Superconductivity
Anomalous field evolution of the mixed-state linewidth in the second superconducting dome of LaFeAsO$_{1-x}M_x$ ($M={\rm F,H}$)
Rustem Khasanov, Pierre Dalmas de Réotier, Samuele Sanna et al. (+9 more)
We report a transverse-field
muon-
spin rotation/relaxation ($\mu$SR) study of the internal-field distribution in the mixed state of LaFeAsO$_{0.89}$F$_{0.11}$ and LaFeAsO$_{0.75}$H$_{0.25}$, representative of the first (SC1) and second (SC2) superconducting domes of the LaFeAsO$_{1-x}M_x$ ($M={\rm F,H}$) family, respectively. Below the superconducting transition temperature $T_{\rm c}$, the linewidth of the internal-field distribution increases in both samples, indicating the formation of a
vortex lattice. Above $T_{\rm c}$, the linewidth remains field dependent and increases approximately linearly with field, consistent with broadening of the powder spectrum caused by an anisotropic Knight shift. After subtraction of this normal-state contribution, the superconducting linewidth $\sigma_{\rm sc}$ exhibits qualitatively different field dependences in the two samples. At 4K, the SC1 ($x_{\rm F}=0.11$) sample shows the expected monotonic decrease with increasing field, whereas the SC2 ($x_{\rm H}=0.25$) sample develops a pronounced local maximum near 3T. A contour representation of $\sigma_{\rm sc}(T,H)$ further reveals a ridge of local maxima whose field position, $H_{\sigma,\max}(T)$, shifts to lower fields upon warming and disappears near $T_{\rm c}$. The anomalous field
evolution observed in the SC2 sample is consistent with an additional field-induced contribution associated with enhanced Pauli-paramagnetic effects, highlighting the distinct electronic character of the two superconducting domes.
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All authors Rustem Khasanov, Pierre Dalmas de Réotier, Samuele Sanna, Gianrico Lamura, Hubertus Luetkens, Matteo Moroni, Pietro Carretta, Rhea Kappenberger, Rowena Wachtel, Bernd Büchner, Sabine Wurmehl, Nikolai D. Zhigadlo
Quantum Physics · Cross-listed from cs.SE
A Framework for Managing the Models of Engineered Quantum Systems
Siyuan Ji, Hayato Ishida, Amal Elsokary et al. (+6 more)
Quantum technologies are maturing into systems that classical engineering must build, verify and maintain. The model-driven community has begun to respond with
quantum-aware pipelines and
languages, and the domain models these produce must be synchronised with the heterogeneous models created and owned by other communities. We argue that existing synchronisation approaches are insufficient for engineered
quantum systems. A
quantum system description captures superposition and
entanglement, which a model transformation could remove undetected, while every structural check passes. To address this, we present the
Quantum Systems Model Management (QSysMM) Framework, which guides the construction and synchronisation of the models of a
quantum system into a digital single source of truth. The framework features four concerns: ontological, abstraction, composition and exposure, each given the treatment that engineered
quantum systems require. Within this framework, we propose a
Quantum Systems Modelling
Language (QSysML) on the SysML v2 technology stack, and we close with a proposal that matures this synchronisation core into full model management for
quantum systems.
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All authors Siyuan Ji, Hayato Ishida, Amal Elsokary, Stephen Powley, Catherine White, Alexandre Zagoskin, Ran Wei, Maria Aslam, Michael J. de C. Henshaw
Materials Science
Oxygen-nonstoichiometry-driven phase transition in $\mathrm{Sr}_{1-x}\mathrm{Nd}_{x}\mathrm{CoO}_{3-\delta}$ ($x = 0.1, 0.2, 0.3$) perovskites
Nina Tereshko, Roman Lanovsky, Olivier Toulemonde et al. (+5 more)
We report a systematic study of the interplay between oxygen nonstoichiometry,
crystal structure, and
magnetic/electrotransport properties in $\mathrm{Sr}_{1-x}\mathrm{Nd}_{x}\mathrm{CoO}_{3-\delta}$ ($x = 0.1, 0.2, 0.3$). High-resolution
neutron powder diffraction combined with synchrotron x-ray powder diffraction reveals that increasing the oxygen content induces a structural transition from a layered $I4/mmm$ ($2a_p \times 2a_p \times 4a_p$) to an oxygen-deficient orthorhombic $Pmmm$ ($a_p \times a_p \times 2a_p$) phases with preferential oxygen-vacancy occupation. This transition is accompanied by a crossover from G-type
antiferromagnetic with a weak
ferromagnetic component to a
ferromagnetic state, and a drastic decay in resistivity. The
evolution of the
magnetic and transport properties is discussed in terms of changes in the Co
spin state, enhanced Co $3d$ - O $2p$ orbital overlap upon oxygen uptake, and a magnetically inhomogeneous
ferromagnetic state associated with residual oxygen vacancies and mixed $\mathrm{Co}^{3+}/\mathrm{Co}^{4+}$ valence. Our findings experimentally confirm that the stabilization of the layered "314" structure is driven by the presence and ordering of oxygen vacancies rather than A-site cation ordering, whereas the oxygen-deficient oxidized compounds represent an intermediate orthorhombic state preceding fully stoichiometric phases.
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All authors Nina Tereshko, Roman Lanovsky, Olivier Toulemonde, Maxim Bushinsky, Stanislav Savvin, Vadim Sikolenko, Lingyan Xu, Aleksandr Nikitin
High Energy Astrophysical Phenomena
Magnetospheric flows in X-ray pulsars II: Heating, cooling and ionization degree at sub-critical accretion
Alexander A. Mushtukov, Alexander Y. Potekhin, Valery F. Suleimanov et al. (+2 more)
Magnetospheric
accretion flows in X-ray
pulsars shape their spectra, polarization, and variability. We model the thermal balance of the flow enveloping the
neutron star magnetosphere in the sub-critical regime ($L \lesssim 10^{37}\,\mathrm{erg\,s^{-1}}$), where radiation forces do not control the dynamics and single Compton scatterings dominate. The energy budget includes Compton heating by surface X-rays, compressional (adiabatic) heating in the converging flow, and radiative cooling dominated by free-free emission and contributed also by cyclotron emission. We show that the interplay of these processes leads to efficient cooling of the flow in the inner magnetosphere. We compute the flow temperature profile as a function of luminosity and find that near the
stellar surface the temperature can fall to a few tens of eV at $L < 10^{35}\,\mathrm{erg\,s^{-1}}$. Under such conditions, the accreting
plasma, modelled here as pure hydrogen, is no longer fully ionized. In the strong
magnetic fields typical for X-ray
pulsars, such temperatures permit partial recombination of electrons and
protons into neutral hydrogen. As a result, a significant fraction of the flow becomes weakly ionized, while external illumination ionizes this gas only partially within a geometrically thin layer immediately above the
neutron star surface. This implies that magnetospheric
accretion at low luminosities proceeds through a partially ionized medium, in contrast to the commonly assumed fully ionized flow.
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All authors Alexander A. Mushtukov, Alexander Y. Potekhin, Valery F. Suleimanov, Andrew Yu, Sergey S. Tsygankov
Materials Science
Enabling temperature controlled in-situ vapor dosing for lab source X-ray reflectivity measurements
Erin E. Dunphy, Mara A. Fischer, Sasha R. Neefe et al. (+4 more)
X-ray Reflectivity (XRR) is a valuable technique for probing buried interfaces in complex systems relevant to thin-film, membrane, and battery applications, among others. However, many operando and in situ reflectivity
cells are designed for use at synchrotron facilities, limiting the broader accessibility of these measurements. We present an XRR transmission
cell that enables in situ vapor dosing and temperature-dependent experiments on in-house diffractometers. We demonstrate its capabilities with two case studies: the adsorption of water into polyamide (PA) membranes on silicon and temperature-dependent restructuring of polystyrene (PS) pseudo brushes on alumina. Vapor dosing allows for controlled release of vapor into the
cell, allowing operation across a wide range of conditions from rough
vacuum to saturation. We demonstrate that the
manifold can reach 90-95% of saturated pressures, with the measurements presented here spanning 0-250 mbar, which is desirable for adsorption isotherms. Heating studies performed between 25 and 200C demonstrate the ability to resolve Ångstrom scale structural changes in a surface bound
polymer. These results establish a novel streamlined approach to temperature controlled vapor dosing on a laboratory diffractometer, offering straightforward probe-molecule exchange,
vacuum-sealed operations, and variable temperature capabilities.
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All authors Erin E. Dunphy, Mara A. Fischer, Sasha R. Neefe, Devin L. Shaffer, Anthony P. Straub, Michael F. Toney, J. Will Medlin
Disordered Systems and Neural Networks
Interwoven long-range order induced by random fields
Jeremiah Bender and Thomas Vojta
We propose a distinct type of long-range ordered phase that can occur in classical and
quantum many-particle systems. It is induced by
impurities and defects that locally break a subset of the order-parameter
symmetries, i.e., by random-field disorder that couples to a composite vestigial order parameter. The proposed “implectic” phase is characterized by spontaneous
symmetry breaking on the background of the spatially interwoven domain structure created by the random fields. We explicitly demonstrate the existence of this phase in a layered $J_1-J_2$ Ising magnet by means of large-scale Monte Carlo simulations. We then discuss numerous potential applications in systems featuring charge and
spin density wave order including frustrated magnets, cuprate and iron-based
superconductors, and ultracold atoms.
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Quantum Physics
Static entanglement structure and adiabatic Bell-state preparation in the tripartite quantum Rabi model
Li-Li Gao, Zi-Xuan Chen, Long-Jie Li et al. (+4 more)
The tripartite
quantum Rabi model couples two
qubits to a bosonic mode through a collective
spin-oscillator interaction, providing a simple setting for studying two-
qubit entanglement. In the zero-detuning limit, the triplet part of the spectrum splits into branches with zero and maximal
entanglement, while the antisymmetric singlet ladder remains exactly decoupled. Within the triplet sector, finite detuning turns the crossings between these branches into avoided crossings and redistributes this
entanglement. We identify an eigenbranch whose
entanglement grows from nearly zero to a nearly maximal value through such avoided-crossing mixing. The weak-coupling level ordering yields a simple analytic criterion for whether this eigenbranch has a separable weak-coupling endpoint. A three-state effective model explains how the Bell-state component becomes dominant as the coupling increases. We further use a finite-time linear ramp of the collective coupling to
benchmark the final coupling and ramp time required for high Bell-state fidelity. These results show how collective
spin-oscillator coupling reorganizes spectral
entanglement and connects static branch structure to finite-time Bell-state preparation.
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All authors Li-Li Gao, Zi-Xuan Chen, Long-Jie Li, Zi-Cheng Liu, A-Long Zhou, Chuan-Cun Shu, Zi-Min Li
Fluid Dynamics
NeuroForge: Self-Auditing Neural CFD Surrogates with Calibrated Physics-Residual Trust
Ali Jabbary and Kasra Ghanavati
Machine-learning surrogates for computational fluid dynamics (CFD) predict steady flow fields far faster than classical solvers, but emit a single field with no built-in way to know whether to trust it – especially out of distribution. We make the surrogate audit itself against the governing physics: we compute the discretised steady-state Reynolds-averaged (RANS) residual of the prediction and ask what jobs it can do. Our central finding is a clean two-way dissociation: the physics residual is a reliable, backbone-robust trust signal (it tells you where the prediction is wrong) but a poor correction objective (it does not tell you how to fix it). As a trust signal, the residual's per-case rank correlation with field error is consistently positive across three architecturally distinct backbones and a second
dataset of laminar bluff bodies; it flags the worst-decile cases with AUROC $\approx 0.9$, and a distribution-free split-conformal layer attains its target coverage. As a correction objective, the residual fails: reducing it does not reduce field error. The monotone-residual acceptance gate built on it, by contrast, does help. Separately, a learned deep-
equilibrium corrector trained toward ground truth lowers volume-field error on a state-of-the-art backbone; a controlled ablation that removes the residual input matches this gain, so the improvement comes from the learned correction, not from conditioning on the residual. The contribution is a self-
auditing, calibrated trust layer, the residual's two roles (trust signal yes, correction objective no), and the learned correction it accompanies, demonstrated on a competitive surrogate and released as the open-source neuroforge-cfd package.
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Superconductivity
Superconducting dome and field-enhanced superconductivity of PLD synthesized Nd1-xEuxNiO2 thin films
Wenlong Yang, Qiang Zhao, Xingke Fu et al. (+8 more)
We report on the synthesis of infinite-layer Nd1-xEuxNiO2 (0<x<0.7) thin films using pulsed
laser deposition (PLD) followed by topotactic reduction with CaH2. Resistivity measurements on these films reveal a superconducting dome within the doping range 0.2<x<0.5, which is wider than that achieved by molecular beam epitaxy and comparable to that obtained by chemical synthesis. The x=0.3 PLD film exhibits the optimal superconducting transition temperature Tc~31 K, much higher than those grown by other
vacuum epitaxial techniques. This result indicates that PLD is an ideal approach for fabricating high-quality, high-Tc Nd1-xEuxNiO2 superconducting films. Magneto-transport measurements reveal robust field-enhanced and re-entrant superconductivity in both underdoped and overdoped regimes. At low temperatures just above the onset Tc, the
Hall resistance exhibits nonlinear behavior, which may originate from
magnetic impurity scattering. These results highlight the crucial role of
magnetic rare-earth Eu2+ ions in producing the exotic physical properties of the infinite-layer nickelates.
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All authors Wenlong Yang, Qiang Zhao, Xingke Fu, Gaofei Ren, Zhongjing Wu, Zhen Chen, Jianping Sun, Boseng Wang, Jiacai Nie, Pengtao Yang, Jinguang Cheng
Optics
Gain-controlled directional scattering in core-shell nanoparticles mediated by magnetic toroidal dipoles
Tiago J. Arruda
Toroidal dipole moments arise from poloidal current distributions and form a distinct class of electromagnetic excitations with unique near-field characteristics. Using Lorenz-Mie theory, we show that interference between conventional
magnetic and
magnetic toroidal dipoles in core-shell nanoparticles produces Fano resonances and pronounced forward-backward scattering asymmetry. By introducing optical gain in the dielectric core, we demonstrate that the toroidal mode can be selectively enhanced, enabling control of near-field confinement and far-field scattering directionality. As the gain varies, we find that the system undergoes a continuous transition from suppressed backscattering to suppressed forward scattering through an intermediate regime of dominant
magnetic-dipole radiation. This dipolar scattering pattern is associated with a phase resonance of the
magnetic toroidal dipole and a reversal of the poloidal current handedness. These results identify gain-controlled toroidal excitations as a tunable mechanism for directional scattering in nanoscale systems.
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Mesoscale and Nanoscale Physics
Lifshitz-Kosevich Theory of Anomalous Landau Levels in Topological Flat Bands
Chao-Xing Liu
In conventional metals,
quantum oscillations arise from Landau quantization of
Fermi-surface cyclotron orbits, whose dynamics are governed by the
Fermi velocity and cyclotron effective mass within Lifshitz-Kosevich (LK) theory. A perfectly flat band, by contrast, has vanishing group velocity, which would naively imply an infinite cyclotron mass and complete thermal suppression of
quantum oscillations. Yet topological flat bands can support anomalous Landau levels (LLs) whose finite-field spacing is generated by
quantum geometry rather than band
curvature, allowing
quantum oscillations to persist. This work addresses how such anomalous flat-band LLs behave within the LK framework and whether their thermal damping can reveal
quantum geometric information. Using a minimal model with exactly flat topological bands, we derive an LK theory for these anomalous LLs and analyze fixed-density magnetization oscillations. The resulting oscillations exhibit a finite LK effective mass that is substantially larger than the normal-band value and possesses a strong
magnetic-field dependence. In the weak-field limit, this anomalous mass reflects the
quantum geometric origin of the LL spacing and scales inversely with both the
magnetic field and the trace of the
quantum metric. Thus, thermal damping of flat-band
quantum oscillations directly measures the
quantum metric, establishing
quantum oscillations as a probe to flat-band
quantum geometry.
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General Relativity and Quantum Cosmology
Circular orbits and particle collisions close to charged black holes surrounded by scalar clouds
Maria Chivers, Betti Hartmann, Katherine Horton et al. (+1 more)
We study the motion of massive (un)charged test particles in space-times of electric and dyonic black holes which carry scalar hair. We determine the stable and unstable circular orbits and discuss the collision of massive test particles. In particular, we aim at demonstrating how the presence of the scalar hair of the black hole changes the circular orbits and particle collisions, respectively, as compared to the Reissner-Nordström (RN) space-time. We find that in the presence of scalar hair, up to four circular orbits (two unstable and two stable) as well as static orbits with $L=0$ can exist. Particle collisions can generate infinite center-of-mass energy when at least one of the particles is charged, very similar to the RN case. We find, however, that the value of the charge at which this divergence happens depends on the value of the scalar field on the horizon.
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All authors Maria Chivers, Betti Hartmann, Katherine Horton, Yves Brihaye
Mesoscale and Nanoscale Physics
Retarded interaction between opposite chiral edges in anomalous Hall crystals
Wangqian Miao, Mu-Yang Chen, Binghai Yan et al. (+1 more)
An anomalous
Hall crystal combines spontaneous electronic crystallization with a Chern insulating gap, supporting both
chiral edge modes and low-energy electronic
phonons. We show that this coexistence produces a distinct dynamical effect from ordinary Chern
insulators: transverse bulk
phonons can mediate a retarded interaction between counterpropagating
chiral edge modes on opposite sides of the sample, realizing a Luttinger-
liquid variant with delayed inter-edge coupling. Using microscopic time-dependent Hartree–Fock calculations for rhombohedral pentalayer
graphene, we find that lowering the carrier density softens the long-wavelength transverse
phonon mode. Near this instability regime, the resulting boundary-projected
phonon continuum inevitably overlaps with the edge dispersion, thereby enabling their coupling. A smoking-gun probe is a nonlocal measurement: a drive applied to one edge can induce a response on the other edge, delayed by the transverse
phonon time of flight across the sample.
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All authors Wangqian Miao, Mu-Yang Chen, Binghai Yan, Chunli Huang
Cosmology and Nongalactic Astrophysics
R. Cassano, G. Di Gennaro, V. Cuciti et al. (+24 more)
Giant radio halos (RHs) are diffuse, Mpc-scale synchrotron sources observed in a growing fraction of
galaxy clusters. They trace relativistic particles and
magnetic fields in the intracluster medium (ICM), providing a unique window into non-thermal processes and their role in cluster
evolution. RHs are primarily found in merging systems, supporting models in which
turbulence generated during cluster collisions re-accelerates pre-existing electrons to the energies required for the observed
radio emission. In this scenario, the occurrence, power, and spectral properties of RHs depend on the energetics of cluster mergers, with the most massive and dynamically disturbed clusters hosting the most powerful
halos. Low-frequency observations are crucial to uncover ultra-steep-spectrum RHs, a key prediction of turbulent re-acceleration models, and are expected to arise from less energetic merger events. LOFAR has enabled statistical studies of large cluster samples, placing robust constraints on RH occurrence and spectral trends. In this Chapter, we model RH formation and
evolution using Monte Carlo simulations calibrated on LoTSS-DR2 findings, and we present predictions for SKA-Low in the AA4 configuration. Our results show that SKA will probe an unprecedented region of cluster mass and
redshift space, detecting at least $\sim 2500$ RHs up to $z \approx 0.6$, including $\gtrsim 1000$ ultra-steep-spectrum systems, and revealing
halos in clusters down to $\sim 10^{14}\, M_\odot$ and out to $z \approx 1$. These surveys will provide stringent tests of turbulent re-acceleration models and significantly advance our understanding of non-thermal processes in
galaxy clusters.
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All authors R. Cassano, G. Di Gennaro, V. Cuciti, A. Datta, M. Balboni, G. Bernardi, A. Bonafede, A. Botteon, M. Brüggen, G. Brunetti, S. Chatterjee, K. Dolag, S. Ettori, F. Gastaldello, S. Giacintucci, C. Giocoli, M. Gitti, R. Kale, M. Pandey-Pommier, G. W. Pratt, M. Rahaman, M. Rossetti, H. J. A. Röttgering, R. Santra, K. S. L. Srikanth, R. J. van Weeren, T. Venturi
Classical Physics
Tuning Plasma Frequency of Nested Wire Media
Denis Sakhno and Pavel A. Belov
We study nested wire media possessing $C_6$ and $C_4$ rotational
symmetries whose
plasma frequencies can be controlled through breathing deformation. Numerical simulations reveal tunability exceeding $80\%$ and $60\%$ for the considered $C_6$ and $C_4$ breathing geometries, respectively. To describe these structures, we develop an analytical model based on the local field approach within the thin-wire approximation, which confirms the high tunability of the studied wire structures. We also propose an approximation for dense wire media. The developed framework is applicable to the general case of nested wire structures – wire media with an arbitrary parallelogram
lattice and multiple wires per unit
cell.
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Optics
Program-Synthesis-Driven Autodesign of Universal Unitary Operators
Yifei Zhang, Dong Chen, Fan Wang et al. (+6 more)
We demonstrate that AI-driven program synthesis can autonomously discover fundamental strategies for decomposing
unitary matrices in photonic networks. By extending DreamCoder to complex-valued linear
algebra, the system generates decomposition programs achieving the minimal $N(N-1)/2$ Mach-Zehnder interferometers, distinct from both Reck and Clements architectures. Learned programs encode dimension-agnostic invariants: strategies discovered for $5 \times 5$
matrices generalize to higher dimensions such as $64 \times 64$. The discovered programs encode interpretable, dimension-agnostic construction rules. These rules generalize across
matrix sizes without retraining, demonstrating that autonomous program synthesis can serve as a scalable paradigm for
algorithm discovery and the automated design of universal
unitary operators. Beyond universal decompositions, the system automatically exploits
matrix structure to reduce the interferometer count below the universal theoretical bound. For instance, for Householder
matrices, it discovers a dimension-independent rule that requires only $2N-3$ MZIs. This achieves linear, rather than quadratic, scaling and generalizes to arbitrary $N$ without retraining. For
matrices obtained from the singular value decomposition of sparse
matrices, reductions generally increase with sparsity, reaching up to 38% fewer MZIs than the universal theoretical bound $N(N-1)/2$ at 95% sparsity. These MZI reductions translate directly into practical hardware benefits for scalable photonic implementations. Taken together, the system functions as a single unified engine that discovers both universal decomposition rules and
matrix-specific optimizations, without being provided with the structural or analytical properties of the input
matrices.
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All authors Yifei Zhang, Dong Chen, Fan Wang, Wenrui Zhang, Yan Chen, Dingding Han, Jianmin Yuan, Xiangjin Kong, Yu-Gang Ma
Disordered Systems and Neural Networks · Cross-listed from cs.LG
Interpreting learning dynamics of autoencoders: Transient scaling and emerging concepts of the Ising model
Max Weinmann and Miriam Klopotek
We study how unsupervised autoencoders trained on microscopic
spin configurations from the Ising model learn macroscopic, theory-relevant variables underlying the data-generating process. We quantify learning across multiple spatial (coarse-graining) scales and reveal two distinct dynamical regimes that appear sequentially, controlled by the main hyperparameters (model depth, width, and learning rate): one in which magnetization and another in which energy is learned across scales. The first exhibits error fluctuations ordered to scale and learns global averages only; The second gradually resolves smaller scales relevant for the energy representation. Deep models trained at moderate and fast rates become arrested before reaching these regimes. We connect reconstruction errors with the latent representations using a novel analysis of self-recursive trajectories. These intrinsic dynamics are induced by prediction errors, exposing how training drives representation changes for macroscopic concepts. We utilize the intuition that learning operates as a process driven far from
equilibrium by fluctuations from the training data to provide an interpretive basis grounded in both the physical world and the machine models that represent it.
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Quantum Physics
Rank-Refined Quantum-Behaved Particle Swarm Optimization for Quantum Molecular Generation
Sing-Yun Wu, Sheng Yun Wu, I-Min Chiang et al. (+1 more)
This work proposes Rank-Refined
Quantum-Behaved Particle Swarm Optimization (RR-QPSO) for high-dimensional parameter search in
Quantum Molecular Generation (QMG). RR-QPSO targets the optimization bottleneck caused by expensive objective evaluations, where each candidate parameter vector requires
stochastic circuit sampling, bitstring decoding, and molecular evaluation. The method provides a population-based alternative to
Bayesian optimization (BO), combining Sobol-based initialization, a rank-refined mean-best update, and fitness-guided refinement based on validity and uniqueness. Experiments use the 9-heavy-atom QMG
benchmark with a 134-parameter, 20-
qubit CUDA-Q
circuit and particle evaluations parallelized across 8 NVIDIA V100 GPUs. With M=64 particles and T=150 iterations, RR-QPSO reaches VxU = 0.930; increasing the swarm size to M=128 further improves the product to 0.942, compared with 0.902 for BO under the same protocol. A multi-objective extension targeting HBA=4 and HBD=3 further shows that RR-QPSO can guide molecular properties while preserving a higher validity–uniqueness product than BO. These results suggest that optimizer-level design can improve QMG without modifying the chemistry-inspired
circuit or molecular decoding pipeline.
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All authors Sing-Yun Wu, Sheng Yun Wu, I-Min Chiang, Tai-Yue Li
Quantum Physics
Resolvent algebras and limit states of interacting canonical ensembles
Detlev Buchholz
The limit states of canonical ensembles of a large number of interacting
bosons at a given temperature, which are confined by harmonic forces, are studied in the framework of the resolvent
algebra. It is shown that the limits satisfy the KMS condition or are ground states, regardless of the type of interaction. In case of attractive forces, where the ensembles collapse, observables that become meaningless in the limit disappear from the limit representations. For repulsive forces, this can also happen if condensates with an infinite number of particles in the same state (proper condensates) appear in the limit. The resulting structures and their interpretation are illustrated by a simple model. The study of vanishing harmonic forces (thermodynamic limit) involves changes of the dynamics. It is conveniently based on derivations acting on the
algebra. They are given by the commutator of the
Hamiltonians with the elements of the
algebra. To ensure that the images remain in the
algebra, the interaction must be regularized. This is accomplished in a manner that has only a minor impact on the dynamics and may be of broader interest. With this input a relation between the strength of the confining harmonic forces and the number of particles in the ensembles is derived from the condition that the limit states are to be stationary (invariant) under the adjoint action of the unconfined, spatially homogeneous limit dynamics. This relation encompasses the conditions that are frequently used in studies of Bose-Einstein condensates.
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Astrophysics of Galaxies
A UV-to-Near-infrared QSO Composite Spectrum from the SPHEREx All-Sky Survey
Minjin Kim, Yongjung Kim, Woong-Seob Jeong et al. (+19 more)
We present a composite spectrum of $\sim 61,000$ type 1 SDSS QSOs (median $z \approx 1.26$), constructed using SPHEREx spectrophotometric data and covering a rest-frame wavelength range of $0.14-4.5~\mu$m. The SPHEREx mission surveys the entire sky in 102 near-infrared spectral channels spanning $0.75-5.0~\mu$m with a spectral resolution of $R \approx 35-130$, providing a unique
dataset for building a statistically robust QSO composite. We find that the UV and optical continuum of the resulting composite can be described by a power law, $f_\nu \propto \nu^{\alpha_\nu}$, with a best-fit spectral index of $\alpha_\nu = -0.10$, while the near-infrared continuum is well-fit with a spectral index of $-1.46$. The power-law indices in both the optical and near-infrared regimes strongly depend on properties of QSOs, such that more luminous QSOs tend to exhibit flatter UV/optical and steeper near-infrared continua compared to those of less luminous ones. The IR-to-optical flux ratio decreases with increasing AGN luminosity, consistent with the predictions of the receding
torus model. The line ratios of broad emission lines, including H$\alpha$, Pa$\beta$, and Pa$\alpha$, are in good agreement with predictions from Case B recombination, suggesting that internal extinction is almost negligible. The equivalent widths of these emission lines are proportional to AGN luminosity, contrary to the trend expected from the Baldwin effect. Finally, the shape of the composite is sensitive to host-
galaxy contamination, which must be considered when utilizing this QSO composite for subsequent scientific applications.
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All authors Minjin Kim, Yongjung Kim, Woong-Seob Jeong, Yujin Yang, Jeonghyun Pyo, Richard M. Feder, Bomee Lee, Dohyeong Kim, Kyuseok Oh, Jong-Hak Woo, Jeong Hwan Lee, Yun-Ting Cheng, Yi-Kuan Chiang, Asantha Cooray, Brendan P. Crill, Olivier Dore, Andreas L. Faisst, Zhaoyu Huai, Howard Hui, Daniel C. Masters, Chi H. Nguyen, Michael Zemcov
Quantum Physics
Nonlocal Manipulation of Backflow with Quantum Correlations
Ya Xiao, Zhen-Fei Zhang, Yan-Xin Rong et al. (+3 more)
Quantum correlations are central resources for
quantum information processing, yet their ability to manipulate dynamical transmission processes remains largely unexplored. Here, we investigate this ability through backflow, a uniquely interference phenomenon in which local probability flow propagates opposite to the momentum direction. We report the first nonlocal manipulation of backflow in double-slit interference using polarization-path-entangled
photons. By performing local measurements on one
photon, we remotely engineer the relative amplitude and phase of the two paths associated with its partner, manipulating the emergence, spatial distribution, and propagation dynamics of backflow without directly accessing the interfering system. Combining weak measurements to extract the transverse momentum and reconstruct Bohmian trajectories, we provide a direct visualization of the manipulation process with single-pixel spatial resolution. Furthermore, using Werner states with tunable correlation strengths, we reveal a distance-dependent resource requirement for nonlocal backflow manipulation: the minimum correlation strength required to induce backflow increases with propagation distance, progressing from
entanglement to EPR-steering and ultimately Bell nonlocality. Our results show
quantum correlations as operational resources for manipulating transmission dynamics and open new avenues for non-contact manipulation of fragile or inaccessible systems.
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All authors Ya Xiao, Zhen-Fei Zhang, Yan-Xin Rong, Kai Sun, Jin-Shi Xu, Yong-Jian Gu
Quantum Physics
Scaling Adaptive Non-Local Observable Quantum Super-Resolution via Matrix Product States
Shih-Lung Yu, Ming-Kang Ho, Tai-Yue Li et al. (+1 more)
This work presents a
matrix product state (MPS) simulation framework for adaptive non-local observable variational
quantum circuits (ANO-VQCs) in image super-resolution (SR) beyond the practical limits of statevector simulation. Runtime
benchmarks on a single NVIDIA RTX 4070 GPU show that, under the tested shallow-
circuit setting, MPS completes ANO-VQC forward feature extraction for individual inputs up to 16 x 16 pixels (256
qubits), whereas statevector simulation encounters a
memory bottleneck at 6 x 6 inputs (36
qubits) and exact tensor-network (Exact TN) contraction becomes computationally impractical beyond 12 x 12 inputs (144
qubits). For a fixed 7 x 7 input (49
qubits), a bond-dimension sweep over depths L = 1 to L = 4 shows that the required MPS bond dimension increases with
circuit depth. Using Exact TN contraction as the reference, the bond dimension required for near-exact agreement increases from chi = 2 at L = 1 to chi = 16 at L = 4. Finally, 7 x 7 to 28 x 28 Fashion-MNIST SR training with chi = 16 shows that the shallow L = 1 model achieves the lowest loss, lowest LPIPS, and highest PSNR and SSIM among the tested depths. These results highlight MPS as a scalable and controllable simulation backend for ANO-VQC image SR and as a practical tool for studying large-scale
quantum algorithms.
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All authors Shih-Lung Yu, Ming-Kang Ho, Tai-Yue Li, Sheng Yun Wu
Quantum Physics
Efficient Circuit Transpilation of Commuting Gates on 2D Grids
Sabina Drăgoi and Daniel J. Egger
Combinatorial optimization problems are central to many applications but can be challenging to solve.
Quantum approaches such as the
Quantum Approximate Optimization
Algorithm (QAOA) offer new tools with which to tackle such problems. However, QAOA
circuits inherit the interaction structure of the target
Hamiltonian, often resulting in deep
circuits when compiled onto hardware with limited connectivity. Efficient transpilation is therefore critical to their practical performance. In this work, we propose a transpilation scheme for
circuits consisting of blocks of commuting two-
qubit gates on two-dimensional
lattices. Unlike standard approaches based on random initial mappings and fixed routing, our method alternates between constructing problem-dependent SWAP-layer sequences and updating the
qubit layout. By adapting the routing to the required interactions, this yields significantly shorter
circuits for graphs with few edges. We
benchmark our approach on QAOA instances for Maximum Cut (MC) on Random Regular graphs and Maximum Independent Set (MIS) on Erdős-Rényi graphs. Compared to standard methods, we reduce
circuit depth and gate count by about a factor of two, enabling experiments with up to $80$
qubits and improving approximation ratios by up to $6.6\%$ for MC and $9.3\%$ for MIS.
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Quantum Physics
Certified quantum supremacy in entanglement-assisted prepare-measure random-access-code
Rajdeep Paul, Prabuddha Roy and A. K. Pan
We develop a family of semi-device-independent (SDI)
entanglement-assisted prepare-measure (PM) communication games involving two parties, within the $n\rightarrow l$ random-access code (RAC) framework where the sender Alice holds a n-bit string and communicates $l<n$ bits or
qubits to the receiver Bob. In contrast to the standard
quantum PMRAC, here the parties share a prior
entanglement, and Alice applies
quantum operations on her sub-system to encode her inputs and sends to Bob. We first consider the $4\rightarrow l$
entanglement-assisted PMRAC with $l=1$ and $2$ and derive the optimal
quantum success probabilities using an elegant analytical technique. We demonstrate
quantum supremacy over both classical RACs and conventional
quantum PMRACs. Moreover, we exhibit that the optimal
quantum advantage allows one to certify Alice's
unitary operations. We then derive an upper bound on the
quantum success probabilities for $5\rightarrow l$
entanglement-assisted PMRAC with $l=1,2$ and $3$. Further, we extend the demonstration of
quantum advantage for $n\rightarrow n-2$ case where n is arbitrary.
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High Energy Physics (Phenomenology)
On the Origins of the Strong CP Problem
Anthony G. Williams
The conventional strong $CP$ problem arises from the tension between an unrestricted physical parameter $\bar\theta$ and the experimental constraint $\lvert\bar\theta\rvert\lesssim10^{-10}$. In the standard formulation, a global topological classification of gauge-field configuration space leads to integer-valued sectors, $\theta$-
vacua, and $\theta$ as a physical
vacuum angle. Alternatively, a physical
flavor-singlet pseudoscalar phase may be introduced through the
quark mass
matrix. The axial anomaly relates these descriptions through the invariant combination $\bar\theta=\theta+\arg\det M$. We ask the logically prior question of whether known physical principles or observables require the introduction of an independent physical
flavor-singlet $CP$-violating parameter in QCD. We distinguish consequences of local gauge invariance and causal locality from those requiring additional global assumptions or the introduction of a physical
flavor-singlet $CP$-violating parameter. For constant $\theta$, the topological charge density is a total four-divergence with no local variational response to compactly supported field variations, and a nonzero $\theta$ coupling is not required by perturbative renormalization. No established QCD phenomenology requires a physical $\bar\theta$ parameter. Without such a parameter, the topological susceptibility, axial anomaly, 't~Hooft vertex, Leutwyler–Smilga and Witten–Veneziano relations, standard
lattice QCD results, semiclassical instanton solutions, and established phenomenological successes of QCD all remain. Nothing prevents the introduction of $\bar\theta$ as an independent physical parameter, which is consistent with these same QCD results. In this sense, establishing that the strong $CP$ problem is an unavoidable feature of QCD requires showing why a physical $\bar\theta$ parameter is required, rather than merely allowed.
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Nuclear Theory
Causality and Stability of First-Order Relativistic Spin Hydrodynamics with Conserved Charges
Wei Lu, Yang Zhong and Sheng-Qin Feng
We study the causality and stability of first-order relativistic
spin hydrodynamics with particle-number conservation. By deriving the complete dispersion relations of linear perturbations around global
equilibrium, we find that conserved-charge dynamics modifies the sound sector and introduces additional non-hydrodynamic modes absent in the charge-neutral theory. While the structure of
spin relaxation modes remains unchanged, the stability conditions acquire new contributions from charge
diffusion and thermodynamic susceptibilities. More importantly, a particle-number-induced mode is shown to violate the causality condition in the short-wavelength limit. We further demonstrate that particle-number conservation does not remove the instability inherent in first-order
spin hydrodynamics. These results reveal nontrivial interplay between
spin and conserved-charge dynamics and provide important constraints on relativistic
spin hydrodynamic theories at finite density.
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Solar and Stellar Astrophysics
Deepanshu Gurjar, Luke Chamandy, Eric G. Blackman et al. (+3 more)
The common envelope (CE) phase is a key stage in binary
star evolution that is still not very well understood. Once engulfed by the
giant star, the binary companion may accrete envelope material. For
neutron star (NS) companions, such
accretion may in principle occur at mass rates several orders of magnitude above the Eddington limit and may result in
outflows dominated by powerful bi-polar jets with mass-loss rates similar to the
accretion rates. Such jets would impact the morphology of the system and the rate of envelope unbinding, which affect the duration and outcome of the CE event. Employing 3D global hydrodynamic simulations, we study the role of such NS jets in a CE event involving a red
giant branch
star. The jets eventually drill through and break out of the envelope, producing prominent low-density bi-polar lobes. The jets cause about twice as much envelope mass to be unbound ($\sim20\%$ of the envelope) as compared to simulations of the same duration without NS jets ($\sim10\%$). However, the rate of mass unbinding due to the jets decreases towards the ends of the simulations as the jets break out and energetically decouple from the envelope. Moreover, jet activity leads to slightly reduced drag on the binary, decreasing the rate of orbital energy transfer to the envelope. Hence, while such powerful jets can play an important role, negative feedback effects tend to prevent them from dominating envelope unbinding and dictating CE outcomes.
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All authors Deepanshu Gurjar, Luke Chamandy, Eric G. Blackman, Yangyuxin Zou, Baowei Liu, Jason Nordhaus
Quantum Physics
HSF-S: Speed-Optimized Compilation and Acceleration for Hybrid Schrodinger-Feynman Quantum Circuit Emulation
Sechan Park, Kyeongwon Lee, Mundo Jeong et al. (+2 more)
Hybrid Schrodinger-Feynman (HSF) simulation offers an attractive
memory-path tradeoff for exact
quantum-
circuit emulation, but its practical runtime is often dominated by exponential path growth from cross-boundary two-
qubit gates. Existing GPU and FPGA
quantum simulators are largely optimized for full-state Schrodinger execution and therefore do not align well with HSF's path-centric workflow. This paper presents HSF-S, a compiler-accelerator co-designed framework for exact HSF-based
quantum circuit emulation. HSF-S lowers input
circuits to an HSF-compatible basis, formulates a rank-aware effective path-cost model, and applies dependency-preserving reordering together with discounted-gain SWAP insertion to suppress recurring cross-boundary interactions while preserving exact
circuit semantics. A regression-free selector guarantees that the compiled
circuit never increases effective path cost relative to the naive lowered baseline. We further design a dedicated HSF-S accelerator and execution flow, and integrate them into a stand-alone processor for efficient per-path dual-slice evaluation and final accumulation without materializing the full state vector. Across 56
benchmark circuits, HSF-S matches reference amplitudes to within floating-point precision, reduces effective path cost by up to 90.0%, and substantially improves practical tractability, including representative timeout-to-sub-second reductions under a 1-hour budget. On the resulting compiled workloads, the HSF-S processor prototype delivers up to 4.34x additional speedup.
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All authors Sechan Park, Kyeongwon Lee, Mundo Jeong, Chaebin Jung, Woojoo Lee
Mathematical Physics
The existence of full dimensional KAM tori for infinite dimensional Hamiltonian systems with long range interactions
Hongzi Cong, Wanran Ding, Zhihan Zhang et al. (+1 more)
We prove the existence of full dimensional KAM
tori for infinite dimensional mechanical systems exhibiting long range interactions, under a Diophantine condition of Bourgain type [Bourgain2005JFA], in which the radius of the invariant
tori satisfies a slower decay.
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All authors Hongzi Cong, Wanran Ding, Zhihan Zhang, Juan Zhao
Earth and Planetary Astrophysics
High Resolution Optical Methane Linelist from observations of Titan for Cross-Correlation studies
Rafael Rianço-Silva, Pedro Machado, Clara Sousa Silva et al. (+2 more)
Exoplanet atmosphere characterization heavily relies on molecular spectroscopic data. Despite efforts to obtain comprehensive spectral libraries for the chemical characterization of
exoplanet atmospheres, large gaps remain, particularly for larger molecules and higher frequencies at high spectral resolution. One key example is the methane (CH4) optical spectrum. CH4, the simplest hydrocarbon, is a crucial species for
exoplanet atmosphere characterization and a possible biosignature. However, until now, high-resolution linelists at optical wavelengths for CH4 have been very challenging to obtain either experimentally or computationally, leaving the high resolution spectrum of CH4 uncharacterised across most of the visible spectrum. This restricts exploration of CH4 absorption in the optical regime, as upcoming instruments such as ELT-ANDES and VLT-RISTRETTO will start probing the atmospheres of ever smaller
exoplanets in optical wavelengths. To address this spectroscopic data limitation, we observed Titan's optical spectrum, dominated by CH4 absorption, at the highest spectral resolution to date with VLT-ESPRESSO. From it, we produced an empirical, low-temperature high-resolution (R ~ 190000) linelist of CH4 in optical wavelengths which we present here, with thousands of previously unidentified lines. We employ this CH4 linelist (RRS-2026) to build a template suitable for high resolution cross-correlation spectroscopy (HRCCS) studies, a first for CH4 in optical wavelengths. With this new linelist, we performed the first HRCCS detection of CH4 in the atmospheres of Titan and Jupiter using optical high resolution spectra. This work sets the stage for the search for CH4 in
exoplanet atmospheres through HRCCS with current and future ground-based high-resolution optical spectrographs, showcasing how
Solar System observations provide useful products for
exoplanet research.
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All authors Rafael Rianço-Silva, Pedro Machado, Clara Sousa Silva, Sergey Yurchenko, Giovanna Tinetti