Instrumentation and Methods for Astrophysics
On-sky demonstration of reinforcement learning for adaptive optics control
Jalo Nousiainen, Vincent Chambouleyron, Benoit Neichel et al. (+7 more)
Reinforcement learning (RL)-based
algorithms have recently emerged as a promising approach for adaptive optics (AO) control. In simulations and laboratory experiments, they have demonstrated robustness to real-world effects such as
photon and detector noise, misregistration, vibrations, and rapid variations in seeing conditions. However, their performance has not yet been validated on sky. We report the first on-sky demonstration of a reinforcement learning controller for adaptive optics, named Policy Optimization for AO (PO4AO). We further analyze its on-sky behavior and identify directions for improving the
algorithm and its implementation.PO4AO was implemented and deployed on the Papyrus adaptive optics system installed at the Coudé focus of the 1.52 m
telescope (T152) at the OHP. A Python-based implementation was interfaced with the existing real-time controller (DAO RTC) via shared-
memory buffers. The performance of PO4AO was compared to that of a standard integrator controller over several nights, covering a range of flux levels and atmospheric conditions. PO4AO consistently outperformed the standard integrator in all tested configurations. The controller successfully learned and compensated for vibration patterns and demonstrated strong robustness to measurement noise. Once tuned for Papyrus, PO4AO operated in a turnkey fashion, using a single set of hyperparameters across varying observing conditions and science targets. These performance gains were achieved despite a non-optimized Python implementation introducing approximately $750\,\mu\text{s}$ of additional latency, along with control jitter and occasional frame drops. When properly implemented and optimized, PO4AO constitutes a robust and high-performance turnkey controller for single-conjugate adaptive optics systems, paving the way for broader adoption of reinforcement learning strategies in on-sky AO operations.
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All authors Jalo Nousiainen, Vincent Chambouleyron, Benoit Neichel, Sylvain Cetre, Jean-Francois Sauvage, Angelie Alagao, Markus Kasper, Jonathan Dray, Romain Fetick, Byron Engler
Solar and Stellar Astrophysics
Amortized Simulation-Based Inference of Colliding-Wind Binaries from Short, Noisy Image Time Series
Niklas Knöll, Tobias Buck, Lorenzo Branca et al. (+1 more)
Colliding-wind binaries (CWBs), which are systems of two massive
stars whose supersonic winds collide into bow shocks, encode rich information about
stellar wind properties in their multi-frequency emission, e.g. images in the H$\alpha$, X-ray, and
radio wavelengths. Inferring physical parameters (mass-loss rates, terminal wind velocities, orbital elements) from short time-series observations is a compelling but challenging inverse problem, because the forward hydrodynamic simulator is computationally expensive and the likelihood is intractable. We adopt a factorized spatio-temporal architecture for amortized posterior inference that separates spatial encoding from temporal aggregation. This design aligns with the structure of the underlying physical process of local morphology and global dynamical
evolution, induces time-translation equivariance in the learned representation, and improves identifiability in low-signal regimes. Coupled with a neural spline flow conditioned on these spatio-temporal
embeddings of 10-frame H$\alpha$
photon-count time series, we present a complete simulation-based inference pipeline for CWBs. Our method jointly infers seven physical parameters from synthetic observations under realistic detector noise, with posteriors verified as well-calibrated via TARP and SBC diagnostics. The approach naturally expands posterior width in information-poor regimes (low
photon counts) and robustly recovers orbital parameters and mass-loss rates, demonstrating the feasibility of amortized likelihood-free inference for this challenging astrophysical inverse problem.
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All authors Niklas Knöll, Tobias Buck, Lorenzo Branca, Giuseppe Viterbo
Instrumentation and Methods for Astrophysics
SUPPPPRESS: Prototyping and testing liquid-crystal vector vortex coronagraphs with reduced polarization leakage
Rico Landman, David Doelman, Jeroen Rietjens et al. (+16 more)
The
vortex coronagraph is one of the most promising candidates for the Habitable Worlds Observatory (HWO) due to its excellent theoretical performance for an off-axis
telescope. A practical realization can be achieved using
liquid-
crystal polymers to form a vector
vortex coronagraph (VVC). Reaching the $10^{-10}$ contrast required for Earth-like
planet detection is, however, limited by polarization leakage caused by wavelength-dependent deviations from half-wave retardance. This effect can be mitigated using multi-layer twisted retarders to minimize leakage, and by combining the VVC with multiple polarization gratings (mgVVC) to diffract the polarization leakage out of the science path. We present recent progress within the ESA-funded SUPPPPRESS project, which aims to advance the manufacturing, assembly, and testing of high-performance VVCs. Central singularities of 2 and 6 $\mu$m have been achieved for charge 2 and charge 6 VVCs, respectively, with patterning accuracies better than 1 degree root-mean-square error. Fabrication procedures have been developed to produce individual components with a polarization leakage of $3\times10^{-4}$ over a 10% bandwidth and $8\times10^{-4}$ over a 20% bandwidth. We also report on the development of assembly and
alignment procedures for mgVVCs and their metrology. Furthermore, we present initial high-contrast tests at the THD2 bench for both regular VVCs and a double-grating VVC. The double-grating VVC reaches an average contrast between 3 and 10 $\lambda$/D of $2 \times 10^{-8}$ over a small bandwidth and $6\times 10^{-8}$ over a 10% bandwidth. Finally, we report on successful space-environment tests of the assembled
liquid-
crystal masks.
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All authors Rico Landman, David Doelman, Jeroen Rietjens, Iva Laginja, Pierre Baudoz, Kristien Peeters, Chris van Dijk, Yuki Nishie, Yuta Watanabe, Alexander Eigenraam, Mario Vretenar, Joost van den Born, Raphaël Galicher, Johan Mazoyer, Axel Potier, Mariya Krasteva, Matteo Taccola, Felix Bettonvil, Frans Snik
Statistical Mechanics
Dynamical Partition Functions of Stochastic Dynamics via Variational Flows
Zequn Lin and Ying Tang
Nonequilibrium thermodynamics is governed by the dynamical partition function, and its computation in high-dimensional continuous-state dynamics is a longstanding challenge. The Feynman-Kac formalism provides a rigorous representation for generating functions of arbitrary path observables; however, practical evaluation beyond low dimensions or the weak-noise limit is hindered by the curse of dimensionality and the exponentially growing replica demands of trajectory-based methods. Here we develop a mesh-free neural variational framework that realizes the Feynman-Kac
theorem with generative flow models, recasting tilted
stochastic evolution as a time-dependent optimization problem. This approach enables the direct computation of both finite-time and asymptotic trajectory thermodynamics in a unified manner. The method applies to general observables, enabling the evaluation of work,
entropy production, and current fluctuations. We demonstrate the accuracy and scalability of this method in various nonequilibrium systems including high-dimensional cases.
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Medical Physics · Cross-listed from cs.CV
DD-INR: Dynamics-Driven Implicit Neural Representation for Accelerated Whole-Brain Functional MRI Reconstruction
Qiaoxin Li, Caini Pan, Pierre-Antoine Comby et al. (+2 more)
Accelerated acquisition of fMRI enables enhanced detection of neurovascular (BOLD) activity in the
brain, but image reconstruction becomes challenging with high k-space undersampling: Task-evoked BOLD signals are small in magnitude, which traditional anatomical MRI reconstruction methods fail to recover, as they favor spatial accuracy over temporal fidelity. We present DD-INR, a Dynamics-Driven Implicit Neural Representation framework tailored for accelerated fMRI that benefits from incoherent time-varying sampling and a tailored spatiotemporal prior, outperforming traditional methods, demonstrated in simulation and in-vivo acquisition, both in terms of image quality and
retrieval of activation patterns. DD-INR achieves this by splitting the fMRI data into a static background and a temporally varying dynamic component, representing only the dynamics with a dedicated INR, thereby focusing the model's capacity on activation-relevant changes while remaining compact. In general, DD-INR provides a promising framework for accelerated fMRI reconstruction, with the potential to improve the sensitivity and robustness of fMRI studies within practical scan time limits. The source code is available at https://github.com/JoosenLi/DD-INR.
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All authors Qiaoxin Li, Caini Pan, Pierre-Antoine Comby, Chaithya Giliyar, Philippe Ciuciu
Soft Condensed Matter
Spontaneous translation of charged droplets during evaporation on dry surfaces
Riming Xu, Yanbo Li, Jiawen Zhang et al. (+2 more)
Evaporating sessile droplets are usually treated as capillary objects, but droplets generated by routine handling can carry tens to hundreds of picocoulombs of electric charge. Here we combine Faraday-cup charge measurements with optical imaging to determine how such charge evolves as water droplets evaporate on dry
polymer substrates. A zero-time protocol shows that a reproducible initial charge is preserved on poly(methylpentene) (PMP), whereas PDMS, SOCAL-coated surfaces, and polystyrene either exchange, dissipate, or inject charge on contact. On PMP, ensemble-resolved measurements reveal two regimes: the charge remains nearly constant during early evaporation and then decreases abruptly once the droplet reaches a small-volume state. This charge collapse coincides with spontaneous lateral translation rather than jetting or breakup. A Rayleigh-normalized analysis, including a spherical-cap stress correction and measured contact-angle retention scale, shows that motion occurs only after evaporation drives the droplet into a high electro-pinning state. High-speed imaging and kinematic analysis support a picture in which the subsequent motion is governed by repeated contact-line depinning and re-pinning: the total distance traveled is strongly affected by dry-surface pinning, whereas the peak translational velocity serves as a more robust indicator of the discharge strength. These results identify a dry-substrate mode of evaporation-driven electrostatic relaxation, distinct from Coulomb fission on lubricated surfaces, in which substrate electrostatic passivity enables charge retention, droplet geometry selects the instability onset, and whole-droplet translation provides the charge-release pathway.
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All authors Riming Xu, Yanbo Li, Jiawen Zhang, Jin Wang, Yikai Li
Mesoscale and Nanoscale Physics
Spin polarisation signatures of Fractionally Charged Skyrmions in Fractional Quantum Hall states
Odysseas Williams, Stefan Faelt, Christian Reichl et al. (+1 more)
We investigate
spin polarisation and low-energy excitations in fractional
quantum Hall (FQH) states using cavity-polariton spectroscopy of high-mobility GaAs
quantum wells. By measuring the optical coupling strength of interband Landau-level excitations over the range $1/3 \le \nu \le 1$, we extract the
spin polarisation of the electron system as a function of filling factor. Complete suppression of the oscillator strength of the lowest energy excitation, characteristic of singlet trion formation in fully polarised systems, is reported for the first time in this regime. At large
magnetic fields, fully polarised FQH states exhibit symmetric depolarisation away from their quantised fillings, analogous to Skyrmionic behaviour near $\nu=1$. The depolarisation follows an empirical law $S=\nu^*$, where $S$ is the number of
spin flips per added
magnetic flux
quantum and $\nu^*$ the effective Composite
Fermion filling factor. We interpret this behaviour as evidence for Minimal Fractionally Charged Skyrmions (MFCS) formed from bound
spin-flip and quasiparticle excitations.
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All authors Odysseas Williams, Stefan Faelt, Christian Reichl, Werner Wegscheider
Instrumentation and Methods for Astrophysics
UnReal-B : Real-Space DFT Solver for Matter in Extreme Magnetic Fields
Bhalchandra S. Pujari, Andrey Tokarev and Dipanjan Mitra
As new observational technologies reveal increasingly detailed properties of
neutron star surfaces, the demand for accessible and extensible theoretical modeling tools continues to grow. We present UnReal-B, a real-space Density Functional Theory solver for one-dimensional chains of matter in extreme
magnetic fields $B \approx 10^{12} - 10^{15},\mathrm{G}$. By employing the adiabatic approximation, UnReal-B, provides a streamlined numerical framework for calculating the electronic structure of strongly magnetized condensed matter. The solver is benchmarked against published results for several astrophysically relevant elements, demonstrating excellent agreement while maintaining a comparatively simple and transparent implementation. Released as open-source software, UnReal-B facilitates reproducible and community-driven investigations of
neutron-
star surface matter and provides a foundation for future developments motivated by emerging observational constraints.
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Mathematical Physics
Weighted least action principle for Maxwell equations
Jacob Rubinstein and Gershon Wolansky
The Fermat principle of least time determines the path of a single ray of light given its initial and final positions and the medium electromagnetic properties. However, a single ray is not a measurable physical object. We derive here an upgraded variational principle for the
geometric optics limit of Maxwell equations in an arbitrary medium, based on measuring the intensity of the wave on two planes. The principle provides the complete Fresnel rays bundle connecting associated points at the first and second planes. One of the applications of the present theory is to use the reciprocity between Fresnel rays and phase normals to determine the phase of an electromagnetic wave from two intensity measurements.
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Quantum Physics
Noise cancellation by superposition of channels and superactivation of quantum capacity: Experimental realization by NMR
Deepika Bhargava, Arijit Chatterjee, Vishal Varma et al. (+1 more)
Noisy
quantum channels degrade
quantum resources such as coherence and
entanglement and hence pose challenges for realizing
quantum technologies. Coherent control of noisy channels allows us to minimize their effects on the
quantum system. Here we achieve the cancellation of two noisy
quantum channels by superposing their corresponding Stinespring dilation
unitaries. We first arrive at conditions under which superposition of channels results in a valid
quantum channel. We then consider superposing two dephasing channels and observe their destructive interference, thereby effectively recovering the
quantum coherence. On superposing two zero-capacity depolarizing channels, we show superactivation of
quantum capacity. We experimentally realize the cancellation of two dephasing channels using a three-
qubit NMR register. Furthermore, using a five-
qubit NMR register, we realize the cancellation of two depolarization channels and demonstrate superactivation of
quantum capacity.
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All authors Deepika Bhargava, Arijit Chatterjee, Vishal Varma, T. S. Mahesh
Materials Science
Layer-parity-dependent interfacial coupling in Nb$_3$Cl$_8$/graphene van der Waals heterostructures
Hansheng Xu, Yuchen Gao, Xinyue Huang et al. (+8 more)
Strongly correlated two-dimensional systems provide compelling platforms for investigating exotic
quantum phenomena. Niobium chloride (Nb$_3$Cl$_8$), a single-band Mott
insulator, exhibits a remarkable out-of-plane polarization in its topmost layer that oscillates with layer parity, manifesting as an odd-even effect. Using atomic force microscopy (AFM) and Kelvin probe force microscopy (KPFM), this layer-parity-dependent polarization can be effectively characterized through surface morphology and potential mapping, enabling the unambiguous identification of different surface phases. We then fabricated dual-gate
Hall devices by coupling different surface phases of Nb$_3$Cl$_8$ with monolayer
graphene to investigate how the topmost-layer out-of-plane polarization influences interfacial coupling and the resulting transport behavior. Our results reveal significant phase-dependent variations in charge transfer, carrier densities, and hybridization gaps (25.2 meV for Phase 1 and 30.0 meV for Phase 2). Density functional theory calculations corroborate these experimental findings, showing that distinct out-of-plane polarizations in the topmost layer lead to different orbital overlaps and interfacial coupling strengths. These findings highlight the critical importance of surface polarization and orbital orientation in engineering the properties of strongly correlated van der Waals
heterostructures.
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All authors Hansheng Xu, Yuchen Gao, Xinyue Huang, Weihanzhang Guo, Zhijie Ma, Ziqi Liu, Pinfan Gu, Kenji Watanabe, Takashi Taniguchi, Youguo Shi, Yu Ye
High Energy Astrophysical Phenomena
Potential detection of ~ 4.2 keV emission line from GRS 1747-312
Amom Lanchenbi Chanu, Akash Garg, Ranjeev Misra et al. (+1 more)
We present a broadband spectral analysis of the
neutron star LMXB GRS 1747-312 using $\sim$ 40 ks AstroSat data. The source was observed during the decay phase of the 2017 outburst, with an absorbed 1.0-5.5 keV flux of 1.67$^{+0.04}_{-0.07}\times$10$^{-11}$ erg s$^{-1}$ cm$^{-2}$, corresponding to a luminosity of $\sim$(0.9-1.80)$\times$10$^{35}$ erg s$^{-1}$. The continuum is modeled with thermal Comptonization of blackbody emission and interstellar absorption. A mildly broad iron line at $\sim$6.4 keV is fitted with a disc reflection component. Narrow lines below 2 keV are described by a hot
plasma using the XSPEC model APEC. Additionally, there is a potential detection of an emission line at 4.19$^{+0.12}_{-0.10}$ keV with width $\sigma$ = 0.2 $\pm$ 0.2 keV and line flux of 13$^{+10}_{-9}\times$10$^{-5}$ erg s$^{-1}$ cm$^{-2}$. Examination of several short-duration ($\sim$ few kiloseconds) Swift observations at a few times the AstroSat source flux provided upper limits to the line flux of $<$30$\times$10$^{-5}$ erg s$^{-1}$ cm$^{-2}$. The 4.2 keV line likely originates from reflection off the
neutron star surface. Shifting the neutral Fe K$_\alpha$ line from its rest energy of 6.4 keV to 4.2 keV requires a
redshift of z $\sim$ 0.6, consistent with that expected from the surface of a non-spinning 1.4 M$_\odot$, 10 km radius
neutron star. If confirmed, this feature provides a potential direct measurement of gravitational
redshift, allowing us to place strong constraints on the
neutron star's mass-to-radius ratio and gain valuable insights into the equation of state (EOS) of dense matter.
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All authors Amom Lanchenbi Chanu, Akash Garg, Ranjeev Misra, A. Senorita Devi
High Energy Physics (Phenomenology)
Does the Weinberg angle allow a local hidden-variable description for the leptonic decays of an entangled $ZZ$ pair?
Junle Pei
Quantum entanglement in di-
boson systems offers a useful testing ground for exploring the boundary between
quantum-mechanical correlations and classical descriptions based on local hidden variables. In this work, I study the
spin-polarization state of a $Z_1Z_2$ pair produced from the decay of a
spin-0 particle and investigate whether the angular correlations predicted by
quantum field theory (QFT) in the leptonic decays $Z_1(\to e^-_1 e^+_1)Z_2(\to e^-_2 e^+_2)$ can be reproduced by a local hidden-variable theory (LHVT) under angular-momentum conservation. By matching the LHVT angular distribution to the QFT prediction coefficient by coefficient, I derive the conditions under which an LHVT construction exists. For the case $w\neq 0$, I show that, apart from trivial product-state configurations, an LHVT construction exists only for a unique entangled state, corresponding to $a_1=a_3=-a_2=1/\sqrt{3}$ and $b_2=b_3=0$, together with restricted windows of the weak-mixing angle $\theta_W$. For $w=0$, I derive a necessary and sufficient criterion for the existence of an LHVT construction in terms of a closed set of algebraic and positivity conditions. As an application, I consider the phenomenologically relevant interaction $sZ^\mu Z_\mu$ and show that an LHVT construction exists at threshold $m_s=2m_Z$, whereas it does not exist for $m_s>2m_Z$.
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Medical Physics · Cross-listed from cs.CV
Patient-Level Diagnosis of Acute Myeloid Leukemia via Deep Learning Analysis of Bone Marrow Smear
Yuqi Ma, Tianyi Wang, Weihua Meng et al. (+6 more)
Bone marrow smear review remains important for acute myeloid leukemia (AML) assessment, but manual single-
cell interpretation is labor-intensive and patient-level diagnosis requires aggregation of many cellular observations. We present a
cell-to-patient deep learning pipeline for AML-assisted diagnosis from bone marrow smear images. The study included 258 patients from six anonymized centers, including a main cohort of 169 patients from Centers 1-3 and an external validation cohort of 89 patients from Centers 4-6. A 16-category
cell annotation vocabulary was used to describe the global cellular composition, including granulocytic, monocytic, erythroid, lymphoid, eosinophilic, and other
cells. Rather than identifying strict AML blasts or leukemic blasts, the model targets an expert-defined composite category termed Composite Blast-like
Cells (CBLC), comprising N, N1, M, M1, R, R1, J, and J1 according to the project-wide morphological standard. A fixed YOLO-based
segmentation module detected
cells, predicted contours were matched to expert polygon annotations by contour IoU, and standardized single-
cell crops were generated. An EfficientNet-B0 classifier was trained through a two-stage GT-to-YOLO and YOLO-to-YOLO strategy with class-imbalance correction, center-border regularization, and morphology-assisted supervision.
Cell-level predictions were aggregated into patient-level CBLC ratios for AML-oriented diagnostic support. The pipeline achieved stable internal validation and maintained external generalization, with ensemble weighted F1-scores of 0.9076, 0.8696, and 0.9124 on Centers 4, 5, and 6, respectively.
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All authors Yuqi Ma, Tianyi Wang, Weihua Meng, Hongru Chen, Fajin Tao, Qunxian Lu, Lin An, Xiaodong Mo, Gen Yang
Statistical Mechanics
The Two Dimensional Dynamical Bulk Boundary Correspondence: Beyond Two Band Models
Tomasz Masłowski and Nicholas Sedlmayr
A dynamical equivalent of the bulk-boundary correspondence has been suggested to occur in one and two dimensional topological models following sudden quenches. Depending on the topological invariant of the time evolving and initial phases involved large boundary contributions to a dynamical free energy occur. Moreover they occur periodically between the critical times at which this dynamical free energy becomes non-analytic, i.e.~at dynamical
quantum phase transitions. At these critical times the
eigenvalue spectrum of the Loschmidt
matrix which underlies the dynamical free energy closes its gap. The boundary contributions are understood to be due to zero-modes or in-gap bands of this
matrix, forming a close analogy with
equilibrium topological models and their edge modes. The exact cause of this phenomena and its generality remain unknown. In this article we test the dynamical bulk-boundary correspondence for a complicated two dimensional topological
superconductor with a rich phase diagram, allowing quenches between many different Chern numbers. We show that there is no straightforward correspondence between the
equilibrium phases quenched between and the dynamical bulk boundary correspondence. Furthermore the correspondence can depend on the orientation of the edges, suggesting a possible weak topological variant.
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Quantum Physics
Unitary Channel Testing Under a Depolarizing Noise Assumption
Hirak Ghosh, Andrew Jackson and Animesh Datta
We present fast
algorithms $\unicode{x2013}$ under the depolarizing noise assumption, often made in fault-tolerant
quantum computations $\unicode{x2013}$ to test its strength. Our optimal
algorithms answer the following question: is the
quantum channel implemented by a given black box identical to a target
unitary or $\varepsilon$-far from it in the diamond distance, assuming that the deviation is a depolarizing channel with unknown parameter? Our
algorithm has a query complexity of $\Theta(1/\varepsilon).$ The query complexity of the relaxed problem of testing whether the black-box channel is $\varepsilon_1$-close to a target
unitary or $\varepsilon_2$-far in the diamond distance is $\Theta\bigl(\varepsilon_2/(\varepsilon_2 - \varepsilon_1)^2\bigr).$ In both cases, we provide matching lower bounds that hold even for adaptive, ancilla-assisted protocols with multi-outcome incoherent measurements.
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Exactly Solvable and Integrable Systems
Long-time asymptotics of a full Camassa-Holm soliton gas
Dedi Yan, Xianguo Geng and Minxin Jia
We investigate the long-time asymptotics of a full
soliton gas for the Camassa–Holm equation. The analysis starts from a pure-
soliton Riemann–
Hilbert (RH) problem with \(2N\) poles and two distinct types of residue conditions. We prove that, as \(N\to\infty\), this discrete RH problem converges to a limiting
soliton gas RH problem whose jump
matrix contains two nonzero reflection coefficients. In this sense, the limiting problem gives a full
soliton gas model for the Camassa–Holm equation, in contrast to the previously studied half
soliton gas models, whose jump
matrices involve only one nonzero reflection coefficient. The limiting RH problem is analyzed by the Deift–Zhou nonlinear steepest descent method. The presence of two nonzero reflection coefficients requires two different types of triangular factorizations of the jump
matrix and leads to a more delicate \(g\)-function mechanism. The main difficulty lies in the construction of suitable \(g\)-functions adapted to the Camassa–Holm phase, together with the precise control of their behavior near the distinguished point \(k=i/2\) and at infinity. Depending on the location of the spectral endpoints \(\eta_1\) and \(\eta_2\), different \(g\)-function mechanisms arise. In this paper, we focus on Case I and derive the long-time asymptotic formulas in three
elliptic-wave regions of the self-similar plane. In each region, the leading term is given by a finite-gap
elliptic function, while in the central region the first correction is of order \(\mathcal O(t^{-1/2})\) and involves
parabolic cylinder functions.
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Exactly Solvable and Integrable Systems
Large-time asymptotics of a new KdV soliton gas
Dedi Yan, Xianguo Geng and Jiao Wei
We study the large-time asymptotic behavior of a new KdV
soliton gas. We first introduce a pure-
soliton Riemann–
Hilbert(RH) problem with \(2N\) poles and two different types of residue conditions. We show that, as \(N\to\infty\), this discrete problem converges to primitive-potential RH problem introduced by Dyachenko, Zakharov, and Zakharov, and the jump
matrix of this
soliton gas RH problem has two nonzero reflection coefficients. To analyze the large-time behavior, we apply the Deift–Zhou nonlinear steepest descent method together with an appropriate \(g\)-function mechanism. Through a sequence of transformations, the original RH problem is reduced to explicitly solvable model problems on an associated hyperelliptic Riemann surface. This allows us to derive an explicit leading-order asymptotic formula for the solution in terms of Jacobi
elliptic function. The result provides a rigorous asymptotic description of a new KdV
soliton gas and extends the available analysis beyond the previously studied case \(r_2\equiv 0\).
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Quantum Physics
Ultra-high Q-factor superconducting tantalum resonators on 300 mm Si wafers
R. Acharya, D. Perez Lozano, Ts. Ivanov et al. (+13 more)
Superconducting resonators are central to superconducting
quantum information technologies and essential for bosonic
qubit architectures, where long-lived storage modes enable hardware-efficient error correction. Achieving ultra-high quality factors in scalable planar
circuits is challenging because multiple dissipation channels contribute to the total loss. Here we report planar $\alpha$-Ta resonators fabricated on 300 mm ultra-high-resistivity ($>10$ k$\Omega$ cm) intrinsic silicon using industrial processes, achieving median internal Q factors exceeding 40 million and maxima above 60 million. Energy-participation-ratio analysis identifies a dominant participation-controlled interface loss mechanism and places conservative upper bounds on substrate-associated dissipation. For the best-performing substrate, the inferred substrate loss tangent is below $1.0 \times 10^{-8}$, establishing industrial MCZ silicon among the lowest-loss substrate platforms reported for superconducting resonators. At the same time, the exceptionally low losses show no clear correlation with commonly cited silicon substrate metrics such as room-temperature resistivity or
impurity concentrations. More broadly, these studies establish industrial 300 mm processing, careful interface engineering, and 300 mm MCZ silicon substrates as a promising platform for resonator-heavy superconducting
quantum architectures with ultra-high quality factors.
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All authors R. Acharya, D. Perez Lozano, Ts. Ivanov, S. Massar, C. Vrancken, Y. Canvel, Y. Li, A.M. Vadiraj, J. Van Damme, S. Aghaeimeibodi, A. Khalajhedayati, M. Mongillo, O. Painter, D. Wan, A. Potočnik, K. De Greve
Materials Science
Ultra-Soft Ferrimagnetism in a High-Entropy Spinel Oxide Driven by Site-Selective Cation Disorder
Neha Sharma, AmritPal, Nikita Sharma et al. (+6 more)
High-
entropy materials are complex, multifunctional materials that have reshaped the design of advanced functional materials. Their chemically diverse compositions enable access to a broader compositional space than conventional solid solutions, while simultaneously posing significant challenges for fundamental structure property understanding. In this study, we introduce a new highentropy spinel
oxide with an exceptionally low coercivity of 1.8 Oe at room temperature, among the lowest reported for bulk spinel
oxides, and a high electrical resistivity (1560 ohm-cm).
Neutron powder diffraction (NPD) and
magnetic measurements reveal long-range collinear ferrimagnetic ordering (k = 0,0,0) with a transition temperature at 420 K. This rare combination of ultra-soft
magnetic behavior, robust ferrimagnetic ordering well above room temperature, and high resistivity highlights its strong potential as an advanced soft-
magnetic oxide for low-loss, high-frequency applications. Furthermore, X-ray absorption spectroscopy (XAS), Mossbauer spectroscopy, and NPD analyses were combined to determine the cation distribution and site selectivity across the tetrahedral and octahedral sites of the complex structure.
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All authors Neha Sharma, AmritPal, Nikita Sharma, Mathieu Duttine, Denis Pelloquin, S. D. Kaushik, Sanjoy Mahatha, Olivier Toulemonde, Sourav Marik
Instrumentation and Methods for Astrophysics
DIffuse X-ray Explorer (DIXE): Sky Survey Strategy and Collimator Response Demodulation
Jiejia Liu, Chunyang Jiang, Junjie Mao et al. (+3 more)
DIffuse X-ray Explorer (DIXE) is a proposed high-resolution X-ray spectroscopic surveyor aimed at studying large structures of hot gas in the Milky Way. Its payload is designed to have a field of view (FoV) of $10^\circ$ (half-power diameter) and an energy resolution of better than 6 eV, covering an energy range of 0.1-10 keV. It will be mounted on the China Space Station (CSS) and follow the CSS orbit to conduct the survey with fixed zenith pointing in order to optimize the coverage of key science targets. The payload will avoid the Sun passively via an operable sunshade, where a minimum $25^\circ$ angular separation between the pointing axis and the direction of the Sun is required. Two Sun-avoidance strategies are considered: one focusing on minimizing mechanical risk and the other on maximizing exposure time. The one-year exposure maps indicate that DIXE will cover approximately $72.5\%$ of the sky, with typical exposure times of 26 ks and 68 ks for the two strategies, respectively. Although mechanically collimated, the imaging performance of the payload can be enhanced with a demodulation method based on Markov Chain Monte Carlo sampling using the collimator response. Through simulation, we found that the method could achieve a localization accuracy of $1^\circ$ for point-like sources and a spatial resolution of $3^\circ$ for the extended sources of complex surface brightness distribution, both of which are significantly smaller than the FoV.
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All authors Jiejia Liu, Chunyang Jiang, Junjie Mao, Rui Huang, Ruixuan Tian, Wei Cui
High Energy Astrophysical Phenomena
Hubble as a Unique Discovery Engine of the Fate of Massive Stars and Black Hole Formation
Avishai Gilkis, Eva Laplace, Charles D. Kilpatrick et al. (+3 more)
How
stellar-mass black holes are formed is an open question in astrophysics, with very limited observational constraints. It is not known which types of
stars are more likely to produce black holes, and whether the formation process is accompanied by strong or weak electromagnetic transients - or none at all - and this issue remains a critical missing piece in the puzzle of the fate of massive
stars. Recent theoretical work predicts that many
stellar-mass black holes form from hot, UV-luminous massive
stars, including Wolf-Rayet-like progenitors, and searches focused primarily on luminous cool supergiants may therefore miss a substantial fraction of black-hole formation events. While the coming decade will bring major advances in time-domain astronomy through Rubin/LSST, Roman, JWST, and wide-field transient surveys, none of these combines UV sensitivity, sub-arcsecond imaging, and decade-long continuity. HST uniquely enables direct searches for disappearing hot massive
stars associated with black-hole formation. We outline a roadmap for extending HST's role in this area into the 2030s through a dedicated, large program to re-image nearby
galaxies in the UV and identify candidate disappearing
stars and unusual low-luminosity transients identified by complementary surveys. Theoretical event rates imply that the nearby
galaxy population accessible to HST should yield of order one detectable black-hole-forming disappearance event per year. Extending HST operations into the 2030s would therefore provide crucial insights into the unsolved problem of black hole formation.
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All authors Avishai Gilkis, Eva Laplace, Charles D. Kilpatrick, Maria R. Drout, Anna J. G. O'Grady, Christopher A. Tout
High Energy Physics (Phenomenology)
Isospin-symmetry in $pp$ and $AA$ collisions
A.V. Guskov, G.I. Lykasov, A.I. Malakhov et al. (+1 more)
The hypothesis of a violation of isospin-
symmetry in pp and AA collisions is discussed. We show that the ratio of charged-to-neutral kaon cross sections, $R_K~=~\frac{\sigma_{K^+}+\sigma_{K^-}}{2\sigma_{K^0_S}}$, calculated within the similarity approach, including the
gluon transverse momentum dependence (TMD) at low QCD scales, and using the Lund model in the form of the MC generator PYTHIA, is above 1 at energies $\sqrt{s}$ up to 20 GeV, even in the case of isospin-
symmetry conservation. It decreases to 1, when the energy rises to a few TeV (ALICE data). The reason for this is related to the dynamics of kaon production. This energy behavior of $R_K$ does practically not depend on the sort of beam or target.
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All authors A.V. Guskov, G.I. Lykasov, A.I. Malakhov, A.A. Zaitsev
Quantum Physics
Certification of Network Quantum Sensing
Matteo Rosati, Gabriele Bizzarri and Marco Barbieri
The distribution of
quantum sensors on
quantum networks is a key enabler of
quantum technologies in interferometry, gravimetry, timekeeping, biological monitoring, and beyond. Yet, guaranteeing the security of these distributed sensors over noisy, insecure networks remains a formidable challenge. Previous efforts to combine
quantum metrology and cryptography have encountered an apparently unavoidable tension, proposing bounds for security which are only loosely tied to the achievable measurement performance. Here we introduce a
quantum remote sensing protocol that can rigorously certify
privacy and integrity of the estimation. By employing offline bilateral Pauli-twirling, our approach forces the effective
quantum channel into a Bell-diagonal form, independently of the attack. Surprisingly, this also preserves metrological sensitivity without introducing additional experimental overhead. Relying solely on public communication alongside an insecure
quantum link, the protocol enables legitimate users to exactly quantify their estimation error relative to an eavesdropper controlling the channels. We experimentally demonstrate this framework by estimating an optical phase using entangled
photons, observing that the users' precision consistently surpasses the eavesdropper's capabilities across a broad parameter regime. By unifying
quantum cryptography and metrology, our results provide a practical pathway to achieve simultaneous
quantum-limited precision and rigorous information security in real-world
quantum networks.
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High Energy Physics (Phenomenology)
Efficient AI-Inspired Reduction of Feynman Integrals via Tube Seeding
Justin Berman, Francois Charton, Andres Luna et al. (+2 more)
In this paper, we use machine learning to discover a new seeding strategy for integration-by-parts reduction of Feynman integrals, which is a frequent bottleneck in state-of-the-art calculations in theoretical particle and gravitational-wave physics. Our strategy allows us to reduce multi-loop integrals with large numerator powers via essentially the standard Laporta
algorithm but with a sparse selection of seed integrals that grows only linearly with the numerator power, whereas existing strategies lead to growth with a
polynomial power that increases with the complexity of the integral being reduced. The seeds are restricted to a thin tube-like region that connects the target integral to the master integrals along a zigzag path. We demonstrate the power of our approach by reducing non-planar 2-loop 5-point integrals of rank 20 with numerical kinematics over a finite field, which is prohibitively difficult for the Laporta
algorithm with conventional seeding. Going beyond individual integrals, we further demonstrate the reduction of a complete set of top-level rank-10 integrals by dividing the target integrals into several chunks, each of which can be solved by our sparse seeding strategy with considerably less time and a significantly lower
memory footprint than other state-of-the-art strategies, making the approach well-suited for phenomenological applications. We provide a proof-of-principle implementation on GitHub at https://github.com/andreslunagodoy/tube_seeding.
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All authors Justin Berman, Francois Charton, Andres Luna, Matthias Wilhelm, Mao Zeng
Optics
Length-dependent SWIR upconversion spectral response of noncritically phase-matched KTP crystals
Xiao-Hua Wang, Chang-Hao Min, Yin-Hai Li et al. (+2 more)
Noncritically phase-matched (NCPM) KTP
crystals support large-aperture bulk operation, avoid spatial walk-off, and relax angular-
alignment requirements, making them attractive for short-wave infrared upconversion detection. To guide
crystal selection for different detection requirements, we quantitatively characterize how
crystal length affects the coverage and profile of their external upconversion spectral responses. A calibrated Czerny–Turner monochromator is used to measure the responses of 0.5, 1.0, and 2.0 mm
crystals and compare them with theoretical
quantum-efficiency spectra calculated from the phase-matching model. With increasing
crystal length, the response evolves from a broad profile with weak peak separation to a more distinct double-peak structure, accompanied by reduced coverage bandwidth. A representative pump-power measurement further yields the system-level external
quantum-efficiency slope. These results clarify the trade-off between spectral coverage and wavelength selectivity for different
crystal lengths and can be used to choose the
crystal length for SWIR upconversion detection systems.
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All authors Xiao-Hua Wang, Chang-Hao Min, Yin-Hai Li, Zhi-Yuan Zhou, Bao-Sen Shi
Earth and Planetary Astrophysics
A Processing Workflow for Cassini VIMS Jupiter Cubes
Asier Anguiano-Arteaga, Patrick G.J. Irwin, Santiago Pérez-Hoyos et al. (+2 more)
We present a calibrated catalog of Cassini Visible and Infrared Mapping Spectrometer (VIMS) observations of Jupiter, together with the processing workflow used to generate the final publicly available products. Starting from the raw VIMS cubes, the workflow produces radiometrically consistent multi-extension FITS files and includes a revised visible-channel calibration, a revised infrared-channel calibration that resolves a subset of problematic cases not satisfactorily treated by the standard ISIS pipeline, corrections for pointing-related misalignments between spectral cubes and
geometric backplanes, and customized dark signal correction strategies. The final products include calibrated spectral cubes together with geometry backplanes and wavelength information for subsequent scientific analysis. We assess the consistency of the calibrated products through internal validation tests and comparisons with independent reference spectra from the literature. The resulting products provide a uniform and validated data set of Cassini VIMS Jupiter observations for community use. The full catalog is available as a public data set at Zenodo: doi:10.5281/zenodo.19223781.
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All authors Asier Anguiano-Arteaga, Patrick G.J. Irwin, Santiago Pérez-Hoyos, Davide Grassi, Emiliano D'Aversa
High Energy Physics (Theory)
Michael Lublinsky and Hadas Tzarfati
Chiral plasma appears in several areas of physics, historically starting from
primordial plasma in the early Universe, then in
quark-
gluon plasma produced in heavy ion collisions, and, more recently, in Dirac and Weyl semimetals. The major signature of the
plasma is the non-conservation of the axial current due to the
chiral anomaly and the emergence of new, anomaly-induced transport phenomena. In this paper, we study the
plasma exposed to arbitrarily strong constant
magnetic and weak electric fields. Employing all-order gradient resummation, we write down constitutive relations for electric and axial currents parameterized by thirteen momentum- and
magnetic- field-dependent transport coefficient functions. The latter are computed utilizing a theoretical lab for a realistic
plasma, namely a
holographic $U(1)_V \times U(1)_A$ Maxwell–Chern–Simons theory in Schwarzschild–AdS$_5$, in the probe limit. As an application, we revisit the phenomena of negative magnetoresistance and
chiral magnetic waves, beyond the naive hydrodynamic limit.
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Mathematical Physics · Cross-listed from math.AP
Long-wave KdV hierarchy approximation of the NLS hierarchy with nonzero boundary conditions
Robert Wegner
We study the approximation of certain renormalized conserved quantities for the NLS hierarchy with nonzero boundary conditions, in the long-wave regime, by the energies of the KdV hierarchy. We extend this to all $n \in \mathbb{N}$ by proving an approximation result for the transmission coefficient of the Lax operator of the NLS hierarchy, which is a Dirac operator in the nonrelativistic regime, by the transmission coefficient of a Schrödinger operator, which is the Lax operator of the KdV hierarchy. This yields a formal approximation result between the hierarchies, which we quantify using energy methods and previously established well-posedness results.
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Computational Physics
An adaptive framework for the axisymmetric pulsar magnetosphere using physics-informed Kolmogorov-Arnold networks
Spyros Rigas, Ioannis Contopoulos, Georgios Alexandridis et al. (+1 more)
The
pulsar magnetosphere has only recently been addressed using Physics-Informed Neural Networks (PINNs), by deploying a domain-decomposition approach and treating the separatrix and equatorial current sheet as infinitesimally thin discontinuities. However, this baseline requires extensive manual hyperparameter tuning, achieves limited final accuracy and demands several hours of training. We refine this framework by introducing domain-specific neural architectures based on Kolmogorov-Arnold networks, an automated adaptive training pipeline and a physics-based convergence criterion that eliminate the need for manual calibration. The proposed methodology delivers self-consistent axisymmetric magnetosphere solutions with mean squared errors of the PDE residuals at O(1e-6) in double precision - an improvement of two orders of magnitude over the baseline - while achieving convergence in under 20 minutes in single precision. Importantly, the method reliably resolves
stellar radii reduced by up to 80% compared to the baseline, overcoming the severe spatial scale disparities that also challenge traditional solvers. Furthermore, by varying the flux that opens to infinity, we provide a correction to the equation that connects it to the equatorial T-point's position. The complete framework is released as the open-source library PulsarX.
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All authors Spyros Rigas, Ioannis Contopoulos, Georgios Alexandridis, Antonios Nathanail