Mathematical Physics · Cross-listed from math.AP
Homogenization procedure in the Cauchy problem for the elastic composites
Sergey Sergeev and Reinaldo Rodriguez-Ramos
In the present work we consider the problem of the homogenization of the Cauchy problem for the equations of the elasticity. We assume the composite material is constructed as a periodic repetition along the chosen axis of the unit
cell which models to different materials. The homogenization procedure is based on the operator separation of variables, which gives the new incites for the homogenization of the elasticity equations and provides new way of the homogenization and constructing the homogenized equation.
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Solar and Stellar Astrophysics
Fine-scale flare structures and their energetic implications from short-exposure extreme-ultraviolet imaging
Laura A. Hayes, Hannah Collier, Säm Krucker et al. (+5 more)
To capture the brightest and most rapidly evolving phases of
solar flares, the Major
Flare Solar Orbiter Observing Plan employed a dedicated short-exposure mode for the High Resolution Imager at 174 Angstrom (HRIEUV) of the Extreme Ultraviolet Imager. We investigate the spatial and temporal organisation of compact emission in the 19 March 2024 M2.1
flare using high-cadence, short-exposure HRIEUV observations. We combine these 0.04 s observations with hard X-ray timing, imaging, and spectroscopy from the Spectrometer
Telescope for Imaging X-rays (STIX). We characterise impulsive ribbon kernels and later loop strands, and compare footpoint areas measured with HRIEUV, the Atmospheric Imaging Assembly, and STIX to constrain the local energy flux carried by
flare-accelerated electrons. The short-exposure observations reveal compact emission largely obscured by saturation in normal-exposure EUV imaging. The integrated HRIEUV emission evolves co-temporally with the STIX 22-45 keV emission, with no lag discernible beyond the 2 s sampling. The ribbons comprise repeatedly activated kernels with characteristic separations of approximately 1.4-1.7 Mm, while the developing arcade shows a similar strand separation of approximately 1.3 Mm. Kernel and strand widths of approximately 0.4-0.5 Mm lie close to the instrumental resolution limit. The compact HRIEUV footpoint areas are approximately an order of magnitude smaller than those inferred from AIA or STIX, implying nominal local non-thermal energy fluxes on the order of 10^11 erg cm^-2 s^-1 at the hard X-ray peaks. These results reveal a characteristic 1-2 Mm spatial organisation of the
flare emission and demonstrate the value of
flare-optimised EUV imaging for future
solar flare observations.
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All authors Laura A. Hayes, Hannah Collier, Säm Krucker, Daniel Ryan, David Berghmans, Emil Kraaikamp, Muriel Stiefel, Andrew Inglis
Fluid Dynamics
Direct numerical simulation of NOx formation in turbulent lean premixed hydrogen-air flames under engine-relevant conditions
Chao Xu, Yiqing Wang and Riccardo Scarcelli
In this study, direct numerical simulations (DNS) are employed to investigate NOx formation in turbulent lean premixed hydrogen-air flames under engine-relevant conditions. Various
turbulence intensities and molecular transport models are examined to isolate the individual impacts of
turbulence intensity, Lewis number, and preferential
diffusion on local and global NO production. Results show that global NO production is significantly enhanced in all of the turbulent cases, reaching approximately five times the value of the 1D steady flame at a mixture residence time of 0.1 ms. Increasing
turbulence intensity is found to have three competing effects on NO formation: (1) it strengthens
turbulence-instability interactions by inducing local super-adiabatic hot spots and elevating the concentrations of key flame radicals within the flame brush, thereby promoting the NO reaction rate locally; (2) it accelerates the turbulent flame speed, reducing the flame-brush residence time and thus suppressing NO production globally; and (3) it reduces post-flame temperature fluctuations, suppressing thermal NO enhancement in the post-flame zone. As a result, the global NO production is slightly lower at higher
turbulence intensities among all the turbulent cases considered. Lewis number effects are identified as the primary mechanism driving thermodiffusive NO enhancement, with preferential
diffusion playing a secondary role, as evidenced by the nearly identical mean profiles of the NO reaction rate between unity Lewis number turbulent flames and their 1D steady flame counterparts in both the progress variable space and the residence time space. Finally, an excellent correlation between the peak conditional mean NO reaction rate and the stretch factor is identified, and a conceptual model is proposed to improve the predictions of global NO production in practical engine simulations.
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Solar and Stellar Astrophysics
Numerical modelling of recombination-driven stellar winds
Bestin James and Jiří Krtička
Low-temperature
stars have a significant population of neutral hydrogen increasing with height in their atmospheres. This suggests eventual recombination as we move away from their deep photospheric layers. Recombination can potentially drive
stellar winds, particularly in cool and evolved
stars. We aim to verify the possibility of
stellar winds driven by recombination. We also aim to constitute an initial model for this type wind driving. We examine the possibility of recombination-driven
outflows across the HR diagram by comparing the gravitational potential energy per atom to the hydrogen ionization energy. Then we start from a simple analytical model with the addition of an extra heating term to the gas in the Parker wind model. We model the heating term, analogous to the heat released by recombination, and examine how it can drive an
outflow. We implement the model in the code CASTRO and check the hydrodynamic stability of the solution. The added heating drives a steady transonic
outflow in our models, when tested with the parameters of an AGB
star. The heating function affects the solution and the location of the sonic point depends on the location of the heating function itself. Even though the derived hydrodynamic equations are independent of the density, we determine the processes that set the mass-loss rate. By comparing the heating from collisional recombination and cooling due to radiative recombination, we show that relatively high densities are required to release the recombination energy as heat, implying mass-loss rates of the order of 0.1
solar mass per year. Our comparison of energies across the HR diagram suggests a possibility of recombination-driven winds in evolved red
giants and AGB
stars. The main deciding factor for wind launching is the radial distribution of heat released by recombination in a
star's atmosphere. This can in turn affect the mass-loss rate.
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Quantum Physics
Emergent non-Markovianity in time-delayed waveguide QED
Debsuvra Mukhopadhyay and Stuart J. Masson
Quantum systems are invariably coupled to a surrounding environment. A common theoretical method to simplify the problem is to trace over the environment under a Markov approximation, which assumes that the environment holds no
memory over the timescales that the system evolves under. In interacting many-body systems, it is often not trivial to extract which of the multiple collective timescales are relevant. We consider a time-delayed waveguide QED setup with a single excitation. By fixing the maximum propagation time and increasing the number of emitters, we show that, even for small delay times, collective effects are sufficient to cause non-Markovianity. The impact of
memory is intrinsically state-dependent. For superradiant states, the relevant system timescale is the superradiant lifetime while the relevant bath timescale is the end-to-end delay time. For subradiant states, both timescales depend on the structure of the specific state. Our results demonstrate the importance of prudently making Markov approximations in
quantum many-body systems, and highlight potential pitfalls to avoid in scaling up
quantum devices to large system sizes.
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Quantum Physics
The Role of Geometric Analysis in Interferometer Design and Optimization for Gravitational Quantum Entanglement
Alireza Maleki
The pursuit of a
quantum theory of
gravity, aiming to unify general relativity and
quantum mechanics, remains one of the most enduring challenges in physics. Because of the extreme energy scales associated with the Planck regime, direct experimental evidence for
quantum gravity remains elusive. However, recent proposals suggest that
quantum entanglement between two massive particles may provide a pathway to probe the
quantum nature of
gravity. In this study, we examine the interferometer geometries proposed in these works, with particular
attention to the commonly used approximation that neglects phase contributions from the vertical segments of the particle trajectories. Our analysis shows that this approximation can lead to incorrect predictions and, in certain parameter regimes, to null results where
entanglement would otherwise be expected. We derive exact solutions that incorporate the full particle trajectories and demonstrate that the vertical arms can significantly affect the accumulated phase. Crucially, we identify configurations in which the induced
entanglement vanishes entirely, a feature missed by simplified treatments. These findings show that accounting for the full interferometer geometry is not merely a refinement, but is essential for accurately assessing
gravity-induced
entanglement.
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Optics
Towards a universal meta-optics solver via large language models
Huanshu Zhang, Lei Kang, Yuyan Chen et al. (+3 more)
Metasurface design increasingly requires fast models that can operate across structurally distinct device families, rather than retraining a separate surrogate for every geometry class. Conventional neural network surrogates often depend on fixed-dimensional descriptors, family-specific output formats, and repeated architecture tuning, which limits their scalability across heterogeneous meta-atoms. Here, we present a unified large
language model (LLM) workflow for multi-family metasurface modeling and inverse-design. Geometries, design parameters, and optical response channels were converted into a shared instruction-following text format and used to fine-tune Gemma-2-9B across 8 metasurface families. Compared with single-family baselines, the joint model simultaneously predicted the optical responses of all metasurface families while reducing the MSE for each family by an average of 56.5%. The same representation was also used for inverse design. These results show that a shared sequence-based LLM interface can provide a practical route to cross-family metasurface design while reducing the need for task-specific surrogate architectures.
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All authors Huanshu Zhang, Lei Kang, Yuyan Chen, Luxiang Wang, Zhaolong Cao, Douglas H. Werner
General Relativity and Quantum Cosmology
Born Geometry, Metaparticles, and an Effective Geometric Realization of the Modular Black-Hole Remnant: A Phase-Space Resolution of the Schwarzschild Singularity
Paul-Robert Chouha
Recent work on metaparticle black-hole thermodynamics suggested the existence of a finite evaporation endpoint characterized by a minimal horizon area, a maximal Hawking temperature, and a stable cold modular remnant. However, the corresponding spacetime geometry remained unknown. In this work we construct an effective
geometric realization of the modular remnant within the framework of Born geometry, modular spacetime, and metaparticle dynamics. Starting from a doubled phase-space description in which spacetime coordinates are supplemented by dual coordinates, we derive a Born-doubled Schwarzschild geometry governed by a Born-invariant radial distance. The associated modular uncertainty relation prevents arbitrary localization at the phase-space origin, rendering the classical Schwarzschild singularity physically inaccessible and replacing it with a finite modular core. We then incorporate the metaparticle duality constraint, which induces an effective conformal deformation of the Born-
geometric background and generates a nontrivial effective stress-energy tensor. The resulting interior region develops a finite anisotropic source characterized by a tension-dominated radial sector. Localized violations of the radial Null Energy Condition and the Strong Energy Condition arise naturally near the modular core, providing a mechanism through which the focusing assumptions underlying the Hawking–Penrose singularity
theorems are evaded. These results establish an effective
geometric counterpart of the modular remnant inferred from metaparticle black-hole thermodynamics and suggest that the Schwarzschild singularity is replaced by a finite Born-
geometric phase-space structure whose ultraviolet behavior is governed by dual, non-
geometric degrees of freedom.
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Mathematical Physics
A closure criterion for electromagnetic curves on the sphere in a uniform ambient field
C S López-Monsalvo
We consider the motion of a charged test particle confined to the round unit sphere in a uniform ambient
magnetic field. We use an extension of Noether's
theorem for systems with
magnetic forces to reduce the problem to a quadrature. The rotation number of a trajectory, the azimuth it gains over one oscillation in latitude, is a complete
elliptic integral of the third kind in Legendre form. A trajectory closes if and only if that advance is a rational multiple of a full turn. The criterion holds on every level set of the two first integrals. Then, we differentiate the rotation number with respect to the half-cyclotron frequency and sign that derivative on each of the two branches into which a level set divides. The rotation number sees the charge, the mass, the field and the speed through a single dimensionless ratio, that of the half-cyclotron frequency to the speed. A closed trajectory therefore fixes a value of that ratio. We say how many values carry a given rational winding. The poles are attainable on a single level set, where the motion reduces to a pendulum. The field has no flux through the sphere, so it is globally exact. We compute the Mañé strict critical value of the resulting exact
magnetic flow. Above that value the closed trajectories are closed Reeb orbits of an explicit contact form.
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Quantum Physics
Recovery-Free CHSH Nonlocality with Particle Loss
Giovanni Scala and Cosmo Lupo
Can CHSH nonlocality survive particle loss without applying an explicit recovery operation? In principle, any deterministic recovery can be absorbed into the measurement. Operationally, we show that the answer depends on the allowed measurements on the lossy system. We distinguish flagged erasure, in which each lost particle leaves a detectable record, from unflagged deletion, in which no such record remains. For flagged erasure and survival probability $\eta>1/2$, using known
quantum-capacity results, we show measurements that asymptotically approach the
quantum maximum $2\sqrt2$. In contrast, for $\eta\le1/2$, CHSH violation is impossible for both loss models. Then, we construct explicit recovery-free protocols using permutation-invariant encodings built from $n$-
qubit Dicke states $| D_N^n\rangle$ and measurements on the surviving particles. A one-excitation $(N=1)$ encoding violates CHSH for $\eta>1/\sqrt{2}$. Increasing the excitation number $N$ yields a family of protocols that violates CHSH for $\eta>\eta_G=(\sqrt{5}-1)/2$, with the asymptotic golden ratio approached as $N \to \infty$. Finally, we present a sparse-deletion binomial PI protocol that guarantees CHSH violation for up to $O(\sqrt n)$ deletion errors. Our results distinguish fundamental limits imposed by loss from those set by explicit measurements without recovery.
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Mesoscale and Nanoscale Physics
Statistical Disorder in MBE-Grown AlGaAs/GaAs Superlattices for Quantum Bragg Mirrors using Synchrotron X-ray Diffraction
Mateus T. Souza, Germano M. Penello, Guilherme A. Calligaris et al. (+1 more)
AlGaAs/GaAs superlattices grown by Molecular Beam Epitaxy (MBE) are foundational for advanced optoelectronic devices, including
Quantum Bragg Mirror (QBM) infrared detectors. The performance of these devices critically depends on achieving near-perfect periodicity and abrupt interfaces, however, intrinsic statistical fluctuations during MBE growth introduce nanoscale structural disorder that can degrade device efficiency. In this study, we present a comprehensive methodology for quantifying this disorder in a 203-layer QBM device. High-resolution structural characterization was performed using high-energy (25 keV) synchrotron X-ray diffraction. By coupling a recursive dynamical diffraction formalism with an ensemble simulated annealing refinement, we extracted statistically robust, layer-by-layer thickness profiles. Our analysis reveals highly systematic, material-specific deviations from the nominal design: all AlGaAs barrier layers were consistently thinner than nominal by 0.3-0.6 nm. Furthermore, the sequential thickness profile successfully identified a significant 35 nm deficit in the final macroscopic top contact layer and a 40 nm deficit in the first GaAs layer. Achieving a statistical precision of about 0.2 to 0.6 nm (approximately 1-2 atomic monolayers), this non-destructive diagnostic approach provides directly actionable feedback for MBE flux calibration protocols.
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All authors Mateus T. Souza, Germano M. Penello, Guilherme A. Calligaris, Sergio L. Morelhao
Materials Science
Magnetic permeability and zone-folded phonons in layered NiPS$_3$
André A. A. Silva, Eduardo D. Stefanato, Nicolas M. Kawahala et al. (+8 more)
Nickel phosphorus trisulfide (NiPS$_3$) stands out as a Mott
insulator exhibiting XY-type
antiferromagnetic order. In this work, we investigate the electrodynamic response of single-crystalline NiPS$_3$ using Terahertz Time-Domain Spectroscopy (THz-TDS) as a function of temperature. In cases where the
magnetic permeability cannot be approximated to unity, conventional THz transmission analysis is often restricted to the complex refractive index, hindering the distinction between
magnetic and dielectric contributions. To overcome this limitation, we demonstrate an extraction methodology capable of decoupling the
magnetic permeability from the electric permittivity. Assuming that the dielectric contribution remains invariant below the N'eel temperature (TN), we used data from the paramagnetic phase to isolate the intrinsic
magnetic component at 13 K. The angular and thermal dependence of the spectra revealed a
magnon mode near 1 THz (for 0$^\circ$ orientation) and, distinctively, a zone-folded
phonon activated by
symmetry breaking (at 90$^\circ$). The isolated
magnetic permeability was successfully modeled using Drude-Lorentz oscillators, enabling the extraction of fundamental
spin dynamics parameters in this material.
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All authors André A. A. Silva, Eduardo D. Stefanato, Nicolas M. Kawahala, Flávio H. Feres, João Vítor T. P. Vital, Bernardo R. A. Neves, Jan Plutnar, Zdenek Sofer, Ana C. F. Brito, Felix G.G. Hernandez, Raul O. Freitas
Optics
Optically Induced Thermal Runaway in Phase-Change VO2 Nanostructures
Jiří Kabát, Peter Kepič, Andrea Konečná et al. (+1 more)
While thermal runaway occurs across diverse physical disciplines, its presence in subwavelength phase-change photonics remains unexplored because existing thermo-optical models break down near sharp optical transitions. Here, we introduce an iterative multiphysics framework coupling full-wave electrodynamics with heat transfer, and we discover optically induced thermal runaway in vanadium dioxide (VO2) nanostructures. The runaway switching threshold depends on the illumination wavelength, ambient temperature, and underlying substrate, with external thermal biasing significantly reducing the optical intensity required for runaway ignition. Our results push forward the modeling of sharp photothermal transitions and provide essential design principles for active metasurfaces, neuromorphic photonic devices, and nanoscale thermal management.
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All authors Jiří Kabát, Peter Kepič, Andrea Konečná, Filip Ligmajer
Solar and Stellar Astrophysics
Path to Black Hole Astrometric Microlensing from 10-Year KMTNet Database
Andrew Gould
I present a Fisher analysis of the astrometric signature of black holes (BHs) that may lie in the 10-year KMTNet microlensing database, motivated by the recent success of the pilot study by Segev et al. (2026), which reduced the scatter at $I=18$ to $\sigma\sim 10\,$mas. Seeing-limited ground-based observations still suffer from a great deal of systematics, but under the assumption that these systematics can be controlled, I find that with this nominal precision, the Einstein radius can be measured with errors $\sigma(\theta_{\rm E})\sim 0.5\,$mas in the most intensively monitored fields ($\sim 12\,$deg$^2$), and hence to twice that value in an additional $\sim 28\,$deg$^2$ area. This precision hardly depends on whether the peak of the event is during the observing season or not, as long as the impact parameter is within the broad range that is accessible to photometric recognition of the event, i.e., $u_0\lesssim 1.5$. However, longer events do have somewhat better precision. The analysis presented here ignores blending, but this is a good first approximation for most sources $I\lesssim 18$, which lie near or on the
giant branch. I outline a practical program, combining photometric and astrometric searches, aimed at identifying isolated BHs in the KMTNet database and measuring their masses and distances.
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Materials Science
Above Room-Temperature Phase Transition in Helicoidal 2D Halide Perovskite Enables Pyro-Phototronic Control
Zinnia Mallick, Rajashi Haldar, Sudip Naskar et al. (+4 more)
Bridging pyro-phototronic and ferroelectric properties in a single material not only gives rise to exotic physical phenomena but also provides strategy to build-up next-generation multi-functional energy harvesting devices. The layered halide perovskites are emerging class of synergetic 2D-materials of exceptional light-induced functionalities. Here, we report synthesis of a lead-free perovskite (3-fluorobenzylamine)2CuCl4 of partially fluorinated aromatic rings. Molecular chains are
chiral in helicoids so to render flexibility, energy-transfer, and freedom to tailor tunable pyro-phototronics on light illumination. The fluorinated framework promotes ferroelectric-to-paraelectric transition point (TC), as high as \textasciitilde 412 K of wide range of workably. A
giant pyro-photronic response is distinctly evident even upon UV-visible light-illuminations. A significantly high pyro-photronic current of 60 nA was achieved under an illumination of {\lambda}ex\textasciitilde 365 nm (27 mW) in a self-powered configuration. Consequently, an intricate coupling of the spontaneous polarization to the optical properties is visualized from the piezo response force microscopy (PFM) responses. In particular, the polar domains get diminished reversibly in on-off steps of the light irradiations. It indicates, the light provides another degree of the freedom to control the features for the applications of optoelectronic devices, optical
memories, photo/thermo-chromic systems, and energy-harvesters.
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All authors Zinnia Mallick, Rajashi Haldar, Sudip Naskar, Bapan Jana, Maheswaran Shanmugam, Shanker Ram, Dipankar Mandal
Mesoscale and Nanoscale Physics
Magnetic Communication with an Acoustically Actuated Magnetoelectric Resonator and a Quantum Diamond Magnetometer
Christopher T.-K. Lew, Andrew D. M. Charles, Brant C. Gibson et al. (+2 more)
Wireless communication via propagating
magnetic fields is a communication modality that has recently garnered significant interest for short-to-medium range communication in conductive mediums, such as
underwater and underground, where existing approaches utilizing electric fields are highly inefficient. Typical implementations of
magnetic communication make use of loop
antennas as both the transmitter and receiver, with the sensitivity and frequency response scaling with and inversely with the loop cross-sectional area, respectively. Here, we explore an alternative hybrid
magnetic communication system consisting of an highly radiation efficient and compact acoustically actuated magnetoelectric resonator as the transmitter, and a highly sensitive micrometer scale
quantum magnetometer based on nitrogen-vacancy centers in diamond as the receiver, with their core properties unconstrained by size. We demonstrate amplitude and phase-encoded transmission and reception of AC
magnetic fields at $f_{\mathrm{AC}}$ = 20 kHz, achieving a sensitivity of 50 pT/$\sqrt{\mathrm{Hz}}$ and 1.2 mrad/$\sqrt{\mathrm{Hz}}$, respectively. This work establishes the use of hybrid magnetoelectric resonator and
quantum diamond magnetometer communication system as a viable alternative to existing loop-based approaches.
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All authors Christopher T.-K. Lew, Andrew D. M. Charles, Brant C. Gibson, Jean-Philippe Tetienne, David A. Broadway
Solar and Stellar Astrophysics
Diversity of stripped-envelope supernova light curves from interaction with binary-driven circumstellar material
Dandan Wei, Fabian R. N. Schneider, Philipp Podsiadlowski et al. (+2 more)
A growing number of core-collapse
supernovae (CCSNe) exhibit diverse light-curve morphologies that indicate strong interaction with dense, pre-existing circumstellar material (CSM). Understanding the physical origin of such CSM is essential for exploring the late-stage
evolution of SN progenitors. Non-conservative mass transfer during binary interactions provides a promising channel for producing dense CSM before core collapse. Using the
stellar evolution code MESA, we simulate post-common-envelope binaries that give rise to ultra-stripped progenitors and self-consistently construct the CSM from mass loss during binary
evolution. We further analytically predict the resulting bolometric and
radio light curves by following the shock dynamics of SN ejecta interacting with the CSM. We find that surface-radius variations in the ultra-stripped progenitors trigger multiple episodes of mass transfer and produce diverse CSM density profiles, including detached shells and multi-peaked structures. Interaction with such CSM gives rise to non-monotonic, multi-peaked optical and
radio light curves that qualitatively resemble features observed in some stripped-envelope SNe. Long-term multi-wavelength monitoring of stripped-envelope SN candidates, particularly at late times, will be crucial for probing structured CSM and constraining the mass-loss history of stripped progenitors. Our results suggest that SN-CSM interaction in binaries hosting ultra-stripped progenitors provides a possible channel for producing diverse light-curve morphologies, highlighting a potential connection between the pre-SN
evolution of massive binary
stars and the diversity of their explosive transients.
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All authors Dandan Wei, Fabian R. N. Schneider, Philipp Podsiadlowski, Takashi J. Moriya, Eva Laplace
Fluid Dynamics
Quantifying the effect of resonant amplitude and frequency of phononic material vibrations on the coupled fluid-structure interaction dynamics in separated aerodynamic flows
Vinod Ramakrishnan, Arturo M. Burgos, Sangwon Park et al. (+2 more)
Phononic materials (PMs) with engineered resonances have been leveraged for fluid-structure interaction (FSI) with fluid flow instabilities, yielding beneficial outcomes such as transition delay, stabilized hypersonic boundary layers, and increased aerodynamic lift. Prior PM-FSI studies primarily identify spatio-temporal flow scales of interest and choose PM structural parameters producing structural dynamics conducive for FSI. However, a fully-coupled FSI system generally produces complex coupled dynamics that is not accurately captured by studying either physical system in isolation. In this context, our prior work established behavioral parameters that govern the coupled PM-FSI dynamics in a separated aerodynamic flow over a limited parameter range. Adopting this framework, this paper explores strongly-coupled high-fidelity PM-FSI simulations over a broader range of two behavioral parameters—truncation resonance frequency and displacement amplitude—to establish their quantitative (linear/cubic) relations to the coupled frequency, lift force, and circulation in the coupled system response. In addition, the results indicate the presence of distinct FSI regimes, depending on the proximity of the truncation resonance frequency or its sub-/super-harmonics to the
vortex-shedding frequency. FSI dynamics ranging from multi-/single-frequency dynamics, downshifted coupling frequency due to fluid-added mass effects, generation of non-linear harmonics to convergence of FSI dynamics to the rigid plate case are observed. These results reiterate the importance of the PM frequency and amplitude in determining the coupled FSI dynamics, and the proposed quantitative relations provide a new pathway for designing PMs for aerodynamic flow control to achieve beneficial outcomes, e.g., lift force enhancement.
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All authors Vinod Ramakrishnan, Arturo M. Burgos, Sangwon Park, Andres Goza, Kathryn H. Matlack
Mathematical Physics
Large Deviations for the Bose–Einstein Condensate of the Ideal Gas in the Canonical Ensemble
Andreas Deuchert and Xuanyu Li
We consider a non-interacting Bose gas governed by a general one-particle
Hamiltonian in the canonical ensemble. Our main results are large-deviation estimates for the number of particles in the Bose–Einstein condensate. We show that the left- and right-tail probabilities decay at different exponential rates as the number of particles tends to infinity.
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High Energy Physics (Theory)
Ning Bao and Jacob March
The Ryu-Takayanagi formula equates the area of a minimal surface with the von Neumann
entropy of a boundary subregion, and leaves two things about that identification open. The first is how sharply a geometry fixes an
entropy. Fannes-Audenaert answers with a
Hilbert-space dimension, which diverges as the cutoff is removed however close the two states are. We replace it with the capacity of
entanglement, the variance of the modular energy, whose square root grows like the square root of the entangling area where the dimensional factor grows like the regulated volume. The bound is dimension-free and saturated, and it makes the ambiguity of the
entropy subextensive for any perturbation whose capacity is small compared with $S_{vN}^2$ times the trace norm. The second is what the area means for a single state, since compression and dilution rates are defined only for many copies while a geometry describes one. When a single replica saddle dominates near $\alpha = 1$, every smooth Rényi
entropy at fixed $\alpha > 1$ agrees with $S_{vN}$ to $\textit{O}(\sqrt{S_{vN}})$, as do the smooth min- and max-
entropies. The minimal surface therefore fixes every one-shot
entropy of the state at once, with large central charge playing the role of large copy number in the asymptotic equipartition property. As a consequence we bound how far outside the
holographic entropy cone a
holographic state can appear to fall, leaving estimation and certification open.
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High Energy Physics (Experiment)
Efficient binned profile likelihood minimization for precision measurements with RABBIT
David Walter, Josh Bendavid and Kenneth Long
Precision measurements at the LHC increasingly rely on binned profile maximum likelihood fits with thousands of bins and nuisance parameters, and the High-Luminosity LHC will push these numbers further. Fast and robust minimization of such likelihoods is crucial for timely analysis development and accurate inference. We present Rabbit (Rapid Automatic Bin-Based Inference Tool), a Python framework that exploits differentiable programming in TensorFlow 2 to perform this task on CPUs and GPUs. Automatic differentiation provides exact gradients and Hessian-vector products for a trust-region minimizer operating in Krylov subspaces, and just-intime compilation yields near-C++ execution speed. Rabbit implements flexible statistical models with analytic treatments where possible, supports symmetrization options that establish Gaussian approximations and a linearized likelihood formulation with deterministic solutions, and focuses on measuring physical observables through differentiable transformations of the model, including unfolded differential cross sections.
Benchmarks on synthetic models demonstrate excellent scaling with the number of bins and parameters, outperforming established tools in challenging regimes where these fail to converge within reasonable time.
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Instrumentation and Methods for Astrophysics
Microscopy assessment of two multiple-transient candidates
Jun Yang and Beatriz Villarroel
We present a microscopy-based assessment of two representative cases of multiple-transient candidates identified on historical photographic plates: the nine-transient event of 12 April 1950 (XE325) and the triple-transient event of 19 July 1952 (XE186). These events consist of spatially clustered, point-like sources detected within single long-exposure plates, lacking the streaks expected from moving objects and therefore suggestive of short-duration flashes. We analyse microscopy images of the original glass-plate material together with an independent copy plate and archival metadata, and we register these images against the published survey digitizations so that individual catalogued sources can be located. In both cases the candidates appear slightly sharper and more compact than typical
stellar point spread functions, qualitatively consistent with sub-second to few-second emission during exposures of $\sim 50$~min, and they are reproducible across different representations of the same field, which disfavours a digitization-artifact origin. However, microscopy of individual point-like features cannot by itself separate a short-duration flash from an intrinsic emulsion defect, because the two scenarios produce qualitatively similar signatures at the single-source level. We also show that the multi-observatory parallax test, while powerful in principle, is not feasible for these two specific events with presently available material, owing to the absence of a simultaneous second-site plate reaching comparable depth. We conclude that resolving the nature of these events requires population-level statistics and, where future observations allow, purpose-built multi-station imaging. This work provides a proof-of-concept framework for combining microscopy with archival analysis in the study of historical transient phenomena.
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Optics
Loss-tolerant hybrid metasurface mirror for reducing coating Brownian noise in precision optical cavities
Swadha Pandey, Evan D. Hall, Peter Fritschel et al. (+1 more)
We propose a hybrid mirror design that places an embedded metasurface beneath a Bragg reflector, combining the low coating Brownian noise of metasurface mirrors with the low optical loss of conventional multilayer coatings. Unlike previous hybrid designs, which place the metasurface at the input surface, our design positions it below the Bragg stack, reducing the optical field incident on the loss-prone resonant layer. For a design operating at 1064 nm, we show that this reduces absorption from 24 ppm for a bare metasurface to 7 ppm for the hybrid. We introduce a general method for calculating the coating Brownian noise of hybrid metasurface-multilayer mirrors at arbitrary coupling strength, extending prior methods to coherently combine a beam-scale mean-field contribution with the periodic, sub-wavelength-scale response of the metasurface. Applying this to our design, we find a reduction in Brownian noise amplitude spectral density relative to an equivalent-reflectance Bragg mirror by a factor of 1.6. Finally, we show that this design has higher angular tolerance than a bare metasurface mirror, maintaining higher reflectance over an angular range of 1 degree. This work provides a practical path towards incorporating low-noise metasurface mirrors into precision optical cavities, while minimizing optical loss and angular sensitivity.
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All authors Swadha Pandey, Evan D. Hall, Peter Fritschel, Matthew Evans
Accelerator Physics
A European high-energy heavy-ion facility for electronics irradiation based at CERN: Concept Design Report
Edgar Cristopher Cortés García, Ruben García Alia, Matthew Alexander Fraser et al. (+2 more)
This proposal presents a concept design for a European high-energy heavy-ion facility dedicated to electronics radiation-effects testing, directly addressing the critical challenges of global beam time shortages and energy limitations in existing facilities. Aligned with the HORIZON-CL4-2026-SPACE-03-85 call under Horizon Europe's Cluster 4 (Digital, Industry, and Space), the facility will enhance European sovereignty in space technology by providing approximately 1,900 additional hours of heavy-ion beam time annually–a 50% increase in European capacity–and extending the accessible ion energy range up to 100 MeV/nucleon, significantly improving penetration capabilities for state-of-the-art electronics testing. The facility will leverage CERN's Low Energy Ion Ring (LEIR) synchrotron, integrating a dedicated extraction system, transfer line, and user experimental area. The project timeline includes a technical design study, followed by infrastructure and hardware production, installation, commissioning, and user operations. Funding will be secured through a collaborative framework involving CERN and the European Union, ensuring sustainable deployment and long-term operational success.
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All authors Edgar Cristopher Cortés García, Ruben García Alia, Matthew Alexander Fraser, Maciej Slupecki, Markus Widorski
Materials Science
Laser-Induced Rashba Spin-Orbit Torques in Multiferroic Semiconductor (Ge,Mn)Te
Zeynab Sadeghi, Tomas Ostatnicky, Eva Schmoranzerova et al. (+8 more)
The multiferroic
semiconductor (Ge,Mn)Te exhibits ferroelectricity, strong Rashba
spin-orbit coupling, and carrier-mediated
magnetic order, making it a unique platform for exploring the interplay between electronic, structural, and
magnetic degrees of freedom. In this study, we investigate the ultrafast magnetization dynamics of Ge0.85Mn0.15Te using time-resolved magneto-optical spectroscopy. By separating
magnetic and nonmagnetic contributions in the transient response, we identify two distinct
laser-induced
magnetic phenomena, both arising from a photoinduced effective
spin-orbit torque. Coherent magnetization precession is driven by a
laser-induced increase in hole concentration, which modifies the occupation of Rashba split,
spin-locked valence band states and shifts the position of the
magnetic easy axis. The transient change in
magnetic properties, observed as variations in the amplitude and coercive field of the pump-induced change in ellipticity hysteresis loops, is attributed to
laser-induced modifications of the ferroelectric sublattice displacement, which affect the ferroelectric polarization and the associated Rashba
spin-orbit interaction. While the first type of optical
spin-orbit torque has already been observed in the diluted
magnetic semiconductor (Ga,Mn)As, the second effect is unique to the multiferroic Rashba
semiconductor (Ge,Mn)Te, opening new opportunities for all-optical manipulation of
magnetic order and
spin-orbit torque generation in
spin-orbitronic devices.
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All authors Zeynab Sadeghi, Tomas Ostatnicky, Eva Schmoranzerova, Jozef Kimak, Dominik Kriegner, Helena Reichlova, Lukas Nadvornik, Gunther Springholz, J. Hugo Dil, Juraj Krempasky, Petr Nemec
Quantum Physics
Misunderstanding Convivial Solipsism: the Necessity of a Perspectival Logic
Herve Zwirn
Convivial Solipsism is easily misunderstood. Because it denies the absoluteness of observed events while preserving the universality of
quantum mechanics, it invites objections that are often formulated in a classical, non-perspectival
language. Such objections appear powerful only because they smuggle back into the discussion the very assumptions that Convivial Solipsism rejects. This article reconstructs a family of misunderstandings that arise in discussions of Convivial Solipsism, especially in connection with Wigner's friend and extended Wigner's friend scenarios. The aim is not merely defensive. The objections are useful because they identify the conceptual discipline required by any interpretation that takes non-absolute facts seriously. The central claim is that observational facts must be indexed to perspectives. A statement such as "the friend saw outcome A" is not a complete factual statement within Convivial Solipsism. It must be reformulated as "from the friend's perspective, the friend saw outcome A" or "from Wigner's perspective, the friend reported outcome B." The mistake consists in removing these indices and then treating the resulting expressions as if they belonged to a single global factual domain. This leads to apparent contradictions and to false dilemmas concerning consciousness, communication, other minds, and intersubjectivity. When that is taken into account, it appears that Convivial Solipsism is not a retreat into psychological solipsism, but a discipline of perspectival discourse. It is also shown that perspectival logic stands to classical logic as the
quantum calculus of probability stands to Kolmogorovian probability theory.
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Plasma Physics
Apokamp-type Gas Discharge Phenomenon: Experimental and Theoretical Backgrounds
Vasily Yu. Kozhevnikov, Andrey V. Kozyrev, Aleksandr O. Kokovin et al. (+5 more)
The apokamp discharge is an atmospheric-pressure
plasma jet generated at the bending point of the discharge channel between high-voltage and floating-potential electrodes. The jet propagates perpendicularly to the interelectrode discharge channel without convection. In ambient air, the apokamp length reaches several centimeters, and the temperature of its tip is 100-250 {\deg}C. The typical apokamp propagation speed ranges from 100 to 220 km/s. The proposed time-dependent theoretical model explains the phenomenon. The discharge modeling confirms the tendencies observed in various experiments on the problem.
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All authors Vasily Yu. Kozhevnikov, Andrey V. Kozyrev, Aleksandr O. Kokovin, Aleksey G. Sitnikov, Eduard A. Sosnin, Victor A. Panarin, Victor S. Skakun, Victor F. Tarasenko
Cosmology and Nongalactic Astrophysics
Cross-simulator transfer with foundation model summaries: Towards robust SKA-era reionization inference
Yannic Pietschke, Caroline Heneka, Ayodele Ore et al. (+1 more)
Simulation-based inference (SBI) for parameter estimation is vulnerable to model misspecification: neural summaries and density
estimators trained on a specific forward model typically fail when applied to data drawn from another model, or from real observations, and no training simulator can capture the full observational pipeline of a real measurement exactly. We show that a self-supervised
Vision Transformer (ViT), pretrained label-free on a fast approximate simulator, produces transferable data summaries that generalize across simulators. Without retraining, it can be reused as a frozen encoder to infer astrophysical parameters from a completely different simulator that resolves the radiative transfer explicitly, on which it has never seen either data or parameters. As a concrete use case in 21cm cosmology, SKATR, a ViT pretrained with a Joint
Embedding Predictive Architecture (JEPA), serves as a foundation model for reionization inference from upcoming SKA measurements: SKATR is pretrained once on 67k low-cost, noiseless semi-numerical 21cmFAST lightcones, then frozen and applied to hydrodynamical Loreli II lightcones, where a lightweight conditional flow matching head infers five astrophysical parameters; the encoder is never shown Loreli data, its parameters, or any noise. In our comparison, SKATR yields the most precise and best-calibrated posteriors across all five parameters, matching the accuracy of the fully-supervised in-domain baseline while requiring 2.6x fewer radiative-transfer simulations. Under realistic SKA AA* noise, only SKATR remains simultaneously accurate, informative, and calibrated, outperforming even a supervised baseline retrained from scratch on noisy data. Self-supervised pretraining on computationally efficient semi-numerical simulations is therefore a viable route to calibrated, simulator- and noise-agnostic reionization inference for the SKA-era.
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All authors Yannic Pietschke, Caroline Heneka, Ayodele Ore, Romain Meriot
Quantum Physics
Enhancing the phase sensitivity of a Mach-Zehnder interferometer beyond the Heisenberg limit through dynamic squeezing
Lakshya Bhardwaj, Ankit Tiwari, Mohan Sarovar et al. (+1 more)
We propose a method to enhance the phase sensitivity of a Mach-Zehnder interferometer, independent of its input states. This is achieved by applying squeezing sequences to one arm of the interferometer. By alternating between squeezing along orthogonal quadratures, we demonstrate that the phase sensitivity of a Mach-Zehnder interferometer can be generically enhanced. Since this enhancement is independent of the input states, the proposed dynamic squeezing method allows for further improvement in phase sensitivity when combined with non-classical input states. We compare the dynamic squeezing approach with existing
quantum sensing protocols and show that super-Heisenberg scaling can be achieved. Finally, we demonstrate that the scheme is robust against moderate
photon loss.
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All authors Lakshya Bhardwaj, Ankit Tiwari, Mohan Sarovar, Christian Arenz
Astrophysics of Galaxies
COSMOS-Web: From early star-formation enhancement to late suppression in galaxy groups
R. C. Arango-Toro, C. Laigle, J. Lewis et al. (+29 more)
Galaxy groups trace dense environments where interactions, gas removal, and reduced
accretion may drive quenching. Common diagnostics trace
star formation over short timescales ($\lesssim100$ Myr); time-resolved
star formation histories (SFHs) separate recent changes from longer-term
evolution at fixed mass and
redshift. Using COSMOS-Web data, we test how group environment correlates with
star-formation activity and its
evolution with
cosmic time and group-centric distance, contrasting high-richness groups with excluded field
galaxies. We combine COSMOS2025/COSMOS-Web
stellar masses and non-parametric SFHs with group detections and memberships from AMICO (Adaptive Matched Identifier of Clustered Objects), comparing stacked SFHs of matched group and field
galaxies and measuring how the SFH offset evolves with group-centric distance for the richest groups. Massive
galaxies ($\log(M_\star/M_\odot)>10.5$) show the largest offsets but are already quenched in both environments. For lower masses ($8.1<\log(M_\star/M_\odot)<10.5$), suppression is clearest at $z<1.5$ (deficit up to 0.8 dex), while at $z>1.5$ SFHs show weak suppression or occasional enhancement. The radial signal evolves similarly: quenching is broad at low $z$, the inner-outer contrast sharpens at $z\gtrsim1$, and any ordering at $z\gtrsim2$ is tentative given growing uncertainties in the AMICO centroids. These results suggest an evolving picture: groups are more mixed at early epochs, with both suppressed and occasionally elevated SFHs, partly reflecting high-$z$ uncertainties, while suppression dominates from $z\lesssim1.5$, most clearly for low-to-intermediate-mass
galaxies. Inner-region
galaxies likely spend more time in the group potential, undergo more passages through dense intra-group gas, and accrete less pristine cold gas, making quenching progressively clearer with
cosmic time.
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All authors R. C. Arango-Toro, C. Laigle, J. Lewis, M. Joly, G. Toni, C. M. Casey, J. S. Kartaltepe, O. Ilbert, M. Shuntov, H. B. Akins, L. Paquereau, Y. Dubois, M. Franco, G. A. Mamon, G. Aufort, A. L. Faisst, Z. Ghaffari, G. Gozaliasl, H. Hatamnia, M. Hirschmann, M. Huertas-Company, A. M. Koekemoer, R. Laishram, D. Le Borgne, G. Leroy, H. J. McCracken, L. Moscardini, A. Nuñez-Castiñeyra, J. R. Rhee, R. M. Samir, M. Trebitsch, L. Tresse