Quantum Physics
Identifying the Sign of Coherent Over-Rotations with Logarithmically Many Pauli Settings
Yi Pan, Meng Hsiu Tsai, Weihang You et al. (+6 more)
Calibrating a
quantum processor means estimating gate-error parameters from data, and a hard-to-estimate parameter is usually assumed to leave a weak signature more repetitions will resolve. Coherent over-rotations break that premise. For commuting single- and two-
qubit transverse over-rotations with known support on a computational-basis input, the passive histogram is exactly invariant under a sign group acting on the coherent angles, of order $2^{n+1}$ for the complete family with $n\ge2$, so no
estimator resolves the signs uniformly at any sample size. A calibration correction applied with the wrong sign doubles the rotation error it should remove. At zero angle the obstruction turns continuous, with a Fisher information singular along every coherent direction and an infinite Cramér-Rao bound. At generic angles the continuous defect clears for $5\le n\le8$, the range we compute, while the sign degeneracy persists. Covering the support removes both, and a design resolves the signed angles uniformly exactly when it covers. On $|\eta_R|<\pi/2$, $0\le p_R<1/2$ coverage is constructive, returning each angle in closed form from a ratio of two measured expectations without knowing the rates. A twirl-free code of $\lceil\log_2(n+1)\rceil$ added product-Pauli settings covers, and for the complete family none uses fewer. Conditioning then sets the Cramér-Rao cost, and we give its floor explicitly. Exact computation matches the theory, the passive fit stays at chance on the signs at every budget while the closed-form inverse recovers them, and angle magnitudes on two IBM Heron processors follow the conditioning ordering.
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All authors Yi Pan, Meng Hsiu Tsai, Weihang You, Hanqi Jiang, Junhao Chen, Wei Zhang, Isaac Lyngaas, Yingfeng Wang, Tianming Liu
Physics and Society
Reconstructing the Probability Measure of a Multi-group Curie-Weiss Model with Interacting Groups
Miguel Ballesteros, Gerardo Franco Cordova, Fedro Guillen et al. (+1 more)
We study the problem of reconstructing the probability measure of a multi-group version of the Curie-Weiss or mean-field model of ferromagnetism from a sample of the voting behaviour the population. While originally used to study phase transitions in statistical mechanics, the Curie-Weiss or mean-field model has been applied to study phenomena where many
agents interact with each other, in particular in case of a heterogeneous population with identifiable subpopulations. The degree of social cohesion within social groups manifests in the way the members of the group influence each others' decisions as well as how they behave under outside influence from voters belonging to another group. Contrary to single-group Curie-Weiss models, here we have a larger number of coupling parameters which have to be estimated. While the maximum likelihood
estimator of the coupling parameters has desirable statistical properties in theory, computational challenges make applications to larger populations impractical. Therefore, we analyse an
estimator based on asymptotic approximations to the behaviour of the Curie-Weiss model valid for large populations. Due to the wide applicability of models such as Curie-Weiss, the
estimator is potentially useful in disciplines such as political science, sociology, automated voting, and preference aggregation.
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All authors Miguel Ballesteros, Gerardo Franco Cordova, Fedro Guillen, Gabor Toth
High Energy Physics (Theory)
On the strong coupling limit of Yang-Mills matrix models
Adrien Martina and Harish Murali
We study the strong coupling limit of mass deformed Yang–Mills
matrix models, with the aim of understanding when the
matrices become effectively commuting. The Yang–Mills interaction classically drives the
matrices toward mutually commuting valleys, where the
matrices can potentially be interpreted as coordinates of an emergent space. However, taking into consideration the integration measure, commutativity is not automatic since the commuting locus is entropically suppressed, and in the bosonic models with $D\geq3$ the strong coupling limit remains non-commuting. We find that
fermions change this competition in a sharp way. As the number of fermionic degrees of freedom is increased, there is a critical value $\mathcal N_c=2(D-2)$, realized by the supersymmetric Yang–Mills
matrix models, at which the
matrices commute at strong coupling. The same critical models also exhibit universality under deformations by $O(N^2)$, or huge, operators: the normalized
eigenvalue densities are insensitive to the microscopic details of the huge operators. Increasing the number of
fermions beyond the critical point still gives commuting
matrices, but the huge-operator universality is lost. Thus commutativity and universality are related but distinct: the
matrix models with supersymmetric field content sit at the critical boundary where we have both.
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High Energy Astrophysical Phenomena
XMM-Newton and Swift Unveil Another X-Ray Transient in NGC 4945, XMM J130514.64-493311.27
Ryan W. Pfeifle, Kimberly A. Weaver, Jenna M. Cann et al. (+2 more)
NGC 4945 hosts a Compton-thick, low luminosity AGN and a
nuclear starburst in its core and has been the subject of many previous X-ray investigations of the AGN emission structure,
nuclear starburst properties, and ultraluminous X-ray (ULX) source populations. Indeed, NGC 4945 has proven to be a rich system for ULX and X-ray transients, with at least four X-ray transients being reported over the last 15 years. Here we report the detection of an X-ray transient source, XMM J130514.64-493311.27, in NGC 4945 in the latest and deepest XMM-Newton observation of NGC 4945 to-date. The source lies $\sim5.5'$ south of the
nucleus and was not detected in any previous XMM-Newton or Chandra imaging, but the source was detected by Swift-XRT in 2008, 2019, and in 2022, the latter of which coincides roughly with our new XMM-Newton imaging; we are therefore tracing the most recent outburst of this object with XMM-Newton. The source is soft with $\Gamma\approx3$, and our spectroscopic analysis suggests the source is best characterized by a multicolor disk + power law model or, alternatively, a multicolor disk + thermal
plasma model, with a 0.3-10 keV X-ray luminosity of $\sim2.2-2.3\times10^{38}$. We find no evidence for a counterpart in the optical, near-infrared, ultraviolet, or in the
radio, but we identify a candidate counterpart in NEOWISE mid-IR light curves. We propose that this X-ray source is an X-ray binary within NGC 4945 caught during its most recent active phase.
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All authors Ryan W. Pfeifle, Kimberly A. Weaver, Jenna M. Cann, Murray Brightman, Miranda McCarthy
High Energy Physics (Phenomenology)
Gauge coupling beta functions and gauge field anomalous dimensions at four loops in the Standard Model
M.A.Bezuglov, B.A.Kniehl and V.N.Velizhanin
We present the beta functions of the gauge couplings and the anomalous dimensions of the gauge fields in the unbroken phase of the Standard Model at four loops.
Quantum Physics
Flow-based Phase-space Tomography of Continuous-variable Quantum States
Owen Dugan, Rumen Dangovski, Peter Y. Lu et al. (+1 more)
Continuous-variable
quantum state
tomography is limited by the cost of resolving non-Gaussian structure in high-dimensional phase space. We introduce QST-Flow, a
quantum state
tomography framework via flow-based generative modeling that represents experimentally accessible phase-space quasiprobability distributions with normalized, samplable neural densities rather than a truncated density
matrix. The framework has two variants: QST-QFlow models the positive Husimi-$Q$ function with a single normalizing flow, while QST-WFlow models sign-changing Wigner functions as a trainable difference of two normalized flows. This construction preserves quasiprobability normalization and enables exact density evaluation, direct sampling, and importance-sampled learning from finite phase-space measurements without a fixed grid.
Benchmarks on non-Gaussian cat, binomial, Gottesman-Kitaev-Preskill, number, and Fock states show accurate single-mode reconstructions, extension to multimode states, robustness on noisy Wigner data, and improved reconstruction error compared with prior machine-learning
tomography methods. QST-Flow opens a promising route toward scalable, measurement-efficient phase-space
tomography of nonclassical bosonic systems.
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All authors Owen Dugan, Rumen Dangovski, Peter Y. Lu, Di Luo
Quantum Gases
Complexity transition in the Dicke model of light-matter interaction
Yicheng Zhang and Erhai Zhao
Tuning the coupling strength $g$ of an interacting
quantum system may drive a sudden change in its ground-state or thermal properties. To identify and grasp non-analytical, or even discontinuous, transitions in far-from-
equilibrium dynamics proves more challenging. Recently Krylov complexity $C_K$ has offered fresh insights about operator growth, thermalization, and chaos in
quantum dynamics. Yet it remains unclear if, and how, changing $g$ can trigger a sharp transition in the complexity measures. Here we present evidence for such a transition by mapping out the complexity phase diagram of the paradigmatic Dicke model describing two-level atoms coupled to a cavity
photon mode. Two qualitatively different regimes of dynamics are identified and characterized. At the transition, the slope of $C_K$ changes suddenly to coincide with a jump in the Krylov
entropy. We elucidate the nature of the regime change from the wave packet dynamics in Krylov space, where a particle is confined by a roughly linear potential but hops as if it lives in a Rindler reference frame. The competition between confinement, which leads to bouncing, and deconfinement by Rindler hopping, which leads to the destruction of wave packet analogous to gravitational spaghettification, is sensitive to the disorder in Lanczos coefficients. The framework outlined here can be applied to other
quantum many-body systems.
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Strongly Correlated Electrons
Ziwei Wang, Charlie Raca and Steven H. Simon
Quantum geometric quantities have featured heavily in the discussion of the properties of
quantum systems in recent years. Among quantities most commonly discussed is the variance of Berry
curvature and the integral of the trace of the
quantum metric tensor. Despite their usefulness, it is known that they suffer from one significant complication: for a tight-binding model, the
quantum geometric quantities depend not only on the parameters of the tight-binding model itself, but also the real space geometry of the tight-binding model, the so-called "orbital
embedding". One explicitly geometry-independent quantity is therefore the minimal value of the
quantum geometric quantity out of all possible real space geometries. In this work, we demonstrate that, if the tight-binding model is compatible with certain spatial
symmetries, then the real space geometry that minimizes the variance of the Berry
curvature or the integral of the trace of the
quantum metric tensor must obey all those spatial
symmetries. We further show that the statement is applicable to systems with
magnetic translation
symmetries and other composite
symmetries, with implications for the
quantum geometry of the Hofstadter model.
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Lattice Field Theory
Parallel Tempered Metadynamics for full QCD
Timo Eichhorn, Gianluca Fuwa, Christian Hoelbling et al. (+1 more)
We present an
algorithm that addresses topological freezing in
lattice QCD simulations by combining parallel tempering with collective-variable-based enhanced sampling methods, and apply it to a particularly challenging system with $N_f = 2$ staggered
fermions. We find that the
algorithm unfreezes the system, which is otherwise completely frozen for approximately 40000 Molecular Dynamics Units with the Rational Hybrid Monte Carlo
algorithm.
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All authors Timo Eichhorn, Gianluca Fuwa, Christian Hoelbling, Lukas Varnhorst
Quantum Physics
A geometric framework for spin relaxation
Sophia N. Fricke, Kieren A. Harkins, Ashok Ajoy et al. (+1 more)
Spin relaxation is conventionally described by two independent phenomenological rates - longitudinal ($R_1$) and transverse ($R_2$) - whose separation obscures a deeper structural unity. Here we develop a
geometric framework in which dissipation is represented by a single covariant relaxation tensor acting in Liouville space, from which $R_1$ and $R_2$ emerge as complementary projections. This tensor structure is not merely formal but is experimentally accessible through pulse sequences that probe noncommuting directions in
spin space. Using hyperpolarized $^{13}C$
spins in diamond with nitrogen-vacancy centers, we show that commuting pulse trains yield effective relaxation
matrices that are approximately diagonal, while noncommuting sequences produce off-diagonal components that vary with transmitter frequency offset and pulse ordering, providing evidence that relaxation is a directional process governed by a tensor rather than a pair of scalar rates. Complementary measurements of
geometric phase demonstrate that noncommuting dynamics introduce ordering-dependent effects that are separable from dissipation, consistent with the interpretation of relaxation as
geometric transport on the state
manifold. This framework unifies Bloch, Redfield, and Lindblad descriptions within a coordinate-independent formulation and provides a natural
language for relaxation in driven, anisotropic, and non-
equilibrium spin systems.
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All authors Sophia N. Fricke, Kieren A. Harkins, Ashok Ajoy, Jeffrey A. Reimer
Optics
An integrated all-van der Waals nanobeam laser
Aris Koulas-Simos, Pietro Metuh, Athanasios Paralikis et al. (+7 more)
Transition-metal dichalcogenides offer a promising platform for integrated coherent light sources, yet lasing has largely relied on hybrid photonic architectures without direct
quantum-optical verification. Here, we demonstrate an all-van der Waals (all-vdW) high-$\beta$ nanobeam
laser based on a WS$_2$/MoSe$_2$/WS$_{2}$
heterostructure, with the MoSe$_2$ monolayer directly integrated in the WS$_{2}$-based optical resonator for optimal gain-mode overlap. The devices exhibit efficient
exciton-cavity coupling at cryogenic temperatures, strongly directional and linearly polarized emission, soft nonlinear input-output characteristics and linewidth narrowing, enabling lasing operation with $\beta$ near unity. Excitation-power-dependent
photon-autocorrelation measurements reveal a transition from thermal to Poissonian
photon statistics, with $g_{\mathrm{peak}}^{(2)}(0)$ decreasing from $(1.28\,\pm\,0.09)$ near threshold to $(1.07\,\pm\,0.07)$ above threshold, directly verifying lasing operation. Furthermore, temporal broadening of the autocorrelation uncovers fluctuation-dominated lasing dynamics. These results establish all-vdW
heterostructures as a highly attractive platform for integrated coherent light sources in layered-material photonic architectures and scalable
quantum-photonic
circuits.
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All authors Aris Koulas-Simos, Pietro Metuh, Athanasios Paralikis, Kartik Gaur, Maximilian Klonz, Imad Limame, Bárbara L. T. Rosa, Chirag C. Palekar, Battulga Munkhbat, Stephan Reitzenstein
Quantum Physics
James Benstead, Michael Garn, Neil Gaspar et al. (+5 more)
To maximize the value of fault-tolerant
quantum computers, it is essential to develop concrete applications beyond well-established domains such as chemistry and condensed-matter physics. Here we construct and compile
quantum algorithms to simulate the structure of atomic
nuclei – a topic that has received relatively little
attention from the
quantum computing community despite its similarities to the electronic structure problem in chemistry – via effective shell-model
Hamiltonians and no-core-shell-model
Hamiltonians with three-body interactions derived from
chiral effective field theory. Furthermore, we provide
quantum resource estimates, in terms of Toffoli gate and
qubit counts, for these
algorithms, which, to our knowledge, are the first such estimates for fault-tolerant
quantum simulation of atomic
nuclei. Notably, the estimates for $^{32}$Mg and $^{219}$At shell-model
Hamiltonians are comparable to recent estimates of Femoco simulations, a standard
benchmark in chemistry. For no-core-shell-model
Hamiltonians suitable for light
nuclei (up to $^{40}$Ca or so), we find that resource requirements are significantly higher, suggesting that more bespoke strategies are required to make such simulations practicable. Throughout this work, we draw upon the similarities between
nuclear and electronic structure problems, while also highlighting challenges that are specific to the former. We hope this work will spur long-term collaborations between the
nuclear and
quantum computing community with the ultimate goal of realizing useful
nuclear simulations on
quantum computers.
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All authors James Benstead, Michael Garn, Neil Gaspar, Sean Greenaway, Angus Kan, Lloyd La Ronde, Chandan Sarma, Paul Stevenson
Astrophysics of Galaxies
Identifying and Distinguishing Quenching Galaxies with Spatially Resolved Star Formation in the Hubble Frontier Fields
Cameron Lawlor-Forsyth, Michael L. Balogh, Sean L. McGee et al. (+1 more)
We investigate the nature and prevalence of different quenching signatures for 1437
galaxies with $M_{*} \geqslant 10^{8}~\mathrm{M}_{\odot}$ and $\text{SFR} \geqslant 10^{-3}~M_{\odot}~\text{yr}^{-1}$ in the Hubble Frontier Fields through spatially resolved spectral energy distribution fitting with FAST++. We use the morphological metrics previously presented in our series of investigations to quantify the distribution of
star formation, and use a $k$-nearest neighbors
algorithm to classify quenching
galaxies into different quenching pathways, including an inside-out pathway and an outside-in pathway. We find 129
galaxies have morphologies consistent with an inside-out quenching pathway, and 70 are consistent with an outside-in pathway. Inside-out quenching
galaxies are $0.8^{+0.2}_{-0.1}~\text{dex}$ more massive compared to outside-in quenching
galaxies, where both populations are more massive in clusters than the field, by $0.8^{+0.3}_{-0.1}~\text{dex}$. Inside-out quenching
galaxies are found more often in clusters (106/129), compared to outside-in quenching
galaxies (25/70). In clusters, the fraction of inside-out quenching
galaxies strongly increases with mass, representing ${\sim}$30% of the non-quenched
galaxy population at high masses. A milder
evolution is seen in the field. The fraction of outside-in quenching
galaxies is independent of mass, representing ${\lesssim}$10% of the non-quenched population, in both the cluster and field. We find no strong dependence for the fraction of any population with estimated infall time, except massive inside-out quenching
galaxies, which increase in fraction with increasing infall time.
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All authors Cameron Lawlor-Forsyth, Michael L. Balogh, Sean L. McGee, Gregory H. Rudnick
Quantum Physics
Enhancing Entanglement Purification with Shared Randomness
Allen Zang, Bikun Li, Xinan Chen et al. (+4 more)
Entanglement purification protocols (EPPs) are essential for improving
entanglement fidelity to support fault-tolerant distributed
quantum information processing. Practical
entanglement sources are often heterogeneous and source labels may be unavailable at the EPP layer. We show that classical shared randomness, together with buffer
memories, can enhance
entanglement purification when source labels are unavailable, without state characterization or EPP
circuit optimization. The strategy is to accumulate multiple
entanglement distribution rounds and then use shared randomness to shuffle all the stored entangled states before packaging them as inputs to the EPP. For any $n$ Werner sources and any fixed $n$-to-1 bilocal Clifford EPP, we prove that accumulating and shuffling improves the expected success probability and the success-weighted output Bell fidelity over the baseline without accumulating and shuffling, for every $n$, for every finite number of accumulation rounds and in the asymptotic limit, and the improvement increases monotonically with the number of accumulation rounds.
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All authors Allen Zang, Bikun Li, Xinan Chen, Eric Chitambar, Liang Jiang, Martin Suchara, Tian Zhong
Quantum Physics
Strategic Plan for Neutral Atom Quantum Computation
Adrian J. Menssen, Tout Wang, Michael Gullans et al. (+53 more)
We present a strategic plan for neutral atom
quantum computation, bringing together hardware development and theory advancements to achieve the goal of practical
quantum advantage. The concept of practical
quantum advantage is defined, along with how to verify claims of advantage, and approaches to designing
quantum algorithms that deliver practical advantage. Future directions for neutral atom
quantum processor hardware are described: scaling-up system size,
Qubit encodings and atomic platforms, going further below threshold with neutral-atom logical-
qubit performance, continuous reloading of
qubits, and fast readout. We also explore opportunities for scalable integrated photonic control technologies. Alongside hardware advancements, new developments in
quantum error correction and compilation of
quantum circuits are proposed. Finally, we examine the opportunity of networking multiple neutral atom
quantum processors together to perform distributed
quantum computing and overcome possible limitations of a single system.
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All authors Adrian J. Menssen, Tout Wang, Michael Gullans, Tom Manovitz, Jacob M. Taylor, Jason Cong, Josiah Sinclair, Ziv Aqua, Daniel J. Blumenthal, J. Pablo Bonilla Ataides, Johannes Borregaard, Antoine Browaeys, Paola Cappellaro, Soonwon Choi, Alexandre Cooper, Robin Côté, Jacob P. Covey, Alexandre Dauphin, Ivana Dimitrova, Matt Eichenfield, Dirk Englund, Jacob Freedman, Akihisa Goban, Brandon Grinkemeyer, Andi Gu, Ruonan Han, Dominik Hangleiter, Aram W. Harrow, Liang Jiang, Eun-ah Kim, Felix W. Knollmann, Aleksander Kubica, Thierry Lahaye, Lucas Lassabliere, Joonho Lee, Bingzhao Li, Mo Li, Wan-Hsuan Lin, Mikhail D. Lukin, Varun Menon, Thomas Propson, Akbar Safari, Mark Saffman, Pascal Scholl, Alexander Schuckert, Giulia Semeghini, Jonathan Simon, David Spierings, Daniel Bochen Tan, Shai Tsesses, Vladan Vuletic, Hanrui Wang, Hanyu Wang, Susanne Yelin, Johannes Zeiher, Hengyun Zhou
Quantum Physics
Unconditional Unclonable Encryption
Prabhanjan Ananth, Seyoon Ragavan and Amit Sahai
We give an unconditional construction of information-theoretically secure one-time private-key unclonable encryption for one-bit messages, with efficient encryption and decryption and exponentially small unclonable-indistinguishability advantage. Previous work by Bhattacharyya and Culf (Nature Physics, 2026) and Bhattacharyya, Broadbent, and Culf (arXiv:2603.08916) either only showed inverse-
polynomial security loss or required inefficient encryption/decryption operations; we avoid both of these caveats. Our scheme's key is a uniformly random non-identity phase-free Pauli on $n$
qubits, and bit $a$ is encrypted as a random $(-1)^a$ eigenstate of that Pauli. We prove that the probability that both receivers recover the bit is at most $1/2 + O\left(2^{-n/2}\right).$ By a lower bound due to Broadbent, Culf, and Rochette (IACR Communications in Cryptology, 2026), this is the best probability bound achievable with $n$-
qubit ciphertexts while ensuring perfect correctness (up to the constant hidden in the $O(\cdot)$).
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High Energy Physics (Phenomenology)
Neural solutions of coupled ghost and gluon Dyson–Schwinger equations in Landau gauge
Rodrigo Carmo Terin
The coupled ghost and
gluon Dyson–Schwinger equations (DSEs) of four-dimensional Landau-gauge Yang–Mills (YM) theory are solved with a neural representation trained only from renormalized equation residuals. The neural and fixed-point solutions agree at the percent level and remain stable under changes of initialization, network size, integration grid, and infrared boundary condition. Variations of the three-
gluon vertex model produce substantially larger effects than the neural error. The MiniMOM ultraviolet running and the sign change of the
gluon Schwinger function are also reproduced within the limitations of the truncation.
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Quantum Physics
Alexander Makarovskiy, Adam Taylor, Zhenghao Li et al. (+5 more)
Variational
quantum algorithms are a leading approach to near-term
quantum computing, but their scalability can be limited by barren plateaus and the sampling cost of resolving small changes in the loss landscape. Here, we study the trainability of passive linear-optical
quantum circuits and introduce a framework based on the ratio of sample variance to
circuit variance. This ratio determines the number of
circuit samples required to resolve local loss differences and gradients to proportional accuracy. We apply this framework to
photon-number observables and identify both trainable and non-trainable regimes. Supported by analytic results and a numerically observed
polynomial decay of the
circuit variance, we find that fixed-order
photon-number
polynomials require only polynomially many samples as the system size grows, whereas high-order
polynomials and observables based on output probabilities generally require exponentially many samples. Within the trainable regime, we further identify classes of observables in which
quantum estimation achieves a
polynomial speed-up over multiple classical methods. Within this family, neural network observables provide one practical construction that allow measurement outcomes to be efficiently processed into the desired
polynomial. These results establish photonic variational
quantum computing as a promising platform for near-term applications.
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All authors Alexander Makarovskiy, Adam Taylor, Zhenghao Li, Michael Hanks, Aubrey Clark, M. S. Kim, Ian Walmsley, William Clements
Instrumentation and Detectors
Disentangling mixed neutron fields: multi-source identification from few detected events
David Breitenmoser, William Heriot, Peter Marleau et al. (+2 more)
Identifying
neutron-emitting materials is central to
nuclear nonproliferation, safeguards,
nuclear forensics, and emergency response, yet remains difficult when several sources contribute simultaneously: relevant fission, $(\alpha,\text{n})$, and fusion sources emit broad, strongly overlapping energy distributions, and the associated spectral inversion is severely ill-conditioned. Here we demonstrate quantitative identification of mixed
neutron fields directly from scatter-based (
recoil) spectroscopy measurements, together with simultaneous estimation of the emission rate of each contributing source and a rigorous statistical confidence level for every candidate source combination. Using a compact $21.6\,\mathrm{cm}^3$ organic-glass scintillator spectrometer, we correctly identify Cf-252, a deuterium–deuterium (DD)
neutron generator, and their mixture with decisive statistical support ($>\!4\sigma$), and further resolve a weak deuterium–tritium contaminant in the nominal DD generator field. High-fidelity Monte Carlo simulations spanning exhaustive single-, two-, and three-source mixtures show that identification requires remarkably little information: between $\mathcal{O}(10^1)$ and $\mathcal{O}(10^6)$ detected
recoil events, set primarily by spectral similarity, mixture complexity, and emission-rate imbalance. For the compact spectrometer used here, this corresponds to acquisition times as short as a few minutes. These results substantially extend the operational reach of simple single-volume
neutron spectrometers, enabling rapid, quantitative, and confidence-calibrated attribution of complex
neutron fields in field-deployable instruments.
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All authors David Breitenmoser, William Heriot, Peter Marleau, Shaun D. Clarke, Sara A. Pozzi
High Energy Physics (Phenomenology)
Heavy neutral leptons from light scalar in fixed target and forward search experiments
ShivaSankar K.A., Souvik Das, Arindam Das et al. (+1 more)
The observation of
neutrino masses strongly motivates $U(1)_{B-L}$ extensions of the Standard Model, in which heavy neutral
leptons acquire Majorana masses through spontaneous $U(1)_{B-L}$
symmetry breaking and generate light
neutrino masses via the seesaw mechanism. In this framework, the singlet scalar responsible for
symmetry breaking mixes with the SM
Higgs boson, allowing it to be produced in rare
meson decays. We investigate a scenario in which this light scalar promptly decays into a pair of long-lived heavy
neutrinos that subsequently decay into visible charged
leptons and
hadrons through light-heavy
neutrino mixing inside the proposed Forward Physics Facility (FPF) at the FCC-hh and the SHiP beam-dump experiment. Taking into account realistic detector geometries, decay probabilities, and visible branching fractions, we estimate the projected sensitivities to the scalar-
Higgs mixing angle as a function of the scalar mass and to the light-heavy
neutrino mixing as a function of the heavy
neutrino mass. We find that FPF and SHiP can significantly extend the discovery reach for both light scalars and long-lived heavy
neutrinos beyond existing experimental limits, providing powerful and complementary probes of
neutrino-mass generation and hidden-sector physics.
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All authors ShivaSankar K.A., Souvik Das, Arindam Das, Sanjoy Mandal
Quantum Physics
Beyond Calabrese-Cardy Scaling: Exceptional-Point Sensitivity and the de Sitter RT Surface
Kuang-Hung Chou
Entanglement entropy at one-dimensional criticality typically follows the Calabrese–Cardy scaling. In the non-Hermitian critical free-
fermion systems studied here, however, we find an additional interval-independent contribution $S_{\rm res}=\log(\Delta L)$, which allows the
entropy to remain sensitive to energy gaps below the finite-size scale, $\Delta<1/L$. We refer to this term as the residual
entropy. To understand its infrared origin, we examine finite-depth non-
unitary continuous multiscale
entanglement renormalization on a ring. Terminating the critical RG
circuit before its singular final layer leaves a two-site infrared state. We calculate the
entropy of this state directly from its correlation
matrix and recover the same \(\log(\Delta L)\) dependence. The emergent de Sitter geometry provides a complementary
geometric interpretation: extremal curves associated with different boundary intervals extend to a common infrared endpoint, suggesting how the
entanglement retained there can contribute equally to their
entropies.
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Quantum Physics
Lei Zhang, Yusheng Zhao, Yimeng Cao et al. (+10 more)
Formal verification is becoming increasingly practical for
quantum computing, yet the ability of AI
agents to construct machine-checkable proofs in this domain remains unmeasured. We introduce Lean-QuantumAlg-Bench and Lean-QIT-Bench, two Lean 4
benchmarks containing 36 and 40
theorem-completion tasks for
quantum algorithms and
quantum information theory, respectively. Every task compiles in a fixed environment and is evaluated by deterministic proof checking and targeted semantic review, with difficulty weights assigned before model execution. We evaluate four models-GPT-5.5, Kimi K3, DeepSeek V4-Pro, and MiniMax M3-within a common
theorem-proving framework under two settings: a task-only baseline and library-augmented deduction (LAD), which additionally provides access to a verified domain library. The highest difficulty-weighted scores are 60.4 out of 100 on the
quantum-
algorithm benchmark and 59.6 out of 100 on the
quantum-information
benchmark. LAD improves both score and completion rate in all eight model-
benchmark comparisons, with gains of up to 15.9 points, providing evidence that verified libraries can strengthen domain-specific proof
agents. The results reveal recurring weaknesses of agentic proving in areas such as
quantum simulation,
quantum learning,
quantum information measures, and
entanglement theory. Monetary and wall-clock costs per score point also vary substantially across models, highlighting important capability-efficiency trade-offs. We expect these
benchmarks to establish a reproducible baseline for developing more capable and reliable proof
agents, and to pave the way toward self-evolving AI scientists for advancing
quantum information science.
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All authors Lei Zhang, Yusheng Zhao, Yimeng Cao, Ranyiliu Chen, Mingrui Jing, Jizhe Lai, Ziao Tang, Jingu Xie, Hongshun Yao, Xuanqiang Zhao, Guocheng Zhen, Chengkai Zhu, Xin Wang
High Energy Physics (Experiment)
Measurements of the electroweak production of a $W$ boson in association with two jets at $\sqrt{s}=13\,\mathrm{TeV}$ with the ATLAS detector
ATLAS Collaboration
Measurements of the electroweak production of a $W$
boson in association with two jets at high dijet invariant mass are performed using a
dataset from $140\,\mathrm{fb}^{-1}$ of $\sqrt{s}=13\,\mathrm{TeV}$
proton-
proton collisions recorded by the ATLAS detector at the LHC. The measurements are made in a fiducial region where the $W$
boson's production via vector-
boson fusion is enhanced. The fiducial region requires at least two jets, an electron or a
muon, and a
neutrino, assuming a leptonic $W$ decay. In addition to the integrated production cross-section, differential cross-sections unfolded to particle level are determined as functions of observables which characterise angular properties of the two highest-energy jets, the kinematics of the $W$
boson, and the transverse momenta of the highest-energy jet and the charged
lepton. Results are interpreted in the context of an effective field theory, and the limits placed on anomalous triple-gauge-
boson couplings are among the most stringent to date for linear terms of the extended Lagrangian.
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Mesoscale and Nanoscale Physics
Probing the nonlocality of Landau levels in GaAs quantum wells through modified Purcell factors, Lamb shifts and dipole emitted spectra
Lara Greten, Sabrina Meyer, Christina Schröder et al. (+2 more)
In a two-dimensional electron gas, a strong perpendicular
magnetic field confines electrons to quantized cyclotron orbits, giving rise to Landau levels with discrete orbit radii. Even the smallest Landau orbit, set by the
magnetic length, spans tens of nanometers for fields of a few Tesla, imposing an intrinsic nonlocal response to electromagnetic excitations. From a microscopic theory of the nonlocal susceptibility, we derive the Green's function, the central quantity governing all electromagnetic interactions, and evaluate Purcell factors, Lamb shifts, and emission spectra from a proximal dipole emitter beyond the Markov and rotating-wave approximations. Significant nonlocal effects resulting from spatial dispersion of the Landau level response modify the response for experimentally relevant situations up to distances of hundreds of nanometers and, in particular, brighten locally dipole-forbidden transitions due to near-field gradients at multiples of the cyclotron frequency. The relevant length scales are typical of state-of-the-art nanostructured terahertz architectures, and some of our nonlocal features are consistent with recent experiments using Landau level polaritons.
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All authors Lara Greten, Sabrina Meyer, Christina Schröder, Andreas Knorr, Stephen Hughes
Superconductivity
Sequential Topological Superconductivity in a Square Lattice with Chiral Charge Density Waves
Zhong-Xian Jin, Junkang Huang, Yu-Xuan Li et al. (+1 more)
The interplay between charge order and superconductivity offers a fertile ground for emergent
quantum phases. Here we theoretically investigate a square-
lattice superconductor coexisting with a composite charge density wave (CDW) consisting of a real bond modulation (charge bond order, CBO) and an imaginary hopping modulation (
chiral flux phase, CFP) that breaks time-reversal
symmetry. We uncover that, while CFP alone does not induce
topology in square
lattices, its coexistence with CBO drives the system into two topologically nontrivial superconducting phases with Chern numbers $C=+2$ and $C=-2$. The low-temperature thermal
Hall conductivity $\kappa_{xy}$ exhibits quantized plateaus proportional to the Chern number, providing a clear experimental fingerprint. Our results establish the square
lattice as a pristine platform for engineering topological superconductivity through the synergy of real and imaginary bond modulations.
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All authors Zhong-Xian Jin, Junkang Huang, Yu-Xuan Li, Tao Zhou
Quantum Physics
Unified theory of classical and quantum semiparametric efficiency
Mankei Tsang
In classical and
quantum statistics, high-dimensional unknown parameters are abundant and it is often prudent to make minimal assumptions about them using so-called semiparametric models. To attack a wide range of semiparametric problems in one broad stroke, we present a unified treatment of statistical efficiency for classical and
quantum semiparametric models, generalizing the Cramér-Rao and Helstrom bounds beyond finite-dimensional parameters. We introduce the fundamental concepts in abstract and
geometric terms before applying them to many examples, covering general classical and
quantum models as well as the paradigmatic special cases of Gaussian and Poisson fields. We give an in-depth treatment of channels in the semiparametric efficiency theory and advocate the use of the singular value decomposition to elucidate the statistical effects of channels. To demonstrate the utility of the formalism, we apply it to coherent and incoherent optical imaging problems, assuming an arbitrary field or intensity on the object plane without parametric assumptions. Our formalism enables us to compute classical and
quantum limits to coherent and incoherent imaging resolution in statistical terms. For subdiffraction incoherent imaging, we demonstrate that spatial-mode demultiplexing can be far superior to direct imaging in estimating generalized
Fourier coefficients and come closer to the
quantum limits. We envision our theory becoming an essential tool for both classical and
quantum statistics with useful applications to sensing and imaging, whenever minimal assumptions about a high-dimensional parameter should be made.
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Statistical Mechanics
Optimal feedback control under stepwise equilibration and partial observation
Francesco Mottes and Michael P. Brenner
Many microscopic machines rely on noisy signals to direct nonequilibrium transformations and operate in a timescale-separated regime. We consider feedback protocols in which a system equilibrates between rapid, measurement-conditioned changes of its energy landscape. In this limit, the partially observable control problem reduces exactly to a finite-horizon Bellman recursion over
Hamiltonian updates. For a harmonic trap translated to a prescribed target under noisy position measurements, we solve this recursion analytically. The optimal protocol balances its response to the estimated fluctuation against progress toward the target, exploiting information early while enforcing the endpoint near the deadline. The minimum work decomposes into a positive thermodynamic-length transport cost and a negative information-enabled extraction term set by the fraction of
equilibrium fluctuations resolved by the measurement. When a fixed intervention cost exceeds the asymptotic extraction per cycle, it selects a finite optimal number of cycles. We show that, in this translated harmonic case, the minimum thermodynamic cost of creating and resetting the measurement record always exceeds this threshold, making the optimal cycle count finite and the net work non-negative for any measurement channel.
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Quantum Physics
Extended Single-Atom Tweezer Arrays in High-Cooperativity Cavity-QED
Thomas Picot, Clément Raphin, Marcel Kern et al. (+4 more)
A central challenge for cavity-QED-based
quantum technologies is to make high-cooperativity optical interfaces compatible with site-resolved arrays of single atoms. Here, we demonstrate optical tweezer arrays of individual $^{87}$Rb atoms inside a fiber Fabry-Perot microcavity with single-atom cooperativity $\mathcal{C} \sim 90$. We combine background-free site-resolved fluorescence imaging of extended arrays with collective coupling to a common cavity mode for arrays with a mean atom number up to $\bar{N} \simeq 36$. These results establish a high-cooperativity platform for many-body cavity-QED with site-resolved detection and control.
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All authors Thomas Picot, Clément Raphin, Marcel Kern, Pierre-Antoine Bourdel, Théo Ahamdach, Jakob Reichel, Romain Long
High Energy Physics (Theory)
Revealing the conformal symmetry of the discrete series scalars in dS${}_2$
Lukas W. Lindwasser
On two-dimensional
manifolds with nonzero constant
Ricci curvature, there exists an infinite sequence of scalar fields with nonzero mass parameter that admit a pair of (anti)-holomorphic currents. After suitably defining the theory in de Sitter space ($\mathrm{dS}_2$), correlation functions of these currents obey global conformal Ward identities. We address the question of how this global conformal
symmetry manifests as an action on the scalar field. An essential step is in leveraging an equivalent description of the scalar field in terms of a conformal Killing tensor. Through this, we find a conformal
symmetry transformation that acts locally on the conformal Killing tensor, but non-locally on the scalar field. We show that the equation of motion transforms covariantly with respect to these conformal transformations, and further find a traceless stress tensor in both $\mathrm{dS}_2$ and $\mathrm{AdS}_2$, locally defined in terms of the conformal Killing tensor, which generates the global conformal isometry transformations.
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Atomic Physics
Experimental realization of a rotating radio-frequency ion trap for precision metrology
Sun Yool Park, Anzhou Wang, Kia Boon Ng et al. (+7 more)
We discuss the experimental realization of the rotating
radio-frequency (rrf) trap, proposed by Hasegawa and Bollinger [Phys. Rev. A 72, 043403 (2005)]. Compared to a traditional linear rf (lrf) Paul trap, the rrf trap is a closer analogy to the popular mechanical lecture demonstration for a Paul trap. In an ion trap with reslistic, non-ideal electrode geometry, the rrf trap averages over angular variations in the effective potential. This averaging provides more uniform confinement and reduces ion loss at equal confinement strength compared with the lrf trap. This feature makes the rrf trap configuration advantageous for precision metrology application, such as electron electric dipole moment (eEDM) measurements.
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All authors Sun Yool Park, Anzhou Wang, Kia Boon Ng, Patricia Hector Hernandez, Addison Hartman, Tuan Anh Nguyen, Rohan Kompella, Michail Athanasakis-Kaklamanakis, Jun Ye, Eric A. Cornell