Quantum Physics · Cross-listed from hep-th
Iterative Gauging is Deconstruction
Sebastian Franco and Diego Rodriguez-Gomez
A recent construction showed that iteratively gauging
symmetries of a
quantum field theory can generate an emergent extra spatial dimension. Here we identify the precise mechanism underlying this phenomenon: it is dimensional deconstruction, the procedure by which an extra dimension is encoded in the structure of a quiver gauge theory. We demonstrate this by showing that the standard deconstruction action, upon dualizing the Goldstone fields on the
Higgs branch, is exactly equivalent to the action produced by iterative gauging. The dictionary is transparent: quiver nodes correspond to gauge fields, and quiver links correspond to the gauge fields introduced to couple to
magnetic symmetries. We further show that starting by gauging the electric rather than the
magnetic symmetry produces the deconstructed theory written in the dual variables, with all coupling constants inverted.
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Quantum Physics
Quantum Information Decoupling Beyond Finite Dimensions
Hayata Yamasaki
Quantum information decoupling is a pillar of
quantum information theory, underlying
quantum communication, error correction, and information recovery. However, its existing formulations rely on random
unitary operations tied to finite-dimensional assumptions on
quantum systems. Here we establish a decoupling framework for arbitrary separable, possibly infinite-dimensional systems. For finite-dimensional inputs and arbitrary separable reference/output systems, we derive error bounds on one-shot decoupling for completely positive maps in terms of sandwiched Rényi conditional
entropies. For partial-trace decoupling with finite-dimensional references, the error exponent is optimal up to the known critical rate. To handle infinite-dimensional inputs, we assume finite
entropy of the manipulated system. We construct finite-rank projections on independent and identically distributed (IID) states to restrict randomization to a projected finite-dimensional subspace, while ensuring high success probability by including auxiliary components in the discarded subsystem at asymptotically negligible cost. This leads to an infinite-dimensional IID partial-trace decoupling protocol achieving optimal asymptotic dimension rates. As an application, we construct an infinite-dimensional
quantum-state-merging protocol, a mother protocol of
quantum information theory. Under finite
entropy of Alice's marginal, it achieves the same
quantum-communication and total-cost rates as in finite dimensions, governed by mutual information and conditional
entropy. These results show that the operational interpretation of entropic quantities through these achievable rates constitutes a universal principle beyond finite dimensions. More broadly, our framework provides foundational tools for exploring
quantum information regardless of whether we model the physical world using finite- or infinite-dimensional spaces.
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Quantum Physics · Cross-listed from hep-ph
Qubit-qubit-qutrit quantum correlations in $H \to f \bar f V$
Michał Banacki, Misaki Ohta, Abhyoudai S. Shaleena et al. (+5 more)
We perform an extensive analysis of the
quantum correlations carried by the
qubit-
qubit-qutrit pure state arising in the decay of a massive scalar into a
fermion-antifermion pair and a massive gauge
boson, $H \to f \bar f V$, specialising to the
Higgs boson decay $h \to \tau^- \tau^+ Z$. Working with the exact tree-level
spin state and its systematic expansion around the massless-
fermion limit, we obtain analytic control over the entire phase space: the bipartite
entanglement measures, the genuine $2 \otimes 2 \otimes 3$
entanglement structure (the Miyake classification), as well as the Bell-inequality violations and the non-stabiliserness (magic) are all mapped and reproduced by compact formulas. The bipartite measures exhibit a monogamy-like trade-off between the
fermion pair and the
fermion-
boson pairs. The state is genuinely $2 \otimes 2 \otimes 3$ entangled over almost the entire phase space, most strongly in the collinear regions. We derive, for the first time, semi-analytical expressions for the tight $4 \times 4 \times 2$ Bell inequalities of the $2 \otimes 2 \otimes 3$ system, generalising the optimisation previously available only for three
qubits, and find that the local-hidden-variable bound is violated over the entire phase space, reaching within a few per cent of the
quantum bound at the upper endpoint of the di-tau mass spectrum. We further extend the stabiliser Rényi
entropy and the non-local magic to systems with unequal local dimensions, and show that the near-endpoint state carries almost exactly one bit of non-local magic, which peaks at $\log_2 \frac{27}{7} \simeq 1.95$ in the collinear regions. The differential decay rate concentrates precisely in the most nonclassical region of the phase space.
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All authors Michał Banacki, Misaki Ohta, Abhyoudai S. Shaleena, Paweł Caban, Michał Eckstein, Kazuki Sakurai, Michael Spannowsky, Paweł Horodecki
Quantum Physics · Cross-listed from physics.chem-ph
Where to Find ICEC? - Screening 2442 Systems for Interparticle Coulombic Electron Capture
Fabian L. Hofmann, Elena M. Jahr and Elke Fasshauer
Interparticle Coulombic Electron Capture (ICEC) provides an environment-assisted pathway for electron attachment that can compete with photorecombination. Here, we present the first comprehensive survey of ICEC in atom-atom and atom-molecule systems, screening 2442 combinations in search of promising candidates for future experimental investigation. We employ the efficient asymptotic approximation to predict ICEC cross sections and electron spectra. Intramolecular
nuclear motion is included, while interparticle
nuclear dynamics is neglected to permit an extensive survey. We identify several classes of atom-atom and atom-molecule systems with favourable ICEC cross sections and ICEC-to-photorecombination ratios, including halogen-halide systems and systems involving a
proton and diatomic molecules such as N$_2$, O$_2$, CO, and NO. These findings point to atmospheric and astrochemical environments in which ICEC may be relevant.
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Quantum Physics
Exact Conditional Momentum Moments for Nonlinear Homodyne Trajectories
Jacob Emerson
Simulation of nonlinear
stochastic master equations generally requires trajectory-level
evolution of large
Hilbert-space density
matrices, making strongly nonlinear continuously monitored systems computationally challenging. Here we identify an exactly solvable class centered on
polynomial Hamiltonians of commuting quadratures with linear damping and homodyne measurement of those same quadratures. For initial states with a Gaussian measured-quadrature marginal and
polynomial conditional-momentum sections, we derive an exact finite
stochastic representation through any fixed momentum order. The result extends to interacting multimode systems, arbitrary measurement efficiency, and finite thermal occupation. Its computational cost is linear in trajectory length and independent of
Hilbert-space dimension, requiring no Fock-space truncation, Gaussian approximation, or approximate moment closure. As an application, we derive an exact causal filter for monitored cubic-phase gates that uses the homodyne record to determine the variance-minimizing momentum displacement. Numerical simulations validate the representation against direct
stochastic-master-equation
evolution, demonstrate substantial speedups over converged Fock-space propagation, and show that this record-conditioned recentering can efficiently recover nonlinear squeezing otherwise lost through trajectory averaging.
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Quantum Physics
Path integral approach to the truncated Wigner approximation of driven-dissipative spins
Viktoria Noel, Michael Fleischhauer and Igor Lesanovsky
Phase-space approaches such as the truncated Wigner approximation (TWA) provide an efficient semiclassical framework for performing approximate simulations of the dynamics of open
quantum many-body systems outside the reach of exact numerical methods but beyond the mean-field level. For bosonic systems, TWA is known to be equivalent to a Keldysh path-integral formulation truncated at second order in the so-called
quantum fluctuations. This semiclassical approach provides an alternative transparent route towards approximate
stochastic equations of motion, which can be efficiently solved. Here we establish the corresponding path-integral formulation for interacting open
spin-$1/2$ systems using the continuous $\mathrm{SU}(2)$ phase space. We show, in particular, that a consistent treatment of dissipation requires correctly mapping operator products onto the curved
spin phase space, leading to
stochastic equations that coincide with those obtained from the continuous TWA formulation and thus reproduce the exact dynamics of a single dissipative
spin. Our results provide a unified field-theoretic foundation for the TWA to dissipative
spin dynamics and offer a systematic starting point for extensions beyond the semiclassical approximation.
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Quantum Physics · Cross-listed from math.CO
A Spectral Proof of the Hypergraph Moore Bound
Alexander Schmidhuber and Matthew B. Hastings
A nonempty subfamily of a $k$-uniform hypergraph is an even cover if every vertex lies in an even number of its hyperedges; for $k=2$ these are edge-disjoint unions of cycles, so the minimum size of an even cover is the natural hypergraph analogue of girth. We prove Feige's 2008
conjecture on the hypergraph Moore bound: there are absolute constants $A$ and $C$ (independent of $k$) such that for every $k\ge3$ and every $1\le\ell\le n$, any $k$-uniform hypergraph on $n$ vertices with more than $C\,n^{k/2}/\ell^{k/2-1}$ hyperedges contains an even cover of size at most $A\,\ell\log(en/\ell)$. Our proof is based on sharp spectral bounds for Kikuchi
matrices, which we expect to be of independent interest; we apply them to the refutation of random constraint satisfaction problems in a companion paper.
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Quantum Physics · Cross-listed from cond-mat.mes-hall
Wayne M. Witzel, Jesse J. Lutz, Matthew D. Grace et al. (+3 more)
The dynamics of a
nuclear spin bath generates
magnetic noise that is a key contributor to the decoherence of electron
spin qubits in electrostatically-defined
quantum dots. In this paper, we extend the cluster correlation expansion (CCE) technique, which has proven useful for predicting solid-state
qubit coherence times across various settings but is limited to shorter time scales, to incorporate
stochastic treatments of cluster dynamics in order to efficiently predict slow drifting Overhauser fields over longer time scales. This approach combines
quantum evolution with classical rate
matrices to enable simulation across a wide range of temporal regimes required to simulate, for example, the long-time convergence of the ergodic $T_2^*$ from Ramsey experiments. Our methodology is validated against experimental data from various silicon
spin qubit systems, demonstrating a strong agreement between simulation and measurement of Ramsey experiments presented in the form of $T_2^*$ versus averaging time, autocorrelation functions, as well as power spectral densities. Furthermore, we demonstrate significant back-action effects through modeling and experiment; specifically, the dynamics of the
nuclear spin bath depends upon the electron
spin occupation schedule. Finally, our modeling quantitatively predicts the benefits from compensating for the slow drift of Overhauser fields in
qubit operations. Our findings indicate that compensating for an Overhauser rotation measured $\Delta t$ in the past results in an effective $T_2^*$, which we denote $\tilde{T}_2^*(\Delta t)$ for clarity, under certain scenarios of interest, can be one or two orders of magnitude larger than the ergodic $T_2^*$ if the Overhauser rotation is re-characterized every 100 milliseconds; that is, $\tilde{T}_2^*(\Delta t = 100~{\rm ms})$ can be $10$ to $100$ times larger than $T_2^*$.
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All authors Wayne M. Witzel, Jesse J. Lutz, Matthew D. Grace, Natalie D. Foster, Ryan M. Jock, Dwight R. Luhman
Quantum Physics · Cross-listed from hep-th
Krylov-Space Memory Cores
Mohsen Alishahiha and Mohammad Javad Vasli
We introduce Krylov-space
memory cores as stationary, depth-resolved structures that reveal how anomalous initial-state
memory is organized inside the Krylov space of otherwise thermalizing nonintegrable systems. The stationary occupation profile identifies where late-time probability is concentrated along the Krylov chain, while complementary diagnostics of residual equilibration fluctuations, deviation from the Gibbs reference, and long-time Krylov-current fluctuations determine the physical character of that region. Across weak thermalization, confinement-induced anomalous dynamics, and many-body scarring, anomalous initial states develop compact low-depth
memory cores that carry appreciable residual fluctuations, Gibbs mismatch, and persistent current-fluctuation activity. These cores are often embedded within substantially broader stationary occupation
halos. The reference states considered, by contrast, do not exhibit a comparable combination of signal strength and spatial compactness. An auxiliary integrable comparison further shows that compact Krylov
memory is state selective rather than a generic consequence of integrability. Krylov-space
memory cores therefore provide a stationary framework for identifying where structured
quantum memory resides and how it remains dynamically encoded.
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Quantum Physics
Observable Estimation in the Absence of Classical Verification
Samantha V. Barron, Bradley Mitchell, Vinay Tripathi et al. (+45 more)
The predictive success of
quantum mechanics underpins many areas of modern science, even as the exact simulation of large, interacting
quantum systems remains beyond the reach of classical computation. This success has been enabled by the remarkable advancement of scalable numerical approximation methods, which often demonstrate practical accuracy despite the absence of formal guarantees. As
quantum simulation pushes into regimes where these approximations struggle, a fundamental challenge arises: How can
quantum outcomes be trusted when reliable classical
benchmarks are unavailable? Here, we establish a framework for the independent validation of
quantum estimates in this setting and present evidence that they provide the most credible result among several considered methods, in the absence of an immediately accessible ground-truth solution. We apply our framework to the semi-scrambling dynamics of a physical model that strains several leading classical simulation methods yet remains experimentally accessible, in part through our introduction of the operator Loschmidt echo. We systematically design a series of experiments using
quantum heuristics that, taken together, test the underlying assumptions and provide strong confidence in the observable estimates obtained from the
quantum computer. We then show how this framework can be extended to place accuracy bounds on
quantum estimates via careful characterization and manipulation of the device noise, transforming the problem of validating the observable estimation to validating the noise model. These results establish a route towards trusted
quantum computation for scientific discovery, independent of classical verification.
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All authors Samantha V. Barron, Bradley Mitchell, Vinay Tripathi, Francesco Grieco, Ilan Rosen, Francesca Pietracaprina, Davide Materia, Alireza Seif, Darvin Wanisch, Ramón L. Panadés-Barrueta, Ewout van den Berg, Jay-U Chung, Andrew Eddins, Sam Ferracin, Guillermo García-Pérez, John Goold, Luke C. G. Govia, Holger Haas, Ian Hincks, Jesse C. Hoke, Zoë Holmes, Su-un Lee, Youngseok Kim, Swarnadeep Majumder, Sabrina Maniscalco, Simone Montangero, Daniel Puzzuoli, Tomaž Prosen, James Raftery, Ricardo Rivera Cardoso, Max Rossmannek, Manuel Rudolph, Brendan Saxberg, Liran Shirizly, Karthik Siva, Joshua Skanes-Norman, Ilaria Siloi, Kevin C Smith, Boris Sokolov, Maika Takita, Yanting Teng, Mao Tian Tan, Joseph Tindall, Zoltán Zimborás, Matteo A.C. Rossi, Minh C. Tran, Sergei N. Filippov, Abhinav Kandala
Quantum Physics · Cross-listed from cond-mat.stat-mech
Samuel H. Pickering, Max McGinley, Bhavik Kumar et al. (+1 more)
Influence
matrices encode the action exerted on local subsystems by the rest of an extended
quantum many-body system during their
evolution. Thus, knowledge of the influence
matrix facilitates computationally efficient simulations of local dynamics. Here we propose a new systematic approach to generating
quantum circuits with complex dynamics for which the influence
matrices can be written down exactly. In contrast to previous frameworks of this kind, such as dual-
unitary circuits, the resulting influence
matrices are non-Markovian, exhibiting nontrivial temporal correlations. We explicitly construct a broad family of
circuits of this kind, based on dressing free-
fermion (matchgate)
circuits with appropriately chosen interaction terms. We show that, contrary to previous solvable instances, these
circuits produce patterns of correlations that closely resemble that of typical many-body systems. Our approach can be directly interpreted in terms of an error correction scheme where the terms breaking the solvability of the influence
matrices play the role of errors.
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All authors Samuel H. Pickering, Max McGinley, Bhavik Kumar, Bruno Bertini
Quantum Physics
Equi-Entropic Maps for Four-Partite Quantum States
Wojciech Bruzda and Zahra Raissi
Absolutely maximally entangled states represent a highly constrained form of multipartite
entanglement and play an important role in
quantum information theory. We investigate a weaker form of uniformity of
entanglement for four-party systems of local dimension $d>2$ that requires the three balanced bipartitions to have equal but not necessarily maximal linear
entropy. We introduce a linear map $\Xi$ that enforces exact equality of
entropies under reshuffling and partial transposition. The transformation arises as the asymptotic limit of an iterative averaging procedure and admits a group-theoretic description in terms of permutations of tensor indices. For Haar-random
unitary inputs, a leading-moment analysis supported by numerical simulations predicts highly entangled outputs whose common
entropy approaches the maximal value as the local dimension grows. We characterize the algebraic structure, fixed points, and asymptotic behavior of this map and its relation to two-
unitary matrices and orthogonal Latin squares.
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Quantum Physics
Sampling hard circuits with verifiably high fidelity
Simon Martiel, Jay-U Chung, Alireza Seif et al. (+9 more)
Sampling-based proposals are prominent candidates for demonstrating
quantum computations beyond the reach of classical supercomputers. However, it has been difficult to combine their complexity-theoretic hardness with two capabilities needed for scalable
quantum computing more generally: suppressing hardware errors, and verifying the
quantum computation itself. Here we address both issues by introducing structured
circuits, which, in addition to provable hardness guarantees, admit an encoding in a
quantum code. This allows us to simultaneously reach high fidelities at high
circuit depths, and to certify an experimental fidelity via the
circuit structure and measurement of code syndromes. The resulting certificate is device dependent, but requires substantially weaker noise assumptions than existing fidelity proxy
benchmarks. We demonstrate our proposal with a $64$-
qubit, depth-$73$ Clifford
circuit, doped with $314$ $T$ gates. We use a total of $76$ physical
qubits to encode this computation in spacetime codes, effectively suppressing gate error rates by $10\times$ after syndrome post-selection, and yielding a state with a fidelity lower bound of $0.349$ with $95\%$ confidence. Our construction is a systematic method for promoting a stabilizer state to a magic state while keeping an error-detected fidelity certificate.
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All authors Simon Martiel, Jay-U Chung, Alireza Seif, Soumik Ghosh, Ian Hincks, Abhinav Deshpande, Hidetaka Manabe, Hanfeng Gu, Feng Pan, Bill Fefferman, Jay M. Gambetta, Ali Javadi-Abhari
Quantum Physics · Cross-listed from cond-mat.stat-mech
Interacting hydrodynamic modes in spinless fermions with dephasing noise
Fabian H.L. Essler and Patrik Penc
We study the non-
equilibrium dynamics of spinless
fermions with dephasing noise in the framework of a many-particle Lindblad equation. Using a mapping to the exactly solvable one-dimensional Hubbard model with purely imaginary tunneling amplitude we analyze the Heisenberg-picture dynamics of operators quartic in
fermions and determine their hydrodynamic projections. We construct the relevant diffusive eigenoperators explicitly and show that, in the quartic sector, they can be interpreted as interacting pairs of bilinear hydrodynamic modes. As a consequence, translationally invariant quartic operators generically exhibit non-vanishing diffusive late-time tails, unlike translationally invariant bilinears. Our results show that the hydrodynamic tails of microscopic operators cannot in general be inferred from
symmetry constraints or coarse-grained fluctuating hydrodynamics alone; they also depend crucially on the spatial structure and effective size of the hydrodynamic eigenoperators.
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Quantum Physics
Effect-valued measurement models and contextuality
Samson Abramsky
We generalize the Abramsky–Brandenburger sheaf-theoretic treatment of contextuality by replacing probability distributions with distributions valued in a convex effect
algebra \(A\). This yields a notion of \(A\)-valued measurement model encompassing probabilistic, deterministic, and
quantum measurement structures within a single framework. States \(\sigma:A\to[0,1]\) induce ordinary empirical models, allowing observable behaviour to be viewed as arising from effect-valued measurement data. This leads to a distinction between internal contextuality of \(A\)-models and observable contextuality after state evaluation. We analyze the relationship between these notions and identify coherence conditions under which observable classical explanations assemble into internal ones. Using the ordered-vector-space representation of effect modules, we show that non-contextuality is characterized by feasibility of an associated cone program, generalizing the linear-programming formulation of contextuality in the probabilistic case. We also introduce an effect-valued contextual fraction and study its relation to observable contextuality witnesses. We show how cone duality leads to a notion of Bell witnesses for contextuality as a direct generalization of Bell inequalities. Finally, we analyze sharp realizability and uniform dilation for measurement models, clarifying the relationship between general POVMs and projective measurements, and show how resource-indexed effect structures induce graded monads generalizing the
quantum monad.
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Quantum Physics
When Quantum States over Spacetime Have No Common Process
Jianqi Sheng
Determining whether observations across spacetime arise from one
quantum process is central to causal inference and to consistent observer-relative descriptions. For
quantum-state-over-spacetime (QSOST) data, this remains obstructed because causally agnostic interferometry compresses process
matrices: every setting can appear physical although its hidden positive completions cannot be glued to a common parent. We formulate this as an inverse positive-lift problem and solve it exactly. Each positive-weight QSOST branch has a unique least positive lift, yielding a data-only common-parent criterion. We prove that settingwise realizability implies common-process realizability for every finite family if and only if the QSOST projection is injective on deterministic processes. Thus any normalized information loss can be exposed as a strict gluing failure. For bipartite
qubits we identify a $63$-dimensional hidden fiber and construct definite-order separations, including a minimal two-setting, two-outcome example with exact noise threshold $\eta=1/\sqrt2$ and a sparse interferometric witness. Under explicit causal-access conditions, we also derive exact delayed fact-inference limits and identify the minimal environment; restoring full access removes only the pre–post gap. These results identify the boundary between spacetime
tomography and global process composition, turning hidden process incompatibility into an experimentally testable phenomenon.
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Quantum Physics
OmniQEC: discovering practical quantum error-correcting codes by an AI scientist
Ge Yan, Shanchuan Li, Pengyue Ma et al. (+5 more)
Quantum error correction (QEC) is indispensable for scalable fault-tolerant
quantum computing. However, discovering QEC codes that remain effective is challenging, as logical performance depends on the interplay between code structure, hardware, syndrome extraction, and decoding, which often impose competing requirements. Here we introduce OmniQEC, an efficient AI scientist for discovering QEC codes suited to deployment on modern
quantum processors. OmniQEC formulates QEC design as an iterative discovery process in which an orchestrator, implemented by advanced large
language models (LLMs), coordinates code generation, code-level screening, syndrome-extraction synthesis, and decoder-based
circuit evaluation. At its core, OmniQEC combines a self-evolving
reasoning mechanism with a slow–fast synergistic workflow: a fast loop explores candidates using inexpensive code-level proxies, whereas a slow loop performs physically grounded
circuit-level evaluation and feeds the resulting evidence back into the search. We evaluate OmniQEC across four qLDPC construction families, three LLM backends, and $14$ total-physical-
qubit budgets per backend. The discovered codes show steadily improving logical-error suppression with increasing physical-
qubit budgets and outperform the BB codes with $[\![72,12,6]\!]$ and $[\![144,12,12]\!]$ under complete-implementation budgets of 98 and 240 physical
qubits, respectively. The discovered codes are hardware-friendly and may be of independent interest for practical QEC implementation. These findings pave the way towards LLM-assisted QEC discovery grounded in physically informed code–
circuit–decoder co-design.
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All authors Ge Yan, Shanchuan Li, Pengyue Ma, Qixin Zhang, Pingchuan Ma, Jianping Wang, Min-Hsiu Hsieh, Yuxuan Du
Quantum Physics
Bipartite Bound Information Exists
Jef Pauwels, Nicolas Gisin and Renato Renner
There exist bipartite
quantum states that cost
entanglement to create, yet from which no singlet can be distilled. This extreme irreversibility is known as bound
entanglement. A quarter-century ago, Gisin and Wolf asked whether classical information theory admits the same phenomenon. Are there correlations, shared by two parties and an eavesdropper, that cost secret bits to create, yet from which none can be distilled? This question is part of a broader program exploring the relation between
quantum and classical information theory. We answer it in the affirmative, providing a simple example, a distribution of two bits and a trit. Bound
entanglement thus has a classical counterpart, bound information. An even more direct correspondence was originally conjectured, namely that measuring purifications of bound-entangled states yields distributions with bound information. The very states that motivated the
conjecture, however, yield no bound information when measured in the standard basis, whereas suitable measurements of purifications of separable states do. The analogy between bound
entanglement and bound information thus lies in the accounting of resources, not in a correspondence between individual
quantum states and the classical probability distributions induced by measuring them.
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Quantum Physics
Lowering the implementation barrier of neutral-atom quantum computing with agentic workflows
Constantin Dalyac, Alexandre Dauphin, Loïc Henriet et al. (+1 more)
Quantum computers are moving from research laboratories to industrial machines accessible via the cloud and integrated into high-performance computing facilities. However, translating theoretical
quantum protocols into hardware experiments remains a major bottleneck, requiring expertise across protocol design, compilation, simulation, and cloud execution. Here, we introduce an agentic workflow that automates this pipeline on neutral-atom
quantum processors (here two Pasqal QPUs available on the cloud) while keeping the researcher in the loop for critical validation. In three case studies from many-body physics and optimization, the
agent went from published paper or patent to a QPU campaign run overnight. In particular, human intervention was crucial to ensure scientific validity: the
agent selected an inadequate observable in one experiment and constructed a plausible but incorrect hardware diagnosis in another, with both failures detected only through domain-expert review. Finally, we use a second
agent to classify a corpus of 633 Rydberg-array arXiv papers and show that nearly half are implementable on present-day QPUs while identifying specific hardware upgrades needed for the rest. Together, these results demonstrate that agentic workflows provide a practical bridge between theoretical ideas and physical hardware, opening
quantum experimentation to a much broader scientific community.
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All authors Constantin Dalyac, Alexandre Dauphin, Loïc Henriet, Christophe Jurczak
Quantum Physics · Cross-listed from hep-th
Curved momentum space and finite Landau spectrum in $\kappa$-Minkowski spacetime
Adrián Huamán Vargas and Vladislav Kupriyanov
We derive the $\kappa$-Poincaré Casimir from the de Sitter geometry of momentum space and employ it as the dynamical constraint governing charged particles within the framework of Poisson gauge theory. The resulting formalism is applied to scalar and
spin-$1/2$ particles in a constant
magnetic field. Within the semiclassical Poisson-gauge framework, exact energy spectra are obtained without expanding in the deformation parameter $1/\kappa$. On the positive-energy branch in bicrossproduct momentum coordinates, identifying these coordinates with the physical momenta entering the gauge coupling imposes an upper bound on their spatial magnitude. This bound leads to a finite number of admissible Landau-level indices and hence to a Highest Landau Level (HLL). In the fermionic case, the truncation is
spin dependent for the factorization adopted here, resulting in a polarized HLL. Possible implications of this ultraviolet truncation and the limitations of the framework are briefly discussed.
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Quantum Physics
Optimal Quantum Eigenvalue Transformation via Linear Combinations of Hermitian Matrices
Yanqiao Wang, Yixuan Liang, Hongjia Chen et al. (+1 more)
We discover two complementary linear-combination-of-Hermitian-
matrices (LCHM) formulations to achieve a general non-normal
matrix eigenvalue transformation $g(A)$. Firstly, for $A=L+\mathrm{i} H$ with Hermitian $L$ and $H$, the vanilla LCHM formula represents $g(A)$ as a kernel integral of $g(\mathrm{i}(H+kL))$, and it contains linear-combination-of-
Hamiltonian-simulation (LCHS) [An, Liu, Lin, Phys. Rev. Lett. 2023] as the special case for
matrix exponentials. Secondly, for the angular Hermitian $X_\theta = \cos\theta L+\sin\theta H$, the Weyl LCHM formula expresses $g(A)$ via integrating $g(\mathrm{e}^{\mathrm{i}\theta} (X_\theta\pm\mathrm{i}(I-X_\theta^2)^{1/2}))$. For the
matrix power $g(A)=A^m$, the
Fourier projection of Weyl LCHM gives \[ A^m=\frac{2}{\pi}\int_0^\pi \text{e}^{\text{i} m\theta}T_m(X_\theta) \text{d}\theta = \frac{2}{N}\sum_{j=0}^{N-1} \text{e}^{\text{i} m\theta_j}T_m(X_{\theta_j}),\quad\theta_j=\frac{\pi j}{N},\quad \text{for every } N>m \] with Chebyshev
polynomial of Hermitian $T_m(X_\theta)$ and $N$ samples. The discrete formula is exact, introduces no truncation and angular quadrature error, and offers $\mathcal{O}(1)$ post-selection weights. LCHM formulas lead to new
quantum eigenvalue transformation (QET)
algorithms. For a degree-$d$
polynomial $p_d(A)$ on $|\psi\rangle$, our QET
algorithm can achieve optimal $\Theta(d)$
circuit depth and optimal $\mathcal{O}(||p_d||_{\infty}/||p_d(A)|\psi\rangle||)$ post-selection repetitions. LCHM-based QETs unify various
quantum linear algebraic problems with near-optimal $\mathcal{\widetilde O}(d\log(d/\epsilon))$ Clifford$+T$ gates, including driven ODEs (reduced to standard LCHS), iterative methods, resolvents, $\log(I+A)$, $(\lambda I+A)^\nu$, Sign and ReLU transforms, and Faber approximation on noncircular domains.
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All authors Yanqiao Wang, Yixuan Liang, Hongjia Chen, Jin-Peng Liu
Quantum Physics
On some potentials based on exponential functions
Francisco M. Fernández
By means of a simple and systematic normalization method we show that some apparently different potentials based on exponential functions are equivalent. Present normalization method only requires that the potential exhibits a minimum and is finite when the radial variable tends to infinity.
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Quantum Physics
Efficient Lindbladian Learning from Constant-Time Pauli Responses
Jiaxing Song, Yukun Zhang, Xiao Yuan et al. (+1 more)
Learning the generator of an open many-body system is more challenging than
Hamiltonian learning: local responses, which can directly reveal coherent interaction terms in closed-system dynamics, may also contain dissipative contributions in open-system dynamics. In this paper, we address this challenge by developing an efficient Lindbladian learning framework for a known local candidate generator dictionary with bounded dissipative support and either bounded dual-interaction-graph degree or bounded unweighted local strength. The framework resolves the coherent-dissipative ambiguity by treating local Pauli responses as a linear system over both types of generator terms. Inverting this response system separates their contributions and makes the individual Lindbladian coefficients accessible from local response data in a fixed short-time window. Within this framework, we develop two efficient learning
algorithms: Chebyshev–Lobatto response interpolation, which uses logarithmically many short
evolution times and has a post-mean cost linear in $M$, with the stated dependence on $\epsilon$, and Single-time projected response contraction, which uses a single fixed
evolution time and globally inverts a truncated response function. Both procedures estimate $M$ candidate coefficients to entrywise accuracy $\epsilon$ using $\widetilde{\mathcal{O}}(M/\epsilon^2)$ sample and classical post-processing complexity. Our theoretical results establish local response inversion as a scalable paradigm for learning, calibrating, and diagnosing complex
quantum systems from experimentally accessible short-time data.
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All authors Jiaxing Song, Yukun Zhang, Xiao Yuan, Yusen Wu
Quantum Physics · Cross-listed from physics.atom-ph
Near-deterministic loading of molecular arrays by microwave-assisted collisions
Etienne F. Walraven, Kang Feng, Jonas Rodewald et al. (+2 more)
Molecular tweezer arrays offer great prospects for
quantum simulation, sensing, and computing, and would benefit from methods that enhance loading efficiency. Whereas light-assisted collisions underpin enhanced loading methods for atomic tweezer arrays, this approach cannot be directly extended to molecular arrays due to collisional loss. We show how this collisional loss can be suppressed by shelving molecules in rotationally or vibrationally excited states, so that a shelved molecule interacts with a newly loaded molecule through a repulsive van der Waals interaction. By introducing microwave assisted collisions, we show how to control the final states and the energy released in a collision between a pair of molecules. Following this controlled collision, one of the two molecules can be ejected, and we explore several strategies for ensuring deterministic ejection. Our schemes rely on currently available techniques for
laser-coolable molecules, and we predict achievable filling fractions up to 96%, paving the way for scalable molecular arrays.
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All authors Etienne F. Walraven, Kang Feng, Jonas Rodewald, Michael R. Tarbutt, Tijs Karman
Quantum Physics
Exponential de Finetti Theorems for Fermionic Gaussian States
Jędrzej Burkat, Michał Studziński and Sergii Strelchuk
We prove an exponential variant of the Gaussian de Finetti
theorem: the subsystems of permutation-invariant, free-fermionic Gaussian states are well approximated by convex combinations of almost-i.i.d. states that are Gaussian on subsets of their parts. Our result provides an error bound between the original state and its approximants that decays exponentially in the number of unconstrained parts, becoming super-exponential when the subsystem under consideration is small. The dependence of our bound on the local
Hilbert space dimension is polylogarithmic, giving an exponential improvement over the standard de Finetti
theorem of [Nat. Phys. 3, 645-649]. Previous works considered Gaussian-symmetric states, which are supported on the trivial irrep of the tensor matchgate representation. We extend these results to the broader class of Gaussian-invariant states, which contains, for example, i.i.d. copies of single-replica mixed Gaussian states. We show that Gaussian-invariant states are precisely the partial traces of Gaussian-symmetric states on locally enlarged replicas and always admit a purification into a larger Gaussian-symmetric state. As an application, we derive explicit convergence bounds for a hierarchy of convex relaxations of
polynomial optimisation over fermionic Gaussian states. For variational energy minimisation, the hierarchy gives lower bounds converging to the global Gaussian minimum. Combined with upper bounds from Gaussian trial states, these bounds quantify how far a variational calculation can be from the best energy attainable within the Gaussian family.
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Quantum Physics · Cross-listed from cond-mat.quant-gas
Tunable state-dependent interactions in collisionally stable mixtures of polar molecules
Hubert J. Jóźwiak, Hanwei Yang, Eugen Dizer et al. (+2 more)
We propose encoding a pseudo-
spin-$1/2$ system in the ground ($v=0$) and first excited ($v=1$) vibrational states of polar molecules. Double microwave shielding simultaneously shields molecules in both states, suppressing two-body losses by orders of magnitude while strictly avoiding three-body recombination. The microwave dressing is state-dependent and results in highly tunable, long-range dipolar Ising exchange ($J_z$), density-density ($V$), and
spin-density ($W$) interactions. These interaction length scales readily exceed the typical interparticle spacing, pushing the molecules deep into the strongly interacting regime. In bulk gases, this enables the exploration of itinerant
quantum magnetism and
quantum droplets with novel anisotropic
spin textures; in optical
lattices, it naturally realizes extended Hubbard and $t$-$J_z$ models, opening new directions in
quantum simulation.
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All authors Hubert J. Jóźwiak, Hanwei Yang, Eugen Dizer, Arthur Christianen, Tijs Karman
Quantum Physics · Cross-listed from cond-mat.quant-gas
Ro-vibrational van der Waals interaction between ultracold polar molecules
Kang Feng, Hanwei Yang, Hubert J. Jóźwiak et al. (+1 more)
We describe the ro-vibrational van der Waals interaction between ultracold polar molecules. This interaction is strong, leading to fast elastic collisions and orders of magnitude suppression of collisional loss. This enables evaporative cooling of
Fermi mixtures of molecules in different ro-vibrational states, without active shielding by applying external fields. The scheme is compatible with microwave shielding, where it enables controlled state dependent interactions, opening up new opportunities for
quantum simulation and
impurity physics. The interaction can also be used to stabilize fermionic molecules in optical
lattices, to control interactions in synthetic dimensions, for enhanced tweezer loading, and direct infrared shielding.
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All authors Kang Feng, Hanwei Yang, Hubert J. Jóźwiak, Tijs Karman
Quantum Physics
Classically Augmented Zero-Noise Extrapolation
Timon Scheiber
We investigate a hybrid
quantum-classical approach to
quantum error mitigation. We propose Classically Augmented Zero-Noise Extrapolation, a hybrid error-mitigation method in which high-noise Richardson extrapolation nodes are replaced by classically simulated estimates. These classical nodes have negligible sampling variance but introduce deterministic simulation bias. We derive the resulting variance reduction under optimal shot allocation and show that, for linear node spacings and fixed index cutoff, the coefficient-level reduction can be exponential. We validate the prediction numerically using Pauli-propagation simulations and demonstrate a reduction in mean-squared error when the truncation bias is sufficiently small.
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Quantum Physics
Verifiable blind probabilistic error cancellation
Bo Yang, Elham Kashefi and Harold Ollivier
Quantum error mitigation (QEM) is an essential tool for mitigating hardware noise without incurring space overhead. Yet, its reliability depends on modeling, calibration, and implementation, leaving end-to-end security on untrusted
quantum hardware unresolved. We address this problem by introducing verifiable blind probabilistic error cancellation (VBPEC), the first secure verification protocol against a fully malicious adversary that integrates QEM. VBPEC brings probabilistic error cancellation (PEC), a widely studied QEM technique, within the scope of composable security by formalizing delegated mitigation as a cryptographic resource in the abstract cryptography framework. The protocol performs PEC with perfect blindness and an exponentially small security error. VBPEC retains the absence of
quantum-space overhead from recent statistically-secure verified
quantum computation protocols and from PEC. The only overhead takes the form of additional repetitions due to the QEM procedure. To achieve this, we extend trap-based verification from deterministic pass/fail checks to statistical tests that benefit from QEM and develop a new proof technique that integrates the corresponding additional deviation sources. Rather than merely tolerating honest noise below a fixed threshold, VBPEC actively cancels it, enabling correctly mitigated estimates to be accepted with high probability without compromising security. Our framework thus establishes an essential route towards secure, reliable, and practical delegated
quantum computation on near-future
quantum hardware: VBPEC fundamentally improves the practicality of verification.
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Quantum Physics
Benchmarking Optical Receivers for Quantum Communication and Randomness Certification
Hamid Tebyanian
The choice of optical receiver determines which properties of the transmitted states remain visible in the observed data and therefore affects the performance of different
quantum protocols. We compare continuous-variable,
photon-counting and hybrid receivers within the same prepare-and-measure framework, using semi-device-independent randomness generation as the main case study. The measurement device is left uncharacterised, while the source is described by the Gram
matrix of its pure signal states using an energy-derived overlap constraint, a magnitude-Gram
benchmark or the full complex Gram
matrix of a certified coherent phase-shift-keyed constellation. Within this framework, the observed receiver statistics are used to bound $H_{\min}(B|X,\Lambda)$ against classical side information correlated with the measurement device but independent of the input. For a fixed Gram
matrix, this bound is obtained from an exact semidefinite program, with complex multi-input cases treated in block-real form and checked through the corresponding dual certificate.
Photon counting alone is phase blind for fixed-modulus phase encoding and therefore certifies no worst-case randomness. Continuous-variable receivers give the highest certified
entropy at moderate energy, while under the nominal source calibration a hybrid receiver performs better at low energy when the beacon-region label is retained in the output. The same receiver statistics also provide receiver-level comparisons for discrete-modulated continuous-variable
quantum key distribution,
quantum reading, covert communication and
quantum-signature verification, without replacing the full security analysis required for each protocol.
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