act with a primary operator on the vacuum state and then time-evolve it with the sequence of the Euclidean and Lorentzian time evolutions. Two-dimensional holographic conformal field theories describe the systems under consideration in this paper. The Euclidean time evolution is induced by the Rindler Hamiltonian and behaves as the regulator that tames the divergence induced by the local operator, while the Lorentzian one is induced by the uniform Hamiltonian. Under these time evolutions, we investigate the time ordering effect of the Rindler Euclidean and uniform Lorentzian time evolution operators. Consequently, we find the remarkable differences between those time evolutions are induced by whether those are unitary or non-unitary. Especially, we find that the unitary time evolution induces the late-time logarithmic growth of the entanglement entropy, while the non-unitary time evolution induces the late-time constant behavior. Furthermore, we investigate the dual gravity of the systems under consideration. Especially, we investigate the gravity duals of the systems with the insertion of the heavy primary operator and show that it is a black brane with a spacetime-dependent horizon. + oai:arXiv.org:2512.18781v1 + hep-th + cond-mat.str-el + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Weibo Mao, Akihiro Miyata, Masahiro Nozaki, Farzad Omidi + + + Dynamical Spectral Function of the Kagome Quantum Spin Liquid + https://arxiv.org/abs/2512.18831 + arXiv:2512.18831v1 Announce Type: cross +Abstract: Quantum spin liquids (QSLs) host exotic fractionalized magnetic and gauge-field excitations whose microscopic origins and experimental verification remain frustratingly elusive. In the absence of static magnetic order, the spin excitation spectrum constitutes the crucial probe of QSL behavior, but its theoretical computation remains a serious challenge. Here we employ state-of-the-art tensor-network methods to obtain the full dynamical spectral function of the $J_1$-$J_2$ kagome Heisenberg model and benchmark our results by tracking their evolution across the magnetically ordered and QSL phases. Reducing $|J_2|/J_1$ causes increasingly strong spin-wave renormalization, flattening these modes then merging them into a continuum characteristic of deconfined spinons at all finite energies in the QSL. The low-energy continuum and the occurrence of gap closure at multiple high-symmetry points identify this gapless QSL as the U(1) Dirac spin liquid. These results establish a unified understanding of spin excitations in highly frustrated quantum magnets and provide clear spectral fingerprints for experimental detection in candidate kagome QSL materials. + oai:arXiv.org:2512.18831v1 + cond-mat.str-el + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Jiahang Hu, Runze Chi, Yibin Guo, B. Normand, Hai-Jun Liao, T. Xiang + + + Making Quantum Accessible: A Seven-Category Framework for K-12 Quantum Education + https://arxiv.org/abs/2512.18886 + arXiv:2512.18886v1 Announce Type: cross +Abstract: We conducted a literature review and expert interviews to determine the most common methods being used to teach quantum physics and quantum computing concepts to primary and secondary students. Based on the findings of this review, we provide a framework of seven categories of teaching approaches for teaching mathematically accessible quantum concepts; they are Defamiliarization, Quantum Picturalism, Spin-First Approach, Einstein-First Approach, Many Paths Approach, Historical Development Approach and Game-based Quantum Learning. We summarise each of these teaching methods and overview their advantages and disadvantages of each method. Our framework makes it easy for physics educators to embrace the diverse methods of teaching quantum physics and quantum computing at the primary and secondary level. + oai:arXiv.org:2512.18886v1 + physics.ed-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Rhea Fernandez, Sarah Hagstrom, Liesel Malanos, Lachlan McGinness, Madeline Mitchell, Saskia Schultz, Elizabeth Sexton + + + Correlation functions of harmonic lattices in d-dimensional space + https://arxiv.org/abs/2512.18958 + arXiv:2512.18958v1 Announce Type: cross +Abstract: We study the correlation functions between the dynamical variables and between their conjugate momenta at sites of a harmonic lattice in the $d$-dimensional Euclidean space. We show that at the thermodynamic limit, they can be expressed in terms of Lauricella's C-type hypergeometric series. Furthermore, using these expressions, we explicitly demonstrate that the correlators near the center of the lattice satisfying Diriclet boundary conditions coincide with those for the lattice with the periodic boundary conditions. By utilizing these expressions, we expect to make it easier to create programs that compute fast and highly precise for the quantum information quantities of subsystems within lattices. + oai:arXiv.org:2512.18958v1 + hep-th + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Masafumi Shimojo, Satoshi Ishihara, Hironobu Kataoka, Atsuko Matsukawa, Kazuo Koyama + + + Replica thermodynamic trade-off relations: Entropic bounds on network diffusion and trajectory observables + https://arxiv.org/abs/2512.18963 + arXiv:2512.18963v1 Announce Type: cross +Abstract: We introduce replica Markov processes to derive thermodynamic trade-off relations for nonlinear functions of probability distributions. In conventional thermodynamic trade-off relations, the quantities of interest are linear in the underlying probability distribution. Some important information-theoretic quantities, such as R\'enyi entropies, are nonlinear; however, such nonlinearities are generally more difficult to handle. Inspired by replica techniques used in quantum information and spin-glass theory, we construct Markovian dynamics of identical replicas and derive a lower bound on relative moments in terms of the dynamical activity. We apply our general result to two scenarios. First, for a random walker on a network, we derive an upper bound on the R\'enyi entropy of the position distribution of the walker, which quantifies the extent of diffusion on the network. Remarkably, the bound is expressed solely in terms of escape rate from the initial node, and thus depends only on local information. Second, we consider trajectory observables in Markov processes and obtain an upper bound on the R\'enyi entropy of the distribution of these observables, again in terms of the dynamical activity. This provides an entropic characterization of uncertainty that generalizes existing variance-based thermodynamic uncertainty relations. + oai:arXiv.org:2512.18963v1 + cond-mat.stat-mech + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yoshihiko Hasegawa + + + Quantum sensing of high-frequency gravitational waves with ion crystals + https://arxiv.org/abs/2512.19053 + arXiv:2512.19053v1 Announce Type: cross +Abstract: A detection method for high-frequency gravitational waves using two-dimensional ion crystals is investigated. Gravitational waves can resonantly excite the drumhead modes of the ion crystal, particularly the parity-odd modes. In the optical dipole force protocol, entanglement between the drumhead modes and the collective spins transfers the excitation of the drumhead modes to the rotation of the total spin. Furthermore, gravitational wave detection beyond the standard quantum limit becomes possible as a squeezed spin state is generated through this entanglement. The sensitivity gets better with a larger ions crystals as well as a larger number of the ions. Future realization of large ion crystals can significantly improve the sensitivity to gravitational waves in the 10 kHz to 10 MHz region. + oai:arXiv.org:2512.19053v1 + gr-qc + hep-ph + physics.atom-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Asuka Ito, Ryuichiro Kitano, Wakutaka Nakano, Ryoto Takai + + + A fast, large-scale optimal transport algorithm for holographic beam shaping + https://arxiv.org/abs/2512.19072 + arXiv:2512.19072v1 Announce Type: cross +Abstract: Optimal transport methods have recently established state of the art accuracy and efficiency for holographic laser beam shaping. However, use of such methods is hindered by severe $\mathcal{O}(N^2)$ memory and $\mathcal{O}(N^2)$ time requirements for large scale input or output images with $N$ total pixels. Here we leverage the dual formulation of the optimal transport problem and the separable structure of the cost to implement algorithms with greatly reduced $\mathcal{O}(N)$ memory and $\mathcal{O}(N\log N)$ to $\mathcal{O}(N^{3/2})$ time complexity. These algorithms are parallelizable and can solve megapixel-scale beam shaping problems in tens of seconds on a CPU or seconds on a GPU. + oai:arXiv.org:2512.19072v1 + physics.optics + physics.atom-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Andrii Torchylo, Hunter Swan, Lucas Tellez, Jason Hogan + + + Asymmetric and chiral dynamics of two-component anyons with synthetic gauge flux + https://arxiv.org/abs/2512.19139 + arXiv:2512.19139v1 Announce Type: cross +Abstract: In this work, we investigate the non-equilibrium dynamics in a one-dimensional two-component anyon-Hubbard model, which can be mapped to an extended Bose-Hubbard ladder with density-dependent hopping phase and synthetic gauge flux. Through numerical simulations of two-particle dynamics and the symmetry analysis, we reveal the asymmetric transport with broken inversion symmetry and two dynamical symmetries in the expansion dynamics. The expansion of two-component anyons is dynamically symmetric under spatial inversion and component flip, when the sign of anyonic statistics phase or the signs of gauge flux and interaction are changed. In the non-interacting case, we show the dynamical suppression induced by both the statistics phase and gauge flux. In the interacting case, we demonstrate that both chiral and antichiral dynamics can be exhibited and tuned by the statistics phase and gauge flux. The dynamical phase regimes with respect to the chiral-antichiral dynamics are obtained. These findings highlight the rich dynamical phenomena arising from the interplay of anyonic exchange statistics, synthetic gauge fields, and interactions in multi-component anyons. + oai:arXiv.org:2512.19139v1 + cond-mat.quant-gas + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Rui-Jie Chen, Ying-Xin Huang, Guo-Qing Zhang, Dan-Wei Zhang + + + Optical parametric free-electron--photon quantum interaction + https://arxiv.org/abs/2512.19255 + arXiv:2512.19255v1 Announce Type: cross +Abstract: Optical parametric processes underpin quantum photonics, while free-electron--photon interactions offer agile pathways to generate nontrivial quantum photonic states. These threads have so far largely progressed independently, whereas placing free electrons in a driven nonlinear system can potentially activate coherent parametric interaction channels for joint state engineering of both types of particles. Here we unify these paradigms by developing a general theoretical framework for parametric free-electron--photon interactions in a nonlinear optical system driven by degenerate parametric down-conversion. Unlike free electrons in a linear bath, here they can couple to Bogoliubov quasiparticles through two detuned phase-matching channels, where the parametric process and free-electron interactions can quantum amplify each other. Seeding the interaction with squeezed vacuum yields gain-only or loss-only electron energy spectra, and enables electron-heralded squeezed Fock states; with bare vacuum, postselecting electron energy sidebands generates high-fidelity Schr\"odinger cat states. Our results show how optical parametric interactions can quantum shape free electrons and photons, potentially enabling a quantum parametric dielectric laser accelerator that mitigates the need for temporal phase synchronization, thereby allowing acceleration probabilities to approach unity even for phase-random electrons. + oai:arXiv.org:2512.19255v1 + physics.optics + cond-mat.mes-hall + physics.acc-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Zetao Xie, Zehai Pang, Yi Yang + + + Protecting Quantum Circuits Through Compiler-Resistant Obfuscation + https://arxiv.org/abs/2512.19314 + arXiv:2512.19314v1 Announce Type: cross +Abstract: Quantum circuit obfuscation is becoming increasingly important to prevent theft and reverse engineering of quantum algorithms. As quantum computing advances, the need to protect the intellectual property contained in quantum circuits continues to grow. Existing methods often provide limited defense against structural and statistical analysis or introduce considerable overhead. In this paper, we propose a novel quantum obfuscation method that uses randomized U3 transformations to conceal circuit structure while preserving functionality. We implement and assess our approach on QASM circuits using Qiskit AER, achieving over 93\% semantic accuracy with minimal runtime overhead. The method demonstrates strong resistance to reverse engineering and structural inference, making it a practical and effective approach for quantum software protection. + oai:arXiv.org:2512.19314v1 + cs.CR + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Pradyun Parayil, Amal Raj, Vivek Balachandran + + + Talking with a ghost: semi-virtual coupled levitated oscillators + https://arxiv.org/abs/2512.19358 + arXiv:2512.19358v1 Announce Type: cross +Abstract: Mesoscopic particles levitated by optical, electrical or magnetic fields act as mechanical oscillators with a range of surprising properties, such as tuneable oscillation frequencies, access to rotational motion, and remarkable quality factors. Coupled levitated particles display rich dynamics and non-reciprocal interactions, with applications in sensing and the exploration of non-equilibrium and quantum physics. In this work, we present a single levitated particle displaying coupled-oscillator dynamics by generating an interaction with a virtual or ``ghost'' particle. This ghost levitated particle is simulated on an analogue computer, and hence its prperties can be dynamically varied. Our work represents a new angle on measurement-based bath engineering and physical simulation, and in the future could lead to the generation of novel cooling mechanisms and complex physical simulation. + oai:arXiv.org:2512.19358v1 + physics.ins-det + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Ronghao Yin, Yugang Ren, Deok Young Seo, Anoushka Sinha, Jonathan D. Pritchett, Qiongyuan Wu, James Millen + + + A deterministic approach for integrating an emitter in a nanocavity with subwavelength light confinement + https://arxiv.org/abs/2512.19372 + arXiv:2512.19372v1 Announce Type: cross +Abstract: We introduce a novel light-matter interface that integrates a nanoscale buried heterostructure emitter into a dielectric bowtie cavity, co-localising the optical hotspot and the electronic wavefunction. This platform enables strong light-matter interaction through deep subwavelength confinement while remaining compatible with scalable fabrication. We show that in this regime an explicit treatment of the emitter's spatial extent is required, and that a confinement-factor approximation more accurately predicts the coupling, revealing design rules inaccessible to dipole-based metrics. For an InP/InGaAsP system, we predict coupling strengths of 0.4-0.7 meV for gap sizes of 50-10 nm, establishing the buried heterostructure-bowtie architecture as a practical route to deterministic strong coupling in solid-state nanophotonics. + oai:arXiv.org:2512.19372v1 + physics.optics + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Valdemar Bille-Lauridsen, Rasmus Elleb{\ae}k Christiansen, Yi Yu, Jesper M{\o}rk + + + Ab initio prediction of strain-tunable spin defects in quasi-1D TiS3 and NbS3 nanowires + https://arxiv.org/abs/2512.19391 + arXiv:2512.19391v1 Announce Type: cross +Abstract: Defects in atomically thin van der Waals materials have recently been investigated as sources of spin-photon entanglement with sensitivity to strain tuning. Unlike many two-dimensional materials, quasi-one-dimensional materials such as transition metal trichalcogenides exhibit in-plane anisotropy resulting in axis-dependent responses to compressive and tensile strains. Herein, we characterize the tunable spin and optical properties of intrinsic vacancy defects in titanium trisulfide (TiS3) and niobium trisulfide (NbS3) nanowires. Within our ab initio approach, we show that sulfur vacancies and divacancies (VS and VD , respectively) in TiS3 and NbS3 adopt strain-dependent defect geometries between in-plane strains of -3 % and 3 %. The calculated electronic structures indicate that both VS and VD possess in-gap defect states with optically bright electronic transitions whose position relative to the conduction and valence bands varies with in-plane strain. Further, our calculations predict that VS in TiS3 and VD in NbS3 exhibit transitions in their ground state spins; specifically, a compressive strain of 0.4 % along the direction of nanowire growth causes a shift from a triplet state to a singlet state for the VS defect in TiS3, whereas a tensile strain of 2.9 % along the same direction in NbS3 induces a triplet ground state with a zero-phonon line of 0.83 eV in the VD defect. Our work shows that the anisotropic geometry of TiS3 and NbS3 nanowires offers exceptional tunability of optically active spin defects that can be used in quantum applications. + oai:arXiv.org:2512.19391v1 + cond-mat.mtrl-sci + cond-mat.mes-hall + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Jordan Chapman, Arindom Nag, Thang Pham, Vsevolod Ivanov + + + Holographic Tensor Networks as Tessellations of Geometry + https://arxiv.org/abs/2512.19452 + arXiv:2512.19452v1 Announce Type: cross +Abstract: Holographic tensor networks serve as toy models for the Anti-de Sitter/Conformal Field Theory (AdS/CFT) correspondence, capturing many of its essential features in a concrete manner. However, existing holographic tensor network models remain far from a complete theory of quantum gravity. A key obstacle is their discrete structure, which only approximates the semi-classical geometry of gravity in a qualitative sense. In \cite{Lin:2024dho}, it was shown that a network of partial-entanglement-entropy (PEE) threads, which are bulk geodesics with a specific density distribution, generates a perfect tessellation of AdS space. Moreover, such PEE-network tessellations can be constructed for more general geometries using the Crofton formula. In this paper, we assign a quantum state to each vertex in the PEE network and develop two holographic tensor network models: the factorized PEE tensor network, which takes the form of a tensor product of EPR pairs, and the random PEE tensor network. In both models we reproduce the exact Ryu-Takayanagi formula by showing that the minimal number of cuts along a homologous surface in the network exactly computes the area of this surface. + oai:arXiv.org:2512.19452v1 + hep-th + gr-qc + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Qiang Wen, Mingshuai Xu, Haocheng Zhong + + + Analytical study of birefringent cavities for axion-like dark matter search + https://arxiv.org/abs/2512.19476 + arXiv:2512.19476v1 Announce Type: cross +Abstract: Light polarization plays a crucial role in optical-cavity experiments; however, mirror birefringence presents a significant challenge that must be addressed carefully. In this study, a rigorous, nonperturbative framework is developed to quantify birefringence effects by incorporating variations in reflectance and polarization misalignment. We analyze the impact of this framework on the sensitivity of axion-like particle (ALP) dark-matter searches. The results show that both birefringence and misalignment contribute to sensitivity degradation in the low-mass regime; however, the adverse effects of misalignment can be mitigated by selecting a postselection angle greater than the misalignment angle. Furthermore, birefringence produces an additional resonance peak in the high-mass region, which remains largely unaffected by misalignment and postselection variations. This rigorous framework underscores the importance of considering birefringence in high-precision optical-cavity experiments for ALP detection. + oai:arXiv.org:2512.19476v1 + hep-ph + gr-qc + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Tadashi Kuramoto, Yasutaka Imai, Takahiko Masuda, Yutaka Shikano, Sayuri Takatori, Satoshi Uetake + + + Open Quantum Systems as Regular Holonomic $\mathcal{D}$-Modules: The Mixed Hodge Structure of Spectral Singularities + https://arxiv.org/abs/2512.19487 + arXiv:2512.19487v1 Announce Type: cross +Abstract: The geometric description of open quantum systems via the Quantum Geometric Tensor (QGT) traditionally relies on the assumption that the physical states form a differentiable vector bundle over the parameter manifold. This framework becomes ill-posed at spectral singularities, such as Exceptional Points, where the eigen-bundle admits no local trivialization due to dimension reduction. In this work, we resolve this obstruction by demonstrating that the family of Liouvillian superoperators $\mathcal{L}(k)$ over a complex parameter manifold $X$ canonically defines a \textbf{regular holonomic $\mathcal{D}_X$-module} $\mathcal{M}$. By identifying the physical coherence order with the Hodge filtration and the decay rate hierarchy with the \textbf{Kashiwara filtration}, we show that the open quantum system underlies a \textbf{Mixed Hodge Module (MHM)} structure in the sense of Saito. + This identification allows us to apply the \textbf{Grothendieck six-functor formalism} rigorously to dissipative dynamics. We prove that the divergence corresponds to a non-trivial cohomology class in $\text{Ext}^1_{\mathcal{D}_X}$, thereby regularizing the Quantum Geometric Tensor without ad-hoc cutoffs. Specifically, the ``singular component'' of the Complete QGT arises as the residue of the connection on the \textbf{Brieskorn lattice} associated with the vanishing cycles functor. + oai:arXiv.org:2512.19487v1 + math-ph + math.AG + math.MP + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Prasoon Saurabh + + + Spin Response of a Magnetic Monopole and Quantum Hall Response in Topological Lattice Models through Local Invariants and Light + https://arxiv.org/abs/2512.19511 + arXiv:2512.19511v1 Announce Type: cross +Abstract: Here, we elaborate on and develop the geometrical approach introduced in K. Le Hur, Physics Reports 1104 1-42 (2025) between the magnetic monopole created from a radial field, quantum physics and topological lattice models through quantum phase transitions. We introduce an effective magnetic moment for a monopole when applying an additional source field along z-direction which also mediates the quantum phase transition. We present its relation with the transverse pumped quantum Hall current. The magnetic susceptibility can be introduced as a measure of the topological invariant i.e. remains quantized within the topological phase until the transition. We show the relation with two-dimensional topological lattice models such as a honeycomb Haldane model in real space. We develop the theory and present a numerical analysis between local invariants in momentum space introduced from Dirac points, correlation functions and the responses to circularly polarized light. We develop the formalism for coupled-planes materials including the possibility of quantum spin Hall effect and address a relation between the Ramanujan infinite alternating series and an interface in real space with a topological number one-half. + oai:arXiv.org:2512.19511v1 + cond-mat.mes-hall + cond-mat.str-el + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Karyn Le Hur, Andrea Baldanza + + + Higher lattice gauge theory from representations of 2-groups and 3+1D topological phases + https://arxiv.org/abs/2512.19608 + arXiv:2512.19608v1 Announce Type: cross +Abstract: We construct a higher lattice gauge theory based on the representation of 2-groups described by a category of crossed modules on a lattice model described by path 2-groupoids. Using these lattice gauge representations, an exactly solvable Hamiltonian for topological phases in 3+1 dimensions is constructed. We show that the ground states of this model are topological observables. + oai:arXiv.org:2512.19608v1 + hep-lat + cond-mat.other + hep-th + math-ph + math.MP + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Lat\'evi M. Lawson, Prince K. Osei + + + Orbital Magnetization Reveals Multiband Topology + https://arxiv.org/abs/2512.19690 + arXiv:2512.19690v1 Announce Type: cross +Abstract: We demonstrate that nontrivial multiband topological invariants of electronic wavefunctions can be revealed through diamagnetic orbital magnetization responses to external magnetic fields. We find that decomposing orbital magnetization into energetic and quantum-geometric contributions allows one to deduce nontrivial multiband topology, provided knowledge of the energy spectrum. We showcase our findings in general effective models with multiband Euler topology. We moreover identify such multiband topological invariants in effective models of strontium ruthenide ($\text{Sr}_2 \text{Ru} \text{O}_4$), which may in principle be verified in the state-of-the-art doping-dependent magnetization measurements. Our reconstruction scheme for multiband invariants sheds a topological perspective on the multiorbital effects in materials realizing unconventional phenomenologies of orbital currents or multiband superconductivity. + oai:arXiv.org:2512.19690v1 + cond-mat.mes-hall + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + cross + http://creativecommons.org/licenses/by/4.0/ + Chun Wang Chau, Robert-Jan Slager, Wojciech J. Jankowski + + + Isolated zero mode in a quantum computer from a duality twist + https://arxiv.org/abs/2308.02387 + arXiv:2308.02387v5 Announce Type: replace +Abstract: Investigating the interplay of dualities, generalized symmetries, and topological defects beyond theoretical models is an important challenge in condensed matter physics and quantum materials. A simple model exhibiting this physics is the transverse-field Ising model, which can host a topological defect that performs the Kramers-Wannier duality transformation. When acting on one point in space, this duality defect imposes the duality twisted boundary condition and binds a single zero mode. This zero mode is unusual as it lacks a localized partner in the same $\mathbb{Z}_2$ sector and has an infinite lifetime, even in finite systems. Using Floquet driving of a closed Ising chain with a duality defect, we generate this zero mode in a digital quantum computer. We detect the mode by measuring its associated persistent autocorrelation function using an efficient sampling protocol and a compound strategy for error mitigation. We also show that the zero mode resides at the domain wall between two regions related by a Kramers-Wannier duality transformation. Finally, we highlight the robustness of the isolated zero mode to integrability- and symmetry-breaking perturbations. Our findings provide a method for exploring exotic topological defects, associated with noninvertible generalized symmetries, in digitized quantum devices. + oai:arXiv.org:2308.02387v5 + quant-ph + cond-mat.mes-hall + cond-mat.str-el + hep-th + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Sutapa Samanta, Derek S. Wang, Armin Rahmani, Aditi Mitra + + + Training robust and generalizable quantum models + https://arxiv.org/abs/2311.11871 + arXiv:2311.11871v4 Announce Type: replace +Abstract: Adversarial robustness and generalization are both crucial properties of reliable machine learning models. In this paper, we study these properties in the context of quantum machine learning based on Lipschitz bounds. We derive parameter-dependent Lipschitz bounds for quantum models with trainable encoding, showing that the norm of the data encoding has a crucial impact on the robustness against data perturbations. Further, we derive a bound on the generalization error which explicitly involves the parameters of the data encoding. Our theoretical findings give rise to a practical strategy for training robust and generalizable quantum models by regularizing the Lipschitz bound in the cost. Further, we show that, for fixed and non-trainable encodings, as those frequently employed in quantum machine learning, the Lipschitz bound cannot be influenced by tuning the parameters. Thus, trainable encodings are crucial for systematically adapting robustness and generalization during training. The practical implications of our theoretical findings are illustrated with numerical results. + oai:arXiv.org:2311.11871v4 + quant-ph + cs.LG + math.OC + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/PhysRevResearch.6.043326 + Physical Review Research 6, 043326, 2024 + Julian Berberich, Daniel Fink, Daniel Pranji\'c, Christian Tutschku, Christian Holm + + + Critical quantum metrology robust against dissipation and non-adiabaticity + https://arxiv.org/abs/2403.04475 + arXiv:2403.04475v3 Announce Type: replace +Abstract: Critical systems near quantum phase transitions were predicted to be useful for improvement of metrological precision, thanks to their ultra-sensitive response to a tiny variation of the control Hamiltonian. Despite the promising perspective, realization of criticality-enhanced quantum metrology is an experimentally challenging task, mainly owing to the extremely long time needed to encode the signal to some physical quantity of a critical system. We here circumvent this problem by making use of the critical behaviors in the Jaynes-Cummings model, comprising a single qubit and a photonic resonator, to which the signal field is coupled. The information about the field amplitude is encoded in the qubit's excitation number in the dark state, which displays a divergent changing rate at the critical point. The most remarkable feature of this critical sensor is that the performance is insensitive to the leakage to bright eigenstates, caused by decoherence and non-adiabatic effects. We demonstrate such a metrological protocol in a superconducting circuit, where an Xmon qubit, interacting with a resonator, is used as a probe for estimating the amplitude of a microwave field coupled to the resonator. The measured quantum Fisher information exhibits a critical quantum enhancement, confirming the potential of this system for quantum metrology. + oai:arXiv.org:2403.04475v3 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Jia-Hao L\"u, Wen Ning, Fan Wu, Ri-Hua Zheng, Ken Chen, Xin Zhu, Zhen-Biao Yang, Huai-Zhi Wu, Shi-Biao Zheng + + + Anomaly inflow for CSS and fractonic lattice models and dualities via cluster state measurement + https://arxiv.org/abs/2405.15853 + arXiv:2405.15853v2 Announce Type: replace +Abstract: Calderbank-Shor-Steane (CSS) codes are a class of quantum error correction codes that contains the toric code and fracton models. A procedure called foliation defines a cluster state for a given CSS code. We use the CSS chain complex and its tensor product with other chain complexes to describe the topological structure in the foliated cluster state, and argue that it has a symmetry-protected topological order protected by generalized global symmetries supported on cycles in the foliated CSS chain complex. We demonstrate the so-called anomaly inflow between CSS codes and corresponding foliated cluster states by explicitly showing the equality of the gauge transformations of the bulk and boundary partition functions defined as functionals of defect world-volumes. We show that the bulk and boundary defects are related via measurement of the bulk system. Further, we provide a procedure to obtain statistical models associated with general CSS codes via the foliated cluster state, and derive a generalization of the Kramers-Wannier-Wegner duality for such statistical models with insertion of twist defects. We also study the measurement-assisted gauging method with cluster-state entanglers for CSS/fracton models based on recent proposals in the literature, and demonstrate a non-invertible fusion of duality operators. Using the cluster-state entanglers, we construct the so-called strange correlator for general CSS/fracton models. Finally, we introduce a new family of subsystem-symmetric quantum models each of which is self-dual under the generalized Kramers-Wannier-Wegner duality transformation, which becomes a non-invertible symmetry. + oai:arXiv.org:2405.15853v2 + quant-ph + cond-mat.stat-mech + cond-mat.str-el + hep-th + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.21468/SciPostPhys.17.4.113 + SciPost Phys. 17, 113(2024) + Takuya Okuda, Aswin Parayil Mana, Hiroki Sukeno + + + Unified Architecture for Quantum Lookup Tables + https://arxiv.org/abs/2406.18030 + arXiv:2406.18030v2 Announce Type: replace +Abstract: Quantum access to arbitrary classical data encoded in unitary black-box oracles underlies interesting data-intensive quantum algorithms, such as machine learning or electronic structure simulation. The feasibility of these applications depends crucially on gate-efficient implementations of these oracles, which are commonly some reversible versions of the boolean circuit for a classical lookup table. We present a general parameterized architecture for quantum circuits implementing a lookup table that encompasses all prior work in realizing a continuum of optimal tradeoffs between qubits, non-Clifford gates, and error resilience, up to logarithmic factors. Our architecture assumes only local 2D connectivity, yet recovers results that previously required all-to-all connectivity, particularly, with the appropriate parameters, poly-logarithmic error scaling. We also identify novel regimes, such as simultaneous sublinear scaling in all parameters. These results enable tailoring implementations of the commonly used lookup table primitive to any given quantum device with constrained resources. + oai:arXiv.org:2406.18030v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + 10.1103/d896-mktn + Phys. Rev. Research 7, 043230 (2025) + Shuchen Zhu, Aarthi Sundaram, Guang Hao Low + + + Towards Arbitrary Time-frequency Mode Squeezing with Self-conjugated Mode Squeezing in Fiber + https://arxiv.org/abs/2406.19991 + arXiv:2406.19991v2 Announce Type: replace +Abstract: Optical parametric amplification generates squeezed light in device-specific sets of time-frequency eigenmodes, and it has been widely accepted that detection and utilization of squeezing must comply with this modal constraint. We show that this constraint can be considerably relaxed under the continuous-wave pump and broadband phase-matching approximation, where the modal decomposition is non-unique. Specifically, any time-frequency mode with "self-conjugated" spectral symmetry can approximate a squeezing eigenmode, and partial homodyne detection can herald squeezing in arbitrary time-frequency modes. We demonstrate this using a high-efficiency, low-loss all-fiber source, measuring 4.38 +- 0.11dB and 0.88 +- 0.09 dB squeezing on partially coherent and chaotic self-conjugated modes. Using a bichromatic self-conjugated mode with reduced local-oscillator noise, we achieve 7.50 +- 0.12dB squeezing, which represents the highest level reported for fully guided-wave squeezing sources based on chi(2) and chi(3) nonlinearities. + oai:arXiv.org:2406.19991v2 + quant-ph + physics.optics + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Han Liu, Meng Lon Iu, Noor Hamdash, Amr S. Helmy + + + Probability and fidelity of teleportation in a two-mode continuous variable cluster state via an insufficiently selective measurement + https://arxiv.org/abs/2407.09921 + arXiv:2407.09921v2 Announce Type: replace +Abstract: Continuous-variable projective measurements can not select individual measurement results as in the discrete case; instead, the possible outcomes are bounded by the selectivity interval of the measurement; then, it is say that continuous-variable measurement devices are insufficiently selective. By utilizing this concept we show that the probability and fidelity of teleportation in a two-mode cluster state can be handled by the localization of the selectivity interval of the measurement apparatus. Besides, we provide a mathematical expression describing the probability distribution of the measurement outcomes in the two-mode cluster, which is a fundamental solution of the heat equation. In addition, we show that the fidelity of teleportation in the two mode cluster is given by the quotient between the squared solution of a non-homogeneous heat equation and the solution of the conventional heat equation. Furthermore, we extend our approach to a configuration involving successive clusters with intermediate corrections between each teleportation step. To exemplify our proposal, we consider the specific case of a squeezed-coherent state as the quantum state under teleportation. + oai:arXiv.org:2407.09921v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Julio Abraham Mendoza Fierro, Luis Manuel Ar\'evalo Aguilar, Marcela Maribel M\'endez Otero + + + Classification of joint quantum measurements based on entanglement cost of localization + https://arxiv.org/abs/2408.00831 + arXiv:2408.00831v2 Announce Type: replace +Abstract: Despite their importance in quantum theory, joint quantum measurements remain poorly understood. An intriguing conceptual and practical question is whether joint quantum measurements on separated systems can be performed without bringing them together. Remarkably, by using shared entanglement, this can be achieved perfectly when disregarding the post-measurement state. However, existing localization protocols typically require unbounded entanglement. In this work, we address the fundamental question: "Which joint measurements can be localized with a finite amount of entanglement?" We develop finite-resource versions of teleportation-based schemes and analytically classify all two-qubit measurements that can be localized in the first steps of these hierarchies. These include several measurements with exceptional properties and symmetries, such as the Bell state measurement and the elegant joint measurement. This leads us to propose a systematic classification of joint measurements based on entanglement cost, which we argue directly connects to the complexity of implementing those measurements. We illustrate how to numerically explore higher levels and construct generalizations to higher dimensions and multipartite settings. + oai:arXiv.org:2408.00831v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/PhysRevX.15.021013 + Phys. Rev. X 15, 021013 (2025) + Jef Pauwels, Alejandro Pozas-Kerstjens, Flavio Del Santo, Nicolas Gisin + + + Modular Architectures and Entanglement Schemes for Error-Corrected Distributed Quantum Computation + https://arxiv.org/abs/2408.02837 + arXiv:2408.02837v2 Announce Type: replace +Abstract: Connecting multiple smaller qubit modules by generating high-fidelity entangled states is a promising path for scaling quantum computing hardware. The performance of such a modular quantum computer is highly dependent on the quality and rate of entanglement generation. However, the optimal architectures and entanglement generation schemes are not yet established. Focusing on modular quantum computers with solid-state quantum hardware, we investigate a distributed surface code's error-correcting threshold and logical failure rate. We consider both emission-based and scattering-based entanglement generation schemes for the measurement of non-local stabilizers. Through quantum optical modeling, we link the performance of the quantum error correction code to the parameters of the underlying physical hardware and identify the necessary parameter regime for fault-tolerant modular quantum computation. In addition, we compare modular architectures with one or two data qubits per module. We find that the performance of the code depends significantly on the choice of entanglement generation scheme, while the two modular architectures have similar error-correcting thresholds. For some schemes, thresholds nearing the thresholds of non-distributed implementations ($\sim0.4 \%$) appear feasible with future parameters. + oai:arXiv.org:2408.02837v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + 10.1038/s41534-025-01146-2 + Siddhant Singh, Fenglei Gu, S\'ebastian de Bone, Eduardo Villase\~nor, David Elkouss, Johannes Borregaard + + + One-milligram torsional pendulum toward experiments at the quantum-gravity interface + https://arxiv.org/abs/2408.09445 + arXiv:2408.09445v4 Announce Type: replace +Abstract: Probing the possibility of entanglement generation through gravity offers a path to tackle the question of whether gravitational fields possess a quantum mechanical nature. A potential realization necessitates systems with low-frequency dynamics at an optimal mass scale, for which the microgram-to-milligram range is a strong contender. Here, after refining a figure-of-merit for the problem, we present a 1-milligram torsional pendulum operating at 18 Hz. We demonstrate laser cooling its motion from room temperature to 240~microkelvins, surpassing by over 20-fold the coldest motions attained for oscillators ranging from micrograms to kilograms. We quantify and contrast the utility of the current approach with other platforms. The achieved performance and large improvement potential highlight milligram-scale torsional pendulums as a powerful platform for precision measurements relevant to future studies at the quantum-gravity interface. + oai:arXiv.org:2408.09445v4 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Sofia Agafonova, Pere Rossello, Manuel Mekonnen, Onur Hosten + + + On the Computational Power of QAC0 with Barely Superlinear Ancillae + https://arxiv.org/abs/2410.06499 + arXiv:2410.06499v4 Announce Type: replace +Abstract: $\mathrm{QAC}^0$ is the family of constant-depth polynomial-size quantum circuits consisting of arbitrary single qubit unitaries and multi-qubit Toffoli gates. It was introduced by Moore [arXiv: 9903046] as a quantum counterpart of $\mathrm{AC}^0$, along with the conjecture that $\mathrm{QAC}^0$ circuits can not compute PARITY. In this work we make progress on this longstanding conjecture: we show that any depth-$d$ $\mathrm{QAC}^0$ circuit requires $n^{1+3^{-d}}$ ancillae to compute a function with approximate degree $\Theta(n)$, which includes PARITY, MAJORITY and $\mathrm{MOD}_k$. We further establish superlinear lower bounds on quantum state synthesis and quantum channel synthesis. This is the first superlinear lower bound on the super-linear sized $\mathrm{QAC}^0$. Regarding PARITY, we show that any further improvement on the size of ancillae to $n^{1+\exp(-o(d))}$ would imply that PARITY $\not\in$ QAC0. These lower bounds are derived by giving low-degree approximations to $\mathrm{QAC}^0$ circuits. We show that a depth-$d$ $\mathrm{QAC}^0$ circuit with $a$ ancillae, when applied to low-degree operators, has a degree $(n+a)^{1-3^{-d}}$ polynomial approximation in the spectral norm. This implies that the class $\mathrm{QLC}^0$, corresponding to linear size $\mathrm{QAC}^0$ circuits, has approximate degree $o(n)$. This is a quantum generalization of the result that $\mathrm{LC}^0$ circuits have approximate degree $o(n)$ by Bun, Robin, and Thaler [SODA 2019]. Our result also implies that $\mathrm{QLC}^0\neq\mathrm{NC}^1$. + oai:arXiv.org:2410.06499v4 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Anurag Anshu, Yangjing Dong, Fengning Ou, Penghui Yao + + + Axiomatization of R\'enyi Entropy on Quantum Phase Space + https://arxiv.org/abs/2410.15976 + arXiv:2410.15976v5 Announce Type: replace +Abstract: Phase-space versions of quantum mechanics -- from Wigner's original distribution to modern discrete-qudit constructions -- represent some states with negative quasi-probabilities. Conventional Shannon and R\'enyi entropies become complex-valued in this setting and lose their operational meaning. Building on the axiomatic treatments of R\'enyi (1961) and Dar\'oczy (1963), we develop a conservative extension that applies to signed finite phase spaces and identify a single admissible entropy family, which we call signed R\'enyi $\alpha$-entropy (for a free parameter $\alpha \ge 0$). The obvious signed Shannon candidate is ruled out because it violates extensivity. We prove four results that bolster the usefulness of the new measure. (i) It serves as a witness of the presence of cancellation, detecting the coexistence of positive and negative weight in a signed measure. (ii) For $\alpha > 1$, it is Schur-concave, delivering the intuitive property that mixing increases entropy (iii) The same parametric family obeys a quantum H-theorem, namely, that under de-phasing dynamics entropy cannot decrease. (iv) The $2$-entropy is conserved under discrete Moyal-bracket dynamics, mirroring conservation of von Neumann entropy under unitary evolution on Hilbert space. We also comment on interpreting the R\'enyi order parameter as an inverse temperature. Overall, we believe that our investigation provides good evidence that our axiomatically derived signed R\'enyi entropy may be a useful addition to existing entropy measures employed in quantum information, foundations, and thermodynamics. + oai:arXiv.org:2410.15976v5 + quant-ph + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Adam Brandenburger, Pierfrancesco La Mura + + + Q-Fly: An Optical Interconnect for Modular Quantum Computers + https://arxiv.org/abs/2412.09299 + arXiv:2412.09299v4 Announce Type: replace +Abstract: Much like classical supercomputers, scaling up quantum computers requires an optical interconnect. However, signal attenuation leads to irreversible qubit loss, making quantum interconnect design guidelines and metrics different from conventional computing. Inspired by the classical Dragonfly topology, we propose a multi-group structure where the group switch routes photons emitted by computational end nodes to the group's shared pool of Bell state analyzers (which conduct the entanglement swapping that creates end-to-end entanglement) or across a low-diameter path to another group. We present a full-stack analysis of system performance, a combination of distributed and centralized protocols, and a resource scheduler that plans qubit placement and communications for large-scale, fault-tolerant systems. We implement a prototype three-node switched interconnect to justify hardware-side scalability and to expose low-level architectural challenges. We create two-hop entanglement with fidelities of 0.6-0.76. Our design emphasizes reducing network hops and optical components to simplify system stabilization while flexibly adjusting optical path lengths. Based on evaluated loss and infidelity budgets, we find that moderate-radix switches enable systems meeting expected near-term needs, and large systems are feasible. Our design is expected to be effective for a variety of quantum computing technologies, including ion traps and neutral atoms. + oai:arXiv.org:2412.09299v4 + quant-ph + cs.AR + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Daisuke Sakuma, Tomoki Tsuno, Hikaru Shimizu, Yuki Kurosawa, Monet Tokuyama Friedrich, Kentaro Teramoto, Amin Taherkhani, Andrew Todd, Yosuke Ueno, Michal Hajdu\v{s}ek, Rikizo Ikuta, Rodney Van Meter, Toshihiko Sasaki, Shota Nagayama + + + Witnessing non-stationary and non-Markovian environments with a quantum sensor + https://arxiv.org/abs/2501.05814 + arXiv:2501.05814v2 Announce Type: replace +Abstract: Quantum sensors offer exceptional sensitivity to nanoscale magnetic fluctuations, where non-stationary effects -- such as spin diffusion -- and non-Markovian dynamics arising from coupling to few environmental degrees of freedom play critical roles. Because fully reconstructing the microscopic structure of realistic spin baths is often infeasible, a practical challenge is to identify the dynamical features that are actually encoded in the sensor's decoherence signal. Here, we demonstrate how quantum sensors can operationally characterize the statistical nature of environmental noise, distinguishing between stationary and non-stationary behaviors, as well as Markovian and non-Markovian dynamics. Using nitrogen-vacancy (NV) centers in diamond as a platform, we develop a physical noise model that captures the essential dynamical features of realistic environments relevant to sensor observables -- independently of the microscopic bath details -- and provides analytical predictions for Ramsey decay across different regimes. These predictions are experimentally validated through controlled noise injection with tunable correlation properties. Our results showcase the capability of quantum sensors to isolate and identify key dynamical properties of complex environments, without requiring full microscopic bath reconstruction. This work clarifies the operational signatures of non-stationarity and non-Markovian behavior at the nanoscale and lays the foundation for strategies that mitigates decoherence while exploiting environmental dynamics for enhanced quantum sensing. + oai:arXiv.org:2501.05814v2 + quant-ph + cond-mat.mes-hall + physics.chem-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-nc-nd/4.0/ + 10.1103/13mr-493z + John W. Rosenberg, Mart\'in Kuffer, Inbar Zohar, Rainer St\"ohr, Andrej Denisenko, Analia Zwick, Gonzalo A. \'Alvarez, Amit Finkler + + + All-Optical Photoluminescence Response of Nitrogen-Vacancy Ensembles in Diamond at Low Magnetic Fields + https://arxiv.org/abs/2502.11943 + arXiv:2502.11943v2 Announce Type: replace +Abstract: All-optical (AO), microwave-free magnetometry using nitrogen-vacancy (NV) centers in diamond is attractive due to its broad sample compatibility and reduced experimental complexity. In this work, we investigate room-temperature AO photoluminescence (PL) at low magnetic fields (<2 mT) using diamonds with NV ensembles at ppm concentrations. Measured AO-PL contrast features as a function of applied magnetic field magnitude and direction are correlated with near-degenerate NV electronic spin and hyperfine transitions from different NV orientations within the diamond host. Reasonable agreement is found between low-field AO-PL measurements and model-based simulations of the effects of resonant dipolar interactions between NV centers. Maximum observed AO-PL contrast depends on both NV concentration and laser illumination intensity at 532 nm. These results imply different optimal conditions for low-field AO NV sensing compared to conventional optically detected magnetic resonance (ODMR) techniques, suggesting new research and application opportunities using AO measurements with lower system complexity, size, weight, and power. + oai:arXiv.org:2502.11943v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + 10.1103/ls1d-r771 + Xiechen Zheng, Jeyson T\'amara-Isaza, Zechuan Yin, Johannes Cremer, John W. Blanchard, Connor A. Hart, Michael Crescimanno, Paul V. Petruzzi, Matthew J. Turner, Ronald L. Walsworth + + + Error bounds for composite quantum hypothesis testing and a new characterization of the weighted Kubo-Ando geometric means + https://arxiv.org/abs/2503.13379 + arXiv:2503.13379v4 Announce Type: replace +Abstract: The optimal error exponents of binary composite i.i.d. state discrimination are trivially bounded by the worst-case pairwise exponents of discriminating individual elements of the sets representing the two hypotheses, and in the finite-dimensional classical case, these bounds in fact give exact single-copy expressions for the error exponents. In contrast, in the non-commutative case, the optimal exponents are only known to be expressible in terms of regularized divergences, resulting in formulas that, while conceptually relevant, are practically not very useful. In this paper, we develop further an approach initiated in [Mosonyi, Szil\'agyi, Weiner, IEEE Trans. Inf. Th. 68(2):1032--1067, 2022] to give improved single-copy bounds on the error exponents by comparing not only individual states from the two hypotheses, but also various unnormalized positive semi-definite operators associated to them. Here, we show a number of equivalent characterizations of such operators giving valid bounds, and show that in the commutative case, considering weighted geometric means of the states, and in the case of two states per hypothesis, considering weighted Kubo-Ando geometric means, are optimal for this approach. As a result, we give a new characterization of the weighted Kubo-Ando geometric means as the only $2$-variable operator geometric means that are block additive, tensor multiplicative, and satisfy the arithmetic-geometric mean inequality. We also extend our results to composite quantum channel discrimination, and show an analogous optimality property of the weighted Kubo-Ando geometric means of two quantum channels, a notion that seems to be new. We extend this concept to defining the notion of superoperator perspective function and establish some of its basic properties, which may be of independent interest. + oai:arXiv.org:2503.13379v4 + quant-ph + cs.IT + math-ph + math.FA + math.IT + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + P\'eter E. Frenkel, Mil\'an Mosonyi, P\'eter Vrana, Mih\'aly Weiner + + + Reshaping the Quantum Arrow of Time + https://arxiv.org/abs/2503.13615 + arXiv:2503.13615v2 Announce Type: replace +Abstract: While the microscopic laws of physics are often symmetric under time reversal, most natural processes that we observe are not. The emergent asymmetry between typical and time-reversed processes is referred to as the arrow of time. In quantum physics, an arrow of time emerges when a sequence of measurements is performed on a system. We introduce quantum control tools that can yield dynamics more consistent with time flowing backward than forward. The control tools are based on the explicit construction of a Hamiltonian that can replicate the stochastic trajectories of a monitored quantum system. Such Hamiltonian can reverse the effect of monitoring and, via a feedback process, generate trajectories consistent with a reversed arrow of time. It can also be used to simulate the backward-in-time dynamics of an open quantum system. Finally, we design a feedback-driven continuous measurement engine powered by the energy pumped into the system by the monitoring process. We show the engine can operate under experimentally realizable conditions with feedback delay and finite-efficiency measurements. + oai:arXiv.org:2503.13615v2 + quant-ph + cond-mat.stat-mech + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Luis Pedro Garc\'ia-Pintos, Yi-Kai Liu, Alexey V. Gorshkov + + + Exploration of Design Alternatives for Reducing Idle Time in Shor's Algorithm: A Study on Monolithic and Distributed Quantum Systems + https://arxiv.org/abs/2503.22564 + arXiv:2503.22564v3 Announce Type: replace +Abstract: Shor's algorithm is one of the most prominent quantum algorithms, yet finding efficient implementations remains an active research challenge. While many approaches focus on low-level modular arithmetic optimizations, a broader perspective can provide additional opportunities for improvement. By adopting a mid-level abstraction, we analyze the algorithm as a sequence of computational tasks, enabling systematic identification of idle time and optimization of execution flow. Building on this perspective, we first introduce an alternating design approach to minimize idle time while preserving qubit efficiency in Shor's algorithm. By strategically reordering tasks for simultaneous execution, we achieve a substantial reduction in overall execution time. Extending this approach to distributed implementations, we demonstrate how task rearrangement enhances execution efficiency in the presence of multiple distribution channels. Furthermore, to effectively evaluate the impact of design choices, we employ static timing analysis (STA) -- a technique from classical circuit design -- to analyze circuit delays while accounting for hardware-specific execution characteristics, such as measurement and reset delays in monolithic architectures and ebit generation time in distributed settings. Finally, we validate our approach by integrating modular exponentiation circuits from QRISP and constructing circuits for factoring numbers up to 64 bits. Through an extensive study across neutral atom, superconducting, and ion trap quantum computing platforms, we analyze circuit delays, highlighting trade-offs between qubit efficiency and execution time. Our findings provide a structured framework for optimizing compiled quantum circuits for Shor's algorithm, tailored to specific hardware constraints. + oai:arXiv.org:2503.22564v3 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + 10.1109/TQE.2025.3610800 + Moritz Schmidt, Abhoy Kole, Leon Wichette, Rolf Drechsler, Frank Kirchner, Elie Mounzer + + + Inter-species topological phases via a dynamical gauge field + https://arxiv.org/abs/2504.05390 + arXiv:2504.05390v2 Announce Type: replace +Abstract: We uncover a class of inter-species topological phases in a one-dimensional lattice, loaded with two species of non-identical particles interacting via a dynamical gauge field (DGF). Two types of topological states are found to emerge from different inter-species topology activated by the DGF. Specifically, edge confined states with co-localization of both species arise from an extrinsic inter-species topology, which can be decomposed into the single-particle topology for each species. On the other hand, bulk bound states with extended distribution emerge from an intrinsic inter-species topology that cannot be understood from single-particle ones. The two classes of inter-species topology are found to be independent of each other, characterized by different sets of inter-species topological invariants. Thus, their topological states can coexist in certain parameter regimes and compete with each other, leading to distinguished dynamical signatures. We further propose a feasible cold-atom realization of our model to demonstrate experimental accessibility of inter-species topological phases. Our work establishes inter-species topology as a new organizing principle of topological matter, revealing how correlations between distinct particle species can generate topological phenomena beyond single-particle paradigms. + oai:arXiv.org:2504.05390v2 + quant-ph + cond-mat.quant-gas + cond-mat.str-el + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Zhoutao Lei, Linhu Li + + + Engineering diamond interfaces free of dark spins + https://arxiv.org/abs/2504.08883 + arXiv:2504.08883v3 Announce Type: replace +Abstract: Nitrogen-vacancy (NV) centers in diamond are extensively utilized as quantum sensors for imaging fields at the nanoscale. The ultra-high sensitivity of NV magnetometers has enabled the detection and spectroscopy of individual electron spins, with potentially far-reaching applications in condensed matter physics, spintronics, and molecular biology. However, the surfaces of these diamond sensors naturally contain electron spins, which create a background signal that can be hard to differentiate from the signal of the target spins. In this study, we develop a surface modification approach that eliminates the unwanted signal of these so-called dark electron spins. Our surface passivation technique, based on coating diamond surfaces with a thin titanium oxide (TiO$_2$) layer, reduces the dark spin density. The observed reduction in dark spin density aligns with our findings on the electronic structure of the diamond-TiO$_2$ interface. The reduction, from a typical value of $2,000$~$\mu$m$^{-2}$ to a value below that set by the detection limit of our NV sensors ($200$~$\mu$m$^{-2}$), results in a two-fold increase in Hahn-echo coherence time of near surface NV centers. Furthermore, we derive a comprehensive spin model that connects dark spin relaxation with NV coherence, providing additional insights into the mechanisms behind the observed spin dynamics. Our findings are directly transferable to other quantum platforms, including nanoscale solid state qubits and superconducting qubits. + oai:arXiv.org:2504.08883v3 + quant-ph + cond-mat.mes-hall + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Xiaofei Yu, Evan J. Villafranca, Stella Wang, Jessica C. Jones, Mouzhe Xie, Jonah Nagura, Ignacio Chi-Dur\'an, Nazar Delegan, Alex B. F. Martinson, Michael E. Flatt\'e, Denis R. Candido, Giulia Galli, Peter C. Maurer + + + Performance guarantees of light-cone variational quantum algorithms for the maximum cut problem + https://arxiv.org/abs/2504.12896 + arXiv:2504.12896v3 Announce Type: replace +Abstract: Variational quantum algorithms (VQAs) are promising to demonstrate the advantage of near-term quantum computing over classical computing in practical applications, such as the maximum cut (MaxCut) problem. However, current VQAs such as the quantum approximate optimization algorithm (QAOA) have lower performance guarantees compared to the best-known classical algorithm, and suffer from hard optimization processes due to the barren plateau problem. We propose a light-cone VQA by choosing an optimal gate sequence of the standard VQAs, which enables a significant improvement in solution accuracy while avoiding the barren plateau problem. Specifically, we prove that the light-cone VQA with one round achieves an approximation ratio of 0.7926 for the MaxCut problem in the worst case of $3$-regular graphs, which is higher than that of the 3-round QAOA, and can be further improved to 0.8333 by an angle-relaxation procedure. Finally, our numerical results indicate an exponential speed-up in finding the exact solution using the light-cone VQA compared with the classical algorithm. Using IBM's quantum devices, we demonstrate that the single-round light-cone VQA exceeds the known classical hardness threshold in both 72- and 148-qubit demonstrations, whereas $p$-round $\text{QAOA}$ with $p=1,2,3$ does not in the latter one. Our work highlights a promising route towards solving classically hard problems on practical quantum devices. + oai:arXiv.org:2504.12896v3 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Xiaoyang Wang, Yuexin Su, Tongyang Li + + + Multimode Entangled Squeezed Light Generation and Propagation in a Coupled-Cavity Photonic Crystal + https://arxiv.org/abs/2504.20254 + arXiv:2504.20254v3 Announce Type: replace +Abstract: Entangled multi-mode squeezed states of light have a wide variety of applications in quantum information systems, particularly in the generation of non-Gaussian states of light, which are central to continuous-variable quantum computing. Although theoretical approaches exist to model the nonlinear generation of one- and two-mode entangled states of light in ring resonator systems, these approaches are difficult to implement in modeling more complicated many-cavity systems. In this work, we present an efficient and accurate theoretical approach to modeling the generation and propagation of quantum states of light in lossy coupled-cavity systems containing a two- or three-mode nonlinear resonant structure. Our approach is general and computationally viable even in systems with hundreds of modes. We apply our method to the design and modeling of a multimode photonic crystal coupled-cavity system for the generation of entangled squeezed states of light on-chip. The system consists of a three-mode resonant structure coupled to three coupled-resonator optical waveguides (CROWs) in a square lattice silicon photonic crystal slab. The computational speed of the method allows us to efficiently optimize the system such that the signal and idler light in the two output CROWs remains entangled even after propagating tens of cavities down the CROWs. + oai:arXiv.org:2504.20254v3 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Dylan van Eeden, Marc M. Dignam + + + Augmenting Density Matrix Renormalization Group with Matchgates and Clifford circuits + https://arxiv.org/abs/2505.08635 + arXiv:2505.08635v2 Announce Type: replace +Abstract: Matchgates and Clifford circuits are two types of quantum circuits which can be efficiently simulated classically, though the underlying reasons are quite different. Matchgates are essentially the single particle basis transformations in the Majorana fermion representation which can be easily handled classically, while the Clifford circuits can be efficiently simulated using the tableau method according to the Gottesman-Knill theorem. In this work, we propose a new wave-function ansatz in which matrix product states are augmented with the combination of Matchgates and Clifford circuits (dubbed MCA-MPS) to take advantage of the representing power of all of them. Moreover, the optimization of MCA-MPS can be efficiently implemented within the Density Matrix Renormalization Group method. Our benchmark results on one-dimensional hydrogen chain show that MCA-MPS can improve the accuracy of the ground-state calculation by several orders of magnitude over MPS with the same bond dimension. This new method provides us a useful approach to study quantum many-body systems. The MCA-MPS ansatz also expands our understanding of classically simulatable quantum many-body states. + oai:arXiv.org:2505.08635v2 + quant-ph + cond-mat.str-el + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Jiale Huang, Xiangjian Qian, Zhendong Li, Mingpu Qin + + + Quantum state preparation with polynomial resources: Branched-Subspaces Adiabatic Preparation (B-SAP) + https://arxiv.org/abs/2505.13717 + arXiv:2505.13717v2 Announce Type: replace +Abstract: Quantum state preparation lies at the heart of quantum computation and quantum simulations, enabling the investigation of complex manybody systems across physics, chemistry, and data science. While existing methods such as Variational Quantum Algorithms (VQAs) and Adiabatic Preparation (AP) offer viable pathways, both face substantial limitations. Here we introduce a hybrid algorithm that integrates the conceptual strengths of both VQAs and AP, enhanced via the use of group-theoretic structures and classical post-processing to approximate ground and excited states of many-body Hamiltonian models. We validate our approach by applying it to the one-dimensional XYZ Heisenberg model with periodic boundary conditions, evaluating its performance across a broad range of parameters and system sizes. Our results show accurate preparation of low-energy eigenstates, achieved with circuit depths with polynomial scaling versus system size. + oai:arXiv.org:2505.13717v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Davide Cugini, Giacomo Guarnieri, Mario Motta, Dario Gerace + + + Transformer-Based Neural Quantum Digital Twins for Many-Body Quantum Simulation and Optimal Annealing Schedule Design + https://arxiv.org/abs/2505.15662 + arXiv:2505.15662v2 Announce Type: replace +Abstract: We introduce Transformer-based Neural Quantum Digital Twins (Tx-NQDTs) to simulate full adiabatic dynamics of many-body quantum systems, including ground and low-lying excited states, at low computational cost. Tx-NQDTs employ a graph-informed Transformer neural network trained to predict spectral properties (energy levels and gap locations) needed for annealing schedule design. We integrate these predictions with an adaptive annealing schedule design based on first-order adiabatic perturbation theory (FOAPT), which slows the evolution near predicted small gaps to maintain adiabaticity. Experiments on a D-Wave quantum annealer (N = 10, 15, 20 qubits, 12 control segments) show that Tx-NQDT-informed schedules significantly improve success probabilities despite hardware noise and calibration drift. The optimized schedules achieve success probabilities 2.2-11.7 percentage points higher than the default linear schedule, outperforming the D-Wave baseline in 44 of 60 cases. These results demonstrate a practical, data-driven route to improved quantum annealing performance on real hardware. + oai:arXiv.org:2505.15662v2 + quant-ph + cs.AI + cs.ET + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Jianlong Lu, Hanqiu Peng, Ying Chen + + + Quantum circuits for partial differential equations in Fourier space + https://arxiv.org/abs/2505.16895 + arXiv:2505.16895v2 Announce Type: replace +Abstract: For the solution of partial differential equations (PDEs), we show that the quantum Fourier transform (QFT) can enable the design of quantum circuits that are particularly simple, both conceptually and with regard to hardware requirements. This is shown by explicit circuit constructions for the incompressible advection, heat, isotropic acoustic wave, and Poisson's equations as canonical examples. We utilize quantum singular value transformation to develop circuits that are expected to be of optimal computational complexity. Additionally, we consider approximations suited for smooth initial conditions and describe circuits that make lower demands on hardware. The simple QFT-based circuits are efficient with respect to dimensionality and pave the way for current quantum computers to solve high-dimensional PDEs. + oai:arXiv.org:2505.16895v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/tbzc-w9x8 + Phys. Rev. Research 7, 043326 (2025) + Michael Lubasch, Yuta Kikuchi, Lewis Wright, Conor Mc Keever + + + Tight Generalization of Robertson-Type Uncertainty Relations + https://arxiv.org/abs/2505.19861 + arXiv:2505.19861v2 Announce Type: replace +Abstract: We establish the tightest possible Robertson-type preparation uncertainty relation, which explicitly depends on the eigenvalues of the quantum state. The conventional constant $ \tfrac{1}{4} $ is replaced by a state-dependent coefficient $\frac{(\lambda_{\max} + \lambda_{\min})^2}{4(\lambda_{\max} - \lambda_{\min})^2}$, where $ \lambda_{\max} $ and $ \lambda_{\min}$ denote the largest and smallest eigenvalues of the density operator $\rho$, respectively. This coefficient is optimal among all Robertson-type generalizations and does not admit further improvement.Our relation becomes more pronounced as the quantum state becomes more mixed, capturing a trade-off in quantum uncertainty that the conventional Robertson's relation fails to detect. In addition, our result also provides a strict generalization of the Schr\"oedinger's uncertainty relation, showing that the uncertainty trade-off is governed by the sum of the covariance term and a state-dependent improvement over the Robertson bound. As applications, we also refine error-disturbance trade-offs by incorporating spectral information of both the system and the measuring apparatus,thereby generalizing the Arthurs--Goodman and Ozawa inequalities. + oai:arXiv.org:2505.19861v2 + quant-ph + cond-mat.stat-mech + hep-th + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by/4.0/ + Gen Kimura, Aina Mayumi, Haruki Yamashita - The Quantum Rashomon Effect: A Strengthened Frauchiger-Renner Argument - https://arxiv.org/abs/2011.12716 - arXiv:2011.12716v5 Announce Type: replace -Abstract: The Frauchiger-Renner argument aims to show that `quantum theory cannot consistently describe the use of itself': in many-party settings where agents are themselves subject to quantum experiments, agents may make predictions that contradict observations. Here, we introduce a simplified setting using only three agents, that is independent of the initial quantum state, thus eliminating in particular any need for entanglement, and furthermore does not need to invoke any final measurement and resulting collapse. Nevertheless, the predictions and observations made by the agents cannot be integrated into a single, consistent account. We propose that the existence of this sort of \emph{Rashomon effect}, i.e. the impossibility of uniting different perspectives, is due to failing to account for the limits put on the information available about any given system as encapsulated in the notion of an \emph{epistemic horizon}. - oai:arXiv.org:2011.12716v5 + Quantum Complexity and Chaos in Many-Qudit Doped Clifford Circuits + https://arxiv.org/abs/2506.02127 + arXiv:2506.02127v5 Announce Type: replace +Abstract: We investigate the emergence of quantum complexity and chaos in doped Clifford circuits acting on qudits of odd prime dimension $d$. Using doped Clifford Weingarten calculus and a replica tensor network formalism, we derive exact results and perform large-scale simulations in regimes challenging for tensor network and Pauli-based methods. We begin by analyzing generalized stabilizer entropies, computable magic monotones in many-qudit systems, and identify a dynamical phase transition in the doping rate, marking the breakdown of classical simulability and the onset of Haar-random behavior. The critical behavior is governed by the qudit dimension and the magic content of the non-Clifford gate. Using the qudit $T$-gate as a benchmark, we show that higher-dimensional qudits converge faster to Haar-typical stabilizer entropies. For qutrits ($d=3$), analytical predictions match numerics on brickwork circuits, showing that locality plays a limited role in magic spreading. We also examine anticoncentration and entanglement growth, showing that $O(\log N)$ non-Clifford gates suffice for approximating Haar expectation values to precision $\varepsilon$, and relate antiflatness measures to stabilizer entropies in qutrit systems. Finally, we analyze out-of-time-order correlators and show that a finite density of non-Clifford gates is needed to induce chaos, with a sharp transition fixed by the local dimension, twice that of the magic transition. Altogether, these results establish a unified framework for diagnosing complexity in doped Clifford circuits and deepen our understanding of resource theories in multiqudit systems. + oai:arXiv.org:2506.02127v5 quant-ph - physics.hist-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.stat-mech + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jochen Szangolies + http://creativecommons.org/licenses/by/4.0/ + Beatrice Magni, Xhek Turkeshi - Nonreciprocal Bistability in Coupled Nonlinear Cavity Magnonics - https://arxiv.org/abs/2309.09245 - arXiv:2309.09245v4 Announce Type: replace -Abstract: We propose a coupled nonlinear cavity-magnon system, consisting of two cavities, a second-order nonlinear element, and a yttrium-iron-garnet (YIG) sphere that supports Kerr magnons, to realize the sought-after highly tunable nonreciprocity. We first derive the critical condition for switching between reciprocity and nonreciprocity in the absence of magnon driving, and then numerically demonstrate that strong magnonic nonreciprocity can be achieved by violating this critical condition. When magnons are driven, we show that strong magnonic nonreciprocity can also be attained even within the critical condition. Compared to previous studies, the introduced nonlinear element not only relaxes the critical condition in both the weak and strong coupling regimes, but also offers an alternative means to tune magnonic nonreciprocity. Our work provides a promising avenue for realizing highly tunable nonreciprocal devices based on Kerr magnons. - oai:arXiv.org:2309.09245v4 + Cooling a Qubit using n Others + https://arxiv.org/abs/2506.10059 + arXiv:2506.10059v2 Announce Type: replace +Abstract: In the task of unitarily cooling a quantum system with access to a larger quantum system, known as the machine or reservoir, how does the structure of the machine impact an agent's ability to cool and the complexity of their cooling protocol? Focusing on the task of cooling a single qubit given access to $n$ separable, thermal qubits with arbitrary energy structure, we answer these questions by giving two new perspectives on this task. Firstly, we show that a set of inequalities related to the energetic structure of the $n$ qubit machine determines the optimal cooling protocol, which parts of the machine contribute to this protocol and gives rise to a Carnot-like bound. Secondly, we show that cooling protocols can be represented as perfect matchings on bipartite graphs enabling the optimization of cost functions e.g. gate complexity or dissipation. Our results generalize the algorithmic cooling problem, establish new fundamental bounds on quantum cooling and offer a framework for designing novel autonomous thermal machines and cooling algorithms. + oai:arXiv.org:2506.10059v2 quant-ph - cond-mat.mes-hall - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Chaos, Solitons and Fractals 204, 117777 (2026) - Wei Xiong, Yuan Gong, Zhuanxia Li, Ying-Xia Wu, Yan-Xue Cheng, Jiaojiao Chen + 10.1103/hrph-dbv7 + PRX Quantum 6, 040368 (2025) + Jake Xuereb, Benjamin Stratton, Alberto Rolandi, Jinming He, Marcus Huber, Pharnam Bakhshinezhad - Making the zeroth-order process fidelity independent of state preparation and measurement errors - https://arxiv.org/abs/2312.08590 - arXiv:2312.08590v3 Announce Type: replace -Abstract: In this work, we demonstrate that the zero-fidelity, an approximation to the process fidelity, when combined with randomized benchmarking, becomes robust to state preparation and measurement (SPAM) errors. However, as randomized benchmarking requires randomly choosing an increasingly large number of Clifford elements from the Clifford group when the qubit number increases, this combination is also limited to quantum systems with up to three qubits. To make the zero-fidelity independent of SPAM errors and, at the same time, applicable to multi-qubit systems, we employ a channel noise scaling method similar to the method of global unitary folding, or identity scaling, used for quantum error mitigation. - oai:arXiv.org:2312.08590v3 + Fully Quantum Lattice Gas Automata Building Blocks for Computational Basis State Encodings + https://arxiv.org/abs/2506.12662 + arXiv:2506.12662v3 Announce Type: replace +Abstract: Lattice Gas Automata (LGA) is a classical method for simulating physical phenomena, including Computational Fluid Dynamics (CFD). Quantum LGA (QLGA) is the family of methods that implement LGA schemes on quantum computers. In recent years, QLGA has garnered attention from researchers thanks to its potential of efficiently modeling CFD processes by either reducing memory requirements or providing simultaneous representations of exponentially many LGA states. In this work, we introduce novel building blocks for QLGA algorithms that rely on computational basis state encodings. We address every step of the algorithm, from initial conditions to measurement, and provide detailed complexity analyses that account for all discretization choices of the system under simulation. We introduce multiple ways of instantiating initial conditions, efficient boundary condition implementations for novel geometrical patterns, a novel collision operator that models less restricted interactions than previous implementations, and quantum circuits that extract quantities of interest out of the quantum state. For each building block, we provide intuitive examples and open-source implementations of the underlying quantum circuits. + oai:arXiv.org:2506.12662v3 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + physics.comp-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yu-Hao Chen, Renata Wong, Hsi-Sheng Goan + http://creativecommons.org/licenses/by/4.0/ + 10.1016/j.jcp.2025.114595 + C\u{a}lin A. Georgescu, Merel A. Schalkers, Matthias M\"oller - Entanglement-breaking channels are a quantum memory resource - https://arxiv.org/abs/2402.16789 - arXiv:2402.16789v2 Announce Type: replace -Abstract: Entanglement-breaking channels (equivalently, measure-and-prepare channels) are an important class of quantum operations noted for their ability to destroy multipartite spatial quantum correlations. Inspired by this property, they have also been employed in defining notions of "classical memory", under the assumption that such channels effectively act as a classical resource. We show that, in a single-system multi-time scenario, entanglement-breaking channels are still a quantum memory resource: a qudit going through an entanglement-breaking channel cannot be simulated by a classical system of same dimension. We provide explicit examples of memory-based output generation tasks where entanglement-breaking channels outperform classical memories of the same size. Our results imply that entanglement-breaking channels cannot be generally employed to characterize classical memory effects in temporal scenarios without additional assumptions. - oai:arXiv.org:2402.16789v2 + Characterization of drive-induced unwanted state transitions in superconducting circuits + https://arxiv.org/abs/2506.24070 + arXiv:2506.24070v3 Announce Type: replace +Abstract: Microwave drives are essential for implementing control and readout operations in superconducting quantum circuits. However, increasing the drive strength eventually leads to unwanted state transitions which limit the speed and fidelity of such operations. In this work, we systematically investigate such transitions in a fixed-frequency qubit subjected to microwave drives spanning a 9 GHz frequency range. We identify the physical origins of these transitions and classify them into three categories. (1) Resonant energy exchange with parasitic two-level systems, activated by drive-induced ac-Stark shifts, (2) multi-photon transitions to non-computational states, intrinsic to the circuit Hamiltonian, and (3) inelastic scattering processes in which the drive causes a state transition in the superconducting circuit, while transferring excess energy to a spurious electromagnetic mode or two-level system (TLS) material defect. We show that the Floquet steady-state simulation, complemented by an electromagnetic simulation of the physical device, accurately predicts the observed transitions that do not involve TLS. Our results provide a comprehensive classification of these transitions and offer mitigation strategies through informed choices of drive frequency as well as improved circuit design. + oai:arXiv.org:2506.24070v3 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.1103/r8lf-bb4p - Phys. Rev. Research 7, 043281 (2025) - Lucas B. Vieira, Huan-Yu Ku, Costantino Budroni + 10.1103/zdpg-mhpc + W. Dai, S. Hazra, D. K. Weiss, P. D. Kurilovich, T. Connolly, H. K. Babla, S. Singh, V. R. Joshi, A. Z. Ding, P. D. Parakh, J. Venkatraman, X. Xiao, L. Frunzio, M. H. Devoret - Generalized R\'enyi entropy accumulation theorem and generalized quantum probability estimation - https://arxiv.org/abs/2405.05912 - arXiv:2405.05912v5 Announce Type: replace -Abstract: The entropy accumulation theorem, and its subsequent generalized version, is a powerful tool in the security analysis of many device-dependent and device-independent cryptography protocols. However, it has the drawback that the finite-size bounds it yields are not necessarily optimal, and furthermore it relies on the construction of an affine min-tradeoff function, which can often be challenging to construct optimally in practice. In this work, we address both of these challenges simultaneously by deriving a new entropy accumulation bound. Our bound yields significantly better finite-size performance, and can be computed as an intuitively interpretable convex optimization, without any specification of affine min-tradeoff functions. Furthermore, it can be applied directly at the level of R\'enyi entropies if desired, yielding fully-R\'enyi security proofs. Our proof techniques are based on elaborating on a connection between entropy accumulation and the frameworks of quantum probability estimation or $f$-weighted R\'enyi entropies, and in the process we obtain some new results with respect to those frameworks as well. In particular, those findings imply that our bounds apply to prepare-and-measure protocols without the virtual tomography procedures or repetition-rate restrictions previously required for entropy accumulation. - oai:arXiv.org:2405.05912v5 + Classification of four-qubit pure codes and five-qubit absolutely maximally entangled states + https://arxiv.org/abs/2507.02185 + arXiv:2507.02185v3 Announce Type: replace +Abstract: We prove that every 5-qubit absolutely maximally entangled (AME) state is equivalent by a local unitary transformation to a point in the unique ((5,2,3)) quantum error correcting code C. Furthermore, two points in C are equivalent if and only if they are related by a group of order 24 acting on C. There exists a set of 3 invariant polynomials that separates equivalence classes of 5-qubit AME states. We also show that every 4-qubit pure code is equivalent to a subspace of the unique ((4,4,2)) and construct an infinite family of 3-uniform n-qubit states for even $n\geq 6$. The proofs rely heavily on results from Vinberg and classical invariant theory. + oai:arXiv.org:2507.02185v3 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + math.RT + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Amir Arqand, Thomas A. Hahn, Ernest Y. -Z. Tan + Ian Tan - Deriving the Born Rule from a model of the quantum measurement process - https://arxiv.org/abs/2408.06375 - arXiv:2408.06375v4 Announce Type: replace -Abstract: The quantum mechanics postulate called the Born Rule attributes a probabilistic meaning to a wave function. This paper derives the Born Rule from other quantum principles along with a model of the measurement process. - The nondeterministic nature of quantum measurements is hypothesized to arise from an ignorance of the quantum states of a measuring device's microscopic components. Their interactions with a system to be measured are modeled heuristically with any member of a particular class of stochastic processes, each of which generate the Born Rule. One member of the class appears particularly compatible with properties expected of quantum interactions. - oai:arXiv.org:2408.06375v4 + From Linear Differential Equations to Unitaries: A Moment-Matching Dilation Framework with Near-Optimal Quantum Algorithms + https://arxiv.org/abs/2507.10285 + arXiv:2507.10285v3 Announce Type: replace +Abstract: Quantum speed-ups for dynamical simulation usually demand unitary time-evolution, whereas the large ODE/PDE systems encountered in realistic physical models are generically non-unitary. We present a universal moment-fulfilling dilation that embeds any linear, non-Hermitian flow $\dot x = L x$ with $L=-iH+K$ into a strictly unitary evolution on an enlarged Hilbert space: \[ + ( (l| \otimes I ) + \mathcal T e^{-i \int ( I_A\otimes H +i F\otimes K) dt} + ( |r) \otimes I ) + = \mathcal T e^{\int L dt}, \] provided the triple $( F, (l|, |r) )$ satisfies the compact moment identities $(l| F^{k}|r) =1$ for all $k\ge 0$ in the ancilla space. This algebraic criterion recovers both \emph{Schr\"odingerization} [Phys. Rev. Lett. 133, 230602 (2024)] and the linear-combination-of-Hamiltonians (LCHS) scheme [Phys. Rev. Lett. 131, 150603 (2023)], while also unveiling whole families of new dilations built from differential, integral, pseudo-differential, and difference generators. Each family comes with a continuous tuning parameter \emph{and} is closed under similarity transformations that leave the moments invariant, giving rise to an overwhelming landscape of design space that allows quantum dilations to be co-optimized for specific applications, algorithms, and hardware. + As concrete demonstrations, we prove that a simple finite-difference dilation in a finite interval attains near-optimal oracle complexity. Numerical experiments on Maxwell viscoelastic wave propagation confirm the accuracy and robustness of the approach. + oai:arXiv.org:2507.10285v3 quant-ph - physics.hist-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Alan Schaum + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Xiantao Li + + + Definition of Current Density in Non-Hermitian Quantum Systems + https://arxiv.org/abs/2507.14014 + arXiv:2507.14014v2 Announce Type: replace +Abstract: In recent years, non-Hermitian quantum systems (NHQS) have been actively studied. In conventional quantum mechanics, Hermiticity is a fundamental property of Hamiltonians. In NHQS, however, states evolve under non-Hermitian Hamiltonians and novel physical phenomena are predicted due to the non-Hermiticity. One difference from Hermitian systems is that the continuity equation (CE) does not hold in NHQS even when the number of particles is conserved. In this study, I extended the definition of current density so that CE holds also in NHQS. The newly defined current density does not only satisfy CE but also has physical meanings in the sense that it affects physical observables in the same manner as conventional current density. + oai:arXiv.org:2507.14014v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Hiroto Oka + + + Strong electron-electron interactions in a dilute weakly-localized metal near a metal-to-insulator transition + https://arxiv.org/abs/2508.02793 + arXiv:2508.02793v2 Announce Type: replace +Abstract: Because it is easily switched from insulator to metal either via chemical doping or electrical gating, silicon is at the core of modern information technology and remains a candidate platform for quantum computing. The metal-to-insulator transition in this material has therefore been one of the most studied phenomena in condensed matter physics, and has been revisited with considerable profit each time a new fabrication technology has been introduced. Here we take advantage of recent advances in creating ultra-thin layers of Bohr-atom-like dopants to realize the two-dimensional disordered Hubbard model at half-filling and its metal-to-insulator transition (MIT) as a function of mean distance between atoms. We use gas-phase dosing of dopant precursor molecules on silicon to create arsenic and phosphorus $\delta$-layers as thin as 0.4~nm and as dilute as 10$^{13}$~cm$^{-2}$. On approaching the insulating state, the conventional weak localization effects, prevalent at high dopant densities and due to orbital motion of the electrons in the plane, become dominated by electron-electron interaction contributions which obey a paramagnetic Zeeman scaling law. The latter make a negative contribution to the conductance, and thus cannot be interpreted in terms of an emergent Kondo regime near the MIT. + oai:arXiv.org:2508.02793v2 + quant-ph + cond-mat.str-el + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Nicol\`o D'Anna, Jamie Bragg, Aidan G. McConnell, Jakub Vonka, Procopios C. Constantinou, Juerong Li, Taylor J. Z. Stock, Steven R. Schofield, Neil J. Curson, Y. Soh, Marek Bartkowiak, Simon Gerber, Markus M\"uller, Guy Matmon, Gabriel Aeppli - Asymptotic robustness of entanglement in noisy quantum networks and graph connectivity - https://arxiv.org/abs/2411.12548 - arXiv:2411.12548v2 Announce Type: replace -Abstract: Quantum networks are promising venues for quantum information processing. This motivates the study of the entanglement properties of the particular multipartite quantum states that underpin these structures. In particular, it has been recently shown that when the links are noisy two drastically different behaviors can occur regarding the global entanglement properties of the network. While in certain configurations the network displays genuine multipartite entanglement (GME) for any system size provided the noise level is below a certain threshold, in others GME is washed out if the system size is big enough for any fixed non-zero level of noise. However, this difference has only been established considering the two extreme cases of maximally and minimally connected networks (i.e. complete graphs versus trees, respectively). In this article we investigate this question much more in depth and relate this behavior to the growth of several graph theoretic parameters that measure the connectivity of the graph sequence that codifies the structure of the network as the number of parties increases. The strongest conditions are obtained when considering the degree growth. Our main results are that a sufficiently fast degree growth (i.e. $\Omega(N)$, where $N$ is the size of the network) is sufficient for asymptotic robustness of GME, while if it is sufficiently slow (i.e. $o(\log N)$) then the network becomes asymptotically biseparable. We also present several explicit constructions related to the optimality of these results. - oai:arXiv.org:2411.12548v2 + Optimal Qubit Purification and Unitary Schur Sampling via Random SWAP Tests + https://arxiv.org/abs/2508.05046 + arXiv:2508.05046v2 Announce Type: replace +Abstract: The goal of qubit purification is to combine multiple noisy copies of an unknown pure quantum state to obtain one or more copies that are closer to the pure state. We show that a simple protocol based solely on random SWAP tests achieves the same fidelity as the Schur transform, which is optimal. This protocol relies only on elementary two-qubit SWAP tests, which project a pair of qubits onto the singlet or triplet subspaces, to identify and isolate singlet pairs, and then proceeds with the remaining qubits. For a system of $n$ qubits, we show that after approximately $T \approx n \ln n$ random SWAP tests, a sharp transition occurs: the probability of detecting any new singlet decreases exponentially with $T$. Similarly, the fidelity of each remaining qubit approaches the optimal value given by the Schur transform, up to an error that is exponentially small in $T$. More broadly, this protocol achieves what is known as weak Schur sampling and unitary Schur sampling with error $\epsilon$, after only $2n \ln(n \epsilon^{-1})$ SWAP tests. That is, it provides a lossless method for extracting any information invariant under permutations of qubits, making it a powerful subroutine for tasks such as quantum state tomography and metrology. + oai:arXiv.org:2508.05046v2 quant-ph + cond-mat.dis-nn + cond-mat.stat-mech math-ph math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + nucl-th + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Fernando Lled\'o, Carlos Palazuelos, Julio I. de Vicente + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Shrigyan Brahmachari, Austin Hulse, Henry D. Pfister, Iman Marvian - Minimizing resource overhead in fusion-based quantum computation using hybrid spin-photon devices - https://arxiv.org/abs/2412.08611 - arXiv:2412.08611v2 Announce Type: replace -Abstract: We present three schemes for constructing a (2,2)-Shor-encoded 6-ring photonic resource state for fusion-based quantum computing, each relying on a different type of photon source. We benchmark these architectures by analyzing their ability to achieve the loss tolerance threshold for fusion-based quantum computation using the target resource state. More precisely, we estimate their minimum hardware requirements for fault-tolerant quantum computation in terms of the number of photon sources to achieve on-demand generation of resource states with a desired generation period. Notably, we find that a group of 12 deterministic single-photon sources containing a single matter qubit degree of freedom can produce the target resource state near-deterministically by exploiting entangling gates that are repeated until success. The approach is fully modular, eliminates the need for lossy large-scale multiplexing, and reduces the overhead for resource-state generation by several orders of magnitude compared to architectures using heralded single-photon sources and probabilistic linear-optical entangling gates. Our work shows that the use of deterministic single-photon sources embedding a qubit substantially shortens the path toward fault-tolerant photonic quantum computation. - oai:arXiv.org:2412.08611v2 + Joint parameter estimation and multidimensional reconciliation for continuous-variable quantum key distribution + https://arxiv.org/abs/2508.05558 + arXiv:2508.05558v2 Announce Type: replace +Abstract: Accurate quantum channel parameter estimation is essential for effective information reconciliation in continuous-variable quantum key distribution (CV-QKD). However, conventional maximum likelihood (ML) estimators rely on a large amount of discarded data (or pilot symbols), leading to a significant loss in symbol efficiency. Moreover, the separation between the estimation and reconciliation phases can introduce error propagation. In this paper, we propose a novel joint message-passing scheme that unifies channel parameter estimation and information reconciliation within a Bayesian framework. By leveraging the expectation-maximization (EM) algorithm, the proposed method simultaneously estimates unknown parameters during decoding, eliminating the need for separate ML estimation. Furthermore, we introduce a hybrid multidimensional rotation scheme that removes the requirement for norm feedback, significantly reducing classical channel overhead. To the best of our knowledge, this is the first work to unify multidimensional reconciliation and channel parameter estimation in CV-QKD, providing a practical solution for high-efficiency reconciliation with minimal pilots. + oai:arXiv.org:2508.05558v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + eess.SP + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-sa/4.0/ - 10.1103/8l5g-x3b7 - PRX Quantum 6, 040362 (2025) - Stephen C. Wein, Timoth\'ee Goubault de Brugi\`ere, Luka Music, Pascale Senellart, Boris Bourdoncle, Shane Mansfield + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Jisheng Dai, Xue-Qin Jiang, Peng Huang, Tao Wang, Guihua Zeng - Q-Fly: An Optical Interconnect for Modular Quantum Computers - https://arxiv.org/abs/2412.09299 - arXiv:2412.09299v3 Announce Type: replace -Abstract: Much like classical supercomputers, scaling up quantum computers requires an optical interconnect. However, signal attenuation leads to irreversible qubit loss, making quantum interconnect design guidelines and metrics different from conventional computing. Inspired by the classical Dragonfly topology, we propose a multi-group structure where the group switch routes photons emitted by computational end nodes to the group's shared pool of Bell state analyzers (which conduct the entanglement swapping that creates end-to-end entanglement) or across a low-diameter path to another group. We present a full-stack analysis of system performance, a combination of distributed and centralized protocols, and a resource scheduler that plans qubit placement and communications for large-scale, fault-tolerant systems. We implement a prototype three-node switched interconnect to justify hardware-side scalability and to expose low-level architectural challenges. We create two-hop entanglement with fidelities of 0.6-0.76. Our design emphasizes reducing network hops and optical components to simplify system stabilization while flexibly adjusting optical path lengths. Based on evaluated loss and infidelity budgets, we find that moderate-radix switches enable systems meeting expected near-term needs, and large systems are feasible. Our design is expected to be effective for a variety of quantum computing technologies, including ion traps and neutral atoms. - oai:arXiv.org:2412.09299v3 + Quantum algorithms to detect ODMR-active defects for quantum sensing applications + https://arxiv.org/abs/2508.13281 + arXiv:2508.13281v2 Announce Type: replace +Abstract: Spin defects in two-dimensional materials are a promising platform for quantum sensing. Simulating the defect's optical response and optically detected magnetic resonance (ODMR) contrast is key to identifying suitable candidates. However, existing simulation methods are typically unable to supply the required accuracy. Here, we propose two quantum algorithms to detect an imbalance in the triplet-to-singlet intersystem crossing (ISC) rates between excited states with the same and different spin projections -- a necessary condition for nonzero ODMR response. The lowest-cost approach evaluates whether the evolution of an $S=0$ state under the spin-orbit coupling induces ISC to $S=1$, and also whether there is an imbalance in its intensity depending on the final state spin projection. The second approach works by comparing the emission spectrum of a spin defect with and without the spin-orbit coupling operator, inferring ISC intensity for different spin transition channels from spectrum intensity changes. Additionally, we present an improved scheme to evaluate the defect's optical response, building upon previous work. We study these quantum algorithms in the context of the negatively charged boron vacancy in hexagonal boron nitride. We generate an embedded active space of 18 spatial orbitals using quantum defect embedding theory (QDET) and show that the ISC rate imbalance can be detected with as few as 105 logical qubits and $4.41 \times 10^8$ Toffoli gates. By avoiding direct and costly rate calculations, our methods enable faster screening of candidate defects for ODMR activity, advancing the prospect of using quantum simulations to aid the development of high-performing sensing devices. + oai:arXiv.org:2508.13281v2 quant-ph - cs.AR - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Daisuke Sakuma, Tomoki Tsuno, Hikaru Shimizu, Yuki Kurosawa, Monet Tokuyama Friedrich, Kentaro Teramoto, Amin Taherkhani, Andrew Todd, Yosuke Ueno, Michal Hajdu\v{s}ek, Rikizo Ikuta, Rodney Van Meter, Toshihiko Sasaki, Shota Nagayama + Pablo A. M. Casares, Yanbing Zhou, Utkarsh Azad, Stepan Fomichev, Jack S. Baker, Chen Ling, Debasish Banerjee, Alain Delgado, Juan Miguel Arrazola - Optimal control in phase space applied to minimal-time transfer of thermal atoms in optical traps - https://arxiv.org/abs/2501.10494 - arXiv:2501.10494v4 Announce Type: replace -Abstract: We present an optimal control procedure for the non-adiabatic transport of ultracold neutral thermal atoms in optical tweezers arranged in a one-dimensional array, with focus on reaching minimal transfer time. The particle dynamics are modeled first using a classical approach through the Liouville equation and second through the quantum Wigner equation to include quantum effects. Both methods account for typical experimental noise described as stochastic effects through Fokker-Planck terms. The optimal control process is initialized with a trajectory computed for a single classical particle and determines the phase-space path that minimizes transport time and ensures high transport fidelity to the target trap. This approach provides the fastest and most efficient method for relocating atoms from an initial configuration to a desired target arrangement, minimizing time and energy costs while ensuring high fidelity. Such an approach may be highly valuable to initialize large atom arrays for quantum simulation or computation experiments. - oai:arXiv.org:2501.10494v4 + Predicting open quantum dynamics with data-informed quantum-classical dynamics + https://arxiv.org/abs/2508.17170 + arXiv:2508.17170v2 Announce Type: replace +Abstract: We introduce a data-informed quantum-classical dynamics (DIQCD) approach for predicting the evolution of an open quantum system. The equation of motion in DIQCD is a Lindblad equation with a flexible, time-dependent Hamiltonian that can be optimized to fit sparse and noisy data from local observations of an extensive open quantum system. We demonstrate the accuracy and efficiency of DIQCD for both experimental and simulated quantum devices. We show that DIQCD can predict entanglement dynamics of ultracold molecules (Calcium Fluoride) in optical tweezer arrays. DIQCD also successfully predicts carrier mobility in organic semiconductors (Rubrene) with accuracy comparable to nearly exact numerical methods. + oai:arXiv.org:2508.17170v2 quant-ph - cond-mat.quant-gas - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.stat-mech + physics.comp-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - 10.1103/d857-7cwr - Omar Morandi, Sara Nicoletti, Vladislav Gavryusev, Leonardo Fallani + 10.1103/7lsx-ssjl + Pinchen Xie, Ke Wang, Anupam Mitra, Yuanran Zhu, Xiantao Li, Wibe Albert de Jong, Chao Yang - Computing Efficiently in QLDPC Codes - https://arxiv.org/abs/2502.07150 - arXiv:2502.07150v3 Announce Type: replace -Abstract: It is the prevailing belief that quantum error correcting techniques will be required to build a utility-scale quantum computer able to perform computations that are out of reach of classical computers. The QECCs that have been most extensively studied and therefore highly optimized, surface codes, are extremely resource intensive in terms of the number of physical qubits needed. A promising alternative, QLDPC codes, has been proposed more recently. These codes are much less resource intensive, requiring significantly fewer physical qubits per logical qubit than practical surface code implementations. A successful application of QLDPC codes would therefore drastically reduce the timeline to reaching quantum computers that can run algorithms with proven exponential speedups like Shor's algorithm and QPE. However to date QLDPC codes have been predominantly studied in the context of quantum memories; there has been no known method for implementing arbitrary logical Clifford operators in a QLDPC code proven efficient in terms of circuit depth. In combination with known methods for implementing T gates, an efficient implementation of the Clifford group unlocks resource-efficient universal quantum computation. In this paper, we introduce a new family of QLDPC codes that enable efficient compilation of the full Clifford group via transversal operations. Our construction executes any m-qubit Clifford operation in at most O(m) syndrome extraction rounds, significantly surpassing state-of-the-art lattice surgery methods. We run circuit-level simulations of depth-126 logical circuits to show that logical operations in our QLDPC codes attains near-memory performance. These results demonstrate that QLDPC codes are a viable means to reduce the resources required to implement all logical quantum algorithms, thereby unlocking a reduced timeline to commercially valuable quantum computing. - oai:arXiv.org:2502.07150v3 + Polarization-Controlled Quantum Interference in a Metro-Scale Fiber Network + https://arxiv.org/abs/2509.03701 + arXiv:2509.03701v2 Announce Type: replace +Abstract: We report the first demonstration of multi-photon, dual-state entanglement distribution over a metropolitan-scale commercial fiber network, implemented on the EPB-IonQ Bohr-IV quantum network in Chattanooga, TN, using an all-fiber-optic experimental platform. Employing a spatially degenerate, continuous-wave type-II SPDC bi-photon source and fully fiber-coupled linear optics, we generated a 4-photon entangled state. Through polarization projective measurements on two locally retained photons, we then probabilistically heralded the remaining two photons into either a Bell state (particle-particle entanglement) or a N00N state (mode-mode entanglement), which were then distributed to two spatially separated network nodes. Experimental verification confirmed successful entanglement distribution across the deployed network despite significant channel losses and limited source fidelity. These results highlight the versatility of our polarization-controlled multi-photon entanglement distribution over real-world telecom infrastructure and lay the groundwork for future upgrades, including higher-quality non-degenerate photon sources, White Rabbit timing synchronization for true multi-node entanglement, and active polarization control for enhanced fidelity and long-term stability. + oai:arXiv.org:2509.03701v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Alexander J. Malcolm, Andrew N. Glaudell, Patricio Fuentes, Daryus Chandra, Alexis Schotte, Colby DeLisle, Rafael Haenel, Amir Ebrahimi, Joschka Roffe, Armanda O. Quintavalle, Stefanie J. Beale, Nicholas R. Lee-Hone, Stephanie Simmons + Kazi Reaz, Md Mehdi Hassan, Jacob E. Humberd, Matthew L. Boone, Angel Fraire Estrada, Rick Mukherjee, H. R. Sadeghpour, Girish S. Agarwal, George Siopsis, Tian Li - EHands: Quantum Protocol for Polynomial Computation on Real-Valued Encoded States - https://arxiv.org/abs/2502.15928 - arXiv:2502.15928v3 Announce Type: replace -Abstract: We present EHands, a quantum-native protocol for implementing multivariable polynomial transformations on quantum processors. The protocol introduces four fundamental, reversible operators: multiplication, addition, negation, and parity flip, and employs the Expectation Value ENcoding (EVEN) scheme to represent real numbers as quantum states. Unlike discretization or binary encoding methods, EHands operates directly on vectorized real-valued inputs prepared in the initial state and applies a shallow quantum circuit that depends only on the polynomial coefficients. The result is obtained from the expectation value measured on a single qubit, enabling efficient parallel evaluation of a polynomial across multiple data points using a single circuit. We introduce both a reversible implementation for degree-$d$ polynomials, requiring $3d$ qubits, and a non-reversible variant that uses qubit resets to reduce the requirements to $d+1$ qubits. Both implementations exhibit linear depth scaling in $d$ and are explicitly decomposed into one- and two-qubit gates for direct execution on current quantum processing units. The protocol's effectiveness is demonstrated through experimental validation on IBM's Heron-class quantum processors, showing reliable polynomial approximations of functions like ReLU and arctan. - oai:arXiv.org:2502.15928v3 + Quantum Theory of Distributed-Feedback Parametric Amplifiers and Oscillators + https://arxiv.org/abs/2509.05752 + arXiv:2509.05752v2 Announce Type: replace +Abstract: Optical parametric oscillators are among the best-developed quantum light sources, having already been adopted in precision measurement and underpinning various quantum computing and communication paradigms. Meanwhile, progress in photonic structures such as Bragg gratings has enabled distributed feedback oscillators to become widely established as classical laser sources with desirable properties, as well as enabling a new generation of precision optical sensors. Recent work in fabricating and processing photonic structures in nonlinear media opens the path to combining these two programs to realize distributed feedback parametric oscillators. Such devices have great potential as sources of quantum light, especially for squeezed vacuum, a crucial resource state in emerging quantum technologies. We present an analytic and fully quantum-mechanical model of the dynamics of such devices. This approach yields the key properties of these sources, such as the parametric oscillation threshold, intracavity mode, tunability, and quantum statistics (including entanglement) of the output modes. We also discuss the application of these devices as quantum-enhanced sensors. These results underpin future work on a versatile class of next-generation quantum light sources. + oai:arXiv.org:2509.05752v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jan Balewski, C. Pestano, Mercy G. Amankwah, E. Wes Bethel, Talita Perciano, Roel Van Beeumen + http://creativecommons.org/licenses/by/4.0/ + Alex O. C. Davis, Alex I. Flint - Scalable architecture for measurement induced squeezed light interferometers - https://arxiv.org/abs/2503.14449 - arXiv:2503.14449v3 Announce Type: replace -Abstract: Scalable interferometers lie at the heart of photonic quantum technologies, but their expansion has been fundamentally limited by optical losses that grow with circuit depth. Here, we introduce and experimentally demonstrate a measurement-induced architecture for multimode squeezed-light interferometers that overcomes this barrier. By shifting complexity from deep optical networks to programmable homodyne measurements, we realize effective transformations within a shallow, low-loss platform. We validate the principle with a six-mode device and extend it to a 400-mode interferometer, marking a leap in scale beyond conventional designs. Crucially, this strategy not only enables scalable squeezed light interferometry but also provides a powerful route to the generation of large-scale entangled states - a key requirement for quantum computing, simulation, and communication. Our results establish measurement-induced circuits as a practical pathway toward noisy intermediate-scale quantum (NISQ) applications, and future demonstrations of quantum advantage. - oai:arXiv.org:2503.14449v3 + Diabatic quantum annealing for training energy-based generative models + https://arxiv.org/abs/2509.09374 + arXiv:2509.09374v2 Announce Type: replace +Abstract: Energy-based generative models, such as restricted Boltzmann machines (RBMs), require unbiased Boltzmann samples for effective training. Classical Markov chain Monte Carlo methods, however, converge slowly and yield correlated samples, making large-scale training difficult. We address this bottleneck by applying the analytic relation between annealing schedules and effective inverse temperature in diabatic quantum annealing. By implementing this prescription on a quantum annealer, we obtain temperature-controlled Boltzmann samples that enable RBM training with faster convergence and lower validation error than classical sampling. We further identify a systematic temperature misalignment intrinsic to analog quantum computers and propose an analytical rescaling method that mitigates this hardware noise, thereby enhancing the practicality of quantum annealers as Boltzmann samplers. In our method, the model's connectivity is set directly by the qubit connectivity, transforming the computational complexity inherent in classical sampling into a requirement on quantum hardware. This shift allows the approach to extend naturally from RBMs to fully connected Boltzmann machines, opening opportunities inaccessible to classical training methods. + oai:arXiv.org:2509.09374v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Abhinav Verma, Jacob Hastrup, Jonas S. Neergaard-Nielsen, Ulrik L. Andersen + http://creativecommons.org/licenses/by/4.0/ + Gilhan Kim, Ju-Yeon Gyhm, Daniel K. Park - Benchmarking weak randomness in Quantum and Natural Sources - https://arxiv.org/abs/2504.06899 - arXiv:2504.06899v2 Announce Type: replace -Abstract: Private randomness is a fundamental resource for cryptography, security proofs, and information processing. Quantum devices offer a unique advantage by amplifying weak randomness sources in regimes unattainable by classical means. A central theoretical model for such sources is the Santha-Vazirani (SV) model, yet identifying natural processes that satisfy this model remains a major challenge. Here we take three steps toward addressing this problem. First, we introduce an axiomatic framework for quantifying weak randomness, providing a unified basis for estimating an SV-type source. Second, we develop SVTest, a general-purpose software tool for estimating the SV parameter of an arbitrary data sequence. Third, we apply this framework to both engineered and natural sources. Using data from a self-certifying commercial quantum random number generator with guaranteed min-entropy as a benchmark, we validate the accuracy and limitations of our estimation method. We then analyze geophysical signals associated with seismic activity and find that, depending on the discretization, both earthquakes and local seismic noise can exhibit SV-type randomness. Our results indicate that geophysical phenomena may constitute viable sources of cryptographic randomness, establishing an unexpected connection between quantum information theory and geophysics. - oai:arXiv.org:2504.06899v2 + Comparative Analysis on Two Quantum Algorithms for Solving the Heat Equation + https://arxiv.org/abs/2510.04511 + arXiv:2510.04511v2 Announce Type: replace +Abstract: As of now, an optimal quantum algorithm solving partial differential equations eludes us. There are several different methods, each with their own strengths and weaknesses. In past years comparisons of these existing methods have been made, but new work has emerged since then. Therefore, we conducted a survey on quantum methods developed post-2020, applying two such solvers to the heat equation in one spatial dimension. By analyzing their performance (including the cost of classical extraction), we explore their precision and runtime efficiency advancements between the two, identifying advantages and considerations. + oai:arXiv.org:2510.04511v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Maciej Stankiewicz, Roberto Salazar, Miko{\l}aj Czechlewski, Alejandra Mu\~noz Jensen, Catalina Morales-Y\'a\~nez, Omer Sakarya, Julio Viveros Carrasco, Stephen Walborn, Gustavo Lima, Karol Horodecki + http://creativecommons.org/licenses/by-sa/4.0/ + Samantha Tseng, Abhyudaya Chouhan, Dominic Cupidon - Simulation of a rapid qubit readout dependent on the transmission of a single fluxon - https://arxiv.org/abs/2504.18915 - arXiv:2504.18915v2 Announce Type: replace -Abstract: The readout speed of qubits is a major limitation for error correction in quantum information science. We show simulations of a proposed device that gives readout of a fluxonium qubit using a ballistic fluxon with an estimated readout time of less than 1 nanosecond, without the need for an input microwave tone. This contrasts the prevalent readout based on circuit quantum electrodynamics, but is related to previous studies where a fluxon moving in a single long Josephson junction (LJJ) can exhibit a time delay depending on the state of a coupled qubit. Our readout circuit contains two LJJs and a qubit coupled at their interface. We find that the device can exhibit single-shot readout of a qubit -- one qubit state leads to a single dynamical bounce at the interface and fluxon reflection, and the other qubit state leads to a couple of bounces at the interface and fluxon transmission. Dynamics are initially computed with a separate degree of freedom for all Josephson junctions of the circuit. However, a collective coordinate model reduces the dynamics to three degrees of freedom: one for the fluxonium Josephson junction and one for each LJJ. The large mass imbalance in this model allows us to simulate the mixed quantum-classical dynamics, as an approximation for the full quantum dynamics. Calculations give backaction on the qubit at $\leq 0.1\%$. - oai:arXiv.org:2504.18915v2 + Entanglement in von Neumann Algebraic Quantum Information Theory + https://arxiv.org/abs/2510.07563 + arXiv:2510.07563v2 Announce Type: replace +Abstract: In quantum systems with infinitely many degrees of freedom, states can be infinitely entangled across a pair of subsystems, but are there different forms of infinite entanglement? To understand entanglement in such systems, we use a framework in which subsystems are described by von Neumann algebras on the full system's Hilbert space. Although this approach has been known for over 50 years, an operational justification has been missing so far. We resolve this by deriving the von Neumann algebraic description of subsystems from operational axioms. This raises the question of how physical properties of the subsystem relate to algebraic properties. Our main result shows a surprisingly strong connection: The type classification of von Neumann algebras (types I, II, III, and their respective subtypes) is in one-to-one correspondence with a family of operational entanglement properties. For instance, Connes' classification of type III factors can be formulated in terms of the smallest achievable error when "embezzling" entanglement from the system. Our findings promote the type classification from algebraic bookkeeping to a classification of infinite quantum systems based on the kind of infinite entanglement that they support. + oai:arXiv.org:2510.07563v2 quant-ph - cond-mat.supr-con - Mon, 22 Dec 2025 00:00:00 -0500 + math-ph + math.MP + math.OA + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Waltraut Wustmann, Kevin D. Osborn + 10.15488/19655 + PhD thesis, Leibniz University Hanover, 2025 + Lauritz van Luijk - On Dequantization of Supervised Quantum Machine Learning via Random Fourier Features - https://arxiv.org/abs/2505.15902 - arXiv:2505.15902v3 Announce Type: replace -Abstract: In the quest for quantum advantage, a central question is under what conditions can classical algorithms achieve a performance comparable to quantum algorithms--a concept known as dequantization. Random Fourier features (RFFs) have demonstrated potential for dequantizing certain quantum neural networks (QNNs) applied to regression tasks, but their applicability to other learning problems and architectures remained unexplored. In this work, we derive bounds on the true risk gap between classical RFF models and quantum models for regression and classification tasks with both QNN and quantum kernel architectures. Furthermore, we provide sufficient conditions under which this gap is small and thus the quantum system can be dequantized via the RFF method. We support our findings with numerical experiments that illustrate the practical dequantization of existing quantum kernel-based methods. Our findings not only broaden the applicability of RFF-dequantization but also enhance the understanding of potential quantum advantages in practical machine-learning tasks. - oai:arXiv.org:2505.15902v3 + Gravitational and other shifts of whispering gallery and gravitational state interference patterns of light neutral particles + https://arxiv.org/abs/2510.10536 + arXiv:2510.10536v2 Announce Type: replace +Abstract: We discuss small shifts in the interference patterns of gravitational and whispering gallery quantum states that can be observed with neutrons, atoms, antiatoms, muonium, positronium, and other particles. A gravitational shift of interference patterns of neutron gravitational and whispering-gallery states can be easily observed with cold, very cold, or ultracold neutrons. The developed methods can be used for observing/searching for other shifts in fundamental neutron physics experiments, for instance, for measuring the gravitational constant or constraining the neutron electric charge. A series of such measurements will be made with neutrons at the PF1B/PF2/D17 facilities at the ILL. A peculiar feature of analogous atomic (anti-atomic) experiments is the much smaller effective critical energies of the materials of mirrors for (anti)atoms. We evaluated parameters that make a measurement of the hydrogen and antihydrogen whispering-gallery states and their gravitational shifts feasible. A series of such measurements will be made with hydrogen and deuterium atoms by the GRASIAN collaboration in Vienna and Turku. Such a measurement with antihydrogen atoms may be of interest for the GBAR experiment, the ASACUSA experiment, which is producing a beam of slow antihydrogen atoms, and other experiments at CERN, which study the gravitational properties of antimatter. Quantum reflection of muonium and positronium from material surfaces opens the possibility of observing whispering-galley states, although such measurements remain experimentally challenging. Because of small masses of muonium and positronium, the effective critical energies of the mirror materials are much higher for them than the effective critical energies for hydrogen and other atoms. The observation of gravitational shifts of such states is particularly demanding because of the extremely short lifetimes of these systems. + oai:arXiv.org:2510.10536v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Mehrad Sahebi, Alice Barthe, Yudai Suzuki, Zo\"e Holmes, Michele Grossi + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + V. V. Nesvizhevsky, J. A. Pioquinto, K. Schreiner, S. Baessler, P. Crivelli, F. Nez, S. Reynaud, P. Yzombard, S. A. Vasiliev, E. Widmann - New Paradigm for Integrated Sensing and Communication with Rydberg Atomic Receiver - https://arxiv.org/abs/2506.13304 - arXiv:2506.13304v4 Announce Type: replace -Abstract: The RYDberg Atomic Receiver (RYDAR) has been demonstrated to surmount the limitation on both the sensitivity and operating bandwidth of the classical electronic counterpart, which can theoretically detect indiscernible electric signals below -174 dBm/Hz with optical measurement through Rydberg-state atoms. Such miracle has established a new quantum-based paradigm for communications and sensing, which motivates a revolution of the transceiver design philosophies to fully unleash the potential of RYDAR towards next-generation networks. Against this background, this article provides a thorough investigation of Rydberg atomic communications and sensing from theory to hardware implementations. Specifically, we highlight the great opportunities from the hybridization between the RYDAR and the cutting-edge integrated sensing and communication (ISAC), followed by essential preliminaries of the quantum-based receiver. Then we propose a theoretical framework for broadband ISAC based on RYDAR, demonstrated by the proof-of-concept experiments. Afterwards, the enabling technologies for the ISAC framework are explored ranging from channel characterization, waveform design to array-based receiver configurations, where the open problems are also summarized. Finally, the future applications of RYDAR-based ISAC are envisioned, indicating its significant potential for both civilian and military purposes. - oai:arXiv.org:2506.13304v4 + Liouvillian Exceptional Points in Quantum Brickwork Circuits + https://arxiv.org/abs/2510.10629 + arXiv:2510.10629v3 Announce Type: replace +Abstract: We demonstrate that Liouvillian exceptional points (LEPs), previously explored only in continuous Lindbladian dynamics, also emerge in discrete brickwork completely positive trace-preserving (CPTP) circuits. By analytically solving a minimal two-qubit brickwork model, we identify the conditions under which discrete-time LEPs arise and show that they retain the hallmark square-root eigenvalue splitting and linear-in-time sensitivity enhancement. These results establish a direct bridge between continuous non-Hermitian physics and discrete quantum-circuit architectures, opening a path toward the realization of exceptional-point-based sensing on near-term quantum processors. + oai:arXiv.org:2510.10629v3 quant-ph - physics.atom-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Vladislav Popkov, Mario Salerno + + + Qutrits for physics at the LHC + https://arxiv.org/abs/2510.14001 + arXiv:2510.14001v2 Announce Type: replace +Abstract: The identification of anomalous events, not explained by the Standard Model of particle physics, and the possible discovery of exotic physical phenomena pose significant theoretical, experimental and computational challenges. The task will intensify at next-generation colliders, such as the High-Luminosity Large Hadron Collider (HL-LHC). Consequently, considerable challenges are expected concerning data processing, signal reconstruction, and analysis. This work explores the use of qutrit-based Quantum Machine Learning models for anomaly detection in high-energy physics data, with a focus on LHC applications. We propose the development of a qutrit quantum model and benchmark its performance against qubit-based approaches, assessing accuracy, scalability, and computational efficiency. This study aims to establish whether qutrit architectures can offer an advantage in addressing the computational and analytical demands of future collider experiments. + oai:arXiv.org:2510.14001v2 + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Minze Chen, Tianqi Mao, Yang Zhao, Wei Xiao, Dezhi Zheng, Zhaocheng Wang, Jun Zhang, Sheng Chen + Miranda Carou Lai\~no, Veronika Chobanova, Miriam Lucio Mart\'inez - Adaptive random compiler for Hamiltonian simulation - https://arxiv.org/abs/2506.15466 - arXiv:2506.15466v2 Announce Type: replace -Abstract: Randomized compilation protocols have recently attracted attention as alternatives to traditional deterministic Trotter-Suzuki methods, potentially reducing circuit depth and resource overhead. These protocols determine gate application probabilities based on the strengths of Hamiltonian terms, as measured by the trace norm. However, relying solely on the trace norm to define sampling distributions may not be optimal, especially for continuous-variable and hybrid-variable systems involving unbounded operators, where quantifying Hamiltonian strengths is challenging. In this work, we propose an adaptive randomized compilation algorithm that dynamically updates sampling weights via low-order moment measurements of Hamiltonian terms, assigning higher probabilities to terms with greater uncertainty. This approach improves accuracy without significantly increasing gate counts and extends randomized compilation to continuous-variable and hybrid-variable systems by addressing the difficulties in characterizing the strengths of unbounded Hamiltonian terms. Numerical simulations demonstrate the effectiveness of our method. - oai:arXiv.org:2506.15466v2 + Out-of-Equilibrium Dynamics in a U(1) Lattice Gauge Theory via Local Information Flows: Scattering and String Breaking + https://arxiv.org/abs/2510.16101 + arXiv:2510.16101v2 Announce Type: replace +Abstract: We introduce local information flows as a diagnostic tool for characterizing out-of-equilibrium quantum dynamics in lattice gauge theories. We employ the information lattice framework, a local decomposition of total information into spatial- and scale-resolved contributions, to characterize the propagation and buildup of quantum correlations in real-time processes. Focusing on the Schwinger model, a canonical $(1+1)$-dimensional U(1) lattice gauge theory, we apply this framework to two scenarios. First, in the near-threshold scattering of two vector mesons, we demonstrate that the emergence of correlations at a longer length scale in the information lattice marks the production of heavier scalar mesons. Second, in the dynamics of electric field strings, we clearly distinguish between the confining regime, which evolves towards a steady state with a static correlation profile, and the string-breaking sector. The latter is characterized by dynamic correlation patterns that reflect the sequential formation and annihilation of strings. This information-centric approach provides a direct, quantitative, and interpretable visualization of complex many-body phenomena, offering a promising tool for analyzing dynamics in higher-dimensional gauge theories and experiments on quantum hardware. + oai:arXiv.org:2510.16101v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + hep-lat + hep-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/4nmq-twj8 - Phys. Rev. A 112, 062431 (2025) - Yun-Zhuo Fan, Yu-Xia Wu, Dan-Bo Zhang + Claudia Artiaco, Jo\~ao Barata, Enrique Rico - Fidelity Relations in an Array of Neutral Atom Qubits -- Experimental Validation of Control Noise - https://arxiv.org/abs/2506.16974 - arXiv:2506.16974v2 Announce Type: replace -Abstract: Noise is a hindering factor for current-era quantum computers. In this study, we experimentally validate the theoretical relationships between amplitude noise of the control signal and qubit state fidelity. The experiment comprises a 10x10 site optical tweezer array stochastically loaded with single rubidium-85 atoms. A global microwave field is used to manipulate the state of the hyperfine qubits. With precise control of the time-dependent amplitude of the microwave drive, we apply control signals featuring artificial noise. We systematically analyze the impact of various noise profiles on the fidelity distribution of the quantum states. The measured fidelities are compared against theoretical predictions made using the stochastic Schr\"odinger equation. Our results show a good agreement between the experimentally measured and theoretically predicted results. This validation is consequential, as the model provides critical information on noise identification and optimal control protocols in NISQ-era quantum systems. - oai:arXiv.org:2506.16974v2 + POVM generated quantum trajectories without stochastic differential equations + https://arxiv.org/abs/2510.23058 + arXiv:2510.23058v2 Announce Type: replace +Abstract: In this paper we examine the issue of quantum trajectories generated by QND-POVM's on {\it single} copies of unknown states. After an introduction to various aspects of quantum measurements, we discuss an earlier approach by one of us(NDH) based on Gaussian QND measurement operators that addressed the asymptotic behaviour of such trajectories showing the impossibility of determining the unknown state of a single copy from the statistics of such repeated measurements.The essence of our present work is the so called martingale and super-martingale properties of certain observables, and the consequent martingale convergence theorem. The main result is that asymptotically all trajectories approach either the non-degenerate eigenstates of the system observable, or,density matrices spanned by the degenerate eigenstates of the observable. The proofs given by us are very transparent..A unified treatment of both the degenerate and non-degenerate cases is given with the help of projectors of arbitrary dimensionalities.In the degenerate case we reproduce the L\"uders prescription. The distribution of the trajectories is shown to be given exactly by the Born rule.Similar conclusions were reached, earlier to us, by Bauer et al on the one hand, and, by Amini et al on the other. A detailed comparison of the three approaches is given. A distinctive feature of all three approaches is that no use is made of stochastic differential equations and the conclusions follow directly from quantum mechanics. Alter and Yamomoto were the first to investigate repeated QND measurements on single copies in unknown states. We make detailed comparisons with their works too. We end with a brief discussion of i) the robustness of the results against free evolutions of both the system as well as the probe and ii) the anti-Zeno aspects of the results. + oai:arXiv.org:2510.23058v2 quant-ph - physics.atom-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Deon Janse van Rensburg, Robert de Keijzer, Rogier Venderbosch, Yuri van der Werf, Jesus del Pozo Mellado, Rianne Lous, Edgar Vredenbregt, Servaas Kokkelmans + Rutvij Bhavsar (King's College London), N. D. Hari Dass (Read., IMSc, Chennai) - Instability of explicit time integration for strongly quenched dynamics with neural quantum states - https://arxiv.org/abs/2507.17421 - arXiv:2507.17421v2 Announce Type: replace -Abstract: Neural quantum states have recently demonstrated significant potential for simulating quantum dynamics beyond the capabilities of existing variational ans\"{a}tze. However, studying strongly driven quantum dynamics with neural networks has proven challenging so far. Here, we focus on assessing several sources of numerical instabilities that can appear in the simulation of quantum dynamics based on the time-dependent variational principle (TDVP) with the computationally efficient explicit time integration scheme. Focusing on the restricted Boltzmann machine architecture, we compare solutions obtained by TDVP with analytical solutions and implicit methods as a function of the quench strength. Interestingly, we uncover a quenching strength that leads to a numerical breakdown in the absence of Monte Carlo noise, despite the fact that physical observables don't exhibit irregularities. This breakdown phenomenon appears consistently across several different TDVP formulations, even those that eliminate small eigenvalues of the Fisher matrix or use geometric properties to recast the equation of motion. We provide evidence that the nature of the instability stems from stiffness of the dynamics of the variational parameters, despite the absence of stiffness in the exact quantum dynamics. We conclude that alternative methods need to be developed to leverage the computational efficiency of explicit time integration of the TDVP equations for simulating strongly nonequilibrium quantum dynamics with neural-network quantum states. - oai:arXiv.org:2507.17421v2 + Multi-ensemble Superradiance for Distributed Quantum Sensing + https://arxiv.org/abs/2510.23110 + arXiv:2510.23110v3 Announce Type: replace +Abstract: Multi-ensemble superradiance extends Dicke superradiance to multiple ensembles and supports dark states whose properties depend on the initial state. In the large-\(N\) limit, we derive analytical covariance matrices for these dark states, revealing inter-ensemble entanglement that enhances quantum metrology. The minimum eigenvalue, determined by the curvature of the superradiance potential, corresponds to the optimal multiparameter spin-squeezing coefficient, which is given by the \emph{Rayleigh quotient} of the spin-squeezing matrix, linking metrological sensitivity to the geometric structure of the underlying dynamics. The multiparameter squeezing coefficient provides a variational framework for optimizing metrological performance. These results enable optimal estimation of arbitrary linear combinations of multiple parameters, offering a concrete protocol for distributed quantum sensing and a promising route toward multimode quantum interferometry. + oai:arXiv.org:2510.23110v3 quant-ph - cond-mat.dis-nn - physics.comp-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hrvoje Vrcan, Johan H. Mentink + Kang Shen, Xiangming Hu, Fei Wang - Characterizing and Mitigating Flux Crosstalk in Superconducting Qubits-Couplers System - https://arxiv.org/abs/2508.03434 - arXiv:2508.03434v3 Announce Type: replace -Abstract: Superconducting qubits have achieved exceptional gate fidelities, exceeding the error-correction threshold in recent years. One key ingredient of such improvement is the introduction of tunable couplers to control the qubit-to-qubit coupling through frequency tuning. Moving toward fault-tolerant quantum computation, increasing the number of physical qubits is another step toward effective error correction codes. Under a multiqubit architecture, flux control (Z) lines are crucial in tuning the frequency of the qubits and couplers. However, dense flux lines result in magnetic flux crosstalk, wherein magnetic flux applied to one element inadvertently affects neighboring qubits or couplers. This crosstalk obscures the idle frequency of the qubit when flux bias is applied, which degrades gate performance and calibration accuracy. In this study, we characterize flux crosstalk and suppress it in a multiqubit-coupler chip with multi-Z lines without adding additional readout for couplers. By quantifying the mutual flux-induced frequency shifts of qubits and couplers, we construct a cancellation matrix that enables precise compensation of non-local flux, demonstrating a substantial reduction in Z-line crosstalk from 56.5$\,$permille$\,$to 0.13$\,$permille$\,$ which is close to statistical error. Flux compensation corrects the CZ SWAP measurement, leading to a symmetric map with respect to flux bias. Compared with a crosstalk-free calculated CZ SWAP map, the measured map indicates that our approach provides a near-zero crosstalk for the coupler-transmon system. These results highlight the effectiveness of our approach in enhancing flux crosstalk-free control and supporting its potential for scaling superconducting quantum processors. - oai:arXiv.org:2508.03434v3 + Practical hybrid decoding scheme for parity-encoded spin systems + https://arxiv.org/abs/2510.26189 + arXiv:2510.26189v3 Announce Type: replace +Abstract: We propose a practical hybrid decoding scheme for the parity-encoding architecture. This architecture was first introduced by N. Sourlas as a computational technique for tackling hard optimization problems, especially those modeled by spin systems such as the Ising model and spin glasses, and reinvented by W. Lechner, P. Hauke, and P. Zoller to develop quantum annealing devices. We study the specific model, called the SLHZ model, aiming to achieve a near-term quantum annealing device implemented solely through geometrically local spin interactions. Taking account of the close connection between the SLHZ model and a classical low-density-parity-check code, two approaches can be chosen for the decoding: (1) finding the ground state of a spin Hamiltonian derived from the SLHZ model, which can be achieved via stochastic decoders such as a quantum annealer or a classical Monte Carlo sampler; (2) using deterministic decoding techniques for the classical LDPC code, such as belief propagation and bit-flip decoder. The proposed hybrid approach combines the two approaches by applying bit-flip decoding to the readout of the stochastic decoder based on the SLHZ model. We present simulations demonstrating that this approach can reveal the latent potential of the SLHZ model, realizing soft-annealing concept proposed by Sourlas. + oai:arXiv.org:2510.26189v3 quant-ph - physics.app-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cs.IT + math.IT + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-sa/4.0/ - Myrron Albert Callera Aguila, Nien-Yu Li, Chen-Hsun Ma, Li-Chieh Hsiao, Yi-Shiang Huang, Yen-Chun Chen, Teik-Hui Lee, Chin-Chia Chang, Jyh-Yang Wang, Ssu-Yen Huang, Hsi-Sheng Goan, Chiao-Hsuan Wang, Cen-Shawn Wu, Chii-Dong Chen, Chung-Ting Ke + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yoshihiro Nambu - Quasiprobability Thermodynamic Uncertainty Relation - https://arxiv.org/abs/2508.14354 - arXiv:2508.14354v2 Announce Type: replace -Abstract: We derive a quantum extension of the thermodynamic uncertainty relation where dynamical fluctuations are quantified by the Terletsky-Margenau-Hill quasiprobability, a quantum generalization of the classical joint probability. The obtained inequality plays a complementary role to existing quantum thermodynamic uncertainty relations, focusing on observables' change rather than exchange of charges through jumps and respecting initial coherence. Quasiprobabilities show anomalous behaviors that are forbidden in classical systems, such as negativity; we reveal that negativity or a non-classically enhanced escape rate is necessary to increase an output-to-dissipation ratio beyond classical limitations and show that the requirements are basis-independent and stronger than quantum coherence. To illustrate these statements, we employ a model that can exhibit a dissipationless heat current, which would be prohibited in classical systems; we construct a state that has much coherence but does not lead to a dissipationless current due to the absence of anomalous behaviors in quasiprobabilities. - oai:arXiv.org:2508.14354v2 + Preserving fermionic statistics for single-particle approximations in microscopic quantum master equations + https://arxiv.org/abs/2511.02160 + arXiv:2511.02160v2 Announce Type: replace +Abstract: Microscopic master equations have gained traction for the dissipative treatment of molecular spin and solid-state systems for quantum technologies. Single particle approximations are often invoked to treat these systems, which can lead to unphysical evolution when combined with master equation approaches. We present a mathematical constraint on the system-environment parameters to ensure that microscopically-derived Markovian master equations preserve fermionic, $N$-representable statistics when applied to reduced systems. We demonstrate these constraints for the recently derived unified master equation and universal Lindblad equation, along with the Redfield master equation for cases when positivity issues are not present. For operators that break the constraint, we explore the addition of Pauli factors to recover $N$-representability. This work promotes feasible applications of novel microscopic master equations for realistic chemical systems. + oai:arXiv.org:2511.02160v2 quant-ph - cond-mat.stat-mech - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Kohei Yoshimura, Ryusuke Hamazaki + Mikayla Z. Fahrenbruch, Anthony W. Schlimgen, Kade Head-Marsden - From Chiral Topological Dynamics to Chiral Topological Amplification: Real vs Imaginary Parameters in a Hermitian Bosonic Chain - https://arxiv.org/abs/2508.14560 - arXiv:2508.14560v2 Announce Type: replace -Abstract: We propose a Hermitian quadratic bosonic model (QBH) whose dynamical matrix exhibits distinct topological and dynamical phenomena depending on whether the hopping and pairing amplitudes are real or purely imaginary. In the real-parameter regime, the dynamical matrix is unitarily equivalent to four decoupled copies of the sublattice-symmetric non-Hermitian Su-Schrieffer-Heeger (nSSH2) model, thereby inheriting its topological phases and energy spectrum-including the M\"obius phase, a gapless topological phase with fractional winding number, having no Hermitian counterpart. We show that the dynamics generated by the QBH Hamiltonian naturally reproduce non-Hermitian time evolution, without invoking nonlinear Schr\"odinger dynamics or ad hoc normalization. It is demonstrated by analytically calculating the Loschmidt amplitude and computing the dynamical topological order parameter under periodic boundary conditions, which displays a distinct chiral response in the M\"obius phase. In contrast, when the hopping and pairing terms are taken to be purely imaginary, the dynamical matrix becomes unitarily equivalent to a different version of the sublattice-symmetric non-Hermitian Su-Schrieffer-Heeger (nSSH1) model that supports only two topological phases: trivial and non-trivial, and the M\"obius phase disappears. The latter system exhibits sublattice-dependent chiral amplification under open boundary conditions. We show that this amplification arises from the non-trivial topology of the dynamical matrix, establishing a clear link between topological phase and amplification behavior in the imaginary-parameter regime. - oai:arXiv.org:2508.14560v2 + Motional entanglement in low-energy collisions near shape resonances + https://arxiv.org/abs/2511.02925 + arXiv:2511.02925v2 Announce Type: replace +Abstract: Einstein, Podolsky, and Rosen discussed their paradox in terms of measuring the positions or momenta of two particles. These degrees of freedom can become entangled upon scattering, but how much entanglement can be created in this process? Here we address this question using fully coherent calculations of bipartite scattering in three-dimensional space, quantifying entanglement by the inverse of the single particle purity. We show that the standard plane-wave description of scattering fails to capture the entanglement properties, due to the essential role of quantum uncertainty in the initial state. For a more realistic description of a scattering setup, we find that the entanglement scales linearly with the scattering cross section, including strong enhancement near shape resonances, for sufficiently narrow initial momentum dispersion. We highlight the differences between scattering in one and higher spatial dimensions and discuss how the generation of motional entanglement can be detected in experiments. Our results open the way to probing, controlling, and eventually using entanglement in quantum collisions. + oai:arXiv.org:2511.02925v2 quant-ph - cond-mat.mes-hall - Mon, 22 Dec 2025 00:00:00 -0500 + physics.atom-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kiran Babasaheb Estake, T. R. Vishnu, Dibyendu Roy + Yimeng Wang, Christiane P. Koch - Out-of-time-order correlators bridge classical transport and quantum dynamics - https://arxiv.org/abs/2508.20235 - arXiv:2508.20235v2 Announce Type: replace -Abstract: The out-of-time-order correlator (OTOC) has emerged as a central tool for quantifying decoherence across wide-ranging physical platforms. Here we demonstrate its direct measurement in a classical ensemble using nuclear magnetic resonance (NMR) with a modulated gradient spin echo (MGSE) sequence and extend the method into a multidimensional correlation to track exchange phenomena. Position is encoded through magnetic field gradients and momentum through the velocity autocorrelation function, enabling experimental access to OTOCs for proton motion confined within the self-similar lattice of the metal-organic framework MOF-808. Here, water confined to specified geometries within the MOF pores gives rise to spatially distinct diffusive eigenmodes with characteristic relative entropies. We demonstrate that periodic radiofrequency (rf) driving combined with gradient modulation yields entropy evolution through the selection of distinct diffusion modes. Frequency-resolved diffusion spectra connect these entropy dynamics to classical heat-exchange laws, revealing how operational features of quantum systems are mirrored in confined, macroscopic spin ensembles. - oai:arXiv.org:2508.20235v2 + Universal Thermodynamic Uncertainty Relation for Quantum $f-$Divergences + https://arxiv.org/abs/2511.10817 + arXiv:2511.10817v2 Announce Type: replace +Abstract: We show that any Petz $f$-divergence (where $f$ is operator convex) between quantum states admits a universal $\chi^2$-mixture representation: the distinguishability of $\rho$ from $\sigma$ is obtained as a positive superposition of quadratic contrasts $\chi^2_\lambda$, with nonnegative weights $w_f(\lambda)$ determined explicitly from the Stieltjes representation of the generator $f$. This identifies $\chi^2_\lambda$ as atomic building blocks for quantum $f$-divergences and yields closed-form $w_f$ for canonical choices (relative entropy/KL, Hellinger/Bures, R'{e}nyi). By mapping $\chi^2_\lambda$ into a classical Pearson $\chi^2$, we leverage the Chapman-Robbins variational representation and obtain a tight and universal quantum thermodynamic uncertainty relation: any $f$-divergence is lower bounded by a function of the statistics of quantum observables (mean and variance), reproducing previous and novel results in quantum thermodynamics as applications. + oai:arXiv.org:2511.10817v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.stat-mech + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Sophia N. Fricke, Haiyan Mao, Manas Sajjan, Ashok Ajoy, Velencia Witherspoon, Sabre Kais, Jeffrey A. Reimer + http://creativecommons.org/licenses/by/4.0/ + Domingos S. P. Salazar + + + Exact Stochastic Differential Equations for Quantum Reverse Diffusion + https://arxiv.org/abs/2511.15919 + arXiv:2511.15919v4 Announce Type: replace +Abstract: The ensemble-averaged dynamics of open quantum systems are typically irreversible. We show that this irreversibility need not hold at the level of individually monitored quantum trajectories. Our main results are analytical stochastic differential equations for quantum reverse diffusion, along with corresponding stochastic master equations. These equations describe the exact and approximate stochastic reverse processes for continuously monitored Pauli channels, including time-dependent depolarizing noise. We show that the reverse processes generalize the forward dynamics by combining the noise effects of the forward processes with an additional non-Markovian stochastic drift that dynamically steers a quantum state back to its initial configuration. Consequently, the exact SDEs admit closed-form solutions that can be implemented in real-time without the need for variational techniques. Our findings establish an analytical framework for quantum state recovery, noise-resilient quantum gates, quantum generative modelling, quantum tomography via forward-reverse cycles, and potential paradigms for quantum error correction based on reverse diffusion. + oai:arXiv.org:2511.15919v4 + quant-ph + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 + replace + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Einar Gabbassov - Composable logical gate error in approximate quantum error correction: reexamining gate implementations in Gottesman-Kitaev-Preskill codes - https://arxiv.org/abs/2509.14658 - arXiv:2509.14658v3 Announce Type: replace -Abstract: Quantifying the accuracy of logical gates is paramount in approximate error correction, where perfect implementations are often unachievable with the available set of physical operations. To this end, we introduce a single scalar quantity we call the (composable) logical gate error. It captures both the deviation of the logical action from the desired target gate as well as leakage out of the code space. It is subadditive under successive application of gates, providing a simple means for analyzing circuits. We show how to bound the composable logical gate error in terms of matrix elements of physical unitaries between (approximate) logical computational basis states. In the continuous-variable context, this sidesteps the need for computing energy-bounded norms. - As an example, we study the composable logical gate error for linear optics implementations of Paulis and Cliffords in approximate Gottesman-Kitaev-Preskill (GKP) codes. We find that the logical gate error for implementations of Paulis depends linearly on the squeezing parameter. This implies that their accuracy improves monotonically with the amount of squeezing. For some Cliffords, however, linear optics implementations which are exact for ideal GKP codes fail in the approximate case: they have a constant logical gate error even in the limit of infinite squeezing. This is consistent with previous results about the limitations of certain gate implementations for approximate GKP codes. It shows that findings applicable to ideal GKP codes do not always translate to the realm of physically realizable approximate GKP codes. - oai:arXiv.org:2509.14658v3 + Superradiant decay in non-Markovian Waveguide Quantum Electrodynamics + https://arxiv.org/abs/2511.22332 + arXiv:2511.22332v2 Announce Type: replace +Abstract: An array of initially excited emitters coupled to a one-dimensional waveguide exhibits superradiant decay under the Born-Markov approximation, manifested as a coherent burst of photons in the output field. In this work, we employ tensor-network methods to investigate its non-Markovian dynamics induced by finite time delays in photon exchange among the emitters. We find that the superradiant burst breaks into a structured train of correlated photons, each intensity peak corresponding to a specific photon number. We quantify the emitter-photon and emitter-emitter entanglement generated during this process and show that the latter emerges in the long-time limit, as part of the excitation becomes trapped within the emitters' singlet subspace. We finally consider the decay of the system's most radiant state, the symmetric Dicke state, and show that time delay can lead to decay rates exceeding those predicted by the Markovian approximation. + oai:arXiv.org:2511.22332v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + physics.atom-ph + physics.comp-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Lukas Brenner, Beatriz Dias, Robert Koenig + Rosa Lucia Capurso, Giuseppe Calaj\'o, Simone Montangero, Saverio Pascazio, Francesco V. Pepe, Maria Maffei, Giuseppe Magnifico, Paolo Facchi - A Review of Software for Designing and Operating Quantum Networks - https://arxiv.org/abs/2510.00203 - arXiv:2510.00203v2 Announce Type: replace -Abstract: Quantum network protocol development is crucial to realizing a production-grade network that can support distributed sensing, secure communication, and utility-scale quantum computation. However, the transition from laboratory demonstration to deployable networks requires software implementations of architectures and protocols tailored to the unique constraints of quantum systems. This paper reviews the current state of software implementations for quantum networks, organized around the three-plane abstraction of infrastructure, logical, and control/service planes. We cover software for both designing quantum network protocols (e.g., SeQUeNCe, QuISP, and NetSquid) and operating them, with a focus on essential control/service plane functions such as entanglement, topology, and resource management, in a proposed taxonomy. Our review highlights a persistent gap between theoretical protocol proposals and their realization in simulators or testbeds, particularly in dynamic topology and network management. We conclude by outlining open challenges and proposing a roadmap for developing scalable software architectures to enable hybrid, large-scale quantum networks. - oai:arXiv.org:2510.00203v2 + Delayed Choice Quantum Eraser Experiment Revisited: Causality and Informational Coherence + https://arxiv.org/abs/2511.22827 + arXiv:2511.22827v3 Announce Type: replace +Abstract: An operationally well-defined delayed-choice quantum-eraser experiment is proposed, realizing a genuine delayed choice within presently available quantum-optical technology. A multimode quantum memory supplies a controlled and verifiable delay, ensuring that the choice operation is applied strictly after the observation event. Electronic single-photon interference detection measurements furnish a direct statistical discriminator between the causal and informational coherence hypotheses, based solely on marginal detection statistics and without any post-selection. + oai:arXiv.org:2511.22827v3 quant-ph - cs.NI - cs.SY - eess.SY - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Robert J. Hayek, Joaquin Chung, Rajkumar Kettimuthu + Taku Ohwada - Chaotic many-body quantum dynamics, spectral correlations, and energy diffusion - https://arxiv.org/abs/2510.02198 - arXiv:2510.02198v2 Announce Type: replace -Abstract: We study chaotic many-body quantum dynamics in a minimal model with spatial structure and local interactions. It has a time-independent Hamiltonian, in contrast to quantum circuits and Brownian models, and is simple at the single-site level, in contrast to Sachdev-Ye-Kitaev chains. It is analytically tractable for large local Hilbert space dimension and weak intersite coupling. In this limit we show that energy dynamics is described by a classical master equation and is diffusive. We also show that the spectral form factor can be expressed exactly in terms of the solution to this master equation. For a two-site system we obtain closed-form expressions for both the two-point correlator of energy density and the spectral form factor, in essentially perfect agreement with numerical simulations. For an $L$-site system we show at late times how a linear ramp emerges in the spectral form factor, as universally expected from level repulsion in chaotic quantum systems. Conversely, at earlier times we identify two distinct mechanisms for an increase of the spectral form factor above its ramp value. One of these is associated with energy diffusion and is effective until the Thouless time, which varies as $L^2$. The other involves contributions like those that would appear if the system were composed of many uncoupled subsystems: they generate a large enhancement of the spectral form factor, and are suppressed on a timescale varying as $(\ln L)^2$. Besides being exact for the limit considered, we believe our approach provides the natural approximation even for small local Hilbert space dimension and strong intersite coupling. We present a numerical study of a spin-half chain, finding an early-time enhancement of the spectral form factor which is qualitatively similar to that in our solvable model. - oai:arXiv.org:2510.02198v2 + Optimal Control of thermally noisy quantum gates in a multilevel system + https://arxiv.org/abs/2512.00782 + arXiv:2512.00782v2 Announce Type: replace +Abstract: Quantum systems are inherently sensitive to environmental noise and imperfections in external control fields, posing a significant challenge for the practical implementation of quantum technologies. These noise sources degrade the fidelity of quantum gates, making their mitigation a key requirement for realizing reliable quantum computing. In this study, we apply Optimal Control Theory (OCT) within a thermodynamically consistent framework to design and stabilize high-fidelity quantum gates under Markovian noise. Our approach focuses on thermal relaxation and incorporates these effects into the control protocol, wherein external driving fields not only govern the system's unitary evolution but also modulate its interaction with the environment. By leveraging this interplay, we demonstrate that OCT can enable entropy-modifying processes, such as targeted cooling or heating, while maintaining high-fidelity gate performance in noisy environments. To validate our approach, we employ high-precision numerical methods for an open quantum system implementing one- or two-qubit gates embedded in a larger Hilbert space. The results showcase robust gate operation even under significant dissipative influences, offering a concrete path toward fault-tolerant quantum computation under realistic conditions. + oai:arXiv.org:2512.00782v2 quant-ph - cond-mat.stat-mech - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - J. T. Chalker, Dominik Hahn + Aviv Aroch, Shimshon Kallush, Ronnie Kosloff - Exploiting higher-order correlation functions for photon-statistics-based characterization and reconstruction of arbitrary Gaussian states - https://arxiv.org/abs/2510.09083 - arXiv:2510.09083v2 Announce Type: replace -Abstract: Gaussian states are an essential building block for various applications in quantum optics and quantum information science, yet the precise relation between their second- and third-order correlation functions remains not fully explored. We discuss connections between these correlation functions by constructing an explicit decomposition formula for arbitrary sixth-order moments of ladder operators for general Gaussian states and demonstrate how the derived relations enable state classification from correlation data alone. Whereas violating these relations certifies non-Gaussianity, satisfying them provides evidence for a Gaussian-state description and allows a direct distinction among non-displaced, non-squeezed, and displaced-squeezed sectors of the Gaussian state space. Further, we show that it is not possible to uniquely extract state parameters solely from correlation-function measurements without prior assumptions about the Gaussian state. Resolving this ambiguity requires additional loss-sensitive information, e.g., measuring the mean intensity or the vacuum overlap of each mode. In particular, we show under which circumstances these measurements can be used to reconstruct a generic Gaussian state. - oai:arXiv.org:2510.09083v2 + Adiabaticity Crossover: From Anderson Localization to Planckian Diffusion + https://arxiv.org/abs/2512.06263 + arXiv:2512.06263v3 Announce Type: replace +Abstract: We investigate electron transport in one dimension from the quantum-acoustic perspective, where the coherent-state representation of lattice vibrations results in a time-dependent deformation potential whose rate is set by the sound speed, fluctuation spectrum is set by the temperature, and overall amplitude is set by the electron-lattice coupling strength. We introduce an acceleration-based adiabatic criterion, consistent with the adiabatic theorem and Landau-Zener theory, that separates adiabatic and diabatic dynamics across the $(T,v)$ plane. The discrete classification agrees with a continuous mean-squared acceleration scale and correlates with a coherence measure given by the ratio of coherence length to the initial packet width $L_\phi(t)/\sigma_0$. We identify a broad Planckian domain in which the dimensionless diffusivity $\alpha\!=\!Dm/\hbar$ is of order unity and only weakly depends on the parameters. This domain is more prevalent in diabatic regions and in areas of reduced phase coherence, indicating a dephasing driven crossover from Anderson localization to Planckian diffusion. Using the Einstein relation together with nearly constant $\alpha$, we directly obtain a low temperature tendency $1/\tau_{\rm tr}\propto T$, offering a insight to $T$-linear resistivity in strange metals. These results provide a unified picture that links adiabaticity, dephasing, and Planckian diffusion in dynamically disordered quantum-acoustics. + oai:arXiv.org:2512.06263v3 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Philip Heinzel, Ren\'e Sondenheimer + Tiange Xiang, Yubo Zhang, Joonas Keski-Rahkonen, Anton M. Graf, Eric J. Heller - Non-Markovianity in Quantum Information Processing: Interplay with Quantum Error Mitigation - https://arxiv.org/abs/2510.20224 - arXiv:2510.20224v2 Announce Type: replace -Abstract: Non-Markovian dynamics are typically present in the dynamics of open quantum systems. Despite the rich structure of non-Markovian dynamics, their relevance to quantum information processing (QIP) has been rarely discussed. In this work, we demonstrate that the negativity of the dynamics, a characteristic of non-Markovian dynamics, naturally arises in quantum error correction (QEC) and quantum teleportation. The negativity in open quantum systems is naturally attributed to the information backflow from the environment. We partition the whole Hilbert space into the logical subsystem and the gauge subsystem. The logical subsystem stores the quantum information for QIP, while the gauge subsystem stores the information for recovery of the logical information, i.e., the syndrome measurement outcomes for quantum error correction and Bell measurement outcomes for successful teleportation. We then show that the negativity in quantum information processing appears as a consequence of the feedback operation based on the measurement outcomes of the gauge subsystem. Finally, we show that the negativity of non-Markovianity in QIP reduces the sampling cost of quantum error mitigation (QEM), shedding light on the importance of combination strategies of QEC and QEM in a practical QIP. - oai:arXiv.org:2510.20224v2 + Physics Informed Generative Machine Learning for Accelerated Quantum-centric Supercomputing + https://arxiv.org/abs/2512.06858 + arXiv:2512.06858v2 Announce Type: replace +Abstract: Quantum centric supercomputing (QCSC) framework, such as sample-based quantum diagonalization (SQD) holds immense promise toward achieving practical quantum utility to solve challenging problems. QCSC leverages quantum computers to perform the classically intractable task of sampling the dominant fermionic configurations from the Hilbert space that have substantial support to a target state, followed by Hamiltonian diagonalization on a classical processor. However, noisy quantum hardware produces erroneous samples upon measurements, making robust and efficient configuration-recovery strategies essential for a scalable QCSC pipeline. Toward this, in this work, we introduce PIGen-SQD, an efficiently designed QCSC workflow that utilizes the capability of generative machine learning (ML) along with physics-informed configuration screening via implicit low-rank tensor decompositions for accurate fermionic state reconstruction. The physics-informed pruning is based on a class of efficient perturbative measures that, in conjunction with hardware samples, provide a substantial overlap with the target state. This distribution induces an anchoring effect on the generative ML models to stochastically explore only the dominant sector of the Hilbert space for effective identification of additional important configurations in a self-consistent manner. Our numerical experiments performed on IBM Heron R2 quantum processors demonstrate this synergistic workflow produces compact, high-fidelity subspaces that substantially reduce diagonalization cost while maintaining chemical accuracy under strong electronic correlations. By embedding classical many body intuitions directly into the generative ML model, PIGen-SQD advances the robustness and scalability of QCSC algorithms, offering a promising pathway toward chemically reliable quantum simulations on utility-scale quantum hardware. + oai:arXiv.org:2512.06858v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Suguru Endo, Hideaki Hakoshima, Tomohiro Shitara + http://creativecommons.org/licenses/by/4.0/ + Chayan Patra, Dibyendu Mondal, Sonaldeep Halder, Dipanjali Halder, Mostafizur Rahaman Laskar, Richa Goel, Rahul Maitra - Universal Limits on Quantum Correlations - https://arxiv.org/abs/2510.24950 - arXiv:2510.24950v2 Announce Type: replace -Abstract: Quantum correlations are the singular, defining resource of quantum information science and metrology, forming the basis of every operational advantage that quantum systems hold over classical ones. Yet exact bounds on these correlations-such as the Lieb-Robinson bound on entanglement propagation and the Heisenberg limit on metrological precision-are known only in special cases and have long appeared to arise from unrelated mechanisms. Here we show that these limits share a common geometric origin. We identify a positivity invariant of the block correlation matrix, denoted $\chi$, that quantifies how far a bipartite state lies from the positivity boundary of quantum state space. For any system with a specified observable algebra and parameter-encoding map, every correlation measure determined solely by the positive correlation matrix obeys a $\chi$-dependent inequality. For systems with simple symmetry structures these inequalities take closed analytic form, reproducing the structure of the Heisenberg and Cram\'er-Rao limits and producing new results, including an exact entanglement floor and a universal Fisher-information ceiling even in all-to-all connected quantum networks. We thus demonstrate that positive geometry provides a unified framework for the attainable strength of quantum correlations, linking entanglement, metrological sensitivity, and dynamical causal structure through a single invariant. - oai:arXiv.org:2510.24950v2 + On the emergence of preferred structures in quantum theory + https://arxiv.org/abs/2512.07468 + arXiv:2512.07468v2 Announce Type: replace +Abstract: We assess the possibilities offered by Hilbert space fundamentalism, an attitude towards quantum physics according to which all physical structures (e.g. subsystems, locality, spacetime, preferred observables) should emerge from minimal quantum ingredients (typically a Hilbert space, Hamiltonian, and state). As a case study, we first mainly focus on the specific question of whether the Hamiltonian can uniquely determine a tensor product structure, a crucial challenge in the growing field of quantum mereology. The present paper reviews, clarifies, and critically examines two apparently conflicting theorems by Cotler et al. and Stoica. We resolve the tension, show how the former has been widely misinterpreted and why the latter is correct only in some weaker version. We then propose a correct mathematical way to address the general problem of preferred structures in quantum theory, relative to the characterization of emergent objects by unitary-invariant properties. Finally, we apply this formalism in the particular case we started with, and show that a Hamiltonian and a state are enough structure to uniquely select a preferred tensor product structure. + oai:arXiv.org:2512.07468v2 quant-ph + hep-th math-ph math.MP - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Samuel Alperin + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Antoine Soulas, Guilherme Franzmann, Andrea Di Biagio - Fermionic dynamics on a trapped-ion quantum computer beyond exact classical simulation - https://arxiv.org/abs/2510.26300 - arXiv:2510.26300v2 Announce Type: replace -Abstract: Simulation of the time-dynamics of fermionic many-body systems has long been predicted to be one of the key applications of quantum computers. Such simulations -- for which classical methods are often inaccurate -- are critical to advancing our knowledge and understanding of quantum chemistry and materials, underpinning a wide range of fields, from biochemistry to clean-energy technologies and chemical synthesis. However, the performance of all previous digital quantum simulations of fermions has been matched by classical methods, and it has thus far remained unclear whether near-term, intermediate-scale quantum hardware could offer any computational advantage in this area. Here, we implement an efficient quantum simulation algorithm on Quantinuum's System Model H2 trapped-ion quantum computer for the time dynamics of a 56-qubit system that is too complex for exact classical simulation. We focus on the periodic spinful 2D Fermi-Hubbard model and present evidence of spin-charge separation, where the elementary electron's charge and spin decouple. In the limited cases where ground truth is available through exact classical simulation, we find that it agrees with the results we obtain from the quantum device. Employing long-range Wilson operators to study deconfinement of the effective gauge field between spinons and the effective potential between charge carriers, we find behaviour that differs from predictions made by classical tensor network methods. Our results herald the use of quantum computing for simulating strongly correlated electronic systems beyond the capacity of classical computing. - oai:arXiv.org:2510.26300v2 + Relativistic motion through a thermal bath as a thermodynamic resource + https://arxiv.org/abs/2512.07567 + arXiv:2512.07567v2 Announce Type: replace +Abstract: We show that a localized quantum system following an arbitrary stationary trajectory and weakly interacting with a stationary thermal bath of a massless scalar field is generically driven into a non-Gibbs steady state by relative motion alone, even without external driving or multiple baths. Relative motion between the system and the bath modifies the standard Kubo-Martin-Schwinger (KMS) relation, preventing relaxation to a Gibbs state. The resulting steady states fall into two distinct classes: (i) nonequilibrium steady states (NESS) with persistent probability currents, and (ii) current-free non-Gibbs steady states characterized by a frequency-dependent effective inverse temperature. We then focus on the simplest stationary trajectory, namely uniform relativistic motion with respect to a thermal bath. Using a three-level system as an illustrative example, we demonstrate that the former class can function as noisy stochastic clocks, while the latter possesses finite nonequilibrium free energy, enabling work extraction or storage, highlighting their potential as quantum batteries. + oai:arXiv.org:2512.07567v2 quant-ph - cond-mat.mtrl-sci - Mon, 22 Dec 2025 00:00:00 -0500 + hep-th + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Faisal Alam, Jan Lukas Bosse, Ieva \v{C}epait\.e, Adrian Chapman, Laura Clinton, Marcos Crichigno, Elizabeth Crosson, Toby Cubitt, Charles Derby, Oliver Dowinton, Norhan Eassa, Paul K. Faehrmann, Steve Flammia, Brian Flynn, Filippo Maria Gambetta, Ra\'ul Garc\'ia-Patr\'on, Max Hunter-Gordon, Glenn Jones, Abhishek Khedkar, Joel Klassen, Michael Kreshchuk, Edward Harry McMullan, Lana Mineh, Ashley Montanaro, Caterina Mora, John J. L. Morton, Alberto Nocera, Dhrumil Patel, Pete Rolph, Raul A. Santos, James R. Seddon, Evan Sheridan, Wilfrid Somogyi, Marika Svensson, Niam Vaishnav, Sabrina Yue Wang, Gethin Wright, Eli Chertkov, Henrik Dreyer, Michael Foss-Feig + Rahul Shastri - Programmable digital quantum simulation of 2D Fermi-Hubbard dynamics using 72 superconducting qubits - https://arxiv.org/abs/2510.26845 - arXiv:2510.26845v2 Announce Type: replace -Abstract: Simulating the time-dynamics of quantum many-body systems was the original use of quantum computers proposed by Feynman, motivated by the critical role of quantum interactions between electrons in the properties of materials and molecules. Accurately simulating such systems remains one of the most promising applications of general-purpose digital quantum computers, in which all the parameters of the model can be programmed and any desired physical quantity output. However, performing such simulations on today's quantum computers at a scale beyond the reach of classical methods requires advances in the efficiency of simulation algorithms and error mitigation techniques. Here we demonstrate programmable digital quantum simulation of the dynamics of the 2D Fermi-Hubbard model -- one of the best-known simplified models of electrons in crystalline solids -- at a scale beyond exact classical state-vector simulation. We implement simulations of this model on lattice sizes up to ${6\times 6}$ using 72 qubits on Google's Willow quantum processor, across a range of physical parameters, including different on-site electron-electron interaction strengths and magnetic flux values, and study phenomena including formation of magnetic polarons (charge carriers surrounded by local magnetic polarisation), dynamical symmetry-breaking in stripe-ordered states, attraction of charge carriers on an entangled background state known as a valence bond solid, and the approach to equilibrium through thermalisation. We validate our results against exact calculations in parameter regimes where these are feasible, and compare them to approximate classical simulations performed using tensor network and operator propagation methods. Our results demonstrate that meaningful programmable digital quantum simulation of many-body interacting electron models is now feasible on state-of-the-art quantum hardware. - oai:arXiv.org:2510.26845v2 + Insensitivity points and performance of open quantum interferometers under number-conserving & non-conserving Lindblad dynamics + https://arxiv.org/abs/2512.10559 + arXiv:2512.10559v3 Announce Type: replace +Abstract: We investigate the phase sensitivity of a linear two-mode atom interferometer subject to environmental noise, modeled within the framework of open quantum systems with both number-conserving and non-conserving Lindblad operators. Considering several input states, we first study the cases N=1,2 (N number of particles) and perform numerical simulations for N>2. The sensitivity as a function of the holding time can display divergence points where phase estimation becomes impossible, to which we refer as insensitivity points. We characterize their behavior as the input state, particle number, and noise operator are varied, and we find that their positions are independent of the noise intensity. Moreover, while our fixed measurement scheme may favor number-conserving noise at small N (i.e., having better sensitivity), the Cram\'er-Rao bound reveals that particle non-conserving noise yields strictly lower achievable sensitivity for all particle numbers. + oai:arXiv.org:2512.10559v3 quant-ph - cond-mat.mtrl-sci - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Faisal Alam, Jan Lukas Bosse, Ieva \v{C}epait\.e, Adrian Chapman, Laura Clinton, Marcos Crichigno, Elizabeth Crosson, Toby Cubitt, Charles Derby, Oliver Dowinton, Paul K. Faehrmann, Steve Flammia, Brian Flynn, Filippo Maria Gambetta, Ra\'ul Garc\'ia-Patr\'on, Max Hunter-Gordon, Glenn Jones, Abhishek Khedkar, Joel Klassen, Michael Kreshchuk, Edward Harry McMullan, Lana Mineh, Ashley Montanaro, Caterina Mora, John J. L. Morton, Dhrumil Patel, Pete Rolph, Raul A. Santos, James R. Seddon, Evan Sheridan, Wilfrid Somogyi, Marika Svensson, Niam Vaishnav, Sabrina Yue Wang, Gethin Wright + http://creativecommons.org/licenses/by/4.0/ + Tommaso Favalli, \v{Z}an Kokalj, Andrea Trombettoni - Local spreading of stabilizer R\'enyi entropy in a brickwork random Clifford circuit - https://arxiv.org/abs/2511.07769 - arXiv:2511.07769v2 Announce Type: replace -Abstract: Nonstabilizerness, or magic, constitutes a fundamental resource for quantum computation and a crucial ingredient for quantum advantage. Recent progress has substantially advanced the characterization of magic in many-body quantum systems, with stabilizer R\'enyi entropy (SRE) emerging as a computable and experimentally accessible measure. In this work, we investigate the spreading of SRE in terms of single-qubit reduced density matrices, where an initial product state that contains magic in a local region evolves under brickwork random Clifford circuits. For the case with Haar-random local Clifford gates, we find that the spreading profile exhibits a diffusive structure within a ballistic light cone when viewed through a normalized version of single-qubit SRE, despite the absence of explicit conserved charges. We further examine the robustness of this non-ballistic behavior of the normalized single-qubit SRE spreading by extending the analysis to a restricted Clifford circuit, where we unveil a superdiffusive spreading. - oai:arXiv.org:2511.07769v2 + Decoding 3D color codes with boundaries + https://arxiv.org/abs/2512.13436 + arXiv:2512.13436v2 Announce Type: replace +Abstract: Practical large-scale quantum computation requires both efficient error correction and robust implementation of logical operations. Three-dimensional (3D) color codes are a promising candidate for fault-tolerant quantum computation due to their transversal non-Clifford gates, but efficient decoding remains challenging. In this work, we extend previous decoders for two-dimensional color codes [1], which are based on the restriction of the decoding problem to a subset of the qubit lattice, to three dimensions. Including boundaries of 3D color codes, we demonstrate that the 3D restriction decoder achieves optimal scaling of the logical error rate and a threshold value of 1.55(6)% for code-capacity bit- and phase-flip noise, which is almost a factor of two higher than previously reported for this family of codes [2, 3]. We furthermore present qCodePlot3D, a Python package for visualizing 2D and 3D color codes, error configurations, and decoding paths, which supports the development and analysis of such decoders. These advancements contribute to making 3D color codes a more practical option for exploring fault-tolerant quantum computation. + oai:arXiv.org:2512.13436v2 quant-ph - cond-mat.stat-mech - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Somnath Maity, Ryusuke Hamazaki + http://creativecommons.org/licenses/by/4.0/ + Friederike Butt, Lars Esser, Markus M\"uller - The Pound-Drever-Hall Method for Superconducting-Qubit Readout - https://arxiv.org/abs/2512.03138 - arXiv:2512.03138v2 Announce Type: replace -Abstract: Scaling quantum computers to large sizes requires the implementation of many parallel qubit readouts. Here we present an ultrastable superconducting-qubit readout method using the multi-tone self-phase-referenced Pound-Drever-Hall (PDH) technique, originally developed for use with optical cavities. In this work, we benchmark PDH readout of a single transmon qubit, using room-temperature heterodyne detection of all tones to reconstruct the PDH signal. We demonstrate that PDH qubit readout is insensitive to microwave phase drift, displaying $0.73^\circ$ phase stability over 2 hours, and capable of single-shot readout in the presence of phase errors exceeding the phase shift induced by the qubit state. We show that the PDH sideband tones do not cause unwanted measurement-induced state transitions for a transmon qubit, leading to a potential signal enhancement of at least $14$~dB over traditional heterodyne readout. - oai:arXiv.org:2512.03138v2 + Ground State Energy via Adiabatic Evolution and Phase Measurement for a Molecular Hamiltonian on an Ion-Trap Quantum Computer + https://arxiv.org/abs/2512.14415 + arXiv:2512.14415v2 Announce Type: replace +Abstract: Estimating molecular ground-state energies is a central application of quantum computing, requiring both the preparation of accurate quantum states and efficient energy readout. Understanding the effect of hardware noise on these experiments is crucial to distinguish errors that have low impact, errors that can be mitigated, and errors that must be reduced at the hardware level. We ran a state preparation and energy measurement protocol on an ion-trap quantum computer, without any non-scalable off-loading of computational tasks to classical computers, and show that leakage errors are the main obstacle to chemical accuracy. More specifically, we apply adiabatic state preparation to prepare the ground state of a six-qubit encoding of the H3+ molecule and extract its energy using a noise-resilient variant of iterative quantum phase estimation. Our results improve upon the classical Hartree-Fock energy. Analyzing the effect of hardware noise on the result, we find that while coherent and incoherent noise have little influence, the hardware results are mainly impacted by leakage errors. Absent leakage errors, noisy numerical simulations show that with our experimental settings we would have achieved close to chemical accuracy, even shot noise included. These insights highlight the importance of targeting leakage suppression in future algorithm and hardware development. + oai:arXiv.org:2512.14415v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ibukunoluwa Adisa, Won Chan Lee, Kevin C. Cox, Alicia J. Koll\'ar + http://creativecommons.org/licenses/by/4.0/ + Ludwig N\"utzel, Michael J. Hartmann, Henrik Dreyer, Etienne Granet - Experimental quantum voting using photonic GHZ states - https://arxiv.org/abs/2512.03659 - arXiv:2512.03659v2 Announce Type: replace -Abstract: Quantum communication protocols seek to leverage the unique properties of quantum systems for coordination or communication tasks, usually with guarantees of security or anonymity that exceed what is possible classically. One promising domain of application is elections, where strong such guarantees are essential to ensure legitimacy. We experimentally implement a recently proposed election protocol from Centrone et al. such that no one, including a potential central authority, can know the preferred candidate of any voter other than themself. We conduct a four-party election, generating and distributing four-partite GHZ states with $\approx 89\%$ fidelity and successfully recording voters' intentions $\approx 87\%$ of the time. - oai:arXiv.org:2512.03659v2 + Information-Theoretic Constraints on Variational Quantum Optimization: Efficiency Transitions and the Dynamical Lie Algebra + https://arxiv.org/abs/2512.14701 + arXiv:2512.14701v2 Announce Type: replace +Abstract: Variational quantum algorithms are leading candidates for near-term advantage, yet their scalability is fundamentally limited by the ``Barren Plateau'' phenomenon. While traditionally attributed to geometric concentration of measure, I propose an information-theoretic origin: a bandwidth bottleneck in the optimization feedback loop. By modeling the optimizer as a coherent Maxwell's Demon, I derive a thermodynamic constitutive relation, $\Delta E \leq \eta I(S:A)$, where work extraction is strictly bounded by the mutual information established via entanglement. I demonstrate that systems with polynomial Dynamical Lie Algebra (DLA) dimension exhibit ``Information Superconductivity'' (sustained $\eta > 0$), whereas systems with exponential DLA dimension undergo an efficiency collapse when the rate of information scrambling exceeds the ancilla's channel capacity. These results reframe quantum trainability as a thermodynamic phase transition governed by the stability of information flow. + oai:arXiv.org:2512.14701v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cs.ET + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Francis Marcellino, Mingsong Wu, Rob Thew + Jun Liang Tan - Spectroscopic readout of chiral photonic topology in a single-cavity spin-orbit-coupled Bose-Einstein condensate - https://arxiv.org/abs/2512.08662 - arXiv:2512.08662v2 Announce Type: replace -Abstract: Topological photonic phases are typically identified through band reconstruction, steady-state transmission, or real-space imaging of edge modes. In this work, we present a framework for spectroscopic readout of chiral photonic topology in a single driven optical cavity containing a spin-orbit-coupled Bose-Einstein condensate. We demonstrate that the cavity transmission power spectral density provides a direct and measurable proxy for a momentum- and frequency-resolved photonic Chern marker, enabling topological characteristics to be inferred from spectral data without the need for bulk-band tomography. In the loss-dominated regime, where cavity decay exceeds atomic dissipation, the power spectral density exhibits Dirac-like gapped hybrid modes with a vanishing Chern marker, indicating a trivial phase. When the dissipation imbalance is reversed, a bright, gap-spanning spectral ridge emerges, co-localized with peaks in both the Chern marker and Berry curvature. The complex spectrum reveals parity-time symmetric coalescences and gain-loss bifurcations, marking exceptional points and enabling chiral, gap-traversing transport. By linking noise spectroscopy to geometric and non-Hermitian topology in a minimal cavity-QED architecture, this work provides a framework for spectroscopic detection of topological order in driven quantum systems. This approach offers a pathway to compact, tunable topological photonics across a broad range of light-matter platforms, providing a method for the study and control of topological phases in hybrid quantum systems. - oai:arXiv.org:2512.08662v2 + Practical Challenges in Executing Shor's Algorithm on Existing Quantum Platforms + https://arxiv.org/abs/2512.15330 + arXiv:2512.15330v2 Announce Type: replace +Abstract: Quantum computers pose a fundamental threat to widely deployed public-key cryptosystems, such as RSA and ECC, by enabling efficient integer factorization using Shor's algorithm. Theoretical resource estimates suggest that 2048-bit RSA keys could be broken using Shor's algorithm with fewer than a million noisy qubits. Although such machines do not yet exist, the availability of smaller, cloud-accessible quantum processors and open-source implementations of Shor's algorithm raises the question of what key sizes can realistically be factored with today's platforms. In this work, we experimentally investigate Shor's algorithm on several cloud-based quantum computers using publicly available implementations. Our results reveal a substantial gap between the capabilities of current quantum hardware and the requirements for factoring cryptographically relevant integers. In particular, we observe that circuit constructions still need to be highly specific for each modulus, and that machine fidelities are unstable, with high and fluctuating error rates. + oai:arXiv.org:2512.15330v2 quant-ph - cond-mat.quant-gas - physics.app-ph - physics.optics - Mon, 22 Dec 2025 00:00:00 -0500 + cs.CR + cs.ET + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Kashif Ammar Yasir, Gao Xianlong + Paul Bagourd, Julian Jang-Jaccard, Vincent Lenders, Alain Mermoud, Torsten Hoefler, Cornelius Hempel - Quantumness via Discrete Structures - https://arxiv.org/abs/2512.10063 - arXiv:2512.10063v2 Announce Type: replace -Abstract: Quantum theory departs from classical probabilistic theories in foundational ways. These departures--termed quantumness here--power quantum information and computation. This thesis charts the role of discrete structures in assessing quantumness, synthesizing elements of my postdoctoral research through this lens. After an introduction to the necessary background concepts, I present my work under three broad categories. First, I present work on contextuality that extensively relies on (undirected) graphs and hypergraphs as the discrete structures of interest; more specifically, it relies on invariants associated with them. This work includes Kochen-Specker (KS) contextuality and its operationalization to generalized contextuality, expressed via (hyper)graph-theoretic frameworks. I also present work on KS-contextuality in multiqubit systems and an application of generalized contextuality to a one-shot communication task, both of which rely on hypergraphs. Second, I present work on causality, where the discrete structures of interest are directed graphs. This includes work on indefinite causal order, specifically its connections to the gap between local operations and classical communication (LOCC) and separable operations (SEP), and a device-independent notion of nonclassicality--termed antinomicity--that generalizes Bell nonlocality without global causal assumptions. Finally, I present work on the incompatibility of quantum measurements, its connection to Bell nonlocality, and its role in discriminating between quantum and almost quantum correlations in the single-system setting. The discrete structures of interest here are hypergraphs that model joint measurability relations between quantum measurements. I conclude with a summary and an overview of work that is not covered in this thesis. - oai:arXiv.org:2512.10063v2 + Wave-packet dynamics in pseudo-Hermitian lattices: Coexistence of Hermitian and non-Hermitian wavefronts + https://arxiv.org/abs/2512.15333 + arXiv:2512.15333v2 Announce Type: replace +Abstract: This paper investigates wave-packet dynamics in non-Hermitian lattice systems and reveals a surprising phenomenon: The simultaneous propagation of two distinct wavefronts, one traveling at the non-Hermitian velocity and the other at the Hermitian velocity. We show that this dual-front behavior arises naturally in systems governed by a pseudo-Hermitian Hamiltonian. Using the paradigmatic Hatano-Nelson model as our primary example, we demonstrate that this coexistence is essential for understanding a wide array of unconventional dynamical effects, including abrupt ``non-Hermitian reflections'', sudden shifts of Gaussian wave-packets, and disorder-induced emergent packets seeded by the small initial tails. We present analytic predictions that closely match numerical simulations. These results may offer new insight into the topology of non-Hermitian systems and point toward measurable experimental consequences. + oai:arXiv.org:2512.15333v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + cond-mat.mes-hall + cond-mat.quant-gas + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ravi Kunjwal + Alon Beck, Moshe Goldstein - TreeVQA: A Tree-Structured Execution Framework for Shot Reduction in Variational Quantum Algorithms - https://arxiv.org/abs/2512.12068 - arXiv:2512.12068v2 Announce Type: replace -Abstract: Variational Quantum Algorithms (VQAs) are promising for near- and intermediate-term quantum computing, but their execution cost is substantial. Each task requires many iterations and numerous circuits per iteration, and real-world applications often involve multiple tasks, scaling with the precision needed to explore the application's energy landscape. This demands an enormous number of execution shots, making practical use prohibitively expensive. We observe that VQA costs can be significantly reduced by exploiting execution similarities across an application's tasks. Based on this insight, we propose TreeVQA, a tree-based execution framework that begins by executing tasks jointly and progressively branches only as their quantum executions diverge. Implemented as a VQA wrapper, TreeVQA integrates with typical VQA applications. Evaluations on scientific and combinatorial benchmarks show shot count reductions of $25.9\times$ on average and over $100\times$ for large-scale problems at the same target accuracy. The benefits grow further with increasing problem size and precision requirements. - oai:arXiv.org:2512.12068v2 + Prospects for quantum advantage in machine learning from the representability of functions + https://arxiv.org/abs/2512.15661 + arXiv:2512.15661v2 Announce Type: replace +Abstract: Demonstrating quantum advantage in machine learning tasks requires navigating a complex landscape of proposed models and algorithms. To bring clarity to this search, we introduce a framework that connects the structure of parametrized quantum circuits to the mathematical nature of the functions they can actually learn. Within this framework, we show how fundamental properties, like circuit depth and non-Clifford gate count, directly determine whether a model's output leads to efficient classical simulation or surrogation. We argue that this analysis uncovers common pathways to dequantization that underlie many existing simulation methods. More importantly, it reveals critical distinctions between models that are fully simulatable, those whose function space is classically tractable, and those that remain robustly quantum. This perspective provides a conceptual map of this landscape, clarifying how different models relate to classical simulability and pointing to where opportunities for quantum advantage may lie. + oai:arXiv.org:2512.15661v2 quant-ph - cs.AR - cs.DC - cs.ET - Mon, 22 Dec 2025 00:00:00 -0500 + cs.LG + stat.ML + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Yuewen Hou, Dhanvi Bharadwaj, Gokul Subramanian Ravi + http://creativecommons.org/licenses/by/4.0/ + Sergi Masot-Llima, Elies Gil-Fuster, Carlos Bravo-Prieto, Jens Eisert, Tommaso Guaita - Fundamental bound on entanglement generation between interacting Rydberg atoms - https://arxiv.org/abs/2512.13379 - arXiv:2512.13379v2 Announce Type: replace -Abstract: We analytically derive the fundamental lower bound for the preparation fidelity of a maximally-entangled (Bell) state of two atoms involving Rydberg-state interactions. This bound represents the minimum achievable error $E \geq ( 1 + \pi/2 ) \Gamma/B$ due to spontaneous decay $\Gamma$ of the Rydberg states and their finite interaction strength $B$. Using quantum optimal control methods, we identify laser pulses for preparing a maximally-entangled state of a pair of atomic qubits with an error only $1\%$ above the derived fundamental bound. - oai:arXiv.org:2512.13379v2 + A random purification channel for arbitrary symmetries with applications to fermions and bosons + https://arxiv.org/abs/2512.15690 + arXiv:2512.15690v2 Announce Type: replace +Abstract: The random purification channel maps n copies of any mixed quantum state to n copies of a random purification of the state. We generalize this construction to arbitrary symmetries: for any group G of unitaries, we construct a quantum channel that maps states contained in the algebra generated by G to random purifications obtained by twirling over G. In addition to giving a surprisingly concise proof of the original random purification theorem, our result implies the existence of fermionic and bosonic Gaussian purification channels. As applications, we obtain the first tomography protocol for fermionic Gaussian states that scales optimally with the number of modes and the error, as well as an improved property test for this class of states. + oai:arXiv.org:2512.15690v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + math-ph + math.MP + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Georgios Doultsinos, Antonis Delakouras, David Petrosyan + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Michael Walter, Freek Witteveen - A short history of Quantum Illumination - https://arxiv.org/abs/2512.15415 - arXiv:2512.15415v2 Announce Type: replace -Abstract: Quantum illumination represents one of the most interesting examples of quantum technologies. On the one hand, it can find significant applications; on the other hand, it is one of the few quantum protocols robust against noise and losses. Here we present a short summary of the history of this quantum protocol. - oai:arXiv.org:2512.15415v2 + Instantaneous velocity during quantum tunnelling + https://arxiv.org/abs/2512.16385 + arXiv:2512.16385v2 Announce Type: replace +Abstract: Quantum tunnelling, a hallmark phenomenon of quantum mechanics, allows particles to pass through the classically forbidden region. It underpins fundamental processes ranging from nuclear fusion and photosynthesis to the operation of superconducting qubits. Yet the underlying dynamics of particle motion during tunnelling remain subtle and are still the subject of active debate. Here, by analyzing the temporal evolution of the tunnelling process, we show that the particle velocity inside the barrier continuously relaxes from a large initial value toward a smaller one, and may even approach zero in the evanescent regime. Meanwhile, the probability density within the barrier gradually builds up before reaching its stationary profile, in contrast to existing inherently. In addition, starting from the steady-state equations, we derive an explicit relation between the particle velocity and the barrier width, and show that the velocity in evanescent states approaches zero when the barrier is sufficiently wide. These findings resolve the apparent paradox of a vanishing steady-state velocity coexisting with a finite particle density. We point out that defining an effective speed from the probability density, rather than from the probability current, can lead to spuriously nonzero "stationary speed," as appears to be the case in Ref. [Nature 643, 67 (2025)]. Our work establishes a clear dynamical picture for the formation of tunnelling flow and provides a theoretical foundation for testing time-resolved tunnelling phenomena. + oai:arXiv.org:2512.16385v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + physics.optics + Tue, 23 Dec 2025 00:00:00 -0500 replace - http://creativecommons.org/licenses/by/4.0/ - Marco Genovese, Ivano Ruo-Berchera + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Xiao-Wen Shang, Jian-Peng Dou, Feng Lu, Sen Lin, Hao Tang, Xian-Min Jin The measured speed in the evanescent regime reflects the spatial decay of the wavefunction, not particle motion https://arxiv.org/abs/2512.16580 - arXiv:2512.16580v2 Announce Type: replace + arXiv:2512.16580v3 Announce Type: replace Abstract: The recent paper by Sharoglazova et al. reports an energy-dependent parameter $\nu$ extracted from the spatial distribution of photons in a coupled-waveguide experiment. The authors interpret $\nu$ as the speed of quantum particles, even in the classically forbidden regime, and claim that its finite value contradicts the Bohmian mechanics prediction of zero particle velocity. This challenge arises from a fundamental misunderstanding of the operational meaning of v within the Bohmian ontological framework. We demonstrate that v quantifies the spatial gradient of the wavefunctions amplitude, a geometric property of the guiding field, not the kinematical velocity of point-like particles. The experiment therefore does not challenge but rather illustrates the clean ontological separation between the wave and particle aspects inherent to Bohmian mechanics. - oai:arXiv.org:2512.16580v2 + oai:arXiv.org:2512.16580v3 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace http://arxiv.org/licenses/nonexclusive-distrib/1.0/ Weixiang Ye - Symbolic Pauli Propagation for Gradient-Enabled Pre-Training of Quantum Circuits - https://arxiv.org/abs/2512.16674 - arXiv:2512.16674v2 Announce Type: replace -Abstract: Quantum Machine Learning models typically require expensive on-chip training procedures and often lack efficient gradient estimation methods. By employing Pauli propagation, it is possible to derive a symbolic representation of observables as analytic functions of a circuit's parameters. Although the number of terms in such functional representations grows rapidly with circuit depth, suitable choices of ansatz and controlled truncations on Pauli weights and frequency components yield accurate yet tractable estimators of the target observables. With the right ansatz design, this approach can be extended to system sizes beyond the reach of classical simulation, enabling scalable training for larger quantum systems. This also enables a form of classical pre-training through gradient-based optimization prior to deployment on quantum hardware. The proposed approach is demonstrated on the Variational Quantum Eigensolver for obtaining the ground state of a spin model, showing that accurate results can be achieved with a scalable and computationally efficient procedure. - oai:arXiv.org:2512.16674v2 + Subsystems (in)dependence in GIE proposals + https://arxiv.org/abs/2512.17024 + arXiv:2512.17024v2 Announce Type: replace +Abstract: Recent proposals suggest that detecting entanglement between two spatially superposed masses would establish the quantum nature of gravity. However, these gravitationally induced entanglement (GIE) experiments rely on assumptions about subsystem independence. We sharpen the theoretical underpinnings of such proposals by examining them through the lens of algebraic quantum field theory (AQFT), distinguishing distinct operational and algebraic notions of independence. We argue that state and measurement independence of subsystems, essential to the experimental logic, is nontrivial in the presence of gauge constraints and gravitational dressing. Using gravitationally dressed fields, we recall that commutation relations between spacelike separated observables are nontrivial, undermining strict Hilbert space factorization. We further explore the implications for entanglement witnesses, investigating the Tsirelson bound when subsystem algebras fail to commute, and showing that the Tsirelson bound persists for a suitably symmetrized CHSH observable even though the operational status of such "joint" observables becomes delicate when commensurability fails. Our analysis highlights how even within linearized covariant quantum gravity, violations of microcausality may affect both the interpretation, modelling, and design of proposed laboratory tests of quantum gravity, despite remaining negligible for current experimental regimes. Although we consider GIE-style protocols as a concrete case study, the subsystem-independence issues we highlight are generic to low-energy (perturbative) quantum gravity. Finally, we derive estimates for dressing-induced microcausality violations, which suggest a complementary avenue to current proposals: in principle, bounding dressing-induced microcausality violations themselves as a probe of the quantum nature of gravity. + oai:arXiv.org:2512.17024v2 quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + hep-th + math-ph + math.MP + physics.hist-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace http://creativecommons.org/licenses/by/4.0/ - Saverio Monaco, Jamal Slim, Florian Rehm, Dirk Kr\"ucker, Kerstin Borras + Nicolas Boulle, Guilherme Franzmann - Emergent topological re-entrant phase transition in a generalized quasiperiodic modulated Su-Schrieffer-Heeger model - https://arxiv.org/abs/2412.08067 - arXiv:2412.08067v2 Announce Type: replace-cross -Abstract: We study the topological properties of the one-dimensional generalized quasiperiodic modulated Su-Schrieffer-Heeger model. The results reveal that topological re-entrant phase transition emerges. Through the analysis of a real-space winding number , we divide the emergent topological re-entrant phase transitions into two types. The first is the re-entrant phase transition from the traditional topological insulator phase into the topological Anderson insulator phase, and the second is the re-entrant phenomenon from one topological Anderson insulator phase into another topological Anderson insulator phase. These two types of re-entrant phase transition correspond to bounded and unbounded cases of quasiperiodic modulation, respectively. Furthermore, we verify the above topological re-entrant phase transitions by analyzing the Lyapunov exponent and bulk gap. Since Su-Schrieffer-Heeger models have been realized in various artificial systems (such as cold atoms, optical waveguide arrays, ion traps, Rydberg atom arrays, etc.), the two types of topological re-entrant phase transition predicted in this paper are expected to be realized in the near future. - oai:arXiv.org:2412.08067v2 + Emergent $\mathcal{PT}$-symmetry breaking of collective modes with topological critical phenomena + https://arxiv.org/abs/2103.00450 + arXiv:2103.00450v2 Announce Type: replace-cross +Abstract: The spontaneous breaking of parity-time ($\mathcal{PT}$) symmetry yields rich critical behavior in non-Hermitian systems, and has stimulated much interest, albeit most previous studies were performed within the single-particle or mean-field framework. Here, by studying the collective excitations of a Fermi superfluid with $\mathcal{PT}$-symmetric spin-orbit coupling, we uncover an emergent $\mathcal{PT}$-symmetry breaking in the Anderson-Bogoliubov (AB) collective modes, even as the superfluid ground state retains an unbroken $\mathcal{PT}$ symmetry. {The critical point of the transition is marked by a non-analytic kink in the speed of sound, which derives from the coalescence and annihilation of the AB mode and its hole partner, reminiscent of the particle-antiparticle annihilation. The system consequently becomes immune to low-frequency external perturbations at the critical point, a phenomenon associated with the spectral topology of the complex quasiparticle dispersion. This critical phenomenon offers a fascinating route toward perturbation-free quantum states. + oai:arXiv.org:2103.00450v2 + cond-mat.quant-gas cond-mat.mes-hall + cond-mat.supr-con quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xiao-Ming Wang, Shan-Zhong Li, Zhi Li + 10.1038/s42005-021-00762-6 + Communications Physics 4, 261 (2021) + Jian-Song Pan, Wei Yi, Jiangbin Gong - Probing non-ergodicity and symmetry via coherent forward scattering in a shaken rotor - https://arxiv.org/abs/2503.01777 - arXiv:2503.01777v2 Announce Type: replace-cross -Abstract: The Coherent Backscattering (CBS) peak is a well-known interferential signature of weak localization in disordered or chaotic systems. More recently, a second interference feature -- the Coherent Forward Scattering (CFS) peak -- was predicted to emerge in the regime of strong localization. However, it has never been directly observed. Here we report the first direct observation of the CFS peak and demonstrate its dual role as a signature of non-ergodicity and as a probe of symmetries in quantum chaotic systems. Using a shaken rotor model realized with a Bose-Einstein condensate (BEC) of ultracold atoms in a modulated optical lattice, we investigate dynamical localization in momentum space. The CFS peak emerges in the position distribution as a consequence of non-ergodic dynamics, while its growth timescale reveals the underlying localization length. By finely tuning the modulation, we control time-reversal and parity symmetries and measure their distinct effects on both CBS and CFS peaks. Our results highlight the strong link of both the temporal growth and contrast of the CFS with symmetry and localization, making it a robust probe of these properties. This work opens new directions for characterizing non-ergodicity and symmetries in quantum chaotic or disordered systems, with possible applications in many-body localization and chaos. - oai:arXiv.org:2503.01777v2 + Loop Algorithm for Quantum Transverse Ising Model in a Longitudinal Field + https://arxiv.org/abs/2409.17835 + arXiv:2409.17835v2 Announce Type: replace-cross +Abstract: The quantum transverse Ising model and its extensions play a critical role in various fields, such as statistical physics, quantum magnetism, quantum simulations, and mathematical physics. Although it does not suffer from the sign problem in most cases, the corresponding quantum Monte Carlo algorithm performs inefficiently, especially at a large longitudinal field. The main hindrance is the lack of loop update method which can strongly decrease the auto-correlation between Monte Carlo steps. Here, we successfully develop a loop algorithm with a novel merge-unmerge process. It demonstrates a great advantage over the state-of-the-art algorithm when implementing it to simulate the Rydberg atom chain and Kagome qubit ice. This advanced algorithm suits various systems such as Rydberg atom arrays, trapped ions, quantum materials, and quantum annealers. + oai:arXiv.org:2409.17835v2 + cond-mat.str-el cond-mat.quant-gas + cond-mat.stat-mech quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - F. Arrouas, J. H\'ebraud, N. Ombredane, E. Flament, D. Ronco, N. Dupont, G. Lemari\'e, B. Georgeot, Ch. Miniatura, J. Billy, B. Peaudecerf, D. Gu\'ery-Odelin + 10.1103/s2q3-grd6 + Published in Phys. Rev. B 112, 214441 (2025) + Wei Xu, Xue-Feng Zhang - An Optimally Accurate Lanczos Algorithm in the Matrix Product State Representation - https://arxiv.org/abs/2504.21786 - arXiv:2504.21786v4 Announce Type: replace-cross -Abstract: We improve the convergence of the Lanczos algorithm using the matrix product state representation. As an alternative to the density matrix renormalization group (DMRG), the Lanczos algorithm avoids local minima and can directly find multiple low-lying eigenstates. However, its performance and accuracy are affected by the truncation required to maintain the efficiency of the tensor network representation. In this work, we propose the modified thick-block Lanczos method to enhance the convergence of the Lanczos algorithm with MPS representation. We benchmark our method on one-dimensional instances of the Fermi-Hubbard model and the Heisenberg model in an external field, using numerical experiments targeting the first five lowest eigenstates. Across these tests, our approach attains the best possible accuracy permitted by the given bond dimension. This work establishes the Lanczos method as a reliable and accurate framework for finding multiple low-lying states within a tensor-network representation - oai:arXiv.org:2504.21786v4 + Absence of nontrivial local conserved quantities in the spin-1 bilinear-biquadratic chain and its anisotropic extensions + https://arxiv.org/abs/2411.04945 + arXiv:2411.04945v4 Announce Type: replace-cross +Abstract: We provide a complete classification of the integrability and nonintegrability of the spin-1 bilinear-biquadratic model with a uniaxial anisotropic field, which includes the Heisenberg model and the Affleck-Kennedy-Lieb-Tasaki model. It is rigorously shown that, within this class, the only integrable systems are those that have been solved by the Bethe ansatz method, and that all other systems are nonintegrable, in the sense that they do not have nontrivial local conserved quantities. Here, "nontrivial" excludes quantities like the Hamiltonian or the total magnetization, and "local" refers to sums of operators that act only on sites within a finite distance. This result establishes the nonintegrability of the Affleck-Kennedy-Lieb-Tasaki model and, consequently, demonstrates that the quantum many-body scars observed in this model emerge independently of any conservation laws of local quantities. Furthermore, we extend the proof of nonintegrability to more general spin-1 models that encompass anisotropic extensions of the bilinear-biquadratic Hamiltonian and completely classify the integrability of generic Hamiltonians that possess translational symmetry, $U(1)$ symmetry, time-reversal symmetry, and spin-flip symmetry. Our result accomplishes a breakthrough in nonintegrability proofs by expanding their scope to spin-1 systems. + oai:arXiv.org:2411.04945v4 + cond-mat.stat-mech + math-ph + math.MP + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1103/vjtq-sz21 + Phys. Rev. Research 7, 043297 (2025) + Akihiro Hokkyo, Mizuki Yamaguchi, Yuuya Chiba + + + Additivity, Haag duality, and non-invertible symmetries + https://arxiv.org/abs/2503.20863 + arXiv:2503.20863v2 Announce Type: replace-cross +Abstract: The algebraic approach to quantum field theory focuses on the properties of local algebras, whereas the study of (possibly non-invertible) global symmetries emphasizes global aspects of the theory and spacetime. We study connections between these two perspectives by examining how either of two core algebraic properties -- "additivity" or "Haag duality" -- is violated in a 1+1D CFT or lattice model restricted to the symmetric sector of a general global symmetry. For the Verlinde symmetry of a bosonic diagonal RCFT, we find that additivity is violated whenever the symmetry algebra contains an invertible element, while Haag duality is violated whenever it contains a non-invertible element. We find similar phenomena for the Kramers-Wannier and Rep(D$_8$) non-invertible symmetries on spin chains. + oai:arXiv.org:2503.20863v2 + hep-th cond-mat.str-el - physics.comp-ph + math.OA quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross - http://creativecommons.org/licenses/by/4.0/ - Yu Wang, Zhangyu Yang, Xingyao Wu, Christian B. Mendl + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1007/JHEP08(2025)009 + J. High Energ. Phys. 2025, 9 (2025) + Shu-Heng Shao, Jonathan Sorce, Manu Srivastava - Impact of the honeycomb spin-lattice on topological magnons and edge states in ferromagnetic 2D skyrmion crystals - https://arxiv.org/abs/2506.02192 - arXiv:2506.02192v3 Announce Type: replace-cross -Abstract: Magnons have been intensively studied in two-dimensional (2D) ferromagnetic (FM) skyrmion crystals (SkXs) stabilized on Bravais lattices, particularly triangular and square lattices, where the first magnon gaps are topologically trivial and do not support topological edge states (TESs). In this context, antiferromagnetic (AFM) SkXs on the triangular spin lattice have been considered potentially more interesting for applications, since TESs emerge in the first magnon gap. Meanwhile, the magnon topology of SkXs on non-Bravais spin lattices remains largely unexplored. In this work, we theoretically investigate the magnon band structure and TESs in 2D FM SkXs stabilized on the honeycomb spin lattice, including experimentally motivated parameter sets relevant to van der Waals magnets. We show that TESs emerge in the first magnon gap over significant ranges of the Dzyaloshinskii-Moriya interaction (DMI) and single-ion magnetic anisotropy. Field-induced topological phase transitions modify the number of these TESs before eventually trivializing them, thereby enabling controlled switching of magnonic edge transport. These findings highlight the role of lattice geometry in shaping the magnon topology of noncollinear spin textures. - oai:arXiv.org:2506.02192v3 - cond-mat.mes-hall - cond-mat.mtrl-sci + Symmetry Theories, Wigner's Function, Compactification, and Holography + https://arxiv.org/abs/2505.23887 + arXiv:2505.23887v3 Announce Type: replace-cross +Abstract: The global symmetry data of a $D$-dimensional absolute quantum field theory can sometimes be packaged in terms of a $(D+1)$-dimensional bulk system obtained by extending along an interval, with a relative QFT$_D$ at one end and suitable gapped / free boundary conditions at the other end. The partition function of the QFT$_D$ can then be interpreted as a wavefunction depending on background fields. However, in some cases, it is not possible or simply cumbersome to fix an absolute form of the symmetry data. Additionally, it is also of interest to consider entangled and mixed states of relative QFTs as well as entangled and mixed states of gapped / free boundary conditions. We argue that Wigner's quasi-probabilistic function on phase space provides a physical interpretation of the symmetry data in all such situations. We illustrate these considerations in the case of string compactifications and holographic systems. + oai:arXiv.org:2505.23887v3 + hep-th + cond-mat.str-el quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Doried Ghader, Bilal Jabakhanji + Jonathan J. Heckman, Max H\"ubner, Chitraang Murdia - Lieb-Robinson bounds, automorphic equivalence and LPPL for long-range interacting fermions - https://arxiv.org/abs/2507.03319 - arXiv:2507.03319v2 Announce Type: replace-cross -Abstract: We prove a Lieb-Robinson bound for lattice fermion models with polynomially decaying interactions, which can be used to show the locality of the quasi-local inverse Liouvillian. This allows us to prove automorphic equivalence and the local perturbations perturb locally (LPPL) principle for these systems. The proof of the Lieb-Robinson bound is based on the work of Else et al. (2020), and our results also apply to spin systems. We explain why some newer Lieb-Robinson bounds for long-range spin systems cannot be used to prove the locality of the quasi-local inverse Liouvillian, and in some cases may not even hold for fermionic systems. - oai:arXiv.org:2507.03319v2 - math-ph - math.MP + Axioms of Quantum Mechanics in light of Continuous Model Theory + https://arxiv.org/abs/2506.02029 + arXiv:2506.02029v2 Announce Type: replace-cross +Abstract: The aim of this note is to recast somewhat informal axiom system of quantum mechanics used by physicists (Dirac calculus) in the language of Continuous Logic. + We note an analogy between Tarski's notion of cylindric algebras, as a tool of algebraisation of first order logic, and Hilbert spaces which can serve the same purpose for continuous logic of physics. + oai:arXiv.org:2506.02029v2 + math.LO quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Stefan Teufel, Tom Wessel + Boris Zilber + + + On the reconstruction map in JT gravity + https://arxiv.org/abs/2506.18975 + arXiv:2506.18975v2 Announce Type: replace-cross +Abstract: An open question in AdS/CFT is how to reconstruct semiclassical bulk operators precisely enough that non-perturbative quantum effects can be computed. We propose a set of physically-motivated requirements for such a reconstruction map, and explicitly construct a map satisfying these requirements in Jackiw-Teitelboim (JT) gravity. Our map is found by canonically quantizing "action-angle" variables for JT gravity, which are chosen to ensure that the spectrum of the fundamental quantum theory matches known results from the gravitational path integral. We then study unitary quantum dynamics in this theory, and obtain analytical predictions for the dynamics of the wormhole length, including its quantum fluctuations, leveraging techniques from quantum ergodicity theory. Level repulsion in the non-perturbative JT spectrum implies that the average wormhole length is non-monotonic in time, that fluctuations in wormhole length are non-perturbatively suppressed until nearly the Heisenberg time, and that the late-time-evolved Hartle-Hawking state has a heavy-tailed distribution of lengths. We discuss the implications of our results for the "complexity = volume" conjecture. + oai:arXiv.org:2506.18975v2 + hep-th + nlin.CD + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + 10.1007/JHEP12(2025)045 + JHEP 12 (2025) 045 + Chris Akers, Andrew Lucas, Amit Vikram - Quantum Quasinormal Mode Theory for Dissipative Nano-Optics and Magnetodielectric Cavity Quantum Electrodynamics - https://arxiv.org/abs/2507.05233 - arXiv:2507.05233v3 Announce Type: replace-cross -Abstract: The unprecedented pace of evolution in nanoscale architectures for cavity quantum electrodynamics (cQED) has posed crucial challenges for theory, where the quantum dynamics arising from the non-perturbative dressing of matter by cavity electric and magnetic fields, as well as the fundamentally non-hermitian character of the system are to be treated without significant approximation. The lossy electromagnetic resonances of photonic, plasmonic or magnonic nanostructures are described as quasinormal modes (QNMs), whose properties and interactions with quantum emitters and spin qubits are central to the understanding of dissipative nano-optics and magnetodielectric cQED. Despite recent advancements toward a fully quantum framework for QNMs, a general and universally accepted approach to QNM quantization for arbitrary linear media remains elusive. In this work, we introduce a unified theoretical framework, based on macroscopic QED and complex coordinate transformations, that achieves QNM quantization for a wide class of spatially inhomogeneous, dissipative (with possible gain components) and dispersive, linear, magnetodielectric resonators. The complex coordinate transformations equivalently convert the radiative losses into non-radiative material dissipation, and via a suitable transformation that reflects all the losses of the resonator, we define creation and annihilation operators that allow the construction of modal Fock states for the joint excitations of field-dressed matter. By directly addressing the intricacies of modal loss in a fully quantum theory of magnetodielectric cQED, our approach enables the exploration of modern, quantum nano-optical experiments utilizing dielectric, plasmonic, magnetic or hybrid cQED architectures, and paves the way towards a rigorous assessment of room-temperature quantum nanophotonic technologies without recourse to ad hoc quantization schemes. - oai:arXiv.org:2507.05233v3 + Chiral superfluorescence from perovskite superlattices + https://arxiv.org/abs/2506.22786 + arXiv:2506.22786v2 Announce Type: replace-cross +Abstract: Superfluorescence (SF) is the collective emission of intense, coherent light from an interacting ensemble of quantum emitters1-4. While SF has been observed in several solid-state materials5-8, the spontaneous generation of circularly polarized SF from chiral materials (chiral SF) has not been realized9,10. Here, we report the first observation of chiral SF originating from edge states in large-area (>100 um * 100 um) vertically aligned chiral perovskite superlattices at room-temperature. Theoretical quantum optics calculations describe the transition from initially unpolarized, incoherent spontaneous emission to a coherent chiral SF state, quantitatively reproducing both the experimentally observed generation of circular polarization (up to ~14%) and its reversal in sign with opposite material handedness. Moreover, we show that both the intensity and the degree of circular polarization of chiral SF can be modulated by a weak magnetic field, enabling precise control over solid-state quantum light emission at room temperature. Our findings demonstrate an interplay between chirality and many-body quantum coherence, thereby revealing promising new directions for chirality-controlled quantum-optical applications. + oai:arXiv.org:2506.22786v2 physics.optics + cond-mat.mes-hall + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Qi Wei, Jonah S. Peter, Hui Ren, Weizhen Wang, Luwei Zhou, Qi Liu, Stefan Ostermann, Jun Yin, Songhua Cai, Susanne F. Yelin, Mingjie Li + + + Universal shape-dependence of quantum entanglement in disordered magnets + https://arxiv.org/abs/2507.04557 + arXiv:2507.04557v2 Announce Type: replace-cross +Abstract: Disordered quantum magnets are not only experimentally relevant, but offer efficient computational methodologies to calculate the low energy states as well as various measures of quantum correlations. Here, we present a systematic analysis of quantum entanglement in the paradigmatic random transverse-field Ising model in two dimensions, using an efficient implementation of the asymptotically exact strong disorder renormalization group method. The phase diagram is known to be governed by three distinct infinitely disordered fixed points (IDFPs) that we study here. For square subsystems, it has been recently established that quantum entanglement has a universal logarithmic correction due to the corners of the subsystem at all three IDFPs. This corner contribution has been proposed as an "entanglement susceptibility", a useful tool to locate the phase transition and to measure the correlation length critical exponent. Towards a deeper understanding, we quantify how the corner contribution depends on the shape of the subsystem. While the corner contribution remains universal, the shape-dependence is qualitatively different in each universality class, also confirmed by line segment subsystems, a special case of skeletal entanglement. Therefore, unlike in conformally invariant systems, in general different subsystem shapes are versatile probes to unveil new universal information on the phase transitions in disordered quantum systems. + oai:arXiv.org:2507.04557v2 + cond-mat.dis-nn + cond-mat.stat-mech quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Lars Meschede, Daniel D. A. Clarke, Ortwin Hess + Natalie Love, Istv\'an A. Kov\'acs + + + Quantum Listenings -- Amateur Sonification of Vacuum and other Noises + https://arxiv.org/abs/2507.08813 + arXiv:2507.08813v2 Announce Type: replace-cross +Abstract: The sensory perceptions of vision and sound may be considered as complementary doorways towards interpreting and understanding physical phenomena. We provide a few selected samples where scientific data of systems usually not directly accessible to humans may be listened to. The examples are chosen close to the regime where quantum mechanics is applicable. Visual and auditory renderings are compared with some connections to music, illustrating in particular a kind of fractal complexity along the time axis. + oai:arXiv.org:2507.08813v2 + physics.pop-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by-nc-sa/4.0/ + Carsten Henkel - Squeezed gravitons from superradiant axion fields around rotating black holes - https://arxiv.org/abs/2507.23475 - arXiv:2507.23475v3 Announce Type: replace-cross -Abstract: We propose, in (3+1)-dimensional spacetimes, a novel astrophysical source of squeezed graviton states, due to superradiant axionic clouds surrounding rotating (Kerr-type) black holes (BH). The microscopic origin of these axions is diverse, ranging from the Kalb-Ramond (model-independent) axions and compactification axions in string theory, to \cm contorted geometries exemplified by a totally antisymmetric component of torsion in Einstein-Cartan theory. The axion fields couple to chiral gauge and gravitational Chern-Simons (CS) anomaly terms in the effective gravitational actions. In the presence of a Kerr BH background, such axions lead, upon acquiring a mass, to superradiance and the production of pairs of entangled gravitons in a squeezed state. The specific microscopic origin of the axions is not important, provided they are massive. This multimode squeezed-graviton state is examined through a Takagi-like decomposition, used in quantum optics. In the effective action it is shown that squeezing effects associated with conventional general relativity (GR) dominate, by many orders of magnitude, the corresponding effects due to the CS gravitational anomaly terms. For a sufficiently long lifetime of the axionic cloud of the BH, we find that significant squeezing (quantified through the average number of gravitons with respect to the appropriate vacuum) can be produced from the GR effects. It is also demonstrated explicitly that the structure of the entangled states (when the latter are expressed in a left-right polarization basis) depends highly on whether the GR or the anomalous CS effects produce the entanglement. - oai:arXiv.org:2507.23475v3 + The Sound of an Orbit: A Quantum Spectrum at the ISCO + https://arxiv.org/abs/2507.14254 + arXiv:2507.14254v2 Announce Type: replace-cross +Abstract: We investigate the quantum signature of the innermost stable circular orbit (ISCO), a region of profound importance in black hole astrophysics. By modeling an atom as an Unruh-DeWitt detector coupled to a massless scalar field in the Boulware vacuum, we calculate the excitation rate for a detector following a circular geodesic at the ISCO of a Schwarzschild black hole. In stark contrast to the continuous thermal spectra associated with static or infalling observers, our analysis reveals a unique, non-thermal excitation spectrum characterized by a discrete "frequency comb" of sharp, resonant peaks. We show that the locations of these peaks are determined by the orbital frequency at the ISCO, while their intensity increases dramatically as the orbit approaches this final stability boundary. This distinct spectral signature offers a novel theoretical probe of the quantum vacuum in a strong-field gravitational regime and provides a clear distinction between the quantum phenomena experienced by observers on different trajectories. Our findings have potential implications for interpreting the emission spectra from accretion disks and open new avenues for exploring the connection between quantum mechanics and gravity. + oai:arXiv.org:2507.14254v2 gr-qc hep-th quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by/4.0/ + 10.1002/prop.70048 + Fortschr. Phys. (2025): e70048 + Reggie C. Pantig, Ali \"Ovg\"un + + + FFTArray: A Python Library for the Implementation of Discretized Multi-Dimensional Fourier Transforms + https://arxiv.org/abs/2508.03697 + arXiv:2508.03697v3 Announce Type: replace-cross +Abstract: Partial differential equations describing the dynamics of physical systems rarely have closed-form solutions. Fourier spectral methods, which use Fast Fourier Transforms (FFTs) to approximate solutions, are a common approach to solving these equations. However, mapping Fourier integrals to discrete FFTs is not straightforward, as the selection of the grid as well as the coordinate-dependent phase and scaling factors require special care. Moreover, most software packages that deal with this step integrate it tightly into their full-stack implementations. Such an integrated design sacrifices generality, making it difficult to adapt to new coordinate systems, boundary conditions, or problem-specific requirements. To address these challenges, we present FFTArray, a Python library that automates the general discretization of Fourier transforms. Its purpose is to reduce the barriers to developing high-performance, maintainable code for pseudo-spectral Fourier methods. Its interface enables the direct translation of textbook equations and complex research problems into code, and its modular design scales naturally to multiple dimensions. This makes the definition of valid coordinate grids straightforward, while coordinate grid specific corrections are applied with minimal impact on computational performance. Built on the Python Array API Standard, FFTArray integrates seamlessly with array backends like NumPy, JAX and PyTorch and supports Graphics Processing Unit acceleration. The code is openly available at https://github.com/QSTheory/fftarray under Apache-2.0 license. + oai:arXiv.org:2508.03697v3 + physics.comp-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by/4.0/ + Stefan J. Seckmeyer, Christian Struckmann, Gabriel M\"uller, Jan-Niclas Kirsten-Siem{\ss}, Naceur Gaaloul + + + Near-optimal decomposition of unitary matrices using phase masks and the discrete Fourier transform + https://arxiv.org/abs/2508.20010 + arXiv:2508.20010v2 Announce Type: replace-cross +Abstract: Universal multiport interferometers (UMIs) have emerged as a key tool for performing arbitrary linear transformations on optical modes, enabling precise control over the state of light in essential applications of classical and quantum information processing such as neural networks and boson sampling. While UMI architectures based on Mach-Zehnder interferometer networks are well established, alternative approaches that involve interleaving fixed multichannel mixing layers and phase masks have recently gained interest due to their high robustness to losses and fabrication errors. However, these approaches currently lack optimal analytical methods to compute design parameters with low optical depth. In this work, we introduce a constructive decomposition of unitary matrices using a sequence of $2N+5$ phase masks interleaved with $2N+4$ discrete Fourier transform matrices. This decomposition can be leveraged to design universal interferometers based on phase masks and multimode interference couplers, implementing a discrete Fourier transform, offering an analytical alternative to conventional numerical optimization-based designs and reducing by a factor of 3 the previous best known analytical methods. + oai:arXiv.org:2508.20010v2 + physics.optics + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Panagiotis Dorlis, Nick E. Mavromatos, Sarben Sarkar, Sotirios-Neilos Vlachos + 10.1364/JOSAB.577579 + Journal of the Optical Society of America B Vol. 43, Issue 3, pp. A66-A73 (2026) + Vincent Girouard, Nicol\'as Quesada - Search for Dark Matter Scattering from Optically Levitated Nanoparticles - https://arxiv.org/abs/2508.00815 - arXiv:2508.00815v2 Announce Type: replace-cross -Abstract: The development of levitated optomechanics has enabled precise force sensors that operate in the quantum measurement regime, opening up unique opportunities to search for new physics whose weak interactions may have evaded existing sensors. We demonstrate the detection of impulsive forces acting on optically levitated nanoparticles, where the dominant noise source is provided by measurement backaction. Using these sensors, we search for momentum transfers that may originate from scattering of passing particlelike dark matter. For dark matter that couples to Standard Model neutrons via a generic long-range interaction, this search constrains a range of models in the mass range $1$-$10^7~\mathrm{GeV/}c^2$, placing upper limits on single neutron coupling strength as low as $\leq 1 \times 10^{-7}$ at the 95% confidence level. We also demonstrate the ability of using the inherent directional sensitivity of these sensors to separate possible dark matter signals from backgrounds. Future extensions of the techniques developed here can enable searches for light dark matter and massive neutrinos that can reach sensitivity several orders of magnitude beyond existing searches. - oai:arXiv.org:2508.00815v2 - hep-ex - hep-ph + Visualising Quantum Entanglement Using Interactive Electronic Quantum Dice + https://arxiv.org/abs/2510.04931 + arXiv:2510.04931v2 Announce Type: replace-cross +Abstract: Quantum entanglement remains a challenging concept to teach and visualise due to its microscopic and non-classical nature. We present innovative educational demonstration material consisting of electronic dice that simulate the properties of quantum entanglement through haptic interaction. The system uses displays, orientation sensors, and wireless communication to visualise key quantum mechanical principles such as superposition, measurement, and entanglement correlations. This analogy enables students to experience quantum phenomena through familiar objects, making abstract concepts more tangible. The dice support various educational scenarios, from basic entanglement demonstrations to more complex quantum key distribution experiments, and can be adapted for different educational levels from secondary school to undergraduate physics courses. Initial implementations demonstrate that the interactive nature of the Quantum Dice can help users develop an intuitive understanding of quantum mechanical principles. The low-cost, open source, and robust design makes Quantum Dice accessible to a wider range of educational institutions. + oai:arXiv.org:2510.04931v2 + physics.ed-ph quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - 10.1103/j76m-gcp1 - PRX Quantum 6 (2025), 040367 - Yu-Han Tseng, T. W. Penny, Benjamin Siegel, Jiaxiang Wang, David C. Moore + B. Folkers, A. van Rossum, A. Brinkman, H. K. E. Stadermann + + + Evolution With(out) Time: Relational Holography & BPS Complexity Growth in $\mathcal{N}=2$ Double-Scaled SYK + https://arxiv.org/abs/2510.11777 + arXiv:2510.11777v2 Announce Type: replace-cross +Abstract: How do we describe non-trivial bulk measurements relative to an observer (i.e. relationally) when both the observer and the system it probes may/may not evolve in time? How can we interpret this holographically; particularly for zero-energy BPS states in supersymmetric theories? We address these questions, in the $\mathcal{N}=2$ double-scaled SYK model and its putative bulk dual by: (i) formulating a holographic procedure in the language of quantum reference frames to gravitationally dress bulk observables to ``clocks'' parametrized by both boundary time and R-charge; and (ii) proposing a \emph{new measure of Krylov complexity} with R-charge in the boundary theory that probes zero-energy BPS states. Holographically, this proposal reproduces a relational bulk observable, a BPS wormhole length. We contrast this to the Krylov complexity for Hartle-Hawking states with non-trivial time flow. The latter reproduces the same observable as for the bosonic DSSYK in the semiclassical limit, while its quantum fluctuations can capture supersymmetric corrections depending on the specific initial state. + oai:arXiv.org:2510.11777v2 + hep-th + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Sergio E. Aguilar-Gutierrez - Role of quantum dynamics in coherent and incoherent radiation during tunneling ionization - https://arxiv.org/abs/2508.20619 - arXiv:2508.20619v2 Announce Type: replace-cross -Abstract: Radiation during strong-field tunneling ionization is investigated. The spontaneous as well as the coherent components of the radiation are calculated describing the ionization dynamics via the strong field approximation and the role of the quantum dynamics at tunneling is analyzed. The competition between different mechanisms in different spectral regions is examined. Transition-like radiation (Brunel radiation) is dominated at low-frequencies, Thomson scattering at the laser frequency, and radiative recombination via the three-step process at high-order harmonics. To distinguish the role of the quantum dynamics, simple man Drude models are developed for the coherent as well as for spontaneous radiation, which are based on the electron trajectory out of the tunneling barrier. The quantum dynamics is shown to modify the coherent Brunel radiation for near-zero-frequencies in asymmetric laser pulses. The significant role of free-free transitions is demonstrated for the spontaneous radiation in the low-frequency region. - oai:arXiv.org:2508.20619v2 + Single Sr Atoms in Optical Tweezer Arrays for Quantum Simulation + https://arxiv.org/abs/2510.19816 + arXiv:2510.19816v3 Announce Type: replace-cross +Abstract: We report on the realization of a platform for trapping and manipulating individual $^{88}$Sr atoms in optical tweezers. A first cooling stage based on a blue shielded magneto-optical trap (MOT) operating on the $^1S_0$ -> $^1P_1$ transition at 461 nm enables us to trap approximately $4\times 10^6$ atoms at a temperature of 6.8 mK. Further cooling is achieved in a narrow-line red MOT using the $^1S_0$ -> $^3P_1$ intercombination transition at 689 nm, bringing $4\times 10^5$ atoms down to 5 $\mu$K and reaching a density of $\approx 10^{10}$ cm$^{-3}$. Atoms are then loaded into 813 nm tweezer arrays generated by crossed acousto-optic deflectors and tightly focused onto the atoms with a high-numerical-aperture objective. Through light-assisted collision processes we achieve the collisional blockade, which leads to single-atom occupancy with a probability of about $50\%$. The trapped atoms are detected via fluorescence imaging with a fidelity of $99.986(6)\%$, while maintaining a survival probability of $97(2)\%$. The release-and-recapture measurement provides a temperature of $12.92(5)$ $\mu$K for the atoms in the tweezers, and the ultra-high-vacuum environment ensures a vacuum lifetime higher than 7 min. These results demonstrate a robust alkaline-earth tweezer platform that combines efficient loading, cooling, and high-fidelity detection, providing the essential building blocks for scalable quantum simulation and quantum information processing with Sr atoms. + oai:arXiv.org:2510.19816v3 physics.atom-ph + cond-mat.quant-gas quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Michael Klaiber, Karen Z. Hatsagortsyan, Christoph H. Keitel + 10.3390/atoms14010001 + Atoms 2026, 14(1), 1 + Veronica Giardini, Luca Guariento, Andrea Fantini, Shawn Storm, Massimo Inguscio, Jacopo Catani, Giacomo Cappellini, Vladislav Gavryusev, Leonardo Fallani - Crystal-Field--Driven Magnetoelectricity in the Triangular Quantum Magnet CeMgAl$_{11}$O$_{19}$ - https://arxiv.org/abs/2510.08746 - arXiv:2510.08746v3 Announce Type: replace-cross -Abstract: We report dielectric and magnetoelectric studies of single-crystalline \ce{CeMgAl11O19}, a Kramers triangular magnet embedded in a polarizable hexaaluminate lattice. In zero magnetic field, the permittivity $\varepsilon'(T)$ follows the Barrett law of a quantum paraelectric down to 25 K, below which a broad minimum develops near 3 K without evidence of static ferroelectric or magnetic order. Application of magnetic fields up to \SI{9}{\tesla} shifts this minimum to higher temperatures and broadens it, evidencing a tunable magnetoelectric response.The magnetoelectric coupling was characterized using results from magnetization measurements. The anomaly temperature $T^*$, extracted from the local minimum of $\varepsilon'(T)$, exhibits a linear dependence on the squared magnetization $M^2$, consistent with the biquadratic magnetoelectric coupling allowed in centrosymmetric systems. This magnetoelectric effect, mediated by spin-orbit-entangled Kramers doublets interacting with a frustrated antipolar liquid, establishes \ce{CeMgAl11O19} as a prototype for exploring quantum magnetoelectricity in frustrated systems. - oai:arXiv.org:2510.08746v3 - cond-mat.str-el + The Anderson transition -- a view from Krylov space + https://arxiv.org/abs/2510.26920 + arXiv:2510.26920v3 Announce Type: replace-cross +Abstract: The Krylov subspace expansion is a workhorse method for sparse numerics that has been increasingly explored as source of physical insight into many-body dynamics in recent years. In this work we revisit the venerable Anderson model of localization in dimensions $d=1, 2, 3, 4$ to construct local integrals of motion (LIOM) in Krylov space. These appear as zero eigenvalue edge states of an effective hopping problem in the Krylov superoperator subspace and can be analytically constructed given the Lanczos coefficients. We exploit this idea, focusing on $d=3$, to study the manifestation of the disorder driven Anderson transition in the anatomy of LIOMs. We find that the increasing complexity of the Krylov operators results in a suppression of the fluctuations of the Lanczos coefficients. As such, one can study the phenomenology of the integrals of motion in the disorder averaged Krylov chain. We find edge states localized on vanishing fraction of Krylov space (of dimension $D_K=V^2$ for cubes of volume $V$), both in localized and extended phases. Importantly, in the localized phase, disorder induces powerlaw decaying dimerization in the (Krylov) hopping problem, producing stretched exponential decay of the LIOMs in Krylov space with a stretching exponent $1/2d$. Metallic LIOMs are completely delocalized albeit across only $\propto \sqrt{D_K}$ states. Critical LIOMs exhibit powerlaw decay with an exponent matching the expected value of $0.29$. + oai:arXiv.org:2510.26920v3 + cond-mat.dis-nn + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + J. Clayton Peacock, Vadim Oganesyan, Dries Sels + + + Dirac - von Neumann axioms in the setting of Continuous Model Theory + https://arxiv.org/abs/2511.01900 + arXiv:2511.01900v2 Announce Type: replace-cross +Abstract: We recast the well-known axiom system of quantum mechanics used by physicists (the Dirac calculus) in the language of Continuous Logic. For the basic version of the axiomatic system we prove that along with the canonical continuous model the axioms have approximate finite models of large sizes, in fact the continuous model is isomorphic to an ultraproduct of finite models. We analyse the continuous logic quantifier corresponding to Dirac integration and show that in finite context it has two versions, local and global, which coincide on Gaussian wave-functions. + oai:arXiv.org:2511.01900v2 + math.LO quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://creativecommons.org/licenses/by/4.0/ - Sonu Kumar (Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Prague, Czech Republic, Adam Mickiewicz University, Faculty of Physics and Astronomy, Department of Experimental Physics of Condensed Phase, Pozna\'n, Poland), Ga\"el Bastien (Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Prague, Czech Republic), Maxim Savinov (Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic), Petr Proschek (Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Prague, Czech Republic), Adam Eli\'a\v{s} (Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Prague, Czech Republic), Karol Za{\l}\k{e}ski (Adam Mickiewicz University, NanoBioMedical Centre, Pozna\'n, Poland), Ma{\l}gorzata \'Sliwi\'nska-Bartkowiak (Adam Mickiewicz University, Faculty of Physics and Astronomy, Department of Experimental Physics of Condensed Phase, Pozna\'n, Poland), Ross H. Colman (Charles University, Faculty of Mathematics and Physics, Department of Condensed Matter Physics, Prague, Czech Republic), Stanislav Kamba (Institute of Physics, Czech Academy of Sciences, Prague, Czech Republic) + Boris Zilber - Herman-Kluk-Like Semi-Classical Initial-Value Representation for Boltzmann Operator - https://arxiv.org/abs/2510.14761 - arXiv:2510.14761v2 Announce Type: replace-cross -Abstract: The coherent-state initial-value representation (IVR) for the semi-classical real-time propagator of a quantum system, developed by Herman and Kluk (HK), is widely used in computational studies of chemical dynamics. On the other hand, the Boltzmann operator $e^{-\hat{H}/(k_B T)}$, with $\hat{H}$,$k_B$, and $T$ representing the Hamiltonian, Boltzmann constant, and temperature, respectively, plays a crucial role in chemical physics and other branches of quantum physics. One might naturally assume that a semi-classical IVR for the matrix element of this operator in the coordinate representation (i.e., $ \langle \tilde{x} | e^{-\hat{H}/(k_B T)} | x \rangle$, or the imaginary-time propagator) could be derived via a straightforward ``real-time $\rightarrow$ imaginary-time transformation'' from the HK IVR of the real-time propagator. However, this is not the case, as such a transformation results in a divergence in the high-temperature limit $(T \rightarrow \infty)$. In this work, we solve this problem and develop a reasonable HK-like semi-classical IVR for $ \langle \tilde{x} | e^{-\hat{H}/(k_B T)} | x \rangle$ specifically for systems where either the gradient of the potential energy (i.e., the force intensity) has a finite upper bound, or the potential becomes harmonic in the long-range limit. The integrand in this IVR is a real Gaussian function of the positions $x$ and $\tilde{x}$, which facilitates its application to realistic problems. Our HK-like IVR is exact for free particles and harmonic oscillators, and its effectiveness for other systems is demonstrated through numerical examples. - oai:arXiv.org:2510.14761v2 - physics.chem-ph + Algebraic Obstructions and the Collapse of Elementary Structure in the Kronecker Problem + https://arxiv.org/abs/2511.22856 + arXiv:2511.22856v3 Announce Type: replace-cross +Abstract: While Kronecker coefficients $g(\lambda,\mu,\nu)$ with bounded rows are polynomial-time computable via lattice-point methods, no explicit closed-form formulas have been obtained for genuinely three-row cases in the 87 years since Murnaghan's foundational work. This paper provides such formulas for the first time and identifies a universal structural boundary at parameter value 5 where elementary combinatorial patterns collapse. + We analyze two independent families of genuinely three-row coefficients and establish that for $k \leq 4$, the formulas exhibit elementary structure: oscillation bounds follow the triangular-Hogben pattern, and polynomial expressions factor completely over $\mathbb{Z}$. At the critical threshold $k=5$, this structure collapses: the triangular pattern fails, and algebraic obstructions -- irreducible quadratic factors with negative discriminant -- emerge. + We develop integer forcing, a proof technique exploiting the tension between continuous asymptotics and discrete integrality. As concrete results, we prove that $g((n,n,1)^3) = 2 - (n \mod 2)$ for all $n \geq 3$ -- the first explicit formula for a genuinely three-row Kronecker coefficient -- derive five explicit polynomial formulas for staircase-hook coefficients, and verify Saxl's conjecture for 132 three-row partitions. + oai:arXiv.org:2511.22856v3 + math.CO + cs.CC + math.RT + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by/4.0/ + Soong Kyum Lee + + + Generalizing fusion rules by shuffle: Symmetry-based classifications of nonlocal systems constructed from similarity transformations + https://arxiv.org/abs/2512.02139 + arXiv:2512.02139v2 Announce Type: replace-cross +Abstract: We study fusion rings, or symmetry topological field theories (SymTFTs), which lie outside the non-negative integer matrix representation (NIM-rep), by combining knowledge from generalized symmetry and that from pseudo-Hermitian systems. By applying the Galois shuffle operation to the SymTFTs, we reconstruct fusion rings that correspond to nonlocal CFTs constructed from the corresponding local nonunitary CFTs by applying the similarity transformations. The resultant SymTFTs are outside of NIM-rep, whereas they are ring isomorphic to the NIM-rep of the corresponding local nonunitary CFTs. We study the consequences of this correspondence between the nonlocal unitary model and local nonunitary models. We demonstrate the correspondence between their classifications of massive or massless renormalization group flows and the discrepancies between their boundary or domain wall phenomena. Our work reveals a new connection between ring isomorphism and similarity transformations, providing the fundamental implications of ring-theoretic ideas in the context of symmetry in physics. + oai:arXiv.org:2512.02139v2 + hep-th + cond-mat.stat-mech + cond-mat.str-el + math-ph + math.MP + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://arxiv.org/licenses/nonexclusive-distrib/1.0/ + Yoshiki Fukusumi, Taishi Kawamoto + + + Quantum Simulations of Opinion Dynamics + https://arxiv.org/abs/2512.03770 + arXiv:2512.03770v2 Announce Type: replace-cross +Abstract: Consensus formation is a central problem in collective behavior. In this work, we develop quantum models of opinion dynamics that can be exactly solved and implemented on current quantum hardware. By exploiting quantum superposition, measurement-induced state collapse, and entanglement, our framework captures key features of opinion evolution and allows a systematic investigation of how network connectivity shapes consensus formation. We demonstrate our approach using practical quantum circuits and validate representative cases on IBM Quantum devices for the open-chain. Further results demonstrate that quantum platforms can serve as a viable framework for simulating opinion dynamics and for probing the interplay between leadership, network structure, and collective behavior. + oai:arXiv.org:2512.03770v2 + physics.soc-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by-sa/4.0/ + Xingyu Guo, Xiaoyang Wang, Lingxiao Wang + + + Robust AC vector sensing at zero magnetic field with pentacene + https://arxiv.org/abs/2512.06272 + arXiv:2512.06272v2 Announce Type: replace-cross +Abstract: Quantum sensors based on electronic spins have emerged as powerful probes of microwave-frequency fields. Among other solid-state platforms, spins in molecular crystals offer a range of advantages, from high spin density to functionalization via chemical tunability. Here, we demonstrate microwave vector magnetometry using the photoexcited spin triplet of deuterated pentacene molecules, operating at zero external magnetic field and room temperature. We achieve full three-dimensional microwave field reconstruction by detecting the Rabi frequencies of anisotropic spin-triplet transitions associated with two crystallographic orientations of pentacene in naphthalene crystals. We further introduce a phase alternated protocol that extends the rotating-frame coherence time by an order of magnitude and enables sensitivities of $1~\mu\mathrm{T}/\sqrt{\mathrm{Hz}}$ with sub-micrometer spatial resolution. These results establish pentacene-based molecular spins as a practical and high-performance platform for microwave quantum sensing, and the control techniques are broadly applicable to other molecular and solid-state spin systems. + oai:arXiv.org:2512.06272v2 + cond-mat.mes-hall + physics.app-ph quant-ph - Mon, 22 Dec 2025 00:00:00 -0500 + Tue, 23 Dec 2025 00:00:00 -0500 replace-cross http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Binhao Wang, Fan Yang, Chen Xu, Peng Zhang + Boning Li, Garrett Heller, Jungbae Yoon, Alexander Ungar, Hao Tang, Guoqing Wang, Patrick Hautle, Yifan Quan, Paola Cappellaro + + + Deriving the Eigenstate Thermalization Hypothesis from Eigenstate Typicality and Kinematic Principles + https://arxiv.org/abs/2512.13348 + arXiv:2512.13348v2 Announce Type: replace-cross +Abstract: The eigenstate thermalization hypothesis (ETH) provides a powerful framework for understanding thermalization in isolated quantum many-body systems, yet a complete and conceptually transparent derivation has remained elusive. In this work, we derive the structure of ETH from a minimal dynamical principle, which we term the eigenstate typicality principle (ETP), together with general kinematic ingredients arising from entropy maximization, Hilbert-space geometry, and locality. ETP asserts that in quantum-chaotic systems, energy eigenstates are statistically indistinguishable, with respect to local measurements, from states drawn from the Haar measure on a narrow microcanonical shell. Within this framework, diagonal ETH arises from concentration of measure, provided that eigenstate typicality holds. The structure of off-diagonal matrix elements is then fixed by entropic scaling and the finite-time dynamical correlations of local observables, with ETP serving as the dynamical bridge to energy eigenstates, without invoking random-matrix assumptions. Our results establish ETH as a consequence of entropy, Hilbert-space geometry, and chaos-induced eigenstate typicality, and clarify its regime of validity across generic quantum-chaotic many-body systems, thereby deepening our understanding of quantum thermalization and the emergence of statistical mechanics from unitary many-body dynamics. + oai:arXiv.org:2512.13348v2 + cond-mat.stat-mech + cond-mat.dis-nn + cond-mat.quant-gas + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by/4.0/ + Yucheng Wang + + + A Lindblad-Pauli Framework for Coarse-Grained Chaotic Binary-State Dynamics + https://arxiv.org/abs/2512.17200 + arXiv:2512.17200v2 Announce Type: replace-cross +Abstract: Coarse-graining a chaotic bistable oscillator into a binary symbol sequence is a standard reduction, but it often obscures the geometry of the reduced state space and structural constraints of physically meaningful stochastic evolution. We develop a two-state framework that embeds coarse-grained left/right statistics of the driven Duffing oscillator into a $2\times2$ density-matrix representation and models inter-well switching by a two-rate Gorini--Kossakowski--Sudarshan--Lindblad (GKSL) generator. For diagonal states the GKSL dynamics reduces to the classical two-state master equation.The density-matrix language permits an operational ``Bloch half-disk'' embedding with overlap parameter $c(\varepsilon)$ quantifying partition fuzziness; the GKSL model is fitted to diagonal marginals treating $c(\varepsilon)$ as diagnostic. We derive closed-form solutions, an explicit Kraus representation (generalized amplitude damping with dephasing and rotation), and practical diagnostics for the time-homogeneous first-order Markov assumption (order tests, Chapman--Kolmogorov consistency, run-length statistics, stationarity checks). When higher-order memory appears, we extend the framework via augmented Markov models, constructing CPTP maps through discrete-time Kraus representations; continuous-time GKSL generators may not exist for all empirical transition matrices. We provide a numerical pipeline with templates for validating the framework on Duffing simulations. The density-matrix formalism is an organizational convenience rather than claiming quantum-classical equivalence. + oai:arXiv.org:2512.17200v2 + nlin.CD + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Yicong Qiu, Qiye Zheng + + + Detecting Axion Dark Matter with an Organic Molecular Maser + https://arxiv.org/abs/2512.17271 + arXiv:2512.17271v2 Announce Type: replace-cross +Abstract: We present a novel quantum sensing approach to search for axion-electron interactions around the axion mass of 6 \mueV. In this region, laboratory searches are relatively scarce, and our direct experiment measuring the axion-electron coupling constant reaches the sensitivity of 8 \times 10^{-6} GeV^{-1}. The method, based on an organic molecular maser establishes a proof-of-principle for quantum-enhanced detection, with a corresponding magnetic field sensitivity of 0.85 fT/\sqrt{\rm{Hz}}. The methodology is generic and can be readily extended to other physical systems, further broadening its applicability in quantum sensing and dark matter searches. + oai:arXiv.org:2512.17271v2 + hep-ph + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by-nc-nd/4.0/ + Hongliang Wu, Yuchen Han, Zhengtao Wang, Dezhi Zheng, Yeliang Wang, Liu Yang, Zhiwei Wang, Bo Zhang, Dmitry Budker, Jun Zhang + + + Methods and Tools for Secure Quantum Clouds with a specific Case Study on Homomorphic Encryption + https://arxiv.org/abs/2512.17748 + arXiv:2512.17748v2 Announce Type: replace-cross +Abstract: The rise of quantum computing/technology potentially introduces significant security challenges to cloud computing, necessitating quantum-resistant encryption strategies as well as protection schemes and methods for cloud infrastructures offering quantum computing time and services (i.e. quantum clouds). This research explores various options for securing quantum clouds and ensuring privacy, especially focussing on the integration of homomorphic encryption (HE) into Eclipse Qrisp, a high-level quantum computing framework, to enhance the security of quantum cloud platforms. The study addresses the technical feasibility of integrating HE with Qrisp, evaluates performance trade-offs, and assesses the potential impact on future quantum cloud architectures. The successful implementation and Qrisp integration of three post-quantum cryptographic (PQC) algorithms demonstrates the feasibility of integrating HE with quantum computing frameworks. The findings indicate that while the Quantum One-Time Pad (QOTP) offers simplicity and low overhead, other algorithms like Chen and Gentry-Sahai-Waters (GSW) present performance trade-offs in terms of runtime and memory consumption. The study results in an overall set of recommendations for securing quantum clouds, e.g. implementing HE at data storage and processing levels, developing Quantum Key Distribution (QKD), and enforcing stringent access control and authentication mechanisms as well as participating in PQC standardization efforts. + oai:arXiv.org:2512.17748v2 + cs.CR + quant-ph + Tue, 23 Dec 2025 00:00:00 -0500 + replace-cross + http://creativecommons.org/licenses/by/4.0/ + Aurelia Kusumastuti, Nikolay Tcholtchev, Philipp L\"ammel, Sebastian Bock, Manfred Hauswirth