Optics
Accurate recovery of the two linewidths hidden in laser beatnote statistics
Jingming Chen, Yuanchen Qi, Yuzheng Pang et al. (+12 more)
Photons from ultrastable
lasers can remain coherent over distances approaching the Earth-Sun separation, enabling optical clocks projected to lose less than one second over the age of the Universe. Yet characterizing these
photons poses an identifiability problem: a two-
laser heterodyne measurement produces a single beatnote linewidth that conflates contributions from both
lasers. For more than half a century, the standard solution has been the three-cornered-hat (TCH) method, which requires three independent ultrastable
lasers. Here we derive the mathematical form and elucidate the physical origin of asymmetric beatnote-linewidth distributions arising from finite
photon wave trains, a long-observed feature not captured by canonical Gaussian or Lorentzian statistics. This finding accurately recovers two linewidths hidden in
laser beatnote statistics without a third
laser. The framework consistently captures the observed coherence-length and coherence-time statistics of
photons, while comparison with TCH measurements confirms the quantitative validity of the extracted individual linewidths across five independent ultrastable-
laser datasets spanning nearly two orders of magnitude. Most notably, the method resolves the 7.8-mHz linewidth of a cryogenic silicon-cavity
laser beating with a broader
laser. This transformative function of beatnote-linewidth distributions, together with the resulting method, could fundamentally advance optical clocks and precision metrology.
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All authors Jingming Chen, Yuanchen Qi, Yuzheng Pang, Jie Miao, Congyu Wang, Yuan Yao, Zhi-Ang Chen, Run-Qi Lei, Zheyi Ge, Yanyi Jiang, Xibo Zhang, Xiaopeng Xie, Jianjun Wu, Duo Pan, Jingbiao Chen
Soft Condensed Matter
Mechanical Signature of a Chemically Driven Bath
Tian Huang, Jintae Park, Hyuk Kyu Pak et al. (+1 more)
Using optical tweezers, we demonstrate that the CuAAC click reaction increases the positional fluctuations of a trapped 2 micrometer colloid by at least 20% without altering the trap's corner frequency. This excess variance relaxes to the thermal baseline as reagents are depleted. The additional noise is Gaussian, with a flat power spectrum extending past the corner frequency up to 7 kHz. Notably, the noise amplitude decouples from the macroscale reaction rate, and independent molecular force dipoles are orders of magnitude too small to generate the observed variance. Although the chemical free energy released locally exceeds the energy absorbed by the bead by five orders of magnitude, this energy couples inefficiently. The mechanical action of the reacting bath cannot be represented as a sum of independent molecular events.
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All authors Tian Huang, Jintae Park, Hyuk Kyu Pak, Steve Granick
Quantum Physics
Root-system structure of sloppiness in passive Gaussian metrology
A. Kafuri and B. M. Rodriguez-Lara
Passive transformations of an $n$-mode squeezed probe become locally unidentifiable when the
quantum Fisher
matrix loses rank. For pure zero-mean Gaussian probes, we show that the $C_{n}$ restricted-root system of $\mathrm{Sp}(2n,\mathbb{R})/\mathrm{U}(n)$ governs this exact sloppiness. For squeezing magnitudes $r_{1},\ldots,r_{n}$ in the canonical basis, the roots $2r_{j}$ and $r_{j}\pm r_{k}$ label the local phase rotations and two beam-splitter quadratures, and their vanishing identifies every Fisher-null direction. The associated Fisher weights quantify the approach to each singular wall. At fixed positive mean
photon number, we solve the E-optimal probe-design problem of maximizing the smallest passive Fisher
eigenvalue in two explicit generator normalizations. In the canonical phase and beam-splitter angle convention, the unique optimum in the fundamental Weyl chamber is an arithmetic progression approaching the consecutive-odd-integer dual-Weyl direction at large resource. With an invariant generator norm, the smallest
eigenvalue is independent of the passive frame and the optimum lies exactly on that ray at every resource. Uniform squeezing instead minimizes the local-phase A-optimal cost while leaving one beam-splitter quadrature unidentifiable for every mode pair. Finally, the two quadratures of each identifiable mode pair saturate the
quantum-
geometric incompatibility bound, and the largest compatible passive submodel has $n(n+1)/2$ parameters at a regular spectrum. The resulting classification separates local identifiability, sensitivity optimization, and simultaneous attainability.
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Quantum Physics
Shared Phase Arithmetic for Parallel Quantum Rotations
Anbang Wu, Liqiang Lu, Pu Pang et al. (+3 more)
A layer of diagonal
quantum gates can be specified by an integer-valued function on computational basis states. This description suggests implementing the layer by evaluating that function reversibly and translating its value into a phase using a shared
quantum register. We develop this viewpoint for parallel phase kickback (PPK): the weighted sum of several rotation parameters is computed coherently, added once to a phase-gradient state, and then uncomputed. The construction separates the cost of representing a phase function from the cost of applying it. We prove correctness, give explicit error bounds, and analyze logical gate counts for general weights, pairs of rotations, and weights with disjoint binary support. With Clifford-only encoding, a batch uses at most $4(b-1)$ T gates at $b$-bit phase resolution, excluding initialization. The first phase reference is prepared with independent rotations synthesized by Gridsynth; additional phase-gradient states then follow from the disjoint-support construction with $O(b)$ T gates each. The resulting bounds identify when shared phase arithmetic reduces amortized rotation cost and when encoding overhead limits that advantage.
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All authors Anbang Wu, Liqiang Lu, Pu Pang, Jianwei Yin, Jingwen Leng, Minyi Guo
Quantum Physics
Factorization dynamics between quantum Fisher information and quantum coherence
Xinzhi Zhao, Xinglei Yu, Liangsheng Li et al. (+2 more)
Quantum Fisher information (QFI) quantifies the sensitivity of a
quantum state to a parameter change and plays a key role in
quantum metrology. Meanwhile,
quantum coherence is a crucial resource for
quantum information processing. However, despite extensive studies on various aspects of
quantum metrology, the interplay between the dynamics of the QFI and
quantum coherence remains unexplored. Here, we explore the factorization relationship between the QFI and
quantum coherence, both theoretically and experimentally. We prepare pure states in
qubit and qutrit systems and apply
unitary evolution to investigate this relationship. Our results confirm the factorization law, offering strong evidence for this relationship. Furthermore, we establish a lower bound on the variance of the estimated parameter that does not require the final state information. This approach reveals a deep connection between the QFI and
quantum coherence, providing insights into
quantum parameter estimation. These findings have potential applications in
quantum sensing and
quantum metrology.
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All authors Xinzhi Zhao, Xinglei Yu, Liangsheng Li, Wenting Zhou, Chengjie Zhang
Materials Science · Cross-listed from cs.RO
A robust single-sensing-element tactile sensor for concurrent pressure and tackiness detection with real-time signal decoupling capability
Ying Yang, Mingwei Gu, Jia-Sen Xie et al. (+8 more)
Integrating tackiness sensation into the artificial skin of
humanoid robots significantly enhances their cognitive and operational capabilities. However existing tactile sensors face challenges in decoupling of the
multimodal signal and stability. Here we present a surface-soft tactile sensor that incorporates a
Hall effect sensor and a soft
magnetic composite within a robust elastic framework. The sensor surface indents under pressure and bulges prominently when retracted from sticky surfaces dynamically altering the
Hall sensor-magnet distance. This generates whole-process-traceable and baseline-separated signals enabling real-time differentiation between pressure and pull-off force. This single-sensing-element design facilitates bimodal sensing at the same contact spot while eliminate stress cross-talk enhancing both accuracy and sensitivity. The fusion of a robust framework and magneto-mechanical sensing mechanism equips the sensor with exceptional reliability and excellent signal baseline stability. This tactile sensor holds substantial potential for advancing robotic capabilities in evaluating adhesive properties monitoring rubber aging precisely handling lightweight objects and cognizing natural objects surface characteristics.
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All authors Ying Yang, Mingwei Gu, Jia-Sen Xie, Xingyu Ma, Yan-Na Lu, Lin Zheng, Jinhui Gu, Junshuai Chen, Yunjie Lu, Denys Makarov, Jin Ge
Quantum Gases
Generalized Effective Spin-Chain formalism for multicomponent anyons in one-dimensional optical lattices
Sagarika Basak, Xi-Wen Guan and Han Pu
We develop a generalized effective
spin-chain (GESC) formalism for strongly interacting multicomponent anyons in a one-dimensional (1D) optical
lattice. By mapping particle motion onto spinless
fermions and
spin states onto an ordered chain, this framework provides a
spin–charge-separated perspective on the physical effects of fractional exchange statistics. In the strong-interaction regime, the leading-order charge
Hamiltonian becomes independent of the statistical phase; instead, virtual tunneling through doubly occupied states directly imprints this phase on the
spin-exchange coefficients. The GESC formalism captures ground-state properties of the full Anyon–Hubbard model reported in S.~Basak, X.-W.~Guan, and H.~Pu, unpublished manuscript (2026), and reveals that their statistical dependence is predominantly encoded in the explicit anyonic structure of the observables rather than the underlying
spin ground state. This formalism uncovers that, out of
equilibrium, successive
spin exchanges accumulate direction-dependent phases; the resulting interference drives crossover from dispersive to localized
impurity transport and generates inversion-asymmetric propagation at intermediate statistics. Suppressed expansion persists for identical and distinguishable
impurities, with differences in propagation governed by the interplay between
impurity identity and interaction anisotropy. Ultimately, GESC offers a versatile, computationally efficient theoretical framework that connects macroscopic dynamics to microscopic virtual exchange processes, conferring a unique
spin–charge-separated vantage for resolving how fractional exchange statistics survives strong interactions and manifests distinctly across static and dynamical regimes.
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Quantum Gases
Multicomponent anyons in one-dimensional optical lattices
Sagarika Basak, Xi-Wen Guan and Han Pu
We investigate the ground-state and dynamical properties of multicomponent interacting anyons confined in a one-dimensional (1D) optical
lattice. Adopting the Anyon–Hubbard model, we explore
spin and charge correlations as functions of interaction strength and the anyonic statistical parameter. Our results demonstrate that multicomponent effects combined with fractional exchange statistics substantially reshape both charge and
spin correlations. For fractional exchange statistics, the canonical symmetric shell structure with prominent singularities in the spinor fermionic momentum distribution undergoes notable structural reconstruction, exhibiting emergent asymmetry, new spectral peaks, and broadened singular features. Unlike the Tonks–Girardeau bosonic gas, pseudobosons, representing a limiting case of anyons, cease to display a dominant zero-momentum peak. Instead, a quasi-fermionic shell structure emerges with finite-momentum peaks, whose locations are modulated by
lattice site occupancy and interaction strength. The structure factor of
spin correlations uncovers
antiferromagnetic ordering in spinor anyon systems, with correlation magnitudes tunable by anyonic exchange statistics. Furthermore, quench dynamics analysis reveals the statistical phase parameter as an effective tuning knob. It enables the switching of dipole oscillations between underdamped and overdamped relaxation regimes and governs overall cloud expansion dynamics. Our findings pave the way for exploring statistics-driven ground-state and dynamical phase transitions in spinor anyon systems.
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High Energy Physics (Theory)
Classical Shadows of Higher-Form BRST Anomalies
Ruizhi Shen and Fu-Wen Shu
We formulate a precise sense in which a BRST anomaly may possess a classical phase space shadow. It is the non-equivariance class of a
Hamiltonian symmetry action on covariant phase space. To organize this statement, we introduce the Weil covariant phase space bicomplex, whose basic subcomplex controls equivariant
Hamiltonian lifts. We then compare this purely classical class with local BRST descent. For a
Hamiltonian admissible mixed transgression, the ghost-number-two descendant $a^{2}_{d-1}$ defines a deghostification map to the charge
algebra, which is generated by the failure of the Cartan representative to be equivariant. The induced
cohomology class is independent of Bardeen type changes of descent representative. Thus the classical anomaly is a shadow of the BRST anomaly in the precise sense that both are realizations of the same Weil transgression class, while remaining objects of different theories. As an explicit example, we analyze a five dimensional inflow transgression and show that the classical charge cocycle and the BRST descendant arise as two realizations of the same Weil transgression class.
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High Energy Physics (Theory)
Emergent Symmetries in Ensemble Averages
Masahito Yamazaki
It is widely believed that there are no exact global
symmetries in
quantum gravity. We review recent works showing that global
symmetries can nevertheless emerge after ensemble averages of theories, as encountered in holography. As a precision case study, we discuss the ensemble average of two-dimensional Narain-type conformal field theories associated with an even quadratic form of general signature, which is computed by the Siegel-Weil formula and interpreted as a sum over geometries in a three-dimensional Abelian Chern-Simons theory. Global
symmetries of the bulk anyons can emerge after the average, as T-dualities relating different theories in the ensemble are "folded" into
symmetries of a single theory (duality origami). We discuss the relation to the Swampland program, including the emergence of global
symmetries at infinite distance. Finally, we recast strong-to-weak spontaneous
symmetry breaking (SWSSB) of mixed states as an emergence of
symmetries in ensemble averages; in holography, wormholes connecting the two sides of a thermofield-double construction provide its bulk realization. This motivates a new Swampland
conjecture.
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Quantum Physics
Exponential Advantage of Quantum over Classical References in Leakage Detection
Zheng An
Leakage from a known encoding subspace can be detected by projection. However, the corresponding projector is unavailable when the encoding subspace is not classically specified. Here we show how independent
quantum references prepared by the same encoder enable leakage detection without a classical description of the encoding. A coherent measurement on the references and a single message leaves every state within the two-dimensional encoding subspace, including its
entanglement with a remote system, exactly unchanged. We derive the exact detection law for $M$ ideal references and prove optimality among tests with zero false alarm for every encoding. For orthogonal leakage, the miss probability is asymptotic to $4/M$, independent of the ambient dimension $d$. Measuring all references first, even collectively, gives zero detection at every finite budget under the same zero-false-alarm requirement. For a fixed detection target between zero and one, the optimal measurement-first cost is $\Theta(d/\epsilon)$ at sufficiently small tolerance $\epsilon$ on normal false alarm and conditional disturbance; a dimension-independent coherent budget suffices. For one logical
qubit encoded in three physical
qubits, seven coherent references achieve at least $50\%$ orthogonal-leakage detection, whereas any measurement-first receiver needs at least $588$ under the same $1\%$ normal tolerances.
Quantum references thus support leakage checks without classical reconstruction, with a sample advantage exponential in the number of physical
qubits.
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Materials Science
Frustrated Gd3+ Double Perovskites as High-Performance Magnetocaloric Materials for Sub-100 mK Adiabatic Demagnetization Refrigeration
Tim Treu, Marvin Klinger, Christian Heil et al. (+6 more)
Achieving temperatures below 100 mK is essential for advancing
quantum technologies and exploring fundamental
quantum phenomena. While paramagnetic salts have traditionally enabled adiabatic demagnetization refrigeration (ADR), their limitations have driven the search for more effective alternatives. In this work, we present Gd3+-based double perovskites, Ba2GdSbO6 and Sr2GdSbO6, as high-performance magnetocaloric materials. Starting ADR from 2 K and 5 T, these compounds reach 67 mK and 68 mK in small finite
magnetic fields, and 83 mK and 78 mK in zero field, respectively, which are the lowest reported ADR temperatures for Gd3+ magnets (S = 7/2) under these conditions. The frustrated geometry and the complex interplay of exchange and dipolar interactions suppress their
antiferromagnetic ordering temperatures to 100 and 166 mK for Ba2GdSbO6 and 190 mK for Sr2GdSbO6, while maintaining an outstanding
entropy density of 189 mJ K-1 cm-3 and 201 mJ K-1 cm-3, respectively. Notably, Ba2GdSbO6 sustains sub-100 mK cooling even at finite fields of 0.5 T, making it particularly promising for practical ADR applications.
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All authors Tim Treu, Marvin Klinger, Christian Heil, Hans-Albrecht Krug von Nidda, Vinicius E. S. Frehse, Mamoun Hemmida, Anton Jesche, Alexander A. Tsirlin, Philipp Gegenwart
Plasma Physics
Diffusion prior for KSTAR equilibrium reconstruction under sensor dropout
Hyungkeun Nam and Jaemin Seo
We study
equilibrium reconstruction for the Korea Superconducting Tokamak Advanced Research (KSTAR) device under
magnetic sensor dropout, with a
diffusion model as the prior.
Magnetic measurements leave most components of the toroidal current density $J_\phi$ undetermined, and sensor loss leaves more of them to the prior. The
diffusion model learns only $J_\phi$, conditioned on the coil currents, the
plasma current and the product of major radius and toroidal field, which do not depend on the dropout. The physics enters through a linear forward operator built from sensor response
matrices of the LIUQE code. Because the observations are linear, a variant of decoupled annealing posterior sampling fits them with a closed-form linear correction. On measured signals of 37 KSTAR shots, we switch off a random fraction (0.0 to 0.9, ten settings) of the 124
magnetic channels in use and compare with LIUQE under the same masks, taking the full-sensor LIUQE reconstruction as the label. Both methods fit the remaining channels to a similar level. The median relative distance of $J_\phi$ from the label stays at 3.22–4.07% for the
diffusion reconstruction in all settings, whereas that of LIUQE reaches 11.89% at dropout 0.9. At dropout 0.5–0.9, the
diffusion reconstruction is closer to the label on 27–37 of the 37 shots. At low dropout, LIUQE is closer on most shots. For the derived flux, the
diffusion reconstruction is closer on 21–36 shots at dropout 0.5–0.9, and its error at high dropout comes from the vessel current estimate, not from the prior.
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Accelerator Physics
Calculation of the temporal structure for a pulsed slow positron beam based on superconducting accelerator
H. Q. Zhang, P. Kuang, Y. H. Hu et al. (+4 more)
The development of superconducting accelerator (SCA) provides a novel approach to generating pulsed slow positron beams with high time resolution and high intensity. SCAs can produce electron beams with repetition frequencies on the order of MHz and pulse widths of less than 100 ps. A pulsed positron beam based on SCA can, to a certain extent, preserve the excellent temporal structure of the primary electron beam. However, thermalization,
diffusion, and surface re-emission of positrons in the moderator will inevitably lead to time broadening of positron pulses. In this paper, a calculation model coupling Geant4 Monte Carlo simulations with positron
diffusion theory is established to evaluate the effect of the positron moderation process on time broadening. After being moderated by a tungsten foil, the initial time broadening of the pulsed slow positron beam is approximately 320 ps. By combining the time broadening calculation of pulsed beam during its transport, it is expected that the pulsed slow positron beam generated by the SCA, can be directly applied to the measurement of positron annihilation lifetime.
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All authors H. Q. Zhang, P. Kuang, Y. H. Hu, F. Y. Liu, X. Z. Cao, B. Y. Wang, X. P. Li
Plasma Physics
Experimental demonstration of broadband-laser suppression of cross-beam energy transfer
Guoxiao Xu, Xiaoran Li, Ning Kang et al. (+22 more)
In direct-drive inertial confinement fusion (ICF), cross-beam energy transfer (CBET) redirects a significant fraction of the incident
laser energy out of the
plasma. We report the experimental demonstration that broadband
lasers reduce CBET-enhanced reflected-light return, performed at the low-coherence Kunwu
laser facility with two crossed beams of 0.6% bandwidth and up to 550J at $\sim$2.6$\times$10$^{14}$ W/cm$^{2}$. A coupled ray-tracing model shows that the strong CBET amplification of narrowband reflected light is much weaker under broadband illumination. In symmetric incidence condition of two orthogonal beams, the total fractional scattered energy decreases from 7.57% to 4.64%; in asymmetric incidence condition, which separates stimulated Brillouin scattering (SBS) from specular reflection, the SBS fraction decreases from 3.75% to 0.46% and the specular-reflection fraction decreases from approximately 2.2% to 1.3%. These results establish broadband
lasers as an effective, experimentally validated approach to reducing energy escape through CBET-enhanced reflection in direct-drive ICF.
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All authors Guoxiao Xu, Xiaoran Li, Ning Kang, Huiya Liu, Liang Hao, Zhiyuan Li, Guowei Yang, Honghai An, Xichen Zhou, Jian Wang, Lin Yi, Jun Xiong, Zhiyong Xie, Junjian Ye, Yuchun Tu, Zhiheng Fang, Guo Jia, Wei Wang, Lan Xia, Wei Feng, Lailin Ji, Xiaohui Zhao, Anle Lei, Lifeng Wang, Yanqi Gao
Computational Physics · Cross-listed from cs.LG
SCOPE: Observation-Conditioned Full-Target Prediction for Sparse PDE Inference
Ruichen Xu, Siyao Wang, Fang Wan et al. (+8 more)
Recovering complete physical fields from sparse observations is challenging because the measurements may not uniquely determine the underlying state.
Diffusion-based PDE solvers address this problem through iterative sampling whereas neural operators provide deterministic one-pass predictions. We propose SCOPE (Sparse-Context Observability-aware Predictive
Embeddings) to recover complete PDE fields from sparse observations by coupling full-field latent prediction with physical reconstruction. A shared decoder reconstructs fields from both predicted and complete-view representations so that representation learning is guided by both physical recovery and latent matching. We derive a quadratic risk decomposition at fixed teacher-decoder pairs showing why optimal latent prediction need not yield optimal field reconstruction. We also establish sufficient conditions for decoder improvements on complete inputs to transfer to recovery from partial observations. Experiments across five PDE settings show that SCOPE outperforms mask-aware neural operators on all ten forward and inverse tasks and achieves lower errors than those reported for
diffusion-based solvers including DiffusionPDE and FunDPS. Decoder-only adaptation further improves recovery without retraining the backbone while retaining deterministic single-pass inference.
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All authors Ruichen Xu, Siyao Wang, Fang Wan, Jiacheng Qiu, Wenhan Gao, Jiaxing Zhang, Linsey Pang, Ravid Shwartz-Ziv, Prakhar Mehrotra, Yann LeCun, Yuefan Deng
High Energy Physics (Phenomenology)
Non-global logarithms and fiducial transverse-momentum-dependent observables in deep-inelastic scattering
Shuo Lin and Jian Zhou
Extracting the intrinsic transverse-momentum structure of
quarks from deep-inelastic scattering data requires separating nonperturbative effects from perturbative radiation, which broadens the measured transverse-momentum distributions. We address this problem in electron–
proton scattering, $ep\to eX$, by introducing the fiducial imbalance $\boldsymbol{q}_T$, defined as the vector sum of the scattered electron's transverse momentum and all hadronic transverse momenta within a specified rapidity window. This construction reduces radiative
recoil without requiring jet reconstruction or an explicit jet veto. We account for non-global logarithms (NGLs) arising from correlated soft emissions across the acceptance boundary. The azimuthally averaged NGL contribution is resummed to all orders at leading-logarithmic accuracy in the large-$N_c$ limit using Banfi–Marchesini–Smye
evolution, while the leading NGL correction to the first azimuthal harmonic is included at $\mathcal{O}(\alpha_s^2)$. For the EIC and EicC kinematics considered, widening the rapidity window increases the cross section at low $q_T$, a region particularly sensitive to nonperturbative transverse dynamics, and reduces the dilution of
spin asymmetries by azimuthally symmetric soft
recoil. Both the Sivers single-
spin asymmetry $A_{UT}$ and the worm-gear double-
spin asymmetry $A_{LT}$ increase in magnitude, while the $\boldsymbol{q}_T$ integrated cross section remains unchanged. The unpolarized $\cos\phi$ moment generated by soft
gluon radiation is sensitive to NGL effects, with its ratio definition reducing common normalization uncertainties. The absence of jet reconstruction makes this observable particularly relevant at the lower collision energies of EicC, providing a way to study nonperturbative
spin–momentum correlations by varying the fiducial acceptance.
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Computational Physics · Cross-listed from cs.LG
PDE-OBS: Controlled Evaluation Across Observation Patterns
Ruichen Xu, Siyao Wang, Fang Wan et al. (+7 more)
Physical-field reconstruction and
forecasting depend on both measurement density and spatial layout, yet evaluation under a single observation pattern does not characterize performance when that pattern changes. We introduce PDE-OBS, an integrated benchmarking platform spanning numerical data generation, model training, and inference and evaluation under varying observation conditions. It combines 560,000 fields and trajectories from seven partial differential equation families with configurable observation operators and seven adapted baseline methods for stationary reconstruction and short-horizon
forecasting. Separating observation construction from physical records allows users to specify parameterized patterns and deterministic mixtures for training and testing while preserving prediction targets and data splits. The evaluation protocol uses references trained for each test pattern to compare models on identical test observations and targets, alongside equal-count groups for spatial-layout comparisons. On a 14,000-record subset, we evaluate 441 trained models under nine test patterns, yielding 3,969 evaluations. Mean cross-pattern error exceeds mean matched-pattern error in all 49 PDE-method pairs, and this finding persists in a configuration-matched subset of 117 models. Denser test observations do not consistently reduce error for a fixed model. Mixed-pattern training on five completed pairs reduces large single-pattern transfer errors, although destination-trained references usually remain more accurate. Together, the
benchmark and findings support systematic evaluation of observation-pattern sensitivity and provide a reusable workflow for developing methods under changing measurement conditions. Code: https://github.com/ru1ch3n/PDE-OBS.
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All authors Ruichen Xu, Siyao Wang, Fang Wan, Jiacheng Qiu, Wenhan Gao, Jiaxing Zhang, Linsey Pang, Ravid Shwartz-Ziv, Yann LeCun, Yuefan Deng
Instrumentation and Methods for Astrophysics
ECLIPSE-X: Plate-Scale Calibration as the Binding Constraint on Relativistic Astrometry with Spacecraft Navigation
Pedro J. Llanos
Precision
stellar astrometry near the Sun can constrain the parametrized post-Newtonian (PPN) parameter gamma through gravitational light deflection. This study develops ECLIPSE-X, a localized multi-frame estimation architecture in which one persistent relativistic parameter is estimated simultaneously with frame-dependent spacecraft line-of-sight and roll states, separated by their differing spatial signatures and by the persistence of gamma across frames. The aim is not a competitive determination of gamma, but an assessment of whether such a joint solution and its formal covariance stay statistically valid under realistic astrometric model error. A synthetic field of 250
stars spanning 1.22-8 apparent
solar radii is observed over 40 frames at 5-s cadence; weighted least squares estimates gamma with three
navigation states per frame, and Schur-complement marginalization gives the formal uncertainty in gamma after
navigation coupling. The nominal solution recovers gamma = 1.0001198167 with sigma_gamma = 3.075104e-4, and a 1000-realization ensemble confirms calibration. Perturbations unknown to the
estimator identify plate-scale mismatch as the dominant failure mechanism: a 300-ppm scale error alone inflates the empirical-to-formal uncertainty ratio to 7126.6 with zero 1-sigma and 2-sigma coverage, against 2.18 for catalog-coordinate mismatch and 1.12 for a frame-coherent radial perturbation, while every realization converges numerically: convergence does not guarantee statistical validity. Augmenting the state with a plate-scale parameter restores consistency, at a fixed 21.2% cost in the precision of gamma set by the correlation between the two persistent parameters. A calibration sweep shows the unaugmented
estimator is covariance-consistent only below sigma_p = 2.7884e-8, so the augmented state is a requirement, not a refinement, for near-Sun relativistic astrometric
estimators.
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Quantum Physics
Affine spin-pencil factorization of generalized driven anisotropic Rabi–Stark Hamiltonians in an inhomogeneous orthosymplectic superalgebra
B. M. Rodriguez-Lara, F. H. Maldonado-Villamizar, A. Kafuri et al. (+1 more)
We construct a supersymmetric factorization for generalized driven anisotropic Rabi–Stark
Hamiltonians using an affine factor $\hat{A}=\hat{C}+\hat{a}\hat{D}$ in an inhomogeneous orthosymplectic superalgebra, with two real invertible
spin matrices $\hat{C}$ and $\hat{D}$. The six real pencil parameters constrain nine
Hamiltonian frequencies and one energy offset up to an overall frequency scale. The normal product $\hat{A}^{\dagger}\hat{A}$ has an exact zero-energy ground doublet and, with its antinormal partner $\hat{A}\hat{A}^{\dagger}$, gives a Witten index of two. For distinct pencil roots with finite baseline slopes, coherent gauges define a Bargmann hierarchy and endpoint conditions for exceptional finite-
polynomial states. The
spin grading organizes four limiting cases, comprising two driven-oscillator families with every baseline exact and the constrained anisotropic-Rabi and Rabi–Stark sheets, which meet at the degenerate-
qubit isotropic Rabi model. An aligned interior example adds direct and longitudinal drives, Stark deformation, and intensity-dependent coupling while retaining the factorization.
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All authors B. M. Rodriguez-Lara, F. H. Maldonado-Villamizar, A. Kafuri, A. Moroz
Mathematical Physics · Cross-listed from math.AG
From $3$-spin to Negative $r$-spin: Limits of Cohomological Field Theories and Tautological Relations
Deniz Genlik and Felix Janda
We prove that the negative $r$-
spin tautological relations of Chidambaram–Garcia-Failde–Giacchetto are a consequence of Pixton's $3$-
spin relations, for every $r\ge2$, and deduce that they hold in the tautological Chow ring of $\overline{\mathcal{M}}_{g,n}$. In particular, our result for $r=2$ implies that Kazarian–Norbury $K$-relations hold in Chow. The proof factors through two essential parts. The first part shows that the tautological relations arising from Chiodo's class imply the negative $r$-
spin relations. This requires an intricate study of limiting behavior of the Givental–Teleman graph contributions. In the second part, we show that the Chiodo relations are a consequence of Pixton's $3$-
spin relations as an application of a generalization of Janda's work on tautological relations from CohFTs.
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Mathematical Physics · Cross-listed from math.SP
Bouncing-ball modes in ergodic billiards
Zhenhao Li and Maciej Zworski
We show that for a horizontally stretched Bunimovich billiard, for almost every stretching parameter, there exists a sequence of eigenfunctions concentrating in the rectangular part. Thanks to the work of Markarian–Oliffson Kamphorst–Pinto de Carvalho, we know that for an open set of parameters such billiards are ergodic. The proof is a result of interaction with ChatGPT 6: we were curious if it could establish the existence of bouncing ball modes for Bunimovich or Sinai billiards. That was not successful until we suggested varying the wings. That produced an essentially complete argument for the existence of quasimodes. We then suggested using Hassell's parameter-variation argument which led to the result about eigenfunctions. The argument was then significantly simplified and clarified by the authors.
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Superconductivity
Evanescent-wave Johnson Noise from Superconductors
Hruday Mallubhotla, Gustav Romare, Ilya Esterlis et al. (+3 more)
We compute the evanescent-wave Johnson noise (EWJN) in the
vacuum half-space above a
superconductor, and the resulting relaxation time ($T_1$) of
spin and charge
qubits placed at nanometer distances from the surface. The electromagnetic response is described by a single microscopic transverse current-response kernel $Q(q, \omega)$ for a BCS
superconductor. This is computed for varying densities of both non-
magnetic impurities and
magnetic impurities, for arbitrary frequency and temperature and for wave vectors $q \ll k_F$ (the
Fermi wavevector). When combined with the fluctuation-dissipation
theorem and the nonlocal surface impedances of the half-space, this yields the
magnetic and electric field noise at any distance $z \gg k_F^{-1}$ from the surface, from which we obtain $T_1$. Just below $T_c$ the
magnetic noise is enhanced relative to the normal state by the coherence (Hebel-Slichter-type) peak of the dissipative conductivity and drops exponentially at lower temperatures; the electric noise shows no coherence peak. The theory predicts that there is a zero-temperature noise floor induced by
magnetic impurities. In the gapless regime produced by pair breaking, the finite subgap density of states $\nu(0)$ yields a temperature-independent noise spectral density and a relaxation rate bounded by $T_1^{-1}(T)\le[\nu(0)/\nu_F]^{2}\,T_{1,N}^{-1}(T)$ for $T\ll T_c$, with equality in the extreme nonlocal regime. Here $\nu(0)$ and $\nu_F$ are the superconducting and normal-state densities of states at the
Fermi energy, and $T_{1,N}(T)$ is the relaxation time the same electrode would produce in its normal state at the same temperature.
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All authors Hruday Mallubhotla, Gustav Romare, Ilya Esterlis, Maxim Vavilov, Robert Joynt, Alex Levchenko
Materials Science
Enabling the Ambient Pressure Growth of ScB2 Crystals for AlGaN Power Electronics
Satya K. Kushwaha, Ahamed Raihan, Astrid D. Kengne et al. (+19 more)
Here we report the growth of single crystalline ScB2, an ultrahigh-temperature ceramic, at ambient pressure in a
laser-heated Optical Floating Zone via the travelling solvent method.
Crystals have been grown from both Sc-rich (55-65 at% Sc) and B-rich self-flux (80-83 at% B) at growth rates in the range of 0.2-2 mm/hr. The structure of grown
crystals is in good agreement with an AlB2-type layered hexagonal phase, space group P6/mmm, with
lattice constants a = 3.1423(2) Å\ (resp. 3.1502(3) Å) and c = 3.5084(3) Å\ (resp. 3.5041(3) Å) for
crystals grown under Sc-rich (resp. B-rich) conditions.
Crystals natively grow along the in-plane [100] direction. Electron backscattered diffraction shows that Sc-flux growth results in boules with multiple domains containing Sc inclusions, with the domains highly aligned. In contrast, B-flux boules are single domain after the initial nucleation region. Rocking-curve measurements of B-flux
crystals for the (h000) and (000l) reflections show single peaks, establishing that the
crystals are free from grain boundaries; the asymmetry in the scattered-intensity tails suggests the presence of point defects. Surface X-ray photoemission spectroscopy shows that the electronic environment in B-flux
crystals is superior to that of Sc-flux
crystals and produces highly resolved binding-energy peaks for B 1s and Sc 2p. Work-function measurements for the (11-20) plane give a value of approximately 5 eV, consistent with the highly electrically conductive nature of ScB2. These results demonstrate the viable ambient-pressure growth of ScB2, establish it as a
lattice-matched substrate candidate for Al-rich AlGaN power microelectronics, and show that this growth route enables scalable manufacturing of ScB2 substrates.
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All authors Satya K. Kushwaha, Ahamed Raihan, Astrid D. Kengne, Daniel Joel Harrison, R. Shipra, Han Xie, Evan N. Crites, Allana G. Iwanicki, Luke J. Meiler, Sharad Mahatara, Maxime A. Siegler, Renae N. Gannon, Steven R. Spurgeon, Rajeswari Kolagani, Amitayush Jhu Thakur, Stephan Lany, Patrick E. Hopkins, Jessica L. McChesney, Nancy Haegel, Tyrel M. McQueen, Michael G. Spencer, MVS Chandrashekhar
Mesoscale and Nanoscale Physics
Effects of Longitudinal Spin Current Density Gradient on Spin-Orbit Torque Switching of Perpendicular Magnetization
Guowen Gong, Qianbiao Liu and Lijun Zhu
It has remained a critical open question as to whether a longitudinal
spin current gradient (e.g., due to a gradient in the thickness, composition, or width) can replace the longitudinal
magnetic field required for deterministic
spin-orbit torque switching of normal metal/ferromagnet
heterostructures with perpendicular
magnetic anisotropy. Here, we report robust micromagnetic and experimental evidence that any realistic longitudinal
spin-current density gradient cannot be an effective replacement for a longitudinal
magnetic field to enable deterministic switching of a perpendicular
magnetic anisotropy device. Instead, the longitudinal
spin current density can only modify the nucleation and pulse-timing-sensitive oscillations of
magnetic domains and thus the picosecond-scale strip-like indeterministic switching windows. The same conclusions hold robustly when the transverse effective field associated with the
spin-current pulse (the sum of the Oersted field and field-like torque) is taken into account. The indeterministic switching prevents applications in the presence of finite device-to-device variations and drifts in write current pulse and thermal fluctuations of device parameters. We also experimentally show that, instead of a longitudinal
spin current density gradient, perpendicular
spins are much more effective in deterministic switching of perpendicular
spin torque devices.
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Computational Physics
TT-FDTD: Tensor Train Accelerated Three-Dimensional FDTD With Logarithmic Cost of Spatial Operators
Chris Nguyen and Vladimir Okhmatovski
Quantized tensor-train (QTT) compression is incorporated into a full-vector three-dimensional scattered-field finite-difference time-domain (FDTD) formulation on uniform Yee grids. All six electromagnetic-field components, material-dependent update coefficients, equivalent-current sources, and staggered finite-difference operators are represented in compatible QTT form. Gaussian regularization of voxelized material interfaces is used to reduce the coefficient ranks generated by abrupt dielectric and conductivity transitions. The formulation is evaluated for an anatomically heterogeneous human-head model and a homogeneous dielectric sphere on grids containing up to $512^3$ spatial
cells. The reported results show that interface smoothing substantially reduces material-coefficient ranks and that the TT–FDTD solution reproduces the full-grid transient fields with pointwise absolute errors on the order of $10^{-4}$ in the examined slices. Compared with conventional FDTD, the tensor representation greatly reduces storage at fine discretizations, although tensor contractions and recompression introduce additional per-step computational cost. These results demonstrate the feasibility and
memory–time tradeoff of QTT-accelerated three-dimensional FDTD for large structured-grid simulations.
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Quantum Physics
Improved Quantum Algorithms for Black-Box Abelian Group Decomposition
Junrong Luo, Yinan Li and Francois Le Gall
Decomposing finite Abelian black-box groups into cyclic factors is a basic problem in
quantum computation. We give a
quantum algorithm for decomposing finite Abelian black-box groups by adapting the
quantum sampling and classical
lattice-reduction method of Regev's factoring
algorithm. The
algorithm computes an invariant-factor decomposition and corresponding cyclic generators with high probability. For a group G of order at most 2^n with unique encodings and reversible group-operation cost T_op = Omega(sqrt(n)), our
algorithm uses O(sqrt(n))
quantum circuits, each with O~(n T_op) gates and executed at most O(n) times. For comparison, we consider the Cheung-Mosca
algorithm, which decomposes the Sylow p-subgroups separately. We also consider the common-modulus implementation of the extended Cheung-Mosca
algorithm. Our
algorithm reduces the sum of the
circuit gate counts from O~(n^2 T_op) to O~(n^(3/2) T_op). The total
quantum time bound reduces from O~(n^3 T_op) to O~(n^(5/2) T_op), and the
quantum space bound reduces from O(n^2) to O(n)
qubits. The classical computation uses polynomially many bit operations and group-operation queries. These improvements rely on two technical ingredients. We prove that the integer relation
lattices used in our
algorithm admit, with high probability, integral bases whose vectors have Euclidean norm at most exp(O(sqrt(n))). We preserve the
circuit-size advantage of Regev's
algorithm for group decomposition by incorporating all O(n) sampled generators while keeping the
lattice-reduction dimension at O(sqrt(n)).
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Quantum Physics
Quantum Computing for Network Security Classification: Near-Term Classification and Long-Term Memory Efficiency
Yuqing Li, Poonam Bala Nehru, Yunpeng Zhang et al. (+4 more)
Quantum computing has already been explored in several network-security applications. However, how
quantum computing may contribute to network-security classification in both the near term and the longer term has not been systematically discussed. This paper studies this question through two complementary experiments. First, we evaluate near-term
quantum-kernel support vector machines (SVMs) on practical network-security classification tasks and compare them with classical SVM baselines on KDD Cup 1999, CICIDS2017, and BoT-IoT. Across these runs,
quantum kernels are competitive. They can match or improve classical baselines in some settings, while classical RBF kernels remain stronger in others. This suggests that near-term
quantum-kernel methods should be evaluated as practical,
dataset-dependent alternatives to classical kernels rather than as uniformly superior replacements. Second, we use
quantum oracle sketching (QOS) to study a longer-term
memory advantage for classification with streaming classical samples. In QOS, samples are processed online and used to incrementally construct an approximate
quantum oracle, which provides coherent query access for downstream
quantum algorithms without retaining the entire
dataset. Under the QOS-inspired machine-size estimate, comparable accuracy corresponds to a substantially smaller effective
memory-size proxy than explicit sparse/QRAM-style storage. Compared with a simple streaming proxy, the result is more nuanced because aggressive feature filtering can make the streaming dimension small. This suggests that the long-term value of
quantum computing for network-security classification may lie in
memory-efficient data access rather than immediate runtime speedup. Together, these experiments show how
quantum computing may contribute to network-security classification from near-term classification performance and longer-term
memory efficiency.
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All authors Yuqing Li, Poonam Bala Nehru, Yunpeng Zhang, Danindu Gammanpilage, Xin Jin, Zeguan Wu, Junyu Liu
Statistical Mechanics
Crossover of Scaling Behaviors of Work Cumulants in a Driven Gaussian Field Theory
Yanbo Qiao, Ruohan Xu and H. T. Quan
We derive the finite-temperature characteristic function of work (CFW) for a driven $O(N)$ Gaussian field theory and obtain closed-form expressions for all zero-temperature excess-work cumulants. For gapped protocols, we use adiabatic perturbation theory (APT) to derive the $\tau_Q^{-2}$ scaling for protocols with a nonzero first derivative at either boundary, where $\tau_Q$ is the protocol duration; smoother boundaries lead to faster decay. For power-law protocols approaching the critical point with exponent $p$, we determine the competition between critical excitations and the regular contribution. The $n$th cumulant's critical contribution follows Kibble–Zurek (KZ) scaling $\tau_Q^{-p(d+n)/(p+2)}$ for $d+n<2p+4$, acquires a logarithmic correction $\tau_Q^{-2p}\log\tau_Q$ at $d+n=2p+4$, and scales as $\tau_Q^{-2p}$ above this condition, where $d$ is the spatial dimension. This analytical study of the APT–KZ crossover in a solvable model provides a basis for studying their competition in interacting field theories.
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Materials Science
From Automated Simulation to Autonomous Discovery: A Hierarchical Framework for Agentic Computational Materials Science
Linggang Zhu, Jian Zhou and Zhimei Sun
The convergence of large
language models, materials-specific foundation models, and agentic artificial intelligence is reshaping the paradigm of computational materials discovery. While high-throughput computation, automated workflows, and data-driven modeling have greatly expanded the scale of materials exploration, the core scientific decision-making loop remains largely human-directed. Agentic AI introduces the possibility of systems that can autonomously reason about materials objectives, execute simulations, and refine strategies. However, the rapid emergence of such systems has created a critical need for a unified and operational framework to define, evaluate, and guide scientific autonomy in computational materials discovery. In this Perspective, we propose the Computational Materials
Agent Autonomy Level (CMA-AL) framework, a hierarchical taxonomy defining six levels of autonomous agency in computational materials science: scripted excecutor, LLM-assisted operator, adaptive explorer, experiment-ready modeler, agentic digital twin, and self-extending intelligence. We further map emerging agentic systems onto the framework and identify key scientific and technological challenges toward higher autonomy. CMA-AL provides a common
language for characterizing agentic computational materials discovery, evaluating the maturity of emerging systems, and guiding their
evolution toward increasingly autonomous materials discovery.
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