Plasma Physics
Energy-optimized scaling laws for self-guided laser wakefield accelerators
Petr Valenta, Marcel Lamač, Kyle G. Miller et al. (+4 more)
Laser wakefield acceleration promises compact electron accelerators for applications in medicine, industry, and fundamental science. Yet, despite rapid progress, accurately predicting the electron energy attainable in a given experimental configuration and the acceleration length required to reach it remains an open challenge. Here we use
Bayesian optimization combined with advanced particle-in-
cell simulation techniques to determine the maximum electron energy that a self-guided
laser wakefield accelerator driven by a
laser of a given energy and wavelength can produce. By systematically optimizing the accelerator performance across a range of
laser energies and wavelengths, we derive energy-optimized scaling laws. These scaling laws yield the highest electron energy over the shortest acceleration length possible, are expressed solely in terms of
laser energy and wavelength, and are accompanied by the complete set of
laser and
plasma parameters required to enable the scaling. The resulting scaling laws provide practical guidance for designing state-of-the-art
laser wakefield acceleration experiments operating at their fundamental performance limits.
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All authors Petr Valenta, Marcel Lamač, Kyle G. Miller, Brandon K. Russell, Gabriele M. Grittani, Alec G. R. Thomas, Sergei V. Bulanov
High Energy Physics (Theory) · Cross-listed from math.NT
Modular resurgent structures for vectors
Miranda C. N. Cheng, Ioana Coman, Veronica Fantini et al. (+1 more)
Building on prior results [1], we introduce vector-valued modular resurgent series, whose components exhibit a single infinite tower of singularities in the Borel plane, trivial secondary resurgent series, and Stokes constants given by linear combinations of the coefficients of a vector of $L$-functions. We extend the paradigm of modular resurgence to this setting, emphasizing the role of the Stokes constants and the interplay between the associated vectors of $q$-series and Dirichlet series, and describing the resulting
symmetry relating canonical pairs of vector-valued modular resurgent series. Moreover, we
conjecture that certain vectors of $q$-series with modular resurgent asymptotics are vector-valued
quantum modular forms and can be reconstructed via median resummation. Finally, we show that vectors of $q$-Pochhammer symbols, previously considered in [2], and Eichler integrals of vector-valued modular forms of weight $1/2$ and $3/2$ can be studied within the framework of vector-valued modular resurgence. While the first case amounts to a convenient repackaging of scalar modular resurgence, the second involves a non-trivial representation of the modular group and therefore illustrates the necessity of the vector-valued framework; we establish its modular resurgent structure in general, and work it out in full detail for the unary theta series, whose Eichler integrals are the false theta functions of
quantum topology.
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All authors Miranda C. N. Cheng, Ioana Coman, Veronica Fantini, Claudia Rella
Optics
Nonresonant optomechanical control of structural phases
Jiaojian Shi, Yijing Huang, Christian Heide et al. (+24 more)
Optical tweezers demonstrate how light can exert forces to trap, repel, and manipulate microscopic particles without absorption. Recent theory has suggested that such forces can extend beyond particle manipulation to drive structural phase transitions in solids. Here we apply this optomechanical principle to tin selenide (SnSe), a material where proximity to several different structural phases gives rise to its high thermoelectric figure of merit and makes it a candidate for a switchable topological crystalline
insulator. Whereas the force for standard optical tweezers arises from a gradient in the intensity of a light field, the optomechanical force is mediated by a gradient in the dielectric constant as a function of
phonon coordinate. Unlike conventional methods that rely on resonant excitation and absorption through the imaginary part of the dielectric function, this approach operates dispersively through the real part and can be directly driven by Raman processes, enabling selective transitions with reduced energy cost and ultrafast response. Using time-domain Raman scattering, we show that above a critical mid-infrared field strength the $A_g$ Raman modes disappear abruptly without softening, signaling the formation of a new structural phase. This phase, distinct from those induced by heating or carrier excitation, exhibits large-amplitude and long-lived modulations in its optical response. Complementing this observation, we show also evidence for an equivalent DC-field-driven structural phase transformation to a higher
symmetry phase, as observed by atom probe
tomography. Our study demonstrates the concept of nonresonant optomechanical phase control and defines novel opportunities for synthesizing hidden structural phases with unique functional properties.
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All authors Jiaojian Shi, Yijing Huang, Christian Heide, Elias Hilderbrand, Carl Friedrich Schon, Jan Kottgen, Matthias Wuttig, Burak Guzelturk, Isabel Sedwick, Yukun Li, Haowei Xu, Yuejun Shen, Pooja Donthi Reddy, Viktoryia Shautsova, Mohammad Taghinejad, Duan Luo, Mark L. Brongersma, Kunal Mukherjee, Yuki Kobayashi, Andrew F. May, Eamonn Hughes, Mariano Trigo, David A. Reis, Ju Li, Jian Zhou, Shambhu Ghimire, Aaron M. Lindenberg
High Energy Physics (Phenomenology)
Improved Regge Kinematics and All-Path-Length Corrections to Momentum Broadening in the Quark-Gluon Plasma
Dario van den Berg and Isobel Kolbe
We present a study of transverse momentum broadening for high-energy partons propagating through the
quark-
gluon plasma (QGP), extending the Gyulassy-Levai-Vitev (GLV) formalism to include both all-path-length (APL) corrections and improved sub-Regge kinematics. The standard GLV framework relies on the large separation distance and large formation time approximations, which are well justified in large
nuclei but may become unreliable in small collision systems, where the relevant length and coherence scales are comparable. Working to first order in the opacity expansion, we derive analytic expressions for the transverse momentum broadening distribution and the corresponding momentum transport coefficient, $\hat{q}$, while systematically relaxing these approximations. The APL correction arises from relaxing the large separation distance approximation, whereas the sub-Regge and combined sub-Regge-APL corrections are obtained using an improved set of Regge kinematics beyond the strict Regge limit. We find that these corrections can substantially modify both the transverse momentum broadening distribution and the momentum transport coefficient, particularly for short path lengths and high exchanged momentum, providing a more complete theoretical description of momentum broadening in the QGP.
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Solar and Stellar Astrophysics
Gas Flows and Mass Accretion Rates in Eight Dippers: HD 142666, HD 143006, HD 145718, V935 Sco, DoAr 25, EPIC 204638512, EPIC 205151387, and EPIC 203850058
Michael L. Sitko, Ray W. Russell, Korash D. Assani et al. (+2 more)
One of the scenarios used to explain the dipper phenomenon in
stars is having the innermost disk regions being close to the line of sight to the
star - inclined greater than 60 degrees - regardless of the inclination of the outermost disk ("mis-aligned" or "broken" disks). If the
dust and gas in these disks sample the same material, edge-on disks will be viewed through larger column densities of gas and
dust than the average disk. We have examined inter-night variability of eight Kepler-discovered dipper
stars using the SpeX spectrograph on NASA's Infrared
Telescope facility at a spectral resolving power of R~750. The He I line at 1.083 microns exhibits a wide variety of profiles, which change from night to night. In the majority of cases, an inverse P Cygni profile, indicative of inflowing gas, is present. The line profile (and continuum flux level) often change on time scales of 1 day. The Paschen and Brackett lines also change on similar time scales. In one object, V935 Sco, Pa beta and Br gamma went from being in emission to being in absorption over the course of 5 weeks. In another, EPIC 203850058, Pa beta went from being in emission in 2017 to vanishing altogether in 2018. The
accretion rates determined using Pa beta for these
stars tend to be smaller than those using Br gamma, indicating that the former line is more susceptible to self-absorption than the latter, as would be expected for a highly inclined disk.
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All authors Michael L. Sitko, Ray W. Russell, Korash D. Assani, Lucia Villanueva, Jesus Hernandez
Physics and Society
Towards an LLM-based method for quantifying the sexual content in song lyrics
Ignacio M. Sticco
Reggaeton is one of the most widely consumed music genres in the world, and its lyrics are commonly regarded as highly sexualized. This claim rests mostly on qualitative studies and on small-scale quantitative ones. This paper has two goals. First, we present a reproducible method that uses a large
language model to quantify thematic content in song lyrics along several independent dimensions. The method is not restricted to sexual content. Second, we apply it to a corpus of 1,259 songs by 12 reggaeton artists released between 2002 and 2025. The analysis covers four topics: a
dataset characterization, a per-artist comparison, an analysis of how the dimensions change over time, and a comparison between our sexual-explicitness score and Spotify's own explicit flag. We release the data collection code, the scoring
prompt, and the corpus, so that other researchers can replicate the approach or apply it to their own lyrics
datasets.
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Disordered Systems and Neural Networks · Cross-listed from cs.ET
Reservoir Computing with Heterogeneous Magnetic Metamaterials
R. Yagan, C. Swindells, I. T. Vidamour et al. (+5 more)
Physical reservoir computing utilizes the intrinsic nonlinear and history-dependent dynamics of physical systems to perform machine-learning tasks with minimal training overhead. Here, we introduce a nanomagnetic reservoir computer based on a heterogeneous array of interconnected
magnetic nanorings, combined with multi-channel planar
Hall effect readout. The device comprises subarrays of rings with systematically varied track widths ranging from 500 nm to 300 nm, enabling access to the heterogeneous dynamics of geometrically diverse
magnetic systems within a single reservoir. By applying time-varying input signals as modulations of a driving rotating
magnetic field, we evaluate the nanoring reservoir's performance on nonlinear signal transformation and Mackey-Glass time-series prediction tasks. We find that combining outputs from multiple width-dependent channels significantly reduces the normalized root-mean-square error compared to single-channel readout, with the optimal channel combinations depending on task requirements. These results demonstrate that
geometric heterogeneity provides an additional, experimentally accessible degree of freedom and complementary computational features. Principal component analysis further reveals that a reduced subset of correlated features captures most of the computationally relevant information while suppressing noise contributions. These results demonstrate that controlled
geometric heterogeneity enhances reservoir expressivity and suggest a route toward scalable
magnetic computing architectures in which multi-output
magnetic metamaterials serve as configurable dynamical building blocks for device networks.
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All authors R. Yagan, C. Swindells, I. T. Vidamour, G. Venkat, J. Griffiths, E. Vasilaki, M. O. A. Ellis, T. J. Hayward
Nuclear Theory
Large Amplitude Collective Motion and Dissipation in the Ground State and the First Isomeric Wells in the Neutron-Induced Fission of $^{235}$U
Ibrahim Abdurrahman, Matthew Kafker, Aurel Bulgac et al. (+1 more)
In fission induced by low energy
neutrons, the mother
nucleus spends a significant fraction of the time in the ground state and isomer wells, eventually passing beyond the outer barrier, where the primary fission fragments properties are defined. Despite this, the dynamics of these two early stages have not been investigated using microscopic models. This study examines the
evolution of the mother
nucleus in both wells separately, using time-dependent density functional theory, which has been previously used to treat the saddle-to-scission stage of fission for $^{235}$U(n,f) reactions. These two early stages of fission are essential blocks in the final theory of the formation and
evolution of a compound
nucleus. The present study shows that the dynamics in both wells is strongly dissipative, similar to the dynamics from saddle to scission. It also reveals that while the initial mass asymmetry of the system quickly settles to very small fluctuations in the ground state well, in the isomeric well, the mass asymmetry oscillates with a rather large amplitude, in almost harmonic motion. Furthermore, with low probability,
neutrons are emitted in both wells.
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All authors Ibrahim Abdurrahman, Matthew Kafker, Aurel Bulgac, Ionel Stetcu
High Energy Physics (Theory)
Production of Primordial Black Holes in the Double D3-Brane - anti-D3-Brane Inflation Model
S.-H. Henry Tye
A natural extension of the successful $D3$-${\bar D}3$-brane inflation model in string theory is one with two $D3$-${\bar D}3$-brane pairs, giving rise to a novel feature in string-theory. When the first pair annihilates, $D1$-strings and $F1$-strings are produced. Following the non-commutative
geometric properties in string theory, it is shown by Myers that the presence of the $D3$-charge field strength of the remaining $D3$-${\bar D}3$-brane pair leads to the formation of dielectric $3$-branes – neutral, finite-size bound states of $3$-branes with $D1$-strings. They behave as matter with little or no pressure. Spanning a wide range of masses, they seed
primordial black holes in the early universe.
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General Relativity and Quantum Cosmology
Semilinear wave equations in homothetic hyperboloidal coordinates and tail decay
An{\i}l Zenginoğlu, Sebastiano Bernuzzi and Andrea Nützi
Late-time wave tails decay at different rates along future null infinity and along timelike worldlines at finite radius. A compactified numerical
evolution must represent both the slower decay at null infinity and the faster interior decay, producing an increasingly sharp transition between the two regimes. We address this difficulty for semilinear wave equations in Minkowski spacetime using homothetic hyperboloidal coordinates adapted to the scaling structure of the tail. In these coordinates, the tail approaches a smooth radial profile with the same decay rate at every compactified radius. The formulation therefore avoids the steepening of the radial profile seen in stationary hyperboloidal evolutions, and it reaches late times in a number of steps that grows only logarithmically with retarded time. We demonstrate this approach using pseudospectral simulations in 3+1 dimensions and reproduce the generic decay rates conjectured by Rinne. We also provide numerical evidence consistent with a nongeneric codimension-one cancellation of the leading tail coefficient at null infinity, resulting in a faster decay rate.
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Lattice Field Theory
Chemical Potential and Analytic Continuation for Non-Hermitian Lattice Fermions
Chen-Te Ma and Hui Zhang
We introduce a chemical potential for non-Hermitian
lattice fermions and show that, for even
flavors with degenerate masses and paired chemical potentials $(\mu,-\mu)$ or $(i\mu,i\mu)$, the Hybrid Monte Carlo
algorithm is free of the sign problem. For one-dimensional free
fermions, we demonstrate that the sign problem is a numerical rather than physical obstruction and derive the exact propagator, which is analytic at finite
lattice spacing away from its poles but becomes non-analytic in the continuum limit. Finally, we use AI-assisted fitting to perform analytic continuation from imaginary to real chemical potentials.
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Medical Physics · Cross-listed from eess.SY
Preview-Based Relative-Motion Control of an Insertion Tool for Neural-Thread Placement in Pulsating Tissue
Yongyan Cao and Xiaobo Li
Flexible neural electrode threads must be placed at a prescribed depth while the cortical surface moves with cardiac and respiratory pulsation. A controller tracking a fixed point in the laboratory frame cannot distinguish commanded insertion from tissue motion; the error appears as both a depth offset and relative tip–tissue velocity during contact. This paper formulates thread insertion in tissue-relative coordinates: a harmonic observer predicts delayed cortical-surface motion over the control horizon, a constrained MPC regulates the tip relative to that prediction while limiting actuator effort and lateral relative velocity, and an augmented disturbance state removes the steady offset from persistent contact force and model mismatch. In a 1-DOF MuJoCo
benchmark, the controller reaches RMS relative-placement errors of 12.0\um\ free-space and 1.9\um\ in contact, versus 18.3/176.8\um\ for delayed-feedback impedance and 286.1/275.5\um\ for laboratory-frame PD – the lower contact offset costs more peak contact force (3.43 vs.\ 2.00~mN), since it drives to commanded depth rather than yielding to tissue. A 3-DOF extension reduces lateral shear velocity from 1.34 to 0.50~mm/s at 2.1\um\ lateral placement error, and a feasibility-restoring soft-slack formulation keeps the shear constraint solvable under degraded sensing where a matched hard-constraint controller fails. A two-vertex Lyapunov certificate for the finite-horizon gain holds over $-40\%/{+}50\%$ reflected-mass mismatch, and the 1-DOF QP solves in under 0.4~ms at the 95th percentile. These results are a simulation-based control
benchmark, not a clinical safety claim: the modeled tip is a rigid contact point, and flexible-thread mechanics, a validated force constraint, biological damage thresholds, and hardware-realistic sensing and timing remain necessary before deployment.
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High Energy Physics (Theory)
Numerical Study of Scalar Field Theory on the Fuzzy Onion
Matej Hrmo, Samuel Kováčik and Juraj Tekel
We study the behaviour of the scalar field theory on the fuzzy onion model – a three-dimensional
matrix model consisting of concentric fuzzy spheres of gradually increasing radii. We use a numerical method of
Hamiltonian Monte Carlo simulations to study the phase structure of this theory. We identify the field phases, investigate and describe a phenomenon of dynamical phase transitions and attempt to reconstruct phase transition lines. We compare the results with the well-studied phase structure of the fuzzy sphere. Finally, we identify two boundaries on the phase transitions of the theory, a uniform phase boundary and a critical boundary between the disordered and non-uniform phase.
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Materials Science
A Dataset of Equilibrium State Configurations of Adsorption in Zeolites
Marko Petković, Rachna Ramesh, Vlado Menkovski et al. (+1 more)
Zeolites are crystalline nanoporous materials widely used in adsorption, separation, and catalytic processes. Molecular simulations are commonly used to predict adsorption properties, but most high-throughput adsorption
datasets report only ensemble-averaged quantities such as loadings or isotherms, rather than the molecular configurations from which these averages are obtained. Here, we present AdsZeo, a coordinate-resolved
dataset of
equilibrium methane adsorption configurations in aluminium-substituted, sodium-containing zeolite frameworks. The processed release contains 4,775 framework realisations derived from 191 zeolite
topologies. Each framework realisation was simulated at 13 methane pressures between 0.1 and 100 bar at 298 K using grand canonical Monte Carlo simulations, giving 62,075 production simulations in total. In addition to scalar adsorption records, the
dataset stores production-frame methane pseudo-atom coordinates, mobile Na$^+$ cation coordinates, framework atomic coordinates, per-frame loading and energy statistics, and simulation metadata in a processed DuckDB database. The release contains 12,415,000 saved production-frame records and 1,245,376,215 saved particle-coordinate records. AdsZeo provides coordinate-resolved adsorption data across variations in framework
topology, aluminium content and distribution, sodium cation arrangement, pressure, and methane loading, enabling reuse for adsorption analysis, spatial statistics, density estimation, and machine-learning models for molecular configuration generation in charged zeolite pores.
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All authors Marko Petković, Rachna Ramesh, Vlado Menkovski, Sofía Calero
General Relativity and Quantum Cosmology
Solving Einstein's Vacuum Equations with Physics-Informed Neural Networks: Boundary Conditions and Domain Decomposition
Elly Bayona and Hernando Quevedo
We investigate the application of Physics-Informed Neural Networks (PINNs) to the numerical solution of Einstein's
vacuum field equations for static spacetimes. We first reproduce the Schwarzschild solution and then extend the method to the axisymmetric $q-$metric, a nontrivial exact solution characterized by a mass quadrupole moment. We analyze the influence of boundary conditions, domain decomposition, and equation redundancy on the convergence and stability of the training process. The proposed framework accurately reconstructs the metric functions in the computational domain while maintaining small residual errors. Our results demonstrate that PINNs provide a robust and flexible approach to solving Einstein's equations and offer a promising foundation for investigating gravitational configurations for which exact analytical solutions are unknown.
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Mesoscale and Nanoscale Physics
Layer-Locked Chiral Topological Superconductivity
Yijie Mo and Zhongbo Yan
We uncover a universal mechanism for realizing layer-locked topological phases. Guided by it, we investigate the realization of layer-locked
chiral topological superconductivity-the superconducting analogue of the
quantum anomalous layer
Hall effect-in a nonsymmorphic
bilayer antiferromagnetic system with s-wave pairing. We identify three distinct gate-tunable topological phases and establish a direct correspondence between the nearly quantized layer-resolved Chern numbers and the layer-locking behavior of
chiral Majorana edge states,
vortex-core Majorana zero modes, and nearly quantized thermal
Hall responses.
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Materials Science
Light-Stabilized Metastable Electronic State in NiO with Enhanced Orbital Hybridization
Thomas C. Rossi, Fabio G. Santomauro, Lars Mewes et al. (+19 more)
Light-driven control of electronic structure in correlated metal
oxides offers new opportunities for optimizing materials used in photovoltaic and photoelectrochemical technologies. We show that photoexcitation of NiO, a prototypical transparent
semiconductor and hole-transport material, across its charge-transfer gap produces a long-lived metastable state with enhanced Ni 3d-O 2p orbital hybridization. We characterize this state using Ni K-edge X-ray absorption spectroscopy, which probes how structural and electronic changes affect the unoccupied p density of states during continuous and pulsed ultraviolet excitation. Under pulsed excitation, high carrier densities of approximately 10^20 per cubic centimeter generate a state with a lifetime of approximately 600 picoseconds, in which enhanced hybridization coexists with
lattice heating. By contrast, continuous ultraviolet irradiation at much lower carrier densities of approximately 10^13 per cubic centimeter stabilizes a similar electronic state with negligible
lattice heating, demonstrating that its formation is not solely thermally driven. First-principles DFT+U+V calculations attribute the spectral changes to stronger Ni 3d-O 2p hybridization, which alters the unoccupied Ni 4p states probed by dipole-allowed K-edge transitions. We attribute this change to the dynamic screening of on-site electronic correlations following photoexcitation, which redistributes the charge density. Because orbital hybridization governs carrier transport and charge-transfer energetics, our results identify photoinduced screening as a mechanism for dynamically tuning correlated
oxides and suggest new design principles for optoelectronic materials.
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All authors Thomas C. Rossi, Fabio G. Santomauro, Lars Mewes, Janina Löffler, Dominik Kinschel, Giacomo Rossi, Mario Gutiérrez, Oliviero Cannelli, Boris V. Sorokin, Jochen Rittmann, Jakob Kel, James Budarz, Anna Wach, Adam H. Clark, Emiliano Dal Molin, Maged F. Bekheet, Albert Gili, Sebastian Praetz, Daniel Grötzsch, Delphine Cabaret, Renske M. van der Veen, Majed Chergui
High Energy Physics (Theory)
Holography in flipped AdS/$\mathbb{Z}$: Another approach to dS holography
Bin Chen, Zezhou Hu, Xin-Cheng Mao et al. (+1 more)
Motivated by the subtleties in the conventional dS/CFT correspondence, we explore analytic continuation as a constructive route to de Sitter holography. We show that
quantum field theories in de Sitter space and in a spacetime that we call flipped $\mathrm{AdS}/\mathbb{Z}$ (fAdS) are related by analytic continuation. We then develop a
holographic description of fAdS in terms of a boundary theory referred to as flipped CFT (fCFT). In particular, we construct the extrapolate dictionary for general asymptotically fAdS spacetimes and compute the
holographic two-point functions, finding agreement with an independent derivation based on the conformal
symmetry of fCFT. The analytic continuation relation between fAdS and dS further suggests that fCFT may provide a starting point for an alternative
holographic description of de Sitter physics. As a nontrivial check of this picture, we show that the Cardy formula of fCFT$_2$ reproduces the Bekenstein–Hawking
entropies of the cosmological horizons in both pure dS$_3$ and Kerr-dS$_3$.
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All authors Bin Chen, Zezhou Hu, Xin-Cheng Mao, Shan-Ming Ruan
Quantum Physics
Two-copy distillability of one-copy-undistillable negative-partial-transpose states in every dimension
Gelo Noel M. Tabia, Kai-Siang Chen and Min-Hsiu Hsieh
Whether
entanglement with a negative partial transpose (NPT) can be undistillable is a longstanding open problem. In the canonical family of DiVincenzo et al., the one-copy-undistillable region was conjectured to remain undistillable at all copy numbers. We refute this: in every dimension $d\geq3$, one vertex of this region is two-copy distillable, via an explicit Schmidt-rank-two tight-frame witness. The separation persists on an open set, while other states in the same region are provably two-copy undistillable. Twirling our counterexample into Werner form makes it two-copy undistillable, so this standard reduction can erase finite-copy distillability.
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Space Physics · Cross-listed from cs.CR
Treating Statewide CORS Networks as Spatially Distributed Sensors for GNSS Integrity Monitoring under Unintentional and Deliberate Threats
Minhaj Uddin Ahmad, Sagar Dasgupta, Muhammad Sami Irfan et al. (+3 more)
State departments of transportation (DOTs) in the United States increasingly rely on statewide continuously operating reference station (CORS) networks to support high-precision Global
Navigation Satellite System (GNSS)-based positioning and timing for intelligent transportation systems. These networks also provide continuous observations that can support regional GNSS integrity monitoring. This study develops and demonstrates a framework that treats a statewide CORS network as a spatially distributed sensor system for identifying unintentional (environmental) and intentional (cyber) interference when GNSS measurements deviate from expected spatial patterns. We develop a graph-based Network Consistency Framework (NCF) that evaluates each station against its spatial neighborhood using four metrics: neighborhood residual, spatial gradient, residual, and graph smoothness. These metrics are combined into a Network Consistency Index (NCI). The framework is demonstrated using two consecutive days of four-constellation observations from 50 stations in the Alabama DOT-maintained CORS network, using changes in vertical total electron content ({\Delta}VTEC) and the Rate of TEC Index (ROTI) as spatially coherent observables. The framework quantified network-wide spatial consistency and identified localized anomalies. Detected anomalies indicate stations whose observations deviated from the surrounding regional network, signaling potential integrity issues. Determining whether anomalies result from receiver faults, localized interference, spoofing, or other causes requires further investigation. This study introduces statewide CORS networks as regional GNSS integrity observatories and presents the NCF and NCI for graph-based spatial integrity monitoring. Transportation agencies can implement the framework using existing CORS observations to monitor network integrity and identify localized anomalies.
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All authors Minhaj Uddin Ahmad, Sagar Dasgupta, Muhammad Sami Irfan, Mizanur Rahman, Mashrur Chowdhury, Thejesh Bandi
Mesoscale and Nanoscale Physics
Electronic bistability, discontinuous switching and stochasticity in a two-dimensional semiconductor
S. Jana, M. Kravtsov, A. Ermakov et al. (+12 more)
Bistability - two stable electronic states under the same bias - underlies switching and
memory, but is usually absent in transistors and must be engineered through material means: doped tunnel junctions, filaments in memristors, or phase transitions. Here we demonstrate a transistor with intrinsic electronic bistability in a single chemically homogeneous
crystal. In dual-gated black phosphorus, whose band gap narrows under a perpendicular electric field due to a
giant Stark effect, the gates not only modulate carrier density but also reshape the band profile, forming interband tunnel junctions in the channel. Transport across the two-gate parameter space reveals competing conduction regimes - diffusive, two tunnelling channels and Zener breakdown - whose interplay produces negative differential conductance and transconductance, discontinuous switching, and hysteresis with the state set by gate history. Moreover, the switching remains intrinsically
stochastic, yet statistically stable within a narrow range of gate voltages, providing an electrically programmable source of randomness. Devices based on this principle should be realisable in other two-dimensional
semiconductors, opening a route to next-generation computing architectures in which nonlinearity, switching,
memory and stochasticity are integrated within a single electrostatically programmable element.
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All authors S. Jana, M. Kravtsov, A. Ermakov, X. Zhou, A. Kudriashov, L. Elesin, X. Zhou, A. L. Shilov, D. A. Svintsov, T. Taniguchi, K. Watanabe, K. S. Novoselov, A. Avsar, A. Principi, D. A. Bandurin
Mesoscale and Nanoscale Physics
Time-Reversal-Invariant Altermagnetic Acoustic Crystals
Tianzhi Xia, Han-Rong Xia, Jinglin Liu et al. (+3 more)
Altermagnets have emerged as a new class of
magnetic materials that combine
spin-split electronic bands with zero net magnetization. Extending this paradigm to classical-wave systems has, however, been fundamentally challenging because conventional realizations require broken time-reversal
symmetry (TRS). Here, we overcome this limitation by introducing a pseudospin degree of freedom and constructing a pseudo-time-reversal operator that faithfully reproduces the action of its physical counterpart while preserving actual TRS. Building on this framework, we theoretically propose and experimentally realize the first time-reversal-invariant altermagnetic acoustic
crystal. Acoustic measurements directly reveal pseudospin-dependent band splitting–a defining hallmark of altermagnetism–under strictly TRS-preserving conditions. Moreover, the altermagnetic acoustic
crystal exhibits sublattice-pseudospin locking, enabling flexible control over acoustic pseudospin splitting and filtering. Our work establishes acoustic
crystals as a versatile platform for exploring altermagnetic physics and opens new avenues for
spin-inspired wave manipulation in nonmagnetic devices.
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All authors Tianzhi Xia, Han-Rong Xia, Jinglin Liu, Xiying Fan, Zebin Zhu, Zhen Gao
Nuclear Theory
White dwarf-neutron star matter transition and the effect of light elements
Yao Ma, Yong-Liang Ma, Ruo-Xi Wu et al. (+1 more)
White
dwarfs and
neutron stars are unique laboratories for dense
nuclear matter physics. We develop a single relativistic mean-field framework that treats both classes of compact
star, and the transition between them, on the same footing: the
nuclei of white-
dwarf matter are solved self-consistently as Wigner-Seitz
cells with the full electromagnetic interaction, while the same Lagrangian yields the uniform
nuclear matter of the
neutron-
star interior. Within this unified description we compute light-element white
dwarfs seeded by $^4$He, $^{12}$C, and $^{16}$O, following each fixed-$A$ sequence along its neutronization path and connecting it to the
neutron-
star branch through exact Maxwell junctions, from which the corresponding mass-radius relations are derived. The helium- and carbon-seeded white-
dwarf sequences attain maximum masses of ${\sim}1.4\,M_\odot$ and ${\sim}1.0\,M_\odot$, respectively. On the
neutron-
star branch, the retained light-element envelope changes the predicted radii only at the percent level—by approximately $0.2~$km at $1.4\,M_\odot$, within current observational uncertainties. Providing a consistent zero-temperature equation of state from white-
dwarf to
neutron-
star densities, this unified framework offers a natural starting point for studies of white-
dwarf–
neutron-
star binary mergers, progenitor-
star evolution, decihertz gravitational-wave sources, and related multimessenger phenomena.
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All authors Yao Ma, Yong-Liang Ma, Ruo-Xi Wu, Yue-Liang Wu
Quantum Physics
State preparation via measurement and feedback: pushing relations, state structures, and non-invertible symmetries
Yabo Li, Aditi Mitra and Tsung-Cheng Lu
Quantum circuits with measurements and
unitary feedback (MF) can prepare long-range entangled states in constant depth, but a systematic construction of the MF preparation
circuit for a given target state remains underexplored. We develop such a scheme for one-dimensional states, based on the notion of pushable defects: virtual-bond operators of a
matrix product state that can be pushed through the tensor at the price of a physical feedback
unitary. We show that the set of pushable defects, together with their pushing relations classifies finite-depth MF-preparable states and dictates their preparation
circuits. To each class of the target state $|A\rangle$, we associate a state $|B\rangle$ from which $|A\rangle$ can be prepared using a 1-round MF
circuit; in particular, $|A\rangle$ is preparable from a product state using a
circuit with 1 round of MF whenever $|B\rangle$ is preparable by a finite-depth local
unitary (FDLU)
circuit. For a general target state, the scheme is obtained by iterating this procedure until the associated state is FDLU-preparable. For open-boundary
matrix product states, the scheme is complete: it constructs a preparation
circuit whenever finite-depth MF preparation with left-conditioned feedback corrections is possible. Pushable defects and pushing relations thus emerge as a unifying principle for
quantum state preparation via measurements and feedback. This characterization further reveals an intrinsic connection between MF
circuits and non-invertible
symmetries: states with certain classes of pushing relations are related to a product state by Tambara-Yamagami duality operators, or by continuous cosine
symmetry operators with fusion rules $L_{\alpha} L_{\alpha'} = L_{\alpha+\alpha'} + L_{\alpha-\alpha'}$, together with their generalizations up to (not necessarily transversal) gates.
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Medical Physics · Cross-listed from cs.CV
MRI super-resolution in ten sampling steps using a diffusion bridge model
Mojtaba Safari, Hang Yu, Zach Eidex et al. (+10 more)
Objective. MRI provides excellent soft-tissue contrast, but long acquisition times can cause patient discomfort and lead to motion artifacts, forcing a trade-off between spatial resolution and scan time.
Diffusion-based super-resolution (SR) reconstructs high-resolution (HR) images from low-resolution (LR) inputs, but typically needs many sampling steps and initializes from a Gaussian prior ill-suited to image restoration. We developed an efficient
diffusion framework that reconstructs HR MRI directly from LR data. Approach. We propose super-resolution
diffusion bridge model (SR-DBM), a super-resolution
diffusion bridge model that casts SR as a
stochastic transport between the LR and HR image distributions. Through a Doob's h-transform of a mean-reverting
stochastic differential equation, SR-DBM pins the process to the paired HR and LR images at its endpoints, initializing reconstruction from the measured anatomy rather than from Gaussian noise. The HR image is recovered by a deterministic reverse trajectory in which a network predicts the clean image at each of only ten sampling steps. We evaluated SR-DBM on ultra-high-field 7T
brain T1 MP2RAGE maps and pelvic T2-weighted prostate images against nine comparison methods using PSNR, SSIM, GMSD, and LPIPS. Main results. SR-DBM attained the highest PSNR and SSIM and the lowest GMSD on both
datasets (
brain: 27.66+-1.52 dB, 0.96+-0.02, 7.96+-1.86$; prostate: 27.87+-2.29 dB, 0.80+-0.05, 8.38+- 1.44), with statistically significant gains over every comparison method (two-sided Wilcoxon signed-rank test with Holm correction, p<0.05). The strongest baseline, SR-EMamba, ranked second. Qualitatively, SR-DBM produced the smallest residual errors and best preserved fine structures and lesions.
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All authors Mojtaba Safari, Hang Yu, Zach Eidex, Mingzhe Hu, Ryan J. Sanford, Alexandru Florea, Shansong Wang, Chih-Wei Chang, Erik H Middlebrooks, Aditya Juloori, Stanley L. Liauw, Ralph Weichselbaum, Xiaofeng Yang
General Relativity and Quantum Cosmology
Scalaron-modified null focusing and radial monotonicity in static f(R) gravity
Maickol Muñoz-Palma, Francisco S. N. Lobo, Jean Báez Cuevas et al. (+1 more)
We derive an exact radial monotonicity law for static, spherically symmetric spacetimes in metric \(f(R)\)
gravity. For \(ds^2=A(r)dt^2-dr^2/B(r)-r^2d\Omega^2\), the matter contribution and the scalaron Hessian combine into an effective radial-convergence numerator that fixes the derivative of \(\Q=B/A\). On every connected static interval with \(A>0\), \(B>0\), and \(f_R\equiv df/dR>0\), its sign therefore determines the monotonicity of \(\Q\). The integrated identity retains the finite, generally nonzero value of \(B/A\) at a regular nondegenerate Killing horizon; consequently, a fixed-sign convergence condition orders the horizon endpoint ratios rather than excluding two horizons. A zero-integral obstruction arises for equal endpoint values, including boundaries where \(B\to0\) while \(A\) remains finite and nonzero. Saturation is equivalent to \(B/A=\mathrm{const}\), and in
vacuum requires a scalaron profile linear in the areal radius. We illustrate the strict non-saturated branch, within the General-Relativity sector, using the exact constant-density
stellar interior, and apply the equality and consistency diagnostics to the constant-\(X\) and power-law solutions of Multamäki and Vilja. In particular, in the Schwarzschild–de Sitter two-horizon parameter range, one constant-\(X\) solution crosses \(f_R=0\) inside the complete static patch, while a direct substitution into the original radial equation exposes an unresolved exponent mismatch in the displayed power-law family. The results provide a model-independent static-sector diagnostic and a precise starting point for a future horizon-regular treatment of black-hole interiors.
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All authors Maickol Muñoz-Palma, Francisco S. N. Lobo, Jean Báez Cuevas, Francisco Tello-Ortiz
Biological Physics
Optimal concentration and gradient sensing by perfect monitors
Farshid Jafarpour
Cells often estimate chemical concentrations from only a few diffusing molecules, whose
stochastic motion limits sensing precision. We consider a perfect monitoring instrument that records the instantaneous molecular density throughout a finite region without perturbing the concentration field or distinguishing molecular identities. The standard Berg-Purcell
estimator weights all positions uniformly. Here we derive the optimal spatial weighting within a large class of unbiased
estimators for both concentration and gradient sensing. Variance minimization maps to an electrostatic problem. Surprisingly, although the instrument monitors the entire volume, the optimal
estimator assigns all weight to its boundary, reducing the uncertainty in both concentration and gradient sensing. We extend the results to arbitrary geometries and spatial dimensions.
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Solar and Stellar Astrophysics
Synthetic Fe XIII 1074.7 nm Observations of Torsional Alfvén Waves in Coronal Waveguides
Samuel Skirvin, Richard Morton and Thomas Schad
Torsional Alfvén waves are a promising mechanism for transporting energy through the
solar atmosphere, with implications for coronal heating and
solar wind acceleration. Recently, signatures of torsional Alfvén waves have been observed with the Daniel K. Inouye
Solar Telescope. We aim to investigate the effects of line of sight integration and
plasma conditions on the observable properties of the torsional mode. Here we present three-dimensional magnetohydrodynamic simulations of multiple coronal waveguides, driven by a combination of transverse kink and torsional wave drivers, considering two
plasma regimes representative of active region (AR) and quiet Sun (QS) conditions. Synthetic observables of the Fe~xiii~1074.7~nm coronal emission line are produced using the pyCELP forward-modelling framework to enable direct comparison with spectroscopic observations. In the QS regime, red-blue Doppler asymmetries are associated with the driven torsional waves, though their observed amplitudes are substantially reduced by line-of-sight integration. In contrast, the AR regime exhibits red-blue Doppler asymmetries even in the absence of an imposed torsional driver, which may be misidentified as the $m=0$ torsional Alfvén mode. In the AR setup, the red-blue Doppler asymmetries arise from strong phase mixing, generating shear flows and localised vorticity between waveguides where emission is strongest. The differences between the two regimes are governed by the location of peak emission, which is determined by the degree of density inhomogeneity. Our results support the identification of torsional Alfvén wave signatures in the quiet Sun (a weakly inhomogeneous environment), but caution should be exercised when interpreting spectroscopic observations in strongly inhomogeneous environments such as active regions.
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Mathematical Physics
The $\mathcal{L}$-Calculus for Causal Variational Principles: An Exterior Differential Calculus on Non-Smooth Spaces
Felix Finster, Niky Kamran and Frank van der Top
A differential calculus for causal variational principles is developed, which generalizes the exterior calculus of differential forms and some of the associated differential topological structures to non-smooth spaces. Our calculus includes the exterior derivative, de Rham
cohomology, glueing constructions (restrictions and extensions of differential forms, Mayer-Vietoris sequence), a Künneth formula and Poincaré's lemma. Moreover, we prove versions of Stokes'
theorem and the Gauß divergence
theorem. The constructions and results are illustrated by several examples.
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Instrumentation and Methods for Astrophysics
A Hybrid R-Theta Fiber Positioning Robot Using a Piezoelectric Bender for Radial Motion
Michael Schubnell, Tim Fanning, Andrew Hope et al. (+3 more)
Future massively multiplexed spectroscopic surveys require focal planes with increasingly dense arrays of robotic fiber positioners. The DESI (Dark Energy Spectroscopic Instrument) fiber positioners, based on a two-axis Theta-Phi motorized architecture, have demonstrated excellent reliability and performance during operations and provide the
benchmark for evaluating new concepts. However, proposed next-generation instruments such as Spec-S5 require a substantially smaller positioner pitch than DESI, making direct scaling of the existing design challenging. Here we describe a hybrid R-Theta fiber positioning concept in which the rotation about the central axis is provided by a DESI-like Theta motor, while the radial displacement is produced by a piezoelectric bimorph bender coupled to a lightweight carbon-fiber spine. This design builds on the heritage of the the proven central rotation mechanism while replacing the Phi arm with a compact piezoelectric actuator. We discuss the trade-offs between motorized positioners, piezoelectric slip-stick tilting spines, tubular piezo actuators, and direct piezo-bender actuation. A prototype based on a DESI positioner was fabricated and tested using a commercial bimorph bender and an 8-inch carbon-fiber extension. With closed-loop control using feedback from a fiber-view camera the fiber was brought on target after two corrections with residual stability of approximately 2 microns RMS. These results indicate that direct piezo-bender actuation is a promising approach for compact fiber positioning, provided that closed-loop operation is addressed.
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All authors Michael Schubnell, Tim Fanning, Andrew Hope, Joseph Silber, Greg Tarlé, Nicholas Wenner