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" @@ -7,1238 +7,12 @@ http://www.rssboard.org/rss-specification en-us - Fri, 23 Jan 2026 05:00:05 +0000 + Sat, 24 Jan 2026 05:00:00 +0000 rss-help@arxiv.org - Fri, 23 Jan 2026 00:00:00 -0500 + Sat, 24 Jan 2026 00:00:00 -0500 Saturday Sunday - - Precision limit under weak-coupling with ancillary qubit - https://arxiv.org/abs/2601.15354 - arXiv:2601.15354v1 Announce Type: new -Abstract: We propose a measurement-based quantum metrology protocol in a composite model, where the probe system (a spin ensemble) is coupled to an ancillary two-level system (qubit) with a general Heisenberg XXZ interaction. With an optimized and weak probe-ancilla coupling strength and a proper duration of joint evolution, the two parallel evolution paths of the probe system induced by the unconditional measurement on qubit can transform an eigenstate of the collective angular momentum operator of spin ensemble to be a two-component state with a large distance in eigenspace. The quantum Fisher information about the phase encoded in the probe system of polarized states or their superposition, that could be relaxed to mixed states, can therefore manifest an exact or asymptotic quadratic scaling with respect to the probe size (spin number) $N$. The quadratic scaling behavior is found to be insensitive to the imperfect encoding operator and coupling strength. By virtue of the parity detection on the ancillary qubit or the probe system, the phase sensitivity can approach the Heisenberg limit. We suggest that the unconditional measurement on qubit could become an efficient resource to replace Greenberger-Horne-Zeilinger-like states and squeezing Hamiltonian for exceeding the standard quantum limit in metrology precision. - oai:arXiv.org:2601.15354v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Peng Chen, Jun Jing - - - USDs: A universal stabilizer decoder framework using symmetry - https://arxiv.org/abs/2601.15361 - arXiv:2601.15361v1 Announce Type: new -Abstract: Quantum error correction is indispensable to achieving reliable quantum computation. When quantum information is encoded redundantly, a larger Hilbert space is constructed using multiple physical qubits, and the computation is performed within a designated subspace. When applying deep learning to the decoding of quantum error-correcting codes, a key challenge arises from the non-uniqueness between the syndrome measurements provided to the decoder and the corresponding error patterns that constitute the ground-truth labels. Building upon prior work that addressed this issue for the toric code by re-optimizing the decoder with respect to the symmetry inherent in the parity-check structure, we generalize this approach to arbitrary stabilizer codes. In our experiments, we employed multilayer perceptrons to approximate continuous functions that complement the syndrome measurements of the Color code and the Golay code. Using these models, we performed decoder re-optimization for each code. For the Color code, we achieved an improvement of approximately 0.8% in decoding accuracy at a physical error rate of 5%, while for the Golay code the accuracy increased by about 0.1%. Furthermore, from the evaluation of the geometric and algebraic structures in the continuous function approximation for each code, we showed that the design of generalized continuous functions is advantageous for learning the geometric structure inherent in the code. Our results also indicate that approximations that faithfully reproduce the code structure can have a significant impact on the effectiveness of reoptimization. This study demonstrates that the re-optimization technique previously shown to be effective for the Toric code can be generalized to address the challenge of label degeneracy that arises when applying deep learning to the decoding of stabilizer codes. - oai:arXiv.org:2601.15361v1 - quant-ph - cs.LG - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Hoshitaro Ohnishi, Hideo Mukai - - - The computational two-way quantum capacity - https://arxiv.org/abs/2601.15393 - arXiv:2601.15393v1 Announce Type: new -Abstract: Quantum channel capacities are fundamental to quantum information theory. Their definition, however, does not limit the computational resources of sender and receiver. In this work, we initiate the study of computational quantum capacities. These quantify how much information can be reliably transmitted when imposing the natural requirement that en- and decoding have to be computationally efficient. We focus on the computational two-way quantum capacity and showcase that it is closely related to the computational distillable entanglement of the Choi state of the channel. This connection allows us to show a stark computational capacity separation. Under standard cryptographic assumptions, there exists a quantum channel of polynomial complexity whose computational two-way quantum capacity vanishes while its unbounded counterpart is nearly maximal. More so, we show that there exists a sharp transition in computational quantum capacity from nearly maximal to zero when the channel complexity leaves the polynomial realm. Our results demonstrate that the natural requirement of computational efficiency can radically alter the limits of quantum communication. - oai:arXiv.org:2601.15393v1 - quant-ph - cs.CC - cs.CR - cs.IT - math.IT - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Johannes Jakob Meyer, Jacopo Rizzo, Asad Raza, Lorenzo Leone, Sofiene Jerbi, Jens Eisert - - - Quadratic tensors as a unification of Clifford, Gaussian, and free-fermion physics - https://arxiv.org/abs/2601.15396 - arXiv:2601.15396v1 Announce Type: new -Abstract: Certain families of quantum mechanical models can be described and solved efficiently on a classical computer, including qubit or qudit Clifford circuits and stabilizer codes, free-boson or free-fermion models, and certain rotor and GKP codes. We show that all of these families can be described as instances of the same algebraic structure, namely quadratic functions over abelian groups, or more generally over (super) Hopf algebras. Different kinds of degrees of freedom correspond to different "elementary" abelian groups or Hopf algebras: $\mathbb{Z}_2$ for qubits, $\mathbb{Z}_d$ for qudits, $\mathbb{R}$ for continuous variables, both $\mathbb{Z}$ and $\mathbb{R}/\mathbb{Z}$ for rotors, and a super Hopf algebra $\mathcal F$ for fermionic modes. Objects such as states, operators, superoperators, or projection-operator valued measures, etc, are tensors. For the solvable models above, these tensors are quadratic tensors based on quadratic functions. Quadratic tensors with $n$ degrees of freedom are fully specified by only $O(n^2)$ coefficients. Tensor networks of quadratic tensors can be contracted efficiently on the level of these coefficients, using an operation reminiscent of the Schur complement. Our formalism naturally includes models with mixed degrees of freedom, such as qudits of different dimensions. We also use quadratic functions to define generalized stabilizer codes and Clifford gates for arbitrary abelian groups. Finally, we give a generalization from quadratic (or 2nd order) to $i$th order tensors, which are specified by $O(n^i)$ coefficients but cannot be contracted efficiently in general. - oai:arXiv.org:2601.15396v1 - quant-ph - math-ph - math.MP - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Andreas Bauer, Seth Lloyd - - - Dissipative Quantum Dynamics in Static Network with Different Topologies - https://arxiv.org/abs/2601.15439 - arXiv:2601.15439v1 Announce Type: new -Abstract: We investigate the dissipative dynamics of quantum population and coherence among different network topologies of a quantum network using a quantum spin model coupled to a thermal bosonic reservoir. Our study proceeds in two parts. First, we analyze a small network of Ising spins embedded in a large dissipative bath, modeled via the Lindblad master equation, where temperature arises naturally from system-bath coupling. This approach reveals how network topology shapes quantum dissipative dynamics, providing a basis for controlling quantum coherence through tailored network structures. Second, we propose a mean-field approach that extends the network to larger scales and captures dissipative dynamics in large-scale networks, connecting network topology to quantum coherence in complex systems and revealing the sensitivity of quantum coherence to network structure. Our results highlight how dissipative quantum dynamics depend on network topology, providing insight into the coherent dynamics of entangled states in networks. These results may be extended to dynamics in complex systems such as opinion propagation in social models, epidemiology, and various condensed-phase and biological systems. - oai:arXiv.org:2601.15439v1 - quant-ph - cond-mat.stat-mech - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Wei-Yang Liu, Hsuan-Wei Lee - - - Check-weight-constrained quantum codes: Bounds and examples - https://arxiv.org/abs/2601.15446 - arXiv:2601.15446v1 Announce Type: new -Abstract: Quantum low-density parity-check (qLDPC) codes can be implemented by measuring only low-weight checks, making them compatible with noisy quantum hardware and central to the quest to build noise-resilient quantum computers. A fundamental open question is how constraints on check weight limit the achievable parameters of qLDPC codes. Here, we study stabilizer and subsystem codes with constrained check weight, combining analytical arguments with numerical optimization to establish strong upper bounds on their parameters. We show that stabilizer codes with checks of weight at most three cannot have nontrivial distance. We also prove tight tradeoffs between rate and distance for broad families of CSS stabilizer and subsystem codes with checks of weight at most four and two, respectively. Notably, our bounds are applicable to general qLDPC codes, as they rely only on check-weight constraints without assuming geometric locality or special graph connectivity. In the finite-size regime, we derive numerical upper bounds using linear programming techniques and identify explicit code constructions that approach these limits, delineating the landscape of practically relevant qLDPC codes with tens or hundreds of physical qubits. - oai:arXiv.org:2601.15446v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Lily Wang, Andy Zeyi Liu, Ray Li, Aleksander Kubica, Shouzhen Gu - - - NWQWorkflow: The Northwest Quantum Workflow - https://arxiv.org/abs/2601.15521 - arXiv:2601.15521v1 Announce Type: new -Abstract: This whitepaper presents NWQWorkflow, an end-to-end workflow for quantum application development, compilation, error correction, benchmarking, numerical simulation, control, and execution on a prototype superconducting testbed. NWQWorkflow integrates NWQStudio (programming GUI environment), NWQASM (intermediate representation), QASMTrans (compiler), NWQEC (quantum error correction), QASMBench (benchmarking and characterization), NWQSim (HPC simulation), NWQLib (algorithm library), NWQData (data sets), NWQControl (quantum control), and NWQSC (superconducting testbed). The system enables closed-loop software-hardware co-design and reflects the past eight years of quantum computing research the author has led at PNNL (2018-2026). By releasing most software components as open source or planning their open-source availability, we aim to cultivate a collaborative quantum information science (QIS) ecosystem and support the transition toward a scalable quantum supercomputing era. - oai:arXiv.org:2601.15521v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ang Li - - - A Sublinear-Time Quantum Algorithm for High-Dimensional Reaction Rates - https://arxiv.org/abs/2601.15523 - arXiv:2601.15523v1 Announce Type: new -Abstract: The Fokker-Planck equation models rare events across sciences, but its high-dimensional nature challenges classical computers. Quantum algorithms for such non-unitary dynamics often suffer from exponential {decay in} success probability. We introduce a quantum algorithm that overcomes this for computing reaction rates. Using a sum-of-squares representation, we develop a Gaussian linear combination of Hamiltonian simulations (Gaussian-LCHS) to represent the non-unitary propagator with $O\left(\sqrt{t\|H\|\log(1/\epsilon)}\right)$ queries to its block encoding. Crucially, we pair this with {a} novel technique to directly estimate matrix elements without exponential decay. For $\eta$ pairwise interacting particles discretized with $N$ plane waves per degree of freedom, we estimate reactive flux to error $\epsilon$ using $\widetilde{O}\left((\eta^{5/2}\sqrt{t\beta}\alpha_V + \eta^{3/2}\sqrt{t/\beta}N)/\epsilon\right)$ quantum gates, where $\alpha_V = \max_{r}|V'(r)/r|$. For non-convex potentials, the {sharpest classical} worst-case analytical bounds to simulate the related overdamped Langevin {equation} scale as $O(te^{\Omega(\eta)}/\epsilon^4)$. This {implies} an exponential separation in particle number $\eta$, a quartic speedup in $\epsilon$, and quadratic speedup in $t$. While specialized classical heuristics may outperform these bounds in practice, this demonstrates a rigorous route toward quantum advantage for high-dimensional dissipative dynamics. - oai:arXiv.org:2601.15523v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Tyler Kharazi, Ahmad M. Alkadri, Kranthi K. Mandadapu, K. Birgitta Whaley - - - Bidirectional teleportation using scrambling dynamics: a practical protocol - https://arxiv.org/abs/2601.15536 - arXiv:2601.15536v1 Announce Type: new -Abstract: We show that quantum information scrambling can enable a generic SWAP gate between collective degrees of freedom in systems without universal local control. Our protocol combines the Hayden-Preskill recovery scheme, associated with the black hole information paradox, with quantum teleportation and runs them in parallel and in opposite directions, enabling bidirectional exchange of quantum states through global interactions alone. This approach cleanly distinguishes the roles of information spreading, entanglement, and chaos for enabling both coherent state transfer and recovery. We propose an experimental realization using the Dicke model, which can be realized in cavity-QED and trapped-ion platforms, highlighting the utility of holography in designing practical quantum gates. - oai:arXiv.org:2601.15536v1 - quant-ph - cond-mat.stat-mech - hep-th - nlin.CD - physics.atom-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Amit Vikram, Edwin Chaparro, Muhammad Miskeen Khan, Andrew Lucas, Chris Akers, Ana Maria Rey - - - Spectator-transition crosstalk in a spin-3/2 silicon vacancy qudit in silicon carbide revealed by broadband Ramsey interferometry - https://arxiv.org/abs/2601.15559 - arXiv:2601.15559v1 Announce Type: new -Abstract: Color center spins in 4H-SiC offer a rare combination of wafer-scale materials maturity with long spin coherence and chip-level photonics, making them promising building blocks for scalable quantum technologies. In particular, the silicon vacancy hosts an S=3/2 ground state, a native qudit that enables compact encodings and subspace-selective control, but also introduces spectator transitions: short, detuned pulses can coherently drive non-addressed level pairs and create crosstalk. Here we use broadband Ramsey interferometry to reveal and quantify such spectator-transition crosstalk. Experimentally, the Ramsey Fourier spectra display multiple lines beyond the addressed single-quantum transition. Analytically, we map each line to a pairwise energy difference between qudit levels of the rotating-frame Hamiltonian and assign its weight via compact amplitudes set by the prepared state and the microwave pulse parameters, predicting a deterministic six-branch structure. Numerical time-domain propagation with the experimental sampling reproduces the detuning map, and the measured peak positions coincide with the analytic branch lines without frequency fitting. Together these results provide a practical, spectator-aware framework for multilevel control in the silicon vacancy qudit. The approach offers clear guidance to suppress crosstalk or, conversely, to exploit spectator lines, for example as additional constraints for in situ pulse calibration and for phase-sensitive quantum state and process estimation. - oai:arXiv.org:2601.15559v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jun-Jae Choi, Seung-Jae Hwang, Seoyoung Paik, Juhwan Kim, Jawad UI-Hassan, Nguyen Tien Son, Hiroshi Abe, Takeshi Oshima, Jaekwon Suk, Hyeon-Ho Jeong, Dong-Hee Kim, Sang-Yun Lee - - - Bright Pulsed Squeezed Light for Quantum-Enhanced Precision Microscopy - https://arxiv.org/abs/2601.15565 - arXiv:2601.15565v1 Announce Type: new -Abstract: Squeezed states of light enable enhanced measurement precision by reducing noise below the standard quantum limit. A key application of squeezed light is nonlinear microscopy, where state-of-the-art performance is limited by photodamage and quantum-limited noise. Such microscopes require bright, pulsed light for optimal operation, yet generating and detecting bright pulsed squeezing at high levels remains challenging. In this work, we present an efficient technique to generate high levels of bright picosecond pulsed squeezed light using a $\chi^2$ optical parametric amplification process in a waveguide. We measure $-3.2~\mathrm{dB}$ of bright squeezing with optical power compatible with nonlinear microscopy, as well as $-3.6~\mathrm{dB}$ of vacuum squeezing. Corrected for losses, these squeezing levels correspond to $-15.4^{+2.7}_{-8.7}~\mathrm{dB}$ of squeezing generated in the waveguide. The measured level of bright amplitude pulsed squeezing is to our knowledge the highest reported to date, and will contribute to the broader adoption of quantum-enhanced nonlinear microscopy in biological studies. - oai:arXiv.org:2601.15565v1 - quant-ph - physics.optics - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Alex Terrasson, Lars Madsen, Joel Grim, Warwick Bowen - - - Optimized Slice-Phase Control of Mirror Pulse in Cold-Atom Interferometry with Finite Response Time - https://arxiv.org/abs/2601.15586 - arXiv:2601.15586v1 Announce Type: new -Abstract: Atom interferometers require both high efficiency and robust performance in their mirror pulses under experimental inhomogeneities. In this work, we demonstrated that quantum optimal control designed mirror pulse significantly enhance interferometer performance by using novel adaptive sliced structure. Using gradient ascent pulse engineering (GRAPE), optimized mirror pulse for a Mach-Zehnder light-pulse atom interferometer was designed by discretizing the control into non-uniform phase slices. This design broadened the tolerence to experimentally relevant variations in detuning $[-\Omega_0,\Omega_0]$ and Rabi frequency $[0.1\times\Omega_0,1.9\times\Omega_0]$ ($\Omega_0=2\pi\times25$ kHz), while maintaining high transfer efficiency even when the response-time delays up to 1.6 $\rm{\mu s}$. The optimized pulse was found to be robust to coupling inhomogeneity and velocity spread, offering a significant improvement in robustness over conventional pulse. The adaptive pulse slicing method provides a minimalist strategy that reduces experimental complexity while enhancing robustness and scalability, offering an innovative scheme for quantum optimal control in high precision atom interferometry. - oai:arXiv.org:2601.15586v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/r62p-d86z - Xueting Fang, Doudou Wang, Kun Yuan, Jie Deng, Qin Luo, Xiaochun Duan, Minkang Zhou, Lushuai Cao, Zhongkun Hu - - - Tensor-based phase difference estimation on time series analysis - https://arxiv.org/abs/2601.15616 - arXiv:2601.15616v1 Announce Type: new -Abstract: We propose a phase-difference estimation algorithm based on the tensor-network circuit compression, leveraging time-evolution data to pursue scalability and higher accuracy on a quantum phase estimation (QPE)-type algorithm. Using tensor networks, we construct circuits composed solely of nearest-neighbor gates and extract time-evolution data by four-type circuit measurements. In addition, to enhance the accuracy of time-evolution and state-preparation circuits, we propose techniques based on algorithmic error mitigation and on iterative circuit optimization combined with merging into matrix product states, respectively. Verifications using a noiseless simulator for the 8-qubit one-dimensional Hubbard model using an ancilla qubit show that the proposed algorithm achieves accuracies with 0.4--4.7\% error from a true energy gap on an appropriate time-step size, and that accuracy improvements due to the algorithmic error mitigation are observed. We also confirm the enhancement of the overlap with matrix product states through iterative optimization. Finally, the proposed algorithm is demonstrated on IBM Heron devices with Q-CTRL error suppression for 8-, 36-, and 52-qubit models using more than 5,000 2-qubit gates. These largest-scale demonstrations for the QPE-type algorithm represent significant progress not only toward practical applications of near-term quantum computing but also toward preparation for the era of error-corrected quantum devices. - oai:arXiv.org:2601.15616v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Shu Kanno, Kenji Sugisaki, Rei Sakuma, Jumpei Kato, Hajime Nakamura, Naoki Yamamoto - - - Machine Failure Detection Based on Projected Quantum Models - https://arxiv.org/abs/2601.15641 - arXiv:2601.15641v1 Announce Type: new -Abstract: Detecting machine failures promptly is of utmost importance in industry for maintaining efficiency and minimizing downtime. This paper introduces a failure detection algorithm based on quantum computing and a statistical change-point detection approach. Our method leverages the potential of projected quantum feature maps to enhance the precision of anomaly detection in machine monitoring systems. We empirically validate our approach on benchmark multi-dimensional time series datasets as well as on a real-world dataset comprising IoT sensor readings from operational machines, ensuring the practical relevance of our study. The algorithm was executed on IBM's 133-qubit Heron quantum processor, demonstrating the feasibility of integrating quantum computing into industrial maintenance procedures. The presented results underscore the effectiveness of our quantum-based failure detection system, showcasing its capability to accurately identify anomalies in noisy time series data. This work not only highlights the potential of quantum computing in industrial diagnostics but also paves the way for more sophisticated quantum algorithms in the realm of predictive maintenance. - oai:arXiv.org:2601.15641v1 - quant-ph - cs.LG - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Larry Bowden, Qi Chu, Bernard Cena, Kentaro Ohno, Bob Parney, Deepak Sharma, Mitsuharu Takeori - - - Enhancing the Size of Phase-Space States Containing Sub-Planck-Scale Structures via Non-Gaussian Operations - https://arxiv.org/abs/2601.15654 - arXiv:2601.15654v1 Announce Type: new -Abstract: We observe a metrological advantage in phase-space sensitivity for photon-added cat and kitten states over their original forms, due to phase-space broadening from increased amplitude via photon addition, albeit with higher energy cost. Using accessible non-classical resources, weak squeezing and displacement, we construct a squeezed state and two superposed states: the squeezed cat state and the symmetrically squeezed state. Their photon-added variants are compared with parity-matched cat and KSs using quantum Fisher information and fidelity. The QFI isocontours reveal regimes where KS exhibit high fidelity and large amplitude, enabling their preparation via Gaussian operations and photon addition. Similar regimes are identified for cat states enhanced by squeezing and photon addition, demonstrating improved metrological performance. Moreover, increased amplitude and thus larger phase-space area reduces the size of interferometric fringes, enhancing the effectiveness of quantum error correction in cat codes. - oai:arXiv.org:2601.15654v1 - quant-ph - physics.optics - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Arman, Prasanta K. Panigrahi - - - Quantum-HPC hybrid computation of biomolecular excited-state energies - https://arxiv.org/abs/2601.15677 - arXiv:2601.15677v1 Announce Type: new -Abstract: We develop a workflow within the ONIOM framework and demonstrate it on the hybrid computing system consisting of the supercomputer Fugaku and the Quantinuum Reimei trapped-ion quantum computer. This hybrid platform extends the layered approach for biomolecular chemical reactions to accurately treat the active site, such as a protein, and the large and often weakly correlated molecular environment. Our result marks a significant milestone in enabling scalable and accurate simulation of complex biomolecular reactions - oai:arXiv.org:2601.15677v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kentaro Yamamoto, Riku Masui, Takahito Nakajima, Miwako Tsuji, Mitsuhisa Sato, Peter Schow, Lukas Heidemann, Matthew Burke, Philipp Seitz, Oliver J. Backhouse, Juan W. Pedersen, John Children, Craig Holliman, Nathan Lysne, Daichi Okuno, Seyon Sivarajah, David Mu\~noz Ramo, Alex Chernoguzov, Ross Duncan - - - Fractional squeezing: spectra and dynamics from generalized squeezing Hamiltonian with fractional orders - https://arxiv.org/abs/2601.15693 - arXiv:2601.15693v1 Announce Type: new -Abstract: We generalize the generalized-squeezing problem to include fractional values of the squeezing order $n$. This approach allows us to determine the locations of critical points at which qualitative changes in behaviour occur and accurately predict the behaviour at these critical points, which are challenging for conventional computational methods. Based on our numerical calculations, we identify with a high degree of confidence the point at which the spectrum turns from continuous to discrete and the point at which oscillations turn from having asymptotically infinite amplitudes to finite amplitudes. Furthermore, we numerically investigate the behaviour in the large $n$ regime and provide an intuitive explanation that coincides with the numerical results. - oai:arXiv.org:2601.15693v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Sahel Ashhab - - - Unsplit Spreading: An Overlooked Signature of Long-Range Interaction - https://arxiv.org/abs/2601.15752 - arXiv:2601.15752v1 Announce Type: new -Abstract: In conventional lattice models, the dispersion relation $\omega(k)$ is assumed to be a smooth function. We prove that this smoothness implies the splitting of an initially localized excitation into counter-propagating wave packets. Consequently, unsplit spreading can occur only when $\omega(k)$ develops singular features, precisely what long-range interactions enable. Remarkably, this phenomenon was clearly visible in published quantum simulation experiments as early as 2014, yet it has remained unrecognized or discussed as a distinct physical effect. We show that unsplit spreading emerges in realistic open quantum systems, such as 1D and 2D subwavelength atomic arrays, where the long-lived subradiant states host effective dispersion with the required singularities. Our work establishes unsplit spreading as an experimentally accessible, smoking-gun signature of singular band structure induced by long-range physics. - oai:arXiv.org:2601.15752v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Jian-Feng Wu, Yi Huang, Yu-Xiang Zhang - - - Improving the efficiency of QAOA using efficient parameter transfer initialization and targeted-single-layer regularized optimization with minimal performance degradation - https://arxiv.org/abs/2601.15760 - arXiv:2601.15760v1 Announce Type: new -Abstract: Quantum approximate optimization algorithm (QAOA) have promising applications in combinatorial optimization problems (COPs). We investigated the MaxCut problem in three different families of graphs using QAOA ansats with parameter transfer initialization followed by targeted single layer optimization. For 3 regular (3R), Erdos Renyi (ER), and Barabasi Albert (BA) graphs, the parameter transfer approach achieved mean approximation ratios of 0.9443 for targeted-single layer optimization as compared to 0.9551 of full optimization. It represents 98.88 percent optimal performance, with 8.06 times computational speedup in unweighted graphs. But, in weighted graph families, optimal performance is relatively low (less than 90 percent) for higher nodes graph, suggesting parameter transfer followed by targeted-single-layer optimization is not ideal for weighted graph families, however, we find that for some weighted families (weighted 3-regular) this approach works perfectly. In 8.92 percent test cases, targeted single layer optimization outperformed the full optimization, indicating that complex parameter landscape can trap full optimization in sub-optimal local minima. To mitigate this inconsistency, ridge (L2) regularization is used to smoothen the solution landscape, which helps the optimizer to find better optimum parameters during full optimization and reduces these inconsistent test cases from 8.92 percent to 3.81 percent. This work demonstrates that efficient parameter initialization and targeted-single-layer optimization can improve the efficiency of QAOA with minimal performance degradation. - oai:arXiv.org:2601.15760v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Shubham Patel, Utkarsh Mishra - - - Classical Simulation of Noiseless Quantum Dynamics without Randomness - https://arxiv.org/abs/2601.15770 - arXiv:2601.15770v1 Announce Type: new -Abstract: Simulating noiseless quantum dynamics classically faces a fundamental dilemma: tensor-network methods become inefficient as entanglement saturates, while Pauli-truncation approaches typically rely on noise or randomness. To close the gap, we propose the Low-weight Pauli Dynamics (LPD) algorithm that efficiently approximates local observables for short-time dynamics in the absence of noise. We prove that the truncation error admits an average-case bound without assuming randomness, provided that the state is sufficiently entangled. Counterintuitively, entanglement--usually an obstacle for classical simulation--alleviates classical simulation error. We further show that such entangled states can be generated either by tensor-network classical simulation or near-term quantum devices. Our results establish a rigorous synergy between existing classical simulation methods and provide a complementary route to quantum simulation that reduces circuit depth for long-time dynamics, thereby extending the accessible regime of quantum dynamics. - oai:arXiv.org:2601.15770v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Jue Xu, Chu Zhao, Xiangran Zhang, Shuchen Zhu, Qi Zhao - - - Fermion Doubling in Dirac Quantum Walks - https://arxiv.org/abs/2601.15885 - arXiv:2601.15885v1 Announce Type: new -Abstract: We consider discrete spacetime models known as quantum walks, which can be used to simulate Dirac particles. In particular we look at fermion doubling in these models, in which high momentum states yield additional low energy solutions which behave like Dirac particles. The presence of doublers carries over to the `second quantised' version of the walks represented by quantum cellular automata, which may lead to spurious solutions when introducing interactions. Moreover, we also consider pseudo-doublers, which have high energy but behave like low energy Dirac particles, and cause potential problems regarding the stability of the vacuum. To address these issues, we propose a family of quantum walks, that are free of these doublers and pseudo-doublers, but still simulate the Dirac equation in the continuum limit. However, there remain a small number of additional low energy solutions which do not directly correspond to Dirac particles. While the conventional Dirac walk always has a zero probability for the walker staying at the same point, we obtain the family of walks by allowing this probability to be non-zero. - oai:arXiv.org:2601.15885v1 - quant-ph - hep-lat - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Chaitanya Gupta, Anthony J. Short - - - Improved cryptographic security in teleportation with q-deformed non-maximal entangled states - https://arxiv.org/abs/2601.15902 - arXiv:2601.15902v1 Announce Type: new -Abstract: In this work the machinery of q-deformed algebras are used to enhance cryptographic security during teleportation. We use q-deformed harmonic oscillator states to develop a novel method of teleportation. The deformed states can be expressed in terms of standard oscillator states and the expressions contain certain arbitrary functions of $q$. It is the presence of these arbitrary functions that allows an enhancement of cryptographic security. The specifics are : - (a) q-deformed Bell-like states are constructed which reduce to the usual Bell states when the deformation parameter $q\rightarrow 1$. These deformed states form an orthonormal basis for q-deformed entangled bipartite states when certain arbitrary functions of $q$ satisfy a constraint. - (b) We discuss the generalisation of the usual teleportation protocol with non-maximally entangled states. This generalisation is then employed to construct two new protocols using q-deformed non-maximally entangled states. These states have additional parameters and these have to be shared for decryption after teleportation. Consequently, the cryptographic security is improved. - oai:arXiv.org:2601.15902v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Prabal Dasgupta, Debashis Gangopadhyay - - - Automated quantum circuit optimization with randomized replacements - https://arxiv.org/abs/2601.15934 - arXiv:2601.15934v1 Announce Type: new -Abstract: Quantum circuit optimization - the process of transforming a quantum circuit into an equivalent one with reduced time and space requirements - is crucial for maximizing the utility of current and near-future quantum devices. While most automated optimization techniques focus on transforming circuits into equivalent ones that implement the same unitary, we show that substantial new opportunities for resource reduction can be achieved by (1) allowing approximate local transformations and (2) employing mixed quantum channels to approximate pure circuits. Our novel automated protocol for approximate circuit rewriting is a refined evolution of automated optimization techniques based on the ZX-calculus, where we add a greedy strategy that selectively replaces ZX-diagrams with small phase angles with stochastic mixtures of the identity and carefully chosen over-rotations, which are designed to reduce the overall gate count in expectation while staying within a strict error budget. This approach yields modest two-qubit gate count reduction in random quantum circuits, and achieves a substantial reduction in structured circuits such as the quantum Fourier transform. Fundamentally, our protocol converts experimental noise due to gate applications into deliberately engineered random noise, outperforming many other approximation methods on average. These results highlight the potential of mixed-channel approximations to enhance future quantum circuit performance, suggesting new directions for resource-aware automated quantum compilation beyond pure unitary channels. - oai:arXiv.org:2601.15934v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Marcin Szyniszewski, Aleks Kissinger, Noah Linden, Paul Skrzypczyk - - - Frictional work and entropy production in integrable and non-integrable spin chains - https://arxiv.org/abs/2601.15941 - arXiv:2601.15941v1 Announce Type: new -Abstract: The maximum work extractable from a quantum system is achieved when the system is driven adiabatically. Frictional work then quantifies the difference in work output between adiabatic and non-adiabatic driving. Here we show that frictional work in a non-integrable spin chain is well-described by the diagonal entropy production associated with the build up of quantum coherence. The relationship is characterized by an effective temperature of the final adiabatic state and holds for slow to moderate driving protocols. For fast protocols, the frictional work is instead described by the quantum relative entropy between the final non-adiabatic and adiabatic states. We compare our results to those obtained from an integrable spin chain, in which case the adiabatic state is no longer described by a single temperature. In this case, the frictional work is described by a sum of terms for each independent subspace of the spin chain, which are at different effective temperatures. We show how integrability breaking can enhance work extraction in the adiabatic limit, but degrade work extraction in sufficiently non-adiabatic regimes. - oai:arXiv.org:2601.15941v1 - quant-ph - cond-mat.stat-mech - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Vishnu Muraleedharan Sajitha, Matthew J. Davis, L. A. Williamson - - - Renormalization Treatment of IR and UV Cutoffs in Waveguide QED and Implications to Numerical Model Simulation - https://arxiv.org/abs/2601.15945 - arXiv:2601.15945v1 Announce Type: new -Abstract: We present a non-perturbative, first-principles derivation of renormalization relations for waveguide-QED models, explicitly accounting for the infrared (IR) and ultraviolet (UV) cutoffs that are necessarily introduced in numerical simulations. By formulating the atomic dynamics in the time domain, we obtain explicit expressions linking the bare model parameters to the physically observable atomic frequency and decay rate, and verify their consistency with scattering theory. We further connect these results to standard Feynman diagrams, providing a transparent physical interpretation and ensuring the generality of the approach. Finally, we show how these renormalization relations can be used to parameterize simulations with a minimal frequency bandwidth, simultaneously preserving physical accuracy and reducing computational cost, thereby paving the way for efficient and reliable multi-photon light-matter simulations. - oai:arXiv.org:2601.15945v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Romain Piron, Akihito Soeda - - - Universal Digitized Counterdiabatic Driving - https://arxiv.org/abs/2601.15972 - arXiv:2601.15972v1 Announce Type: new -Abstract: Counterdiabatic driving realizes parameter displacement of an energy eigenstate of a given parametrized Hamiltonian using the adiabatic gauge potential. In this paper, we propose a universal method of digitized counterdiabatic driving, constructing the adiabatic gauge potential in a digital way with the idea of universal counterdiabatic driving. This method has three advantages over existing universal counterdiabatic driving and/or digitized counterdiabatic driving: it does not introduce any many-body and/or nonlocal interactions to an original target Hamiltonian; it can incorporate infinite nested commutators, which constitute the adiabatic gauge potential; and it gives explicit expression of rotation angles for digital implementation. We show the consistency of our method to the exact theory in an analytical way and the effectiveness of our method with the aid of numerical simulations. - oai:arXiv.org:2601.15972v1 - quant-ph - cond-mat.stat-mech - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Takuya Hatomura - - - Semiclassical entanglement entropy for spin-field interaction - https://arxiv.org/abs/2601.15986 - arXiv:2601.15986v1 Announce Type: new -Abstract: We study a general bipartite quantum system consisting of a spin interacting with a bosonic field, with the initial state prepared as the product of a spin coherent state and a canonical coherent state. Our goal is to develop a semiclassical framework to describe the entanglement dynamics between these two subsystems. Using appropriate approximations, we derive a semiclassical expression for the entanglement entropy that depends exclusively on the trajectories of the underlying classical description. By analytically extending the classical phase space into the complex domain, we identify additional complex trajectories that significantly improve the accuracy of the semiclassical description. The inclusion of these complex trajectories allows us to capture the entanglement dynamics with remarkable precision, even well beyond the Ehrenfest time. The approach is illustrated with a representative example, where the role of real and complex trajectories in reproducing the quantum entanglement entropy is explicitly demonstrated. - oai:arXiv.org:2601.15986v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Matheus V. Scherer, Lea F. Santos, Alexandre D. Ribeiro - - - Engineering quantum Mpemba effect by Liouvillian skin effect - https://arxiv.org/abs/2601.16002 - arXiv:2601.16002v1 Announce Type: new -Abstract: We propose a new approach to engineer the quantum Mpemba effect (QME) -- wherein an initial state farther from system relaxes faster than a close one -- by the Liouvillian skin effect (LSE) in open quantum systems. Moreover, the LSE serves as an ideal platform for realizing the QME and the spatial profile of the LSE provides a straightforward pathway for the initial state preparation, thereby enabling readily accessible experimental preparation. Focusing on the quadratic Lindbladians, we consider two concrete cases to design the initial states, thereby realizing the QME. Interestingly, we uncover a new kind of QME (QME-III) that is distinct from the two typical scenarios, manifested as two reversals in the Hilbert-Schmidt distance at two different times. In particular, the LSE provides a physically more intuitive understanding of the QME. - oai:arXiv.org:2601.16002v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Xiang Zhang Chen Sun, Fuxiang Li - - - Wigner's Friend as a Circuit: Inter-Branch Communication Witness Benchmarks on Superconducting Quantum Hardware - https://arxiv.org/abs/2601.16004 - arXiv:2601.16004v1 Announce Type: new -Abstract: We implement and benchmark on IBM Quantum hardware the circuit family proposed by Violaris for estimating operational inter-branch communication witnesses, defined as correlations in classical measurement records produced by compiled Wigner's-friend-style circuits. We realize a five-qubit instance of the protocol as an inter-register message-transfer pattern within a single circuit, rather than physical signaling, and evaluate its behavior under realistic device noise and compilation constraints. The circuit encodes branch-conditioned evolution of an observer subsystem whose dynamics depend on a control qubit, followed by a controlled transfer operation that probes correlations between conditional measurement contexts. - Executing on the ibm_fez backend with 20000 shots, we observe population-based visibility of 0.877, coherence witnesses of 0.840 and -0.811 along orthogonal axes, and a phase-sensitive magnitude of approximately 1.17. While the visibility metric is insensitive to some classes of dephasing, the coherence witnesses provide complementary sensitivity to off-diagonal noise. - This work does not test or discriminate among interpretations of quantum mechanics. Instead, it provides a reproducible operational constraint pipeline for evaluating detectability of non-ideal channels relative to calibrated device noise. - oai:arXiv.org:2601.16004v1 - quant-ph - cs.ET - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Christopher Altman - - - Echoed Random Quantum Metrology - https://arxiv.org/abs/2601.16026 - arXiv:2601.16026v1 Announce Type: new -Abstract: Quantum metrology typically demands the preparation of exotic quantum probe states, such as entangled or squeezed states, to surpass classical limits. However, the need for carefully calibrated system parameters and finely optimized quantum controls imposes limitations on scalability and robustness. Here, we circumvent these limitations by introducing an echoed random process that achieves sensitivity approaching the Heisenberg limit while remaining blind to the random probe state. We demonstrate that by simply driving a Kerr nonlinear mode with random pulses, the emergence of sub-Planck phase-space structures grants high sensitivity, eliminating the need for complex quantum control. The protocol is statistically robust, yielding high performance across broad driving parameter ranges while exhibiting resilience to control fluctuations and photon loss. Broadly applicable to both bosonic and qubit platforms, our work reveals a practical, hardware-efficient, scalable, and optimization-free route to quantum-enhanced metrology in high-dimensional Hilbert spaces. - oai:arXiv.org:2601.16026v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Dong-Sheng Liu, Zi-Jie Chen, Ziyue Hua, Yilong Zhou, Qing-Xuan Jie, Weizhou Cai, Ming Li, Luyan Sun, Chang-Ling Zou, Xi-Feng Ren, Guang-Can Guo - - - Robust Quantum Algorithmic Binary Decision-Making on Displacement Signals - https://arxiv.org/abs/2601.16081 - arXiv:2601.16081v1 Announce Type: new -Abstract: A relevant signal in the quantum domain may manifest as a displacement or a phase shift operator in the bosonic phase space. For a real parameter $\beta$ embedded in such a displacement operator, the task of determining if $\beta \in [\beta_{-th}, \beta_{+th}]$ for real asymmetric thresholds $(\beta_{-th} \ne -\beta_{+th})$ is a binary decision problem. We propose a framework based on generalized quantum signal processing interferometry (GQSPI) on hybrid qubit-bosonic oscillator systems that addresses this parameter detection problem by recasting the practical task of active binary hypothesis testing on quantum systems to that of a polynomial approximation. We achieve a small decision error probability $p_{err}$ on the order of $O(\frac{1}{d}\log{(d)})$, with $d$ as the circuit depth. We analyze the protocol when (i) $\beta$ is a deterministic parameter, and (ii) when $\beta$ is drawn randomly from a known prior distribution. The performance of the sensing protocol under dephasing noise is also shown to be robust. We further extend our protocol from two thresholds to more general multi-threshold cases as well. Overall, the proposed framework enables decision-making over arbitrary thresholds for any general displacement signal in a single or a few shots. - oai:arXiv.org:2601.16081v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Aishwarya Majumdar, Yuan Liu - - - Quantum Metrology under Coarse-Grained Measurement - https://arxiv.org/abs/2601.16106 - arXiv:2601.16106v1 Announce Type: new -Abstract: While quantum metrology enables measurement precision beyond classical limits, its performance is often susceptible to experimental imperfections. Most prior studies have focused on imperfections in quantum states and operations. Here, we investigate the effect of coarse graining in quantum measurement through both theoretical analysis and experimental demonstration. Using an interferometer with a squeezed vacuum and a laser input, we analyze how coarse graining in homodyne detection affects the precision of phase estimation. We evaluate the Fisher information under various coarse-graining conditions and determine, in each case, an optimal estimation strategy that saturates the Cram\'{e}r-Rao bound. Remarkably, even extremely coarse-grained measurement -- with only two bins -- enables phase estimation beyond the standard quantum limit and even achieves a precision that follows the Heisenberg scaling. We experimentally demonstrate quantum-enhanced phase estimation under coarse-grained homodyne detection. To determine an optimal estimation strategy, we employ the method of moments and present calibration procedures that enable its application to general experimental settings. Using only two bins, we observe a quantum enhancement of 1.2 dB compared to the classical method using the ideal measurement, improving towards 3.8 dB as the bin number increases. These results highlight a practical pathway to achieving quantum enhancement under the presence of severe experimental imperfections. - oai:arXiv.org:2601.16106v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Byeong-Yoon Go, Geunhee Gwak, Young-Do Yoon, Sungho Lee, Nicolas Treps, Jiyong Park, Young-Sik Ra - - - Experimental prime factorization via a feedback quantum control - https://arxiv.org/abs/2601.16116 - arXiv:2601.16116v1 Announce Type: new -Abstract: Prime factorization on quantum processors is typically implemented either via circuit-based approaches such as Shor's algorithm or through Hamiltonian optimization methods based on adiabatic, annealing, or variational techniques. While Shor's algorithm demands high-fidelity quantum gates, Hamiltonian optimization schemes, with prime factors encoded as degenerate ground states of a problem Hamiltonian, generally require substantial classical post-processing to determine control parameters. We propose an all-quantum, measurement-based feedback approach that iteratively steers a quantum system toward the target ground state, eliminating the need for classical computation of drive parameters once the problem Hamiltonian is determined and realized. As a proof of principle, we experimentally factor the biprime 551 using a three-qubit NMR quantum register and numerically analyze the robustness of the method against control field-errors. We further demonstrate scalability by numerically implementing the FALQON factorization of larger biprimes, 9,167 and 2,106,287, using 5 and 9 qubits, respectively. - oai:arXiv.org:2601.16116v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Hari Krishnan KB, Vishal Varma, T. S. Mahesh - - - Exceptional points in Gaussian channels: diffusion gauging and drift-governed spectrum - https://arxiv.org/abs/2601.16121 - arXiv:2601.16121v1 Announce Type: new -Abstract: McDonald and Clerk [Phys.\ Rev.\ Research 5, 033107 (2023)] showed that for linear open quantum systems the Liouvillian spectrum is independent of the noise strength. We first make this noise-independence principle precise in continuous time for multimode bosonic Gaussian Markov semigroups: for Hurwitz drift, a time-independent Gaussian similarity fixed by the Lyapunov equation gauges away diffusion for all times, so eigenvalues and non-diagonalizability are controlled entirely by the drift, while diffusion determines steady states and the structure of eigenoperators. We then extend the same separation to discrete time for general stable multimode bosonic Gaussian channels: for any stable Gaussian channel, we construct an explicit Gaussian similarity transformation that gauges away diffusion at the level of the channel parametrization. We illustrate the method with a single-mode squeezed-reservoir Lindbladian and with a non-Markovian family of single-mode Gaussian channels, where the exceptional-point manifolds and the associated gauging covariances can be obtained analytically. - oai:arXiv.org:2601.16121v1 - quant-ph - math-ph - math.MP - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Frank Ernesto Quintela Rodr\'iguez - - - Calibration-Conditioned FiLM Decoders for Low-Latency Decoding of Quantum Error Correction Evaluated on IBM Repetition-Code Experiments - https://arxiv.org/abs/2601.16123 - arXiv:2601.16123v1 Announce Type: new -Abstract: Real-time decoding of quantum error correction (QEC) is essential for enabling fault-tolerant quantum computation. A practical decoder must operate with high accuracy at low latency, while remaining robust to spatial and temporal variations in hardware noise. We introduce a hardware-conditioned neural decoder framework designed to exploit the natural separation of timescales in superconducting processors, where calibration drifts occur over hours while error correction requires microsecond-scale responses. By processing calibration data through a graph-based encoder and conditioning a lightweight convolutional backbone via feature-wise linear modulation (FiLM), we decouple the heavy processing of device statistics from the low-latency syndrome decoding. - We evaluate this approach using the 1D repetition code as a testbed on IBM Fez, Kingston, and Pittsburgh processors, collecting over 2.7 million experimental shots spanning distances up to d = 11. We demonstrate that a single trained model generalizes to unseen qubit chains and new calibration data acquired days later without retraining. On these unseen experiments, the FiLM-conditioned decoder achieves up to an 11.1x reduction in logical error rate relative to modified minimum-weight perfect matching. We observe that by employing a network architecture that exploits the highly asynchronous nature of system calibration and decoding, hardware-conditioned neural decoding demonstrates promising, adaptive performance with negligible latency overhead relative to unconditioned baselines. - oai:arXiv.org:2601.16123v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Samuel Stein, Shuwen Kan, Chenxu Liu, Adrian Harkness, Sean Garner, Zefan Du, Yufei Ding, Ying Mao, Ang Li - - - Quantum Dimension Reduction of Hidden Markov Models - https://arxiv.org/abs/2601.16126 - arXiv:2601.16126v1 Announce Type: new -Abstract: Hidden Markov models (HMMs) are ubiquitous in time-series modelling, with applications ranging from chemical reaction modelling to speech recognition. These HMMs are often large, with high-dimensional memories. A recently-proposed application of quantum technologies is to execute quantum analogues of HMMs. Such quantum HMMs (QHMMs) are strictly more expressive than their classical counterparts, enabling the construction of more parsimonious models of stochastic processes. However, state-of-the-art techniques for QHMM compression, based on tensor networks, are only applicable for a restricted subset of HMMs, where the transitions are deterministic. In this work we introduce a pipeline by which \emph{any} finite, ergodic HMM can be compressed in this manner, providing a route for effective quantum dimension reduction of general HMMs. We demonstrate the method on both a simple toy model, and on a speech-derived HMM trained from data, obtaining favourable memory--accuracy trade-offs compared to classical compression approaches. - oai:arXiv.org:2601.16126v1 - quant-ph - cond-mat.stat-mech - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Rishi Sundar, Thomas Elliott - - - Fair sampling with temperature-targeted QAOA based on quantum-classical correspondence theory - https://arxiv.org/abs/2601.16144 - arXiv:2601.16144v1 Announce Type: new -Abstract: In combinatorial optimization problems with degenerate ground states, fair sampling of degenerate solutions is essential. However, the quantum approximate optimization algorithm (QAOA) with a standard transverse-field mixer induces biases among degenerate states as circuit depth increases. Based on quantum-classical correspondence theory, we propose SBO-QAOA, which employs a temperature-dependent Hamiltonian encoding a Gibbs distribution as its ground state. Numerical simulations show that, unlike standard QAOA, SBO-QAOA yields ground-state probabilities converging to finite-temperature values with uniform distribution among degenerate states. These fairness and temperature-targeting properties are preserved even with only four variational parameters under a linear schedule. - oai:arXiv.org:2601.16144v1 - quant-ph - cond-mat.stat-mech - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Tetsuro Abe, Shu Tanaka - - - Polynomial-time thermalization and Gibbs sampling from system-bath couplings - https://arxiv.org/abs/2601.16154 - arXiv:2601.16154v1 Announce Type: new -Abstract: Many physical phenomena, including thermalization in open quantum systems and quantum Gibbs sampling, are modeled by Lindbladians approximating a system weakly coupled to a bath. Understanding the convergence speed of these Lindbladians to their steady states is crucial for bounding algorithmic runtimes and thermalization timescales. We study two such families of processes: one characterizing a repeated-interaction Gibbs sampling algorithm, and another modeling open many-body quantum thermalization. We prove that both converge in polynomial time for several non-commuting systems, including high-temperature local lattices, weakly interacting fermions, and 1D spin chains. These results demonstrate that simple dissipative quantum algorithms can prepare complex Gibbs states and that Lindblad dynamics accurately capture thermal relaxation. Our proofs rely on a novel technical result that extrapolates spectral gap lower bounds from quasi-local Lindbladians to the non-local generators governing these dynamics. - oai:arXiv.org:2601.16154v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Samuel Slezak, Matteo Scandi, \'Alvaro M. Alhambra, Daniel Stilck Fran\c{c}a, Cambyse Rouz\'e - - - Stabilizer Thermal Eigenstates at Infinite Temperature - https://arxiv.org/abs/2601.16177 - arXiv:2601.16177v1 Announce Type: new -Abstract: Understanding how to analyze highly entangled thermal eigenstates is a central challenge in the study of quantum many-body systems. In this Letter, we introduce a stabilizer-based approach to construct analytically tractable energy eigenstates of nonintegrable many-body Hamiltonians. Focusing on zero-energy eigenstates at infinite temperature, we prove a sharp no-go theorem: stabilizer eigenstates of two-body Hamiltonians cannot satisfy $k$-body microscopic thermal equilibrium for any $k\ge4$. We further show that this bound is tight by explicitly constructing two-body nonintegrable Hamiltonians whose stabilizer eigenstates reproduce thermal expectation values for all two-body and all three-body observables. Finally, we identify the structural origin of this limitation by characterizing the conditions under which a stabilizer state can appear as a zero-energy eigenstate of a Hamiltonian, thereby revealing a fundamental constraint imposed by the few-body nature of interactions. - oai:arXiv.org:2601.16177v1 - quant-ph - cond-mat.stat-mech - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Akihiro Hokkyo - - - Studying energy-resolved transport with wavepacket dynamics on quantum computers - https://arxiv.org/abs/2601.16180 - arXiv:2601.16180v1 Announce Type: new -Abstract: Probing energy-dependent transport in quantum simulators requires preparing states with tunable energy and small energy variance. Existing approaches often study quench dynamics of simple initial states, such as computational basis states, which are far from energy eigenstates and therefore limit the achievable energy resolution. In this work, we propose using wavepackets to probe transport properties with improved energy resolution. To demonstrate the utility of this approach, we prepare and evolve wavepackets on Quantinuum's H2-2 quantum computer and identify an energy-dependent localization transition in the Anderson model on an 8x7 lattice--a finite-size mobility edge. We observe that a wavepacket initialized at low energy remains spatially localized under time evolution, while a high-energy wavepacket delocalizes, consistent with the presence of a mobility edge. Crucial to our experiments is an error mitigation strategy that infers the noiseless output bit string distribution using maximum-likelihood estimation. Compared to post-selection, this method removes systematic errors and reduces statistical uncertainty by up to a factor of 5. We extend our methods to the many-particle regime by developing a quantum algorithm for preparing quasiparticle wavepackets in a one-dimensional model of interacting fermions. This technique has modest quantum resource requirements, making wavepacket-based studies of transport in many-body systems a promising application for near-term quantum computers. - oai:arXiv.org:2601.16180v1 - quant-ph - cond-mat.dis-nn - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Melody Lee, Roland C. Farrell - - - Robust Bell Nonlocality from Gottesman-Kitaev-Preskill States - https://arxiv.org/abs/2601.16189 - arXiv:2601.16189v1 Announce Type: new -Abstract: Bell tests based on homodyne detection are strongly constrained in continuous-variable systems. Can Gottesman-Kitaev-Preskill (GKP) encoding turn homodyne detection into a practical tool for revealing Bell nonlocality? We consider a physically motivated model in which each party performs homodyne detection and digitizes the continuous outcome via a fixed periodic binning, corresponding to logical Pauli measurements. Within this framework, we derive a bipartite no-go: CHSH cannot be violated for Bell-pair states. Moving beyond two parties, we show that finitely squeezed GKP-encoded GHZ and W states nevertheless exhibit strong multipartite nonlocality, violating multipartite Bell inequalities with homodyne-only readout. We quantify the required squeezing thresholds and robustness to loss, providing a route toward homodyne-based Bell tests in continuous-variable systems. - oai:arXiv.org:2601.16189v1 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - new - http://creativecommons.org/licenses/by/4.0/ - Xiaotian Yang, Santiago Zamora, Rafael Chaves, Ulrik L. Andersen, Jonatan Bohr Brask, A. de Oliveira Junior - - - Quantum scientists for disarmament: a manifesto - https://arxiv.org/abs/2601.14282 - arXiv:2601.14282v1 Announce Type: cross -Abstract: We, as researchers in quantum science and technology, are publishing this manifesto to express our deep concerns about the current geopolitical situation and the global race to rearm. We firmly oppose all forms of militarization in our societies and, in particular, within the academic world. We categorically reject the use of our research for military applications, population control, or surveillance. We stand against the practice of military funding for research. This manifesto is a call to action: to confront the elephant in the room of quantum research, and to unite all researchers who share our views. Our main goals are: i) To express, as a unified collective, our rejection of the use of our research for military purposes; ii) To open a debate in our community about the ethical implications of quantum research for military purposes; iii) To create a forum where concerned scientists can share their opinions and join forces in support of demilitarized research; iv) To advocate for the establishment of a public database listing all research projects at public universities funded by military or defense agencies. In what follows, we lay out our concerns and the rationale behind our opposition to the militarization of quantum research. - oai:arXiv.org:2601.14282v1 - physics.soc-ph - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Quantum Scientists for Disarmament - - - Beyond the Einstein-Bohr Debate: Cognitive Complementarity and the Emergence of Quantum Intuition - https://arxiv.org/abs/2601.15314 - arXiv:2601.15314v1 Announce Type: cross -Abstract: Recent high-precision experimental confirmations of quantum complementarity have revitalized foundational debates about measurement, description, and realism. This article argues that complementarity is most productively interpreted as an epistemic principle--constraining what can be simultaneously accessed and represented--rather than as an ontological claim about quantum reality. Reexamining the Einstein-Bohr debate through this lens reveals a persistent tension between descriptive completeness and contextual meaning, a tension experiments clarify but do not dissolve. Building on this analysis, we introduce cognitive complementarity as a structural principle governing reasoning under non-classical uncertainty, where mutually constraining representations cannot be jointly optimized. Within this framework, we propose quantum intuition as a testable cognitive capacity: the ability to sustain representational plurality, regulate commitment timing, and resolve perspective-incompatibilities in a context-sensitive manner. Formulated as a naturalistic construct grounded in shared informational constraints, quantum intuition offers a principled bridge between quantum measurement theory and cognition. This work reframes the historical debate, extends epistemic lessons from quantum foundations into cognitive science, and outlines empirical pathways for studying decision-making in contexts of irreducible uncertainty. - oai:arXiv.org:2601.15314v1 - q-bio.NC - cs.AI - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Lalit Kumar Shukla - - - Non-zero Momentum Implies Long-Range Entanglement When Translation Symmetry is Broken in 1D - https://arxiv.org/abs/2601.15345 - arXiv:2601.15345v1 Announce Type: cross -Abstract: A result by Gioia and Wang [Phys Rev X 12, 031007 (2022)] showed that translationally symmetric states having nonzero momentum are necessarily long range entangled (LRE). Here, we consider the question: can a notion of momentum for non-translation symmetric states directly encode the nature of their entanglement, as it does for translation symmetric states? We show the answer is affirmative for 1D systems, while higher dimensional extensions and topologically ordered systems require further work. While Gioia and Wang's result applies to states connected via finite depth quantum circuits to a translation symmetric state, it is often impractical to find such a circuit to determine the nature of the entanglement of states that break translation symmetry. Here, instead of translation eigenstates, we focus on the many-body momentum distribution and the expectation value of the translation operator in many-body states of systems having broken translation symmetry. We show that in the continuum limit the magnitude of the expectation value of the translation operator $|<T>|$ necessarily goes to $1$ for delocalized states, a proxy for LRE states in 1D systems. This result can be seen as a momentum-space version of Resta's formula for the localization length. We investigate how accurate our results are in different lattice models with and without well-defined continuum limits. To that end, we introduce two models: a deterministic version of the random dimer model, illustrating the role of the thermodynamic and continuum limits for our result at a lattice level, and a simplified version of the Aubry-Andre model, with commensurate hopping for both momentum and position space. Finally, we use the random dimer model as a test case for the accuracy of $|<T>|$ as a localization (and thus entanglement) probe for 1D periodic lattice models without a well-defined continuum limit. - oai:arXiv.org:2601.15345v1 - cond-mat.dis-nn - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Amanda Gatto Lamas, Taylor L. Hughes - - - In-Substrate Imaging of Diamond hBN FET Current via Widefield Quantum Diamond Microscopy - https://arxiv.org/abs/2601.15355 - arXiv:2601.15355v1 Announce Type: cross -Abstract: We demonstrate widefield magnetic imaging of current flow in hydrogen terminated diamond field effect transistors (FETs) through in-substrate nitrogen vacancy (NV) centers. Hydrogen termination of the diamond surface induces a two dimensional hole gas (2DHG), while an ensemble of near surface NV centers located $ \sim 1~\mu m$ below the surface enables noninvasive magnetic imaging of current flow with micrometer scale spatial resolution. The FETs were electrically characterized over a range of drain source biases $V_{ds}= 0$ to $-15V$ and gate voltages,$V_{gs}= +3$ to $-9V$ followed by in situ widefield NV magnetometry during device operation. Magnetic field maps and reconstructed current density distributions directly visualize current injection at the source drain contacts and transport beneath the hBN gated channel. Magnetic field maps reveal current density variations in the channel region owing to non-uniformities or defects in the gate dielectric. In addition, we observe a pronounced enhancement of the drain current ($\sim 600-900 \mu A$) and a shift in the apparent threshold voltage during laser illumination, reflecting photo induced changes in channel electrostatics. By correlating gate dependent magnetic images with simultaneous electrical measurements, we directly link spatial current distributions to FET transfer characteristics, providing new insight into buried interface transport and non-uniform gating effects in the transistor channel. As the methodology is compatible with top gated FETs, it can be used to map channel current distributions with micrometer resolution in emerging channel materials, such as 2D materials and wide bandgap channels, and establish widefield NV magnetometry as a powerful platform for probing charge transport in transistors and Van der Waals dielectric heterostructures. - oai:arXiv.org:2601.15355v1 - cond-mat.mes-hall - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Anuj Bathla, Subrat Kumar Pradhan, Ajit Kumar Dash, Prabhat Anand, M. Girish Chandra, Kenji Watanabe, Takashi Taniguchi, Akshay Singh, Veeresh Deshpande, Kasturi Saha - - - Exploring Quantumness at Long-Baseline Neutrino Experiments - https://arxiv.org/abs/2601.15375 - arXiv:2601.15375v1 Announce Type: cross -Abstract: Violations of classicality can be probed through measurements performed on a system at different times, as proposed by Leggett and Garg. Specifically, violations of Leggett-Garg inequalities suggest the presence of quantum effects in macroscopic systems. Long-baseline neutrino experiments provide some of the longest available propagation distances over which such tests can be performed. Previous studies of Leggett-Garg tests in the neutrino sector have largely focused on showing that the oscillation probabilities can violate classical bounds for certain parameter choices. In this work, we develop a more complete and data-driven framework that treats both the distributions representing the classical and quantum behavior, as well as the experimental uncertainties. We consider MINOS, T2K, NOvA, as well as the upcoming DUNE, and present the respective statistical significance for distinguishing quantum behavior from classical scenarios at these long-baseline neutrino experiments. Among them, we find that T2K yields the most significant violation of classicality, at the level of $\sim 14 \sigma$, with NOvA and projections for DUNE also resulting in a significance of more than $5\sigma$. - oai:arXiv.org:2601.15375v1 - hep-ph - hep-ex - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Murshed Alam, Vedran Brdar, Dibya S. Chattopadhyay - - - Exactly solvable topological phase transition in a quantum dimer model - https://arxiv.org/abs/2601.15377 - arXiv:2601.15377v1 Announce Type: cross -Abstract: We introduce a family of generalized Rokhsar-Kivelson (RK) Hamiltonians, which are reverse-engineered to have an arbitrary edge-weighted superposition of dimer coverings as their exact ground state at the RK point. We then focus on a quantum dimer model on the triangular lattice, with doubly-periodic edge weights. For simplicity we consider a $2\times1$ periodic model in which all weights are set to one except for a tunable horizontal edge weight labeled $\alpha$. We analytically show that the model exhibits a continuous quantum phase transition at $\alpha=3$, changing from a topological $\mathbb{Z}_2$ quantum spin liquid ($\alpha<3$) to a columnar ordered state ($\alpha>3$). The dimer-dimer correlator decays exponentially on both sides of the transition with the correlation length $\xi\propto1/|\alpha-3|$ and as a power-law at criticality. The vison correlator exhibits an exponential decay in the spin liquid phase, but becomes a constant in the ordered phase. We explain the constant vison correlator in terms of loops statistics of the double-dimer model. Using finite-size scaling of the vison correlator, we extract critical exponents consistent with the 2D Ising universality class. - oai:arXiv.org:2601.15377v1 - cond-mat.str-el - cond-mat.stat-mech - math-ph - math.MP - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Laura Shou, Jeet Shah, Matthew Lerner-Brecher, Amol Aggarwal, Alexei Borodin, Victor Galitski - - - Stabilizer-Code Channel Transforms Beyond Repetition Codes for Improved Hashing Bounds - https://arxiv.org/abs/2601.15505 - arXiv:2601.15505v1 Announce Type: cross -Abstract: The quantum hashing bound guarantees that rates up to $1-H(p_I, p_X, p_Y, p_Z)$ are achievable for memoryless Pauli channels, but it is not generally tight. A known way to improve achievable rates for certain asymmetric Pauli channels is to apply a small inner stabilizer code to a few channel uses, decode, and treat the resulting logical noise as an induced Pauli channel; reapplying the hashing argument to this induced channel can beat the baseline hashing bound. We generalize this induced-channel viewpoint to arbitrary stabilizer codes used purely as channel transforms. Given any $ [\![ n, k ]\!] $ stabilizer generator set, we construct a full symplectic tableau, compute the induced joint distribution of logical Pauli errors and syndromes under the physical Pauli channel, and obtain an achievable rate via a hashing bound with decoder side information. We perform a structured search over small transforms and report instances that improve the baseline hashing bound for a family of Pauli channels with skewed and independent errors studied in prior work. - oai:arXiv.org:2601.15505v1 - cs.IT - math.IT - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tyler Kann, Matthieu R. Bloch, Shrinivas Kudekar, Ruediger Urbanke - - - Quantum Coherence Spaces Revisited: A von Neumann (Co)Algebraic Approach - https://arxiv.org/abs/2601.15832 - arXiv:2601.15832v1 Announce Type: cross -Abstract: We describe a categorical model of MALL (Multiplicative Additive Linear Logic) inspired by the Heisenberg-Schr\"odinger duality of finite-dimensional quantum theory. Proofs of formulas with positive logical polarity correspond to CPTP (completely positive trace-preserving) maps in our model, i.e. the quantum operations in the Schr\"odinger picture, whereas proofs of formulas with negative logical polarity correspond to CPU (completely positive unital) maps, i.e. the quantum operations in the Heisenberg picture. The mathematical development is based on noncommutative geometry and finite-dimensional von Neumann (co)algebras, which can be defined as special kinds of (co)monoid objects internal to the category of finite-dimensional operator spaces. - oai:arXiv.org:2601.15832v1 - math.CT - cs.LO - math.FA - math.OA - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Thea Li, Vladimir Zamdzhiev - - - Magic of discrete lattice gauge theories - https://arxiv.org/abs/2601.15842 - arXiv:2601.15842v1 Announce Type: cross -Abstract: Simulation of quantum field theories and fundamental interactions are one of the most challenging tasks in modern particle physics. Classical computers generally fail to reproduce accurate results when it comes to strongly coupled theories such as QCD. Recent developments in quantum technologies open up the possibility of simulating such physical regimes by using quantum computers. In this paper, we study the quantum resource related to the simulability of a quantum theory, i.e. non-stabilizerness for Lattice Gauge Theory (LGT) with discrete symmetry gauge groups. We show that enforcing gauge constraints for $\mathbb{Z}_l$ LGTs has no cost in terms of this resource and discuss the relation between non-abelianity of the gauge group with the average non-stabilizerness of the gauge invariant Hilbert space. - oai:arXiv.org:2601.15842v1 - hep-lat - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - 10.1142/S0219887825500033 - International Journal of Geometric Methods in Modern Physics Vol. 22, No. 06, 2550003 (2025) - Gianluca Esposito, Simone Cepollaro, Luigi Cappiello, Alioscia Hamma - - - Reaching the intrinsic performance limits of superconducting strip photon detectors up to 0.1 mm wide - https://arxiv.org/abs/2601.15971 - arXiv:2601.15971v1 Announce Type: cross -Abstract: Superconducting nanowire single-photon detectors (SNSPDs) have emerged as the highest performing photon-counting detectors, making them a critical technology in quantum photonics and photon-starved optical sensing. However, the performance of SNSPDs is limited not by the intrinsic properties of the superconducting film, but by edge-induced current crowding. Despite extensive materials optimization and increasingly demanding fabrication strategies aimed at mitigating this edge-limited behavior, the device edges continue to limit the maximum device operating current, thereby degrading key performance metrics. Here, we demonstrate for the first time in situ tuning of a detector from an edge-limited to a bulk-limited regime, allowing the device to reach its intrinsic performance limit. Our approach is based on current-biased superconducting "rails" placed on either side of the detector to suppress current crowding at the edges. We show that activation of the rails reduces the dark count rate by nine orders of magnitude and extends the photon detection plateau at 1550 nm by more than 40%. These results are demonstrated on detectors up to 0.1 mm wide, establishing an entirely new class of ultra-wide strip detectors that we call superconducting strip photon detectors (SSPD). Moreover, the ability to suppress edge current crowding using the rails provides a pathway toward SSPDs with strip widths extending into the mm-scale. Such devices will enable large-area, high efficiency SSPD arrays with infrared sensitivity and open new opportunities in applications ranging from biomedical imaging to deep space optical communication. - oai:arXiv.org:2601.15971v1 - cond-mat.supr-con - physics.app-ph - physics.ins-det - physics.optics - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Kristen M. Parzuchowski, Eli Mueller, Bakhrom G. Oripov, Benedikt Hampel, Ravin A. Chowdhury, Sahil R. Patel, Daniel Kuznesof, Emma K. Batson, Ryan Morgenstern, Robert H. Hadfield, Varun B. Verma, Matthew D. Shaw, Jason P. Allmaras, Martin J. Stevens, Alex Gurevich, Adam N. McCaughan - - - Quantum Hall Effect at 0.002T - https://arxiv.org/abs/2601.16015 - arXiv:2601.16015v1 Announce Type: cross -Abstract: Graphene enables precise carrier-density control via gating, making it an ideal platform for studying electronic interactions. However, sample inhomogeneities often limit access to the low-density regimes where these interactions dominate. Enhancing carrier mobility is therefore crucial for exploring fundamental properties and developing device applications. Here, we demonstrate a significant reduction in external inhomogeneity using a double-layer graphene architecture separated by an ultra-thin hexagonal boron nitride layer. Mutual screening between the layers reduces scattering from random Coulomb potentials, resulting in a quantum mobility exceeding. Shubnikov de-Haas oscillations emerge at magnetic fields below 1 mT, while integer quantum Hall features are observed at 0.002T. Furthermore, we identify a fractional quantum Hall plateau at a filling factor of at 2T. These results demonstrate the platform's suitability for investigating strongly correlated electronic phases in graphene-based heterostructures. - oai:arXiv.org:2601.16015v1 - cond-mat.mes-hall - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Alexander S. Mayorov, Ping Wang, Xiaokai Yue, Biao Wu, Jianhong He, Di Zhang, Fuzhuo Lian, Siqi Jiang, Jiabei Huang, Zihao Wang, Qian Guo, Kenji Watanabe, Takashi Taniguchi, Renjun Du, Rui Wang, Baigeng Wang, Lei Wang, Kostya S. Novoselov, Geliang Yu - - - Helical Current of Propagating Dirac Electrons and Geometric Coupling to Chiral Environments - https://arxiv.org/abs/2601.16066 - arXiv:2601.16066v1 Announce Type: cross -Abstract: We show that a propagating Dirac electron with intrinsic spin generically carries a real--space helical conserved current, even in the absence of orbital angular momentum. Using exact Dirac eigenstates in cylindrical confinement, we demonstrate that this helical structure possesses definite handedness, persists into evanescent regions, and is characterized by a geometric helix pitch independent of the longitudinal de~Broglie wavelength. This intrinsic helical geometry enables a local geometric coupling between a propagating electron and a chiral environment, yielding chirality--dependent spin selectivity through current geometry rather than through a spin--orbit coupling term. - oai:arXiv.org:2601.16066v1 - cond-mat.mes-hall - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://creativecommons.org/licenses/by/4.0/ - Ju Gao, Fang Shen - - - A pseudo-bosonic Klein-Gordon field with finite two-points function - https://arxiv.org/abs/2601.16131 - arXiv:2601.16131v1 Announce Type: cross -Abstract: We introduce a class of pseudo-bosonic Klein-Gordon fields in 1+1 dimensions and we discuss some of their properties. This work originates from non Hermitian quantum mechanics and deformed canonical commutation relations. We show that, within this class of fields, there exist a specific subclass with the interesting feature of having finite equal space-time two-points function, contrarily to what happens for {\em standard} Klein-Gordon fields. This, in our opinion, is a relevant aspect of our proposal which is a good motivation to undertake a deeper analysis of this (and related) quantum fields. - oai:arXiv.org:2601.16131v1 - math-ph - hep-th - math.MP - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Fabio Bagarello - - - On the structural properties of Lie algebras via associated labeled directed graphs - https://arxiv.org/abs/2601.16161 - arXiv:2601.16161v1 Announce Type: cross -Abstract: We present a method for associating labeled directed graphs to finite-dimensional Lie algebras, thereby enabling rapid identification of key structural algebraic features. To formalize this approach, we introduce the concept of graph-admissible Lie algebras and analyze properties of valid graphs given the antisymmetry property of the Lie bracket as well as the Jacobi identity. Based on these foundations, we develop graph-theoretic criteria for solvability, nilpotency, presence of ideals, simplicity, semisimplicity, and reductiveness of an algebra. Practical algorithms are provided for constructing such graphs and those associated with the lower central series and derived series via an iterative pruning procedure. This visual framework allows for an intuitive understanding of Lie algebraic structures that goes beyond purely visual advantages, since it enables a simpler and swifter grasping of the algebras of interest beyond computational-heavy approaches. Examples, which include the Schr\"odinger and Lorentz algebra, illustrate the applicability of these tools to physically relevant cases. We further explore applications in physics, where the method facilitates computation of similtude relations essential for determining quantum mechanical time evolution via the Lie algebraic factorization method. Extensions to graded Lie algebras and related conjectures are discussed. Our approach bridges algebraic and combinatorial perspectives, offering both theoretical insights and computational tools into this area of mathematical physics. - oai:arXiv.org:2601.16161v1 - math-ph - math.MP - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Tim Heib, David Edward Bruschi - - - String Breaking and Glueball Dynamics in $2+1$D Quantum Link Electrodynamics - https://arxiv.org/abs/2601.16166 - arXiv:2601.16166v1 Announce Type: cross -Abstract: At the heart of quark confinement and hadronization, the physics of flux strings has recently become a focal point in the field of quantum simulation of high-energy physics (HEP). Despite considerable progress, a detailed understanding of the behavior of flux strings in quantum simulation-relevant lattice formulations of gauge theories has remained limited to the lowest truncations of the gauge field, which are severely limited in their ability to draw conclusions about the quantum field theory limit. Here, we employ tensor network simulations to investigate the behavior of flux strings in a quantum link formulation of $2+1$D quantum electrodynamics (QED) with a spin-$1$ representation of the gauge field. We first map out the ground-state phase diagram of this model in the presence of two spatially separated static charges, revealing distinct microscopic processes responsible for string breaking, including a two-stage breaking mechanism not possible in the spin-$\frac{1}{2}$ formulation. Starting in different initial product state string configurations, we then explore far-from-equilibrium quench dynamics across various parameter regimes, demonstrating genuine $2+1$D real-time string breaking and glueball-like bound state formation, with the latter not possible in the spin-$\frac{1}{2}$ formulation. In and out of equilibrium, we consider different values and placements of the static charges. Finally, we provide efficient qudit circuits for a quantum simulation experiment in which our results can be observed in state-of-the-art ion-trap setups. Our findings lay the groundwork for quantum simulations of flux strings towards the quantum field theory limit. - oai:arXiv.org:2601.16166v1 - hep-lat - cond-mat.quant-gas - nucl-th - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Jiahao Cao, Rohan Joshi, Yizhuo Tian, N. S. Srivatsa, Jad C. Halimeh - - - Majorization theoretical approach to entanglement enhancement via local filtration - https://arxiv.org/abs/2312.02066 - arXiv:2312.02066v2 Announce Type: replace -Abstract: From the perspective of majorization theory, we study how to enhance the entanglement of a two-mode squeezed vacuum (TMSV) state by using local filtration operations. We present several schemes achieving entanglement enhancement with photon addition and subtraction, and then consider filtration as a general probabilistic procedure consisting in acting with local (non-unitary) operators on each mode. From this, we identify a sufficient set of two conditions for these filtration operators to successfully enhance the entanglement of a TMSV state, namely the operators must be Fock-orthogonal (i.e., preserving the orthogonality of Fock states) and Fock-amplifying (i.e., giving larger amplitudes to larger Fock states). Our results notably prove that ideal photon addition, subtraction, and any concatenation thereof always enhance the entanglement of a TMSV state in the sense of majorization theory. We further investigate the case of realistic photon addition (subtraction) and are able to upper bound the distance between a realistic photon-added (-subtracted) TMSV state and a nearby state that is provably more entangled than the TMSV, thus extending entanglement enhancement to practical schemes via the use of a notion of approximate majorization. Finally, we consider the state resulting from $k$-photon addition (on each of the two modes) on a TMSV state. We prove analytically that the state corresponding to $k=1$ majorizes any state corresponding to $2\leq k \leq 8$ and we conjecture the validity of the statement for all $k\geq 9$. - oai:arXiv.org:2312.02066v2 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-sa/4.0/ - 10.1103/PhysRevA.110.042430 - Phys. Rev. A 110, 042430 (2024) - Zacharie Van Herstraeten, Nicolas J. Cerf, Saikat Guha, Christos N. Gagatsos - - - Classical capacity of quantum non-Gaussian attenuator and amplifier channels - https://arxiv.org/abs/2312.15623 - arXiv:2312.15623v2 Announce Type: replace -Abstract: We consider a quantum bosonic channel that couples the input mode via a beam splitter or two-mode squeezer to an environmental mode that is prepared in an arbitrary state. We investigate the classical capacity of this channel, which we call a non-Gaussian attenuator or amplifier channel. If the environment state is thermal, we of course recover a Gaussian phase-covariant channel whose classical capacity is well known. Otherwise, we derive both a lower and an upper bound to the classical capacity of the channel, drawing inspiration from the classical treatment of the capacity of non-Gaussian additive-noise channels. We show that the lower bound to the capacity is always achievable and give examples where the non-Gaussianity of the channel can be exploited so that the communication rate beats the capacity of the Gaussian-equivalent channel (i.e., the channel where the environment state is replaced by a Gaussian state with the same covariance matrix). Finally, our upper bound leads us to formulate and investigate conjectures on the input state that minimizes the output entropy of non-Gaussian attenuator or amplifier channels. Solving these conjectures would be a main step towards accessing the capacity of a large class of non-Gaussian bosonic channels. - oai:arXiv.org:2312.15623v2 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-sa/4.0/ - 10.1142/S0219749924400033 - Int. J. Quantum Inf. 22, 2440003 (2024) - Zacharie Van Herstraeten, Saikat Guha, Nicolas J. Cerf - - - Third-quantized master equations as a classical Ornstein-Uhlenbeck process - https://arxiv.org/abs/2408.11893 - arXiv:2408.11893v3 Announce Type: replace -Abstract: Third quantization is used in open quantum systems to construct a superoperator basis in which quadratic Lindbladians can be turned into a normal form. From it follows the spectral properties of the Lindbladian, including eigenvalues and eigenvectors. However, the connection between third quantization and the semiclassical representations usually employed to obtain the dynamics of open quantum systems remains opaque. We introduce an alternative basis for third quantization that bridges this gap between third quantization and the $Q$ representation by projecting the master equation onto a superoperator coherent-state basis. The equation of motion reduces to a multidimensional complex Ornstein-Uhlenbeck process. - oai:arXiv.org:2408.11893v3 - quant-ph - cond-mat.quant-gas - math-ph - math.MP - physics.class-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by-nc-nd/4.0/ - 10.1103/ntv6-jzvb - Phys. Rev. A 112, 063724 (2025) - L\'eonce Dupays - - - Parallel Logical Measurements via Quantum Code Surgery - https://arxiv.org/abs/2503.05003 - arXiv:2503.05003v3 Announce Type: replace -Abstract: Quantum code surgery is a flexible and low overhead technique for performing logical measurements on quantum error-correcting codes, which generalises lattice surgery. In this work, we present a code surgery scheme, applicable to any qubit stabiliser low-density parity check (LDPC) code, that fault-tolerantly measures many logical Pauli operators in parallel. For a collection of logically disjoint Pauli product measurements supported on $t$ logical qubits, our scheme uses $O\big(t \omega (\log t + \log^3\omega)\big)$ ancilla qubits, where $\omega \geq d$ is the maximum weight of the single logical Pauli representatives involved in the measurements, and $d$ is the code distance. This is all done in time $O(d)$ independent of $t$. Our proposed scheme preserves both the LDPC property and the fault-distance of the original code, without requiring ancillary logical codeblocks which may be costly to prepare. This addresses a shortcoming of several recently introduced surgery schemes which can only be applied to measure a limited number of logical operators in parallel if they overlap on data qubits. - oai:arXiv.org:2503.05003v3 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Alexander Cowtan, Zhiyang He, Dominic J. Williamson, Theodore J. Yoder - - - Variational Perturbation Theory in Open Quantum Systems for Efficient Steady State Computation - https://arxiv.org/abs/2504.00085 - arXiv:2504.00085v2 Announce Type: replace -Abstract: Determining the steady state of an open quantum system is crucial for characterizing quantum devices and studying various physical phenomena. Often, computing a single steady state is insufficient, and it is necessary to explore its dependence on multiple external parameters. In such cases, calculating the steady state independently for each combination of parameters quickly becomes intractable. Perturbation theory (PT) can mitigate this challenge by expanding steady states around reference parameters, minimizing redundant computations across neighboring parameter values. However, PT has two significant limitations: it relies on the pseudo-inverse -- a numerically costly operation -- and has a limited radius of convergence. In this work, we remove both of these roadblocks. First, we introduce a variational perturbation theory (VPT) and its multipoint generalization that significantly extends the radius of convergence even in the presence of non-analytic effects such as dissipative phase transitions. Then, we develop two numerical strategies that eliminate the need to compute pseudo-inverses. The first relies on a single LU decomposition to efficiently construct the steady state within the convergence region, while the second reformulates VPT as a Krylov space recycling problem and uses preconditioned iterative methods. We benchmark these approaches across various models, demonstrating their broad applicability and significant improvements over standard PT. - oai:arXiv.org:2504.00085v2 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Andr\'e Melo, Gaspard Beugnot, Fabrizio Minganti - - - Entropy-based analysis of single-qubit Otto and Carnot heat engines - https://arxiv.org/abs/2505.01567 - arXiv:2505.01567v2 Announce Type: replace -Abstract: From an entropy-based formulation of the first law of thermodynamics in the quantum regime, we investigate the performance of Otto-like and Carnot-like engines for a single-qubit working medium. Within this framework, the first law includes an additional contribution -- coherence work -- that quantifies the energetic cost of deviating the quantum trajectory from its natural unitary evolution. We focus on the efficiency of the heat-to-coherence work conversion and show that the Carnot cycle achieves the classical Carnot efficiency, while the performance of the Otto cycle is upper-bounded by the Carnot efficiency corresponding to the extreme temperatures of the cycle. We identify entropy generation during the isochoric stages as the key source of irreversibility limiting the Otto cycle's efficiency. - oai:arXiv.org:2505.01567v2 - quant-ph - cond-mat.stat-mech - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Andr\'es Vallejo, Catty Lissardy, Santiago Silva-Gallo, Alejandro Romanelli, Raul Donangelo - - - Numerical Optimization Strategies for the Variational Hamiltonian Ansatz in Noisy Quantum Environments - https://arxiv.org/abs/2505.22398 - arXiv:2505.22398v4 Announce Type: replace -Abstract: The prevalence of variational methods in near-term quantum computing makes optimizer choice critical, yet selection is frequently intuition-based. We therefore present a systematic benchmark of eight classical optimization algorithms for variational quantum chemistry using the truncated Variational Hamiltonian Ansatz. Performance is evaluated on H$_2$, H$_4$, and LiH in both full and active-space representations under noiseless and finite-shot sampling noise. Sampling noise substantially reshapes cost landscapes, induces wandering near minima, and flips optimizer rankings: gradient-based methods perform best in noiseless simulations, whereas population-based optimizers, particularly CMA-ES, show greater robustness under finite-shot noise. Optimizer performance is strongly problem dependent: Hartree-Fock initialization aids small systems, but its advantage diminishes with system size. Also, we observe that finite shot sampling frequently violates the lower bound given by the variational principle, a principle that cannot be strictly held in the presence of noise. By exploiting the guaranteed convergence of Evolution Strategies to a steady state distribution defined by the noise floor, we utilize the symmetry of these violations to achieve energy estimation precision beyond the intrinsic sampling limit. - oai:arXiv.org:2505.22398v4 - quant-ph - cs.NA - math.NA - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - S. Ill\'esov\'a, V. Nov\'ak, T. Bezd\v{e}k, C. Possel, M. Beseda - - - Erasure cost of a quantum process: A thermodynamic meaning of the dynamical min-entropy - https://arxiv.org/abs/2506.05307 - arXiv:2506.05307v4 Announce Type: replace -Abstract: The erasure of information is fundamentally an irreversible logical operation, carrying profound consequences for the energetics of computation and information processing. We investigate the thermodynamic costs associated with erasing (and preparing) quantum processes. Specifically, we analyze an arbitrary bipartite unitary gate acting on logical and ancillary input-output systems, where the ancillary input is always initialized in the ground state. We focus on the adversarial erasure cost of the reduced dynamics -- that is, the minimal thermodynamic work cost to erase the logical output of the gate for any logical input, assuming full access to the ancilla but no access to any purifying reference of the logical input state. We determine that this adversarial erasure cost is directly proportional to the negative min-entropy of the reduced dynamics, thereby giving the dynamical min-entropy a clear operational meaning. The dynamical min-entropy can take positive and negative values, depending on the underlying quantum dynamics. The negative value of the erasure cost implies that the extraction of thermodynamic work is possible instead of its consumption during the process. A key foundation of this result is the quantum process decoupling theorem, which quantitatively relates the decoupling ability of a process with its min-entropy. This insight bridges thermodynamics, information theory, and the fundamental limits of quantum computation. - oai:arXiv.org:2506.05307v4 - quant-ph - math-ph - math.MP - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1088/2058-9565/ae34e2 - Quantum Science and Technology, vol. 11, no. 1, page 015038, January 2026 - Himanshu Badhani, Dhanuja GS, Swati Choudhary, Vishal Anand, Siddhartha Das - - - Einstein Electron and Local Branching: Unitarity without Many Worlds --Local Hilbert spaces, boundaries, and quantum nonlocality - https://arxiv.org/abs/2507.16123 - arXiv:2507.16123v2 Announce Type: replace -Abstract: Traditional interpretations of quantum mechanics often present a dichotomy: either the wavefunction collapses upon measurement (Copenhagen), violating unitarity, or the entire universe branches into countless parallel worlds (Many-Worlds), with significant ontological proliferation. The Branched Hilbert Subspace Interpretation (BHSI) resolves this tension by introducing branching strictly within local Hilbert spaces. This framework reinterprets scenarios such as the Einstein 1927 electron-diffraction thought experiment, in which all quantum events are confined to a local Hilbert space, allowing the Born rule to emerge naturally from branch weights. Crucially, BHSI treats branching as a dynamical process tied to information recording. This leads to a testable proposal: a dual-layer experiment in which the particle transit time between layers is shorter than the sensor response time, enabling a direct probe of measurement timing and mismatched or uncommitted outcomes. We argue that a quantum system behaves as a unified whole, an island of coherence, within which unitary branching is confined to the system boundary, without observable correlations with distant, unentangled systems. Finally, we show that quantum nonlocality (e.g., in Bell tests or tunneling) arises naturally from the intrinsic vector-space structure of local Hilbert spaces, rather than from superluminal signaling. - oai:arXiv.org:2507.16123v2 - quant-ph - math-ph - math.MP - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xing M. Wang - - - Local-available quantum correlation swapping in one-parameter X states - https://arxiv.org/abs/2507.23142 - arXiv:2507.23142v3 Announce Type: replace -Abstract: Although introduced for entanglement, quantum repeaters and swapping protocols have been analyzed for other quantum correlations (QC), such as quantum discord. In 2015, Mundarain and Ladr\'on de Guevara [Quantum Inf. Process. 14, 4493 (2015)] introduced local-available quantum correlations (LAQC), which are a promising yet understudied quantum correlation. Recently, Bellorin et al. [Int. J. Mod. Phys. B 36, 22500990 (2022), Int. J. Mod. Phys. B 36, 2250154 (2022)] obtained exact analytical results for the LAQC quantifier of general 2-qubit X states. Building up from those results, we analyzed the LAQC swapping for 2-qubit X states. As expected, we find that if the initial states are non-classical and the one used for the projective measurement is entangled, the final state will generally have non-zero LAQC. Using the properties of this quantum correlation, we establish the conditions for a QCS scheme that leads to a final state with a non-zero LAQC measure. We illustrate these results by analyzing five families of one-parameter 2-qubit X states, including families where the projective measure leads to a separable state, but whose LAQC measure is non-zero. This feature opens the possibility for this quantum correlation to be considered a genuine resource in quantum information technology. - oai:arXiv.org:2507.23142v3 - quant-ph - physics.app-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Hermann L. Albrecht - - - Can a Quantum Computer Simulate Nuclear Magnetic Resonance Spectra Better than a Classical One? - https://arxiv.org/abs/2508.06448 - arXiv:2508.06448v2 Announce Type: replace -Abstract: The simulation of the spectra measured in nuclear magnetic resonance (NMR) spectroscopy experiments is a computationally non-trivial problem which, due to its natural interpretation as a quantum spin problem, maps in a straightforward way to a quantum computer. As such, it represents a problem for which such a device may provide some practical advantage over traditional computing methods. In order to understand the extent to which such problems may indeed provide examples of useful quantum advantage, it is important to understand the limitations of existing classical simulation methods. In this work, we benchmark our own classical solver designed to study such problems. This solver uses a clustering approximation to achieve a resource scaling which is linear in the total number of nuclear spins in a given molecule, for a fixed cluster size. The success of such an approximation would present a stark repudiation to the common claim that such problems require an exponential scaling of resources, the very claim which makes simulating an NMR spectra a candidate for quantum advantage. Our benchmarking results indicate that our approximation performs well throughout, and even somewhat beyond, the more typical experimental regimes. We discuss what implications this may have for future efforts to demonstrate quantum advantage in the context of NMR. - oai:arXiv.org:2508.06448v2 - quant-ph - physics.chem-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Keith R. Fratus, Nicklas Enenkel, Sebastian Zanker, Jan-Michael Reiner, Michael Marthaler, Peter Schmitteckert - - - Gradients, parallelism, and variance of quantum estimates - https://arxiv.org/abs/2509.11214 - arXiv:2509.11214v2 Announce Type: replace -Abstract: Computation of observables and their gradients on near-term quantum hardware is a central aspect of any quantum algorithm. In this work, we first review standard approaches to the estimation of observables with and without quantum amplitude estimation for both cost functions and gradients, discuss sampling problems, and analyze variance propagation on quantum circuits with and without Linear Combination of Unitaries (LCU). Afterwards, we systematically analyze the standard approaches to gradient computation with LCU circuits. Finally, we develop a LCU gradient framework for the most general gradients based on n-qubit gates and for time-dependent quantum control gradient, analyze the convergence behaviour of the circuit estimators, and provide detailed circuit representations of both for near-term and fault-tolerant hardware. - oai:arXiv.org:2509.11214v2 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/publicdomain/zero/1.0/ - Francesco Preti, Michael Schilling, J\'ozsef Zsolt Bern\'ad, Tommaso Calarco, Francisco C\'ardenas-L\'opez, Felix Motzoi - - - Triple-Tone Microwave Control for Sensitivity Optimization in Compact Ensemble Nitrogen-Vacancy Magnetometers - https://arxiv.org/abs/2510.00913 - arXiv:2510.00913v3 Announce Type: replace -Abstract: Ensembles of nitrogen-vacancy (NV) centers in diamond are a well-established platform for quantum magnetometry under ambient conditions. One challenge arises from the hyperfine structure of the NV, which, for the common $^{14}$N isotope, results in a threefold reduction of contrast and thus sensitivity. By addressing each of the NV hyperfine transitions individually, triple-tone microwave (MW) control can mitigate this sensitivity loss. Here, we experimentally and theoretically investigate the regimes in which triple-tone excitation offers an advantage over standard single-tone MW control for two DC magnetometry protocols: pulsed optically detected magnetic resonance (ODMR) and Ramsey interferometry. We validate a master equation model of the NV dynamics against ensemble NV measurements, and use the model to explore triple-tone vs single-tone sensitivity for different MW powers and NV dephasing rates. For pulsed ODMR, triple-tone driving improves sensitivity by up to a factor of three in the low-dephasing regime, with diminishing gains when dephasing rates approach the hyperfine splitting. In contrast, for Ramsey interferometry, triple-tone excitation only improves sensitivity if MW power is limited. Our results delineate the operating regimes where triple-tone control provides a practical strategy for enhancing NV ensemble magnetometry in portable and power-limited sensors. - oai:arXiv.org:2510.00913v3 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Ankita Chakravarty, Romain Ruhlmann, Vincent Halde, David Roy-Guay, Michel Pioro-Ladri\`ere, Lilian Childress, Yves B\'erub\'e-Lauzi\`ere - - - Non-stabilizerness in quantum-enhanced metrological protocols - https://arxiv.org/abs/2510.01380 - arXiv:2510.01380v2 Announce Type: replace -Abstract: Non-stabilizerness (colloquially "magic") characterizes genuinely quantum (beyond-Clifford) operations necessary for preparation of quantum states, and can be measured by stabilizer R\'enyi entropy (SRE). For permutationally symmetric states, we show that the SRE depends, for sufficiently large systems, only on a constant number of expectation values of collective spin operators. This compact description is leveraged for analysis of spin-squeezing protocols, which inherently generate non-stabilizerness. Under one-axis twisting (OAT), the generation of optimal squeezing is accompanied by a logarithmic divergence of SRE with system system size. Continued time evolution under OAT produces metrologically useful "kitten" states-superpositions of rotated GHZ states-that feature many-body Bell correlations but exhibit a smaller, system-size-independent SRE that decreases with increasing Bell-correlation strength. Our results reveal connections between non-stabilizerness, multipartite correlations, and quantum metrology, and provide a practical route to quantify non-stabilizerness in experiments for precision sensing. - oai:arXiv.org:2510.01380v2 - quant-ph - cond-mat.quant-gas - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/tmf9-fyc2 - Phys. Rev. A 113, 012416 (2026) - Tanaus\'u Hern\'andez-Yanes, Piotr Sierant, Jakub Zakrzewski, Marcin P{\l}odzie\'n - - - Quantum matrix arithmetics with Hamiltonian evolution - https://arxiv.org/abs/2510.06316 - arXiv:2510.06316v2 Announce Type: replace -Abstract: The efficient implementation of matrix arithmetic operations underpins the speedups of many quantum algorithms. We develop a suite of methods to perform matrix arithmetics -- with the result encoded in the off-diagonal blocks of a Hamiltonian -- using Hamiltonian evolutions of input operators. We show how to maintain this $\textit{Hamiltonian block encoding}$, so that matrix operations can be composed one after another, and the entire quantum computation takes $\leq 2$ ancilla qubits. We achieve this for matrix multiplication, matrix addition, matrix inversion, Hermitian conjugation, fractional scaling, integer scaling, complex phase scaling, as well as singular value transformation for both odd and even polynomials. We also present an overlap estimation algorithm to extract classical properties of Hamiltonian block encoded operators, analogous to the well known Hadmard test, at no extra cost of qubit. Our Hamiltonian matrix multiplication uses the Lie group commutator product formula and its higher-order generalizations due to Childs and Wiebe. Our Hamiltonian singular value transformation employs a dominated polynomial approximation, where the approximation holds within the domain of interest, while the constructed polynomial is upper bounded by the target function over the entire unit interval. We describe a circuit for simulating a class of sum-of-squares Hamiltonians, attaining a commutator scaling in step count, while leveraging the power of matrix arithmetics to reduce the cost of each simulation step. In particular, we apply this to the doubly factorized tensor hypercontracted Hamiltonians from recent studies of quantum chemistry, obtaining further improvements for initial states with a fixed number of particles. We achieve this with $1$ ancilla qubit. - oai:arXiv.org:2510.06316v2 - quant-ph - cs.DS - cs.NA - math.NA - physics.chem-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Christopher Kang, Yuan Su - - - Verifiable blind observable estimation - https://arxiv.org/abs/2510.08548 - arXiv:2510.08548v2 Announce Type: replace -Abstract: Cryptographic verification is essential for establishing trust in quantum-computing-as-a-service. However, a fundamental gap exists in the current verification landscape: existing efficient protocols are largely restricted to decision problems where correctness is boosted by classical majority voting. This excludes observable estimation, the statistical task underpinning nearly all near-term quantum advantage applications. For such tasks, current verification techniques face a prohibitive trade-off: either weak security guarantees or massive space overhead that exceeds the capacity of near-term hardware. To resolve this, we introduce the Secure Delegated Observable Estimation (SDOE) ideal resource, the first formal cryptographic framework for trustworthy expectation-value estimation within Abstract Cryptography. We then present the Verifiable Blind Observable Estimation (VBOE) protocol, which efficiently constructs this resource. VBOE circumvents the limitations inherent in prior methodologies by enabling the sequential collection of samples with negligible security error, requiring zero extra qubit overhead. By directly averaging computation rounds in classical post-processing, our protocol provides the only known path to rigorous, composable verification for the most common class of near-term quantum-classical hybrid algorithms. This work bridges foundational cryptographic theory with practical quantum tasks, enabling the certification of quantum utility on current and near-future devices. - oai:arXiv.org:2510.08548v2 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Bo Yang, Elham Kashefi, Harold Ollivier - - - Thermodynamics of quantum processes: An operational framework for free energy and reversible athermality - https://arxiv.org/abs/2510.12790 - arXiv:2510.12790v3 Announce Type: replace -Abstract: We explore the thermodynamics of quantum processes (quantum channels) by axiomatically introducing the free energy for channels, defined via the quantum relative entropy with an absolutely thermal channel whose fixed output is in equilibrium with a thermal reservoir. This definition finds strong support through its operational interpretations in designated quantum information and thermodynamic tasks. We construct a resource theory of athermality for quantum processes, where free operations are Gibbs preserving superchannels and golden units are unitary channels with respect to absolutely thermal channel having fully degenerate output Hamiltonian. We exactly characterize the one-shot distillation and formation of quantum channels using hypothesis-testing and max-relative entropy with respect to the absolutely thermal channel. These rates converge asymptotically to the channel free energy (up to a multiplicative factor of half the inverse temperature), establishing its operational meaning and proving the asymptotic reversibility of the athermality. We show the direct relation between the resource theory of athermality and quantum information tasks such as private randomness and purity distillation, and thermodynamic tasks of erasure and work extraction. Our work connects the core thermodynamic concepts of free energy, energy, entropy, and maximal extractable work of quantum processes to their information processing capabilities. - oai:arXiv.org:2510.12790v3 - quant-ph - cond-mat.stat-mech - hep-th - math-ph - math.MP - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Himanshu Badhani, Dhanuja G. S., Siddhartha Das - - - Quantum Energy Teleportation under Equilibrium and Nonequilibrium Environments - https://arxiv.org/abs/2511.01518 - arXiv:2511.01518v2 Announce Type: replace -Abstract: Quantum energy teleportation (QET), implemented via local operations and classical communication, enables carrier-free energy transfer by exploiting quantum resources. While QET has been extensively studied theoretically and validated experimentally in various quantum platforms, enhancing energy output for mixed initial states, as the system inevitably interacts with environments, remains a significant challenge. In this work, we study QET performance in a two-qubit system coupled to equilibrium or nonequilibrium reservoirs. We derive an analytical expression for the energy output in terms of the system Hamiltonian eigenstates, enabling analysis of energy output for mixed states. Using the Redfield master equation, we systematically examine the effects of qubit detuning, nonequilibrium temperature difference, and nonequilibrium chemical potential difference on the energy output. We find that the energy output for mixed states often follows that of the eigenstate with the highest population, and that nonequilibrium environments can enhance the energy output in certain parameter regimes. - oai:arXiv.org:2511.01518v2 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Xiaokun Yan, Kun Zhang, Jin Wang - - - Towards Quantum Software for Quantum Simulation - https://arxiv.org/abs/2511.13520 - arXiv:2511.13520v2 Announce Type: replace -Abstract: Quantum simulation is a leading candidate for demonstrating practical quantum advantage over classical computation, as it is believed to provide exponentially more compute power than any classical system. It offers new means of studying the behaviour of complex physical systems, for which conventionally software-intensive simulation codes based on numerical high-performance computing are used. Instead, quantum simulations map properties and characteristics of subject systems, for instance chemical molecules, onto quantum devices that then mimic the system under study. - Currently, the use of these techniques is largely limited to fundamental science, as the overall approach remains tailored for specific problems: We lack infrastructure and modelling abstractions that are provided by the software engineering community for other computational domains. - In this paper, we identify critical gaps in the quantum simulation software stack-particularly the absence of general-purpose frameworks for model specification, Hamiltonian construction, and hardware-aware mappings. We advocate for a modular model-driven engineering (MDE) approach that supports different types of quantum simulation (digital and analogue), and facilitates automation, performance evaluation, and reusability. Through an example from high-energy physics, we outline a vision for a quantum simulation framework capable of supporting scalable, cross-platform simulation workflows. - oai:arXiv.org:2511.13520v2 - quant-ph - cs.SE - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - 10.1145/3786150.3788611 - Proceedings of the 48th International Conference of Software Engineering 2026, Workshop on Quantum Software Engineering (Q-SE@ICSE'26) - Maja Franz, Lukas Schmidbauer, Joshua Ammermann, Ina Schaefer, Wolfgang Mauerer - - - Precision Bounds for Characterising Quantum Measurements - https://arxiv.org/abs/2512.20091 - arXiv:2512.20091v2 Announce Type: replace -Abstract: Quantum measurements, alongside quantum states and processes, form a cornerstone of quantum information processing. However, unlike states and processes, their efficient characterisation remains relatively unexplored. We resolve this asymmetry by introducing a comprehensive framework for efficient detector estimation that reveals the fundamental limits to extractable parameter information and errors arising in detector analysis - the detector quantum Fisher information. Our development eliminates the need to optimise for the best probe state, while highlighting aspects of detector analysis that fundamentally differ from quantum state estimation. Through proofs, examples and experimental validation, we demonstrate the relevance and robustness of our proposal for current quantum detector technologies. By formalising a dual perspective to state estimation, our framework completes and connects the triad of efficient state, process, and detector tomography, advancing quantum information theory with broader implications for emerging technologies reliant on precisely calibrated measurements. - oai:arXiv.org:2512.20091v2 - quant-ph - physics.ins-det - physics.optics - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1038/s41467-026-68529-7 - Nat. Commun. (2026) - Aritra Das, Simon K. Yung, Lorcan O. Conlon, Ozlem Erkilic, Angus Walsh, Yong-Su Kim, Ping K. Lam, Syed M. Assad, Jie Zhao - - - Entanglement Entropy for Screened Interactions via Dimensional Mapping to Harmonic Oscillators - https://arxiv.org/abs/2601.02877 - arXiv:2601.02877v2 Announce Type: replace -Abstract: We investigate interaction-induced corrections to entanglement entropy by mapping a screened Yukawa-type interaction to an effective harmonic oscillator system with controlled anharmonic perturbations. Starting from a one-dimensional interaction $V(x) = -g^2 e^{-\alpha m x}/x$, we reformulate the problem in terms of a four-dimensional radial oscillator, where the finite screening length generates a systematic hierarchy of polynomial interactions in the radial coordinate. This mapping enables a controlled Rayleigh-Schrodinger perturbative treatment of the ground-state wavefunction and an explicit spectral analysis of the reduced density matrix. Working in the weak-screening regime, we compute the leading non-Gaussian correction arising from the quartic interaction $\rho^4$, which appears at order $\alpha^2$ in the expansion of the Yukawa-like potential. We obtain closed analytic expressions for the resulting small eigenvalues of the reduced density matrix and evaluate their contribution to the von Neumann entanglement entropy. We show that the entropy receives analytic corrections at order $\alpha^2$, originating both from explicit anharmonic state-mixing effects and from the implicit $\alpha$ dependence of the Gaussian width parameter. Our results clarify the distinct roles of harmonic renormalization and genuinely non-Gaussian interactions in generating entanglement, establish a systematic power-counting and normalization scheme for higher-order $\rho^{2n}$ perturbations, and provide a transparent oscillator-based framework for computing entanglement entropy in weakly interacting low-dimensional and field-theoretic systems. - oai:arXiv.org:2601.02877v2 - quant-ph - hep-th - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Akshay Kulkarni, Rahul Nigam - - - Madelung hydrodynamics of spin-orbit coupling: action principles, currents, and correlations - https://arxiv.org/abs/2601.10698 - arXiv:2601.10698v2 Announce Type: replace -Abstract: We exploit the variational and Hamiltonian structures of quantum hydrodynamics with spin to unfold the correlation and torque mechanisms accompanying spin-orbit coupling (SOC) in electronic motion. Using Hamilton's action principle for the Pauli equation, we isolate SOC-induced quantum forces that act on the orbital Madelung--Bohm trajectories and complement the usual force terms known to appear in quantum hydrodynamics with spin. While the latter spin-hydrodynamic forces relate to the quantum geometric tensor (QGT), SOC-induced orbital forces originate from a particular current operator that contributes prominently to the spin current. This distinction between force terms reveals two fundamentally different mechanisms generating quantum spin-orbit correlations. Leveraging the Hamiltonian structure of the hydrodynamic system, we also elucidate spin transport features such as the correlation-induced quantum torques and the current shift in the spin Hall effect. This Hall shift leads to a new definition of the transport spin current thereby addressing an open question in spintronics. Finally, we illustrate the framework via the Madelung--Rashba equations for planar SOC configurations and propose a particle-based scheme for numerical implementation. - oai:arXiv.org:2601.10698v2 - quant-ph - cond-mat.mes-hall - cond-mat.other - math-ph - math.MP - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Cesare Tronci - - - Multiparameter estimation for the superresolution of two incoherent sources - https://arxiv.org/abs/2601.14876 - arXiv:2601.14876v2 Announce Type: replace -Abstract: We experimentally demonstrate the simultaneous estimation of the three parameters characterizing a pair of incoherent optical sources in the sub-Rayleigh regime, enabling super-resolved scene characterization. Using spatial-mode demultiplexing (SPADE) with two demultiplexers--one deliberately shifted--we determine separations well below the diffraction limit and achieve sensitive joint estimation of separation, centroid, and relative brightness over a broad range of scene configurations in a single experimental setting. We benchmark our performance using Fisher-information-based Cram\'er-Rao bounds, and discuss the corresponding quantum limits. We investigate two complementary scenarios: a realistic case with slightly non-identical sources, and an idealized case of indistinguishable sources. - oai:arXiv.org:2601.14876v2 - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace - http://creativecommons.org/licenses/by/4.0/ - Antonin Grateau, Alexander Boeschoten, Tanguy Favin-L\'ev\^eque, Isael Herrera, Nicolas Treps - - - Duality between open systems and closed bilayer systems: Thermofield double states as quantum many-body scars - https://arxiv.org/abs/2304.03155 - arXiv:2304.03155v4 Announce Type: replace-cross -Abstract: We establish a duality between open many-body systems governed by the Gorini-Kossakowski-Sudarshan-Lindblad (GKSL) equation and satisfying the detailed balance condition on the one side, and closed bilayer systems with a self-adjoint Hamiltonian on the other side. Under this duality, the identity operator on the open system side maps to a quantum many-body scar of the dual Hamiltonian $\mathcal H$. This scar eigenstate has a form of a thermofield double state for a single-body conserved quantity entering the detailed balance conditions. A remarkable feature of this thermofield scar is a tunable single-layer entanglement entropy controlled by the reservoir temperature on the open system side. Further, we identify broad classes of many-body open systems with nontrivial explicit eigen operators $Q$ of the Lindbladian superoperator. The expectation values of the corresponding observables exhibit a simple exponential decay, $\langle Q\rangle_t=e^{-\Gamma t} \langle Q \rangle_0$, irrespectively of the initial state. Under the above duality, these eigen operators give rise to additional (towers of) scars. Finally, we point out that more general superoperators (not necessarily of the GKSL form) can be mapped to self-adjoint Hamiltonians of bilayer systems harbouring scars, and provide an example thereof. - oai:arXiv.org:2304.03155v4 - cond-mat.stat-mech - cond-mat.str-el - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - 10.1103/PhysRevB.110.L241105 - Phys. Rev. B 110, L241105 (2024) - Alexander Teretenkov, Oleg Lychkovskiy - - - Vestigial Gapless Boson Density Wave Emerging between $\nu = 1/2$ Fractional Chern Insulator and Finite-Momentum Supersolid - https://arxiv.org/abs/2408.07111 - arXiv:2408.07111v2 Announce Type: replace-cross -Abstract: The roton-triggered charge-density-wave (CDW)is widely studied in fractional quantum Hall (FQH) and fractional Chern insulator (FCI) systems, and there also exist field theoretical and numerical realizations of continuous transition from FCI to superfluid (SF). However, the theory and numerical explorations of the transition between FCI and supersolid (SS) are still lacking. In this work, we study the topological flat-band lattice models with $\nu$ = 1/2 hard-core bosons, where the previous studies have discovered the existence of FCI states and possible direct FCI-SS transitions. While the FCI is robust, we find the direct FCI-SS transition is absent, and there exist more intriguing scenarios. In the case of checkerboard lattice, we find an intermediate gapless CDW state without SF, sandwiched between FCI and SS. This novel state is triggered by the roton instability in FCI and it further continuously brings about the intertwined finite-momentum SF fluctuation when the CDW order is strong enough, eventually transiting into an unconventional finite-momentum SS state. The intermediate gapless CDW state is a vestige from the SS state, since the increasing quantum fluctuation melts only the Larkin-Ovchinnikov-type SF order in SS but its (secondary) product -- the CDW order -- survives. On honeycomb lattice, we find no evidence of SS, but discover an interesting sequence of FCI-Solid I-Solid II transitions, with both solids incompressible. Moreover, in contrast to previous single-roton condensation, this sequence of FCI-Solid I-Solid II transitions is triggered by the softening of multi-roton modes in FCI. Considering the intertwined wave vectors of the CDW orders, Solid I is a vestige of Solid II. Our work provides new horizon not only for the quantum phase transitions in FCI but also for the intertwined orders and gapless states in bosonic systems, which will inspire future studies. - oai:arXiv.org:2408.07111v2 - cond-mat.mes-hall - cond-mat.str-el - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - 10.1103/1bhm-9pk4 - Phys. Rev. B 113, 035141 (2026) - Hongyu Lu, Han-Qing Wu, Bin-Bin Chen, Zi Yang Meng - - - Electrical Interconnects for Silicon Spin Qubits - https://arxiv.org/abs/2411.01366 - arXiv:2411.01366v2 Announce Type: replace-cross -Abstract: Scalable spin qubit devices will likely require long-range qubit interconnects. We propose to create such an interconnect with a resistive topgate. The topgate is positively biased, to form a channel between the two dots; an end-to-end voltage difference across the nanowire results in an electric field that propels the electron from source dot to target dot. The electron is momentum-incoherent, but not necessarily spin-incoherent; we evaluate threats to spin coherence due to spin-orbit coupling, valley physics, and nuclear spin impurities. We find that spin-orbit coupling is the dominant threat, but momentum-space motional narrowing due to frequent scattering partially protects the electron, resulting in characteristic decoherence lengths ~15 mm for plausible parameters. - oai:arXiv.org:2411.01366v2 - cond-mat.mes-hall - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Christopher David White, Anthony Sigillito, Michael J. Gullans - - - Light-induced, fictitious magnetic trapping of cold alkali atoms using an optical tweezers-nanofiber hybrid platform - https://arxiv.org/abs/2412.04809 - arXiv:2412.04809v4 Announce Type: replace-cross -Abstract: We present a magnetic trapping scheme for cold 87Rb atoms based on light-induced fictitious magnetic fields generated by the evanescent field of an optical nanofiber (ONF) integrated with an optical tweezers. We calculate and compare the trapping potentials for both Gaussian and Laguerre-Gaussian modes of the tweezers beam, combined with a quasi-linearly polarized ONF-guided field. Based on the optical powers in the tweezers and ONF modes, we analyze the trap depths and the positions of the potential minima from the nanofiber surface. We show that, by varying the optical powers in the two fields, the trap position can be tuned over several hundred nanometers, while simultaneously influencing the trap depth and trap frequencies. Such control over atom-surface position is essential for studying distance-dependent effects on atoms trapped near a dielectric surface and optimizing atom-photon interfaces for quantum technology applications. - oai:arXiv.org:2412.04809v4 - physics.atom-ph - physics.optics - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by-nc-nd/4.0/ - Alexey Vylegzhanin, Dylan J. Brown, Sergey Abdrakhmanov, Sile Nic Chormaic - - - Non-hermitian Green's function theory with $N$-body interactions: the coupled-cluster similarity transformation - https://arxiv.org/abs/2503.06586 - arXiv:2503.06586v3 Announce Type: replace-cross -Abstract: We present the diagrammatic theory of the irreducible self-energy and Bethe-Salpeter kernel that naturally arises within the Green's function formalism for a general $N$-body non-hermitian interaction. In this work, we focus specifically on the coupled-cluster self-energy generated by the similarity transformation of the electronic structure Hamiltonian. We develop the biorthogonal quantum theory to construct dynamical correlation functions where the time-dependence of operators is governed by a non-hermitian Hamiltonian. We extend the Gell-Mann and Low theorem to include non-hermitian interactions and to generate perturbative expansions of many-body Green's functions. We introduce the single-particle coupled-cluster Green's function and derive the perturbative diagrammatic expansion for the non-hermitian coupled-cluster self-energy in terms of the `non-interacting' reference Green's function, $\tilde{\Sigma}[G_0]$. From the exact equation-of-motion of the single-particle coupled-cluster Green's function, we derive the self-consistent renormalized coupled-cluster self-energy, $\tilde{\Sigma}[\tilde{G}]$, and demonstrate its relationship to the perturbative expansion of the self-energy, $\tilde{\Sigma}[G_0]$. Subsequently, we show that the usual electronic self-energy can be recovered from the coupled-cluster self-energy by neglecting the effects of the similarity transformation. We show how the coupled-cluster ground state energy can be obtained from the coupled-cluster self-energy and provide an overview of the relationship between approximations for the coupled-cluster self-energy, IP/EA-EOM-CC and the $G_0W_0$ approximation. As a result, we introduce the CC-$G_0W_0$ self-energy by leveraging the connections between Green's function and coupled-cluster theory. Finally, we derive the diagrammatic expansion of the coupled-cluster Bethe-Salpeter kernel. - oai:arXiv.org:2503.06586v3 - cond-mat.str-el - cond-mat.mtrl-sci - nucl-th - physics.chem-ph - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Christopher J. N. Coveney, David P. Tew - - - Fusion Dynamics of Majorana Zero Modes - https://arxiv.org/abs/2503.09800 - arXiv:2503.09800v2 Announce Type: replace-cross -Abstract: Braiding and fusion of Majorana zero modes are key elements of any future topological Majorana-based quantum computer. Here, we investigate the fusion dynamics of Majorana zero modes in the spinless Kitaev model, as well as in a spinful model describing magnet-superconductor hybrid structures. We consider various scenarios allowing us to reproduce the fusion rules of the Ising anyon model. Particular emphasis is given to the charge of the fermion obtained after fusing two Majorana zero modes: as long as it remains on the superconductor, charge quantization is absent. When moving the fermion to a non-superconducting region, such as a quantum dot, nearly-quantized charge can be measured. Our findings confirm for both platforms that fusion dynamics of Majorana zero modes can indeed be used for the readout of Majorana qubits. - oai:arXiv.org:2503.09800v2 - cond-mat.mes-hall - cond-mat.supr-con - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/2qxk-wbs6 - Phys. Rev. B 113, 035429 (2026) - Themba Hodge, Tuan Kieu, Jasmin Bedow, Eric Mascot, Dirk K. Morr, Stephan Rachel - - - Bose-Einstein condensation in exotic lattice geometries - https://arxiv.org/abs/2505.16885 - arXiv:2505.16885v2 Announce Type: replace-cross -Abstract: Modern quantum engineering techniques allow for synthesizing quantum systems in exotic lattice geometries, from self-similar fractal networks to negatively curved hyperbolic graphs. We demonstrate that these structures profoundly reshape Bose-Einstein condensation. Fractal lattices dramatically lower the condensation temperature and enhance condensation fluctuations. In a Sierpi\'nski carpet, quasi-degeneracies in the tight-binding spectrum fragment the condensate. Hyperbolic lattices, on the other hand, exhibit condensation features similar to regular three-dimensional lattices, despite their embedding in only two dimensions: The critical temperature increases as the system grows, and the temperature-dependence of the condensate fraction follows the same power-law as for cubic lattices. We explain these similarities through the similarity of the densities of state at low energies. When strong repulsive interactions are included, the gas enters a Mott insulating state. Using a multi-site Gutzwiller approach as well as a simple strong-coupling expansion, for the Sierpi\'nski triangle we find a smooth interpolation between the characteristic insulating lobes of one-dimensional and two-dimensional systems. Our findings establish lattice geometry as a powerful tuning knob for quantum phase phenomena and pave the way for experimental exploration in photonic waveguide arrays and Rydberg-atom tweezer arrays. - oai:arXiv.org:2505.16885v2 - cond-mat.quant-gas - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/dp1h-rfkg - Phys. Rev. A 113, 013320 (2026) - Kamil Dutkiewicz, Marcin P{\l}odzie\'n, Abel Rojo-Franc\`as, Bruno Juli\'a-D\'iaz, Maciej Lewenstein, Tobias Grass - - - Floquet Non-Bloch Formalism for a Non-Hermitian Ladder: From Theoretical Framework to Topolectrical Circuits - https://arxiv.org/abs/2507.23744 - arXiv:2507.23744v2 Announce Type: replace-cross -Abstract: Periodically driven systems intertwined with non-Hermiticity opens a rich arena for topological phases that transcend conventional Hermitian limits. The physical significance of these phases hinges on obtaining the topological invariants that restore the bulk-boundary correspondence, a task well explored for static non-Hermitian (NH) systems, while it remains elusive for the driven scenario. Here, we address this problem by constructing a generalized Floquet non-Bloch framework that analytically captures the spectral and topological properties of time-periodic NH systems. Employing a high-frequency Magnus expansion, we analytically derive an effective Floquet Hamiltonian and formulate the generalized Brillouin zone for a periodically driven quasi-one-dimensional system, namely, the Creutz ladder with a staggered complex potential. Our study demonstrates that the skin effect remains robust (despite the absence of non-reciprocal hopping) across a broad range of driving parameters, and is notably amplified in the low-frequency regime due to emergent longer-range couplings. We further employ a symmetric time frame approach that generates chiral-partner Hamiltonians, whose invariants, when appropriately combined, account for the full edge-state structure. To substantiate the theoretical framework, we propose a topolectrical circuit (TEC) that serves as a viable experimental setting. Apart from capturing the skin modes, the proposed TEC design faithfully reproduces the presence of distinct Floquet edge states, as revealed through the voltage and impedance profiles, respectively. Thus, our work not only offers a theoretical framework for exploring NH-driven systems, but also provides an experimentally feasible TEC architecture for realizing these phenomena stated above in a laboratory. - oai:arXiv.org:2507.23744v2 - cond-mat.mes-hall - cond-mat.other - physics.app-ph - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - 10.1103/s3b6-wz16 - Phys. Rev. Research 7, 043331 (2025) - Koustav Roy, Dipendu Halder, Koustabh Gogoi, B. Tanatar, Saurabh Basu - - - Quantum Bootstrap Approach to a Non-Relativistic Potential for Quarkonium systems - https://arxiv.org/abs/2508.02916 - arXiv:2508.02916v3 Announce Type: replace-cross -Abstract: The quantum bootstrap method is applied to determine the bound-state spectrum of Quarkonium systems using a non-relativistic potential approximation. The method translates the Schr\"odinger equation into a set of algebraic recursion relations for radial moments $\langle r^m \rangle$, which are constrained by the positive semidefiniteness of their corresponding Hankel matrices. The numerical implementation is first validated by calculating the $1S$ and $1P$ mass centroids for both charmonium ($c\bar{c}$) and bottomonium ($b\bar{b}$) systems, finding deviations of less than 0.5\% from experimental data from the Particle Data Group (PDG). This analysis is then extended to the hypothetical toponium ($t\bar{t}$) system, predicting a $1S$ ground state mass of $M \approx 344.3 \text{ GeV}$. This theoretical mass is in agreement with the energy of the recently observed resonance-like enhancement in the $t\bar{t}$ cross-section by the ATLAS and CMS collaborations. This result provides theoretical support for the interpretation of this experimental phenomenon as the formation of a quasi-bound toponium state and highlights the predictive power of the non-relativistic potential approach for systems of two massive quarks. - oai:arXiv.org:2508.02916v3 - hep-ph - hep-lat - hep-th - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://creativecommons.org/licenses/by/4.0/ - Jairo Alexis Lopez, Carlos Sandoval - - - Non-Abelian Statistics for Bosonic Symmetry-Protected Topological Phases - https://arxiv.org/abs/2508.12444 - arXiv:2508.12444v4 Announce Type: replace-cross -Abstract: Symmetry-protected non-Abelian (SPNA) statistics opens new frontiers in quantum statistics and enriches the schemes for topological quantum computing. In this work, we propose a new paradigm of SPNA statistics in one-dimensional correlated bosonic symmetry-protected topological (SPT) phases and uncover exotic universal features from a systematic investigation. In particular, we show that for generic bosonic SPT phases described by real Hamiltonians, the SPNA statistics of topological zero modes fall into two distinct classes. The first class exhibits conventional braiding of hard-core bosonic zero modes. Furthermore, we discover a second class of unconventional braiding statistics characterized by a nonlinear transformation, featuring a fractionalization of the first class and reminiscent of the non-Abelian statistics of symmetry-protected Majorana pairs. The two distinct classes of statistics have topological origin in classifying non-Abelian Berry phases for braiding processes of real-Hamiltonian systems, distinguished by whether the holonomy involves a reflection operation. To illustrate, we focus on a specific bosonic SPT phase with particle-hole symmetry, and demonstrate that both classes of braiding statistics can be feasibly realized in a tri-junction with and without the aid of a controlled defect, respectively. Analytic and numerical results are given. We demonstrate how to encode logical qubits and implement both single- and two-qubit gates using the two classes of SPNA statistics. Finally, we propose feasible experimental schemes to observe these predictions and identify the parameter regimes for the high-fidelity braiding, paving the way for the experimental observation of our results in the near future. - oai:arXiv.org:2508.12444v4 - cond-mat.str-el - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Hong-Yu Wang, Bao-Zong Wang, Jian-Song Hong, Xiong-Jun Liu - - - TeMFpy: a Python library for converting fermionic mean-field states into tensor networks - https://arxiv.org/abs/2510.05227 - arXiv:2510.05227v2 Announce Type: replace-cross -Abstract: We introduce TeMFpy, a Python library for converting fermionic mean-field states to finite or infinite matrix product state (MPS) form. TeMFpy includes new, efficient, and easy-to-understand algorithms for both Slater determinants and Pfaffian states. Together with Gutzwiller projection, these also allow the user to build variational wave functions for various strongly correlated electron systems, such as quantum spin liquids. We present all implemented algorithms in detail and describe how they can be accessed through TeMFpy, including full example workflows. TeMFpy is built on top of TeNPy and, therefore, integrates seamlessly with existing MPS-based algorithms. - oai:arXiv.org:2510.05227v2 - cond-mat.str-el - cond-mat.mes-hall - cond-mat.supr-con - physics.comp-ph - quant-ph - Fri, 23 Jan 2026 00:00:00 -0500 - replace-cross - http://arxiv.org/licenses/nonexclusive-distrib/1.0/ - Simon H. Hille, Attila Szab\'o -