Instrumentation and Detectors
HeteroViT: A Versatile Single-Layer Vision Transformer Concept, Co-Designed for Distributed Real-Time Data Reduction on Scientific Detectors
Abhilasha Dave, Weijian Zheng, Antonino Miceli et al. (+3 more)
Next-generation X-ray detectors generate data faster than any system can affordably store or process. LCLS-II, the upgraded Linac Coherent Light Source at SLAC, produces data on the order of terabytes per second, with raw-data transfer and storage projected to be prohibitively costly, even though much of the data is not scientifically useful. This concept paper focuses on two major points. The first is versatility: a deliberately tiny, single-layer
Vision Transformer (ViT) is enough to serve distinct scientific quick-evaluation tasks. We demonstrate this on two very different problems: (a) a supervised hit/miss/maybe classification on the CSPAD
dataset, made to resemble ePixUHR-like detector frames, and (b) a self-supervised latent space for rare-event detection in X-ray diffraction spanning two learning paradigms, two output types, and two detector modalities, with one small backbone. The second is hardware co-design: because the ViT's blocks are structurally uniform, the model maps cleanly onto the heterogeneous hardware already present in the LCLS detector pipeline (ASIC -> FPGA -> GPU) under a simple rule one ASIC is one
token so the data is reduced progressively at each stage and a keep/discard decision is produced in real time at the edge. The two claims reinforce each other: versatility is precisely what justifies freezing the front-end in silicon, since a reusable front-end is only worth committing to hardware if it serves many tasks. We are explicit that this is a concept supported by early software analysis, not a hardware demonstration. The natural and primary next phase is the hardware implementation of this distributed pipeline. The decisive evidence still owed an end-to-end latency budget, ASIC feasibility of the in-sensor
embedding, and the false-negative behavior that matters for a data veto defines that program. HeteroViT is our first step toward it.
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All authors Abhilasha Dave, Weijian Zheng, Antonino Miceli, Dionisio Doering, Ryan Herbst, Angelo Dragone
Quantum Physics
Structure and information measures of few-electron systems under a spherically symmetric Gaussian potential within a density functional approach
Raveena Arya, Santanu Mondal and Amlan K. Roy
Energies of H, He-like ($Z=2-18$) ions, Li, and Be are investigated under a spherically symmetric Gaussian potential through a density functional formalism. The radial Kohn-Sham equation has been solved by invoking a work function-based exchange potential. The effect of electron correlation is analyzed by incorporating two functionals: a local parameterized Wigner functional and a non-linear gradient- and
Laplacian-dependent Lee-Yang-Parr (LYP) functional. The generalized pseudospectral method is employed to provide accurate numerical eigenfunctions and
eigenvalues. This allows nonuniform, optimal spatial discretization fulfilling the Dirichlet boundary conditions. This work demonstrates a possible manipulation of energy by controlling dot parameters. Apart from ground states, exploratory results are also reported for low-lying excited state $1s2s$ ($^{1,3}S$) of He atom. Companion calculations are also performed for various information-theoretic measures, such as Shannon
entropy in position ($S_{r}$), momentum ($S_{p}$) spaces, and Fisher information in position space ($I_{r}$). The behavior of correlation functionals in presence of Gaussian potential is examined critically. We find that energy increases, $S_{r}$ exhibits minima, while $S_{p}$, $I_{r}$ attain maxima for a decrease in the width of potential, whereas an increase in potential depth further amplifies these effects across all properties. The Fisher-Shannon plane reveals a progressive localization as well as the compression of electronic density, and thereby indicates a weakening of relative electron-correlation effects. In the Collin's
conjecture, it gives rise to a non-linear loop-like feature. Much of the results are presented here for the first time.
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Quantum Physics
How Stark units enter SIC overlaps
Ingemar Bengtsson and Gary McConnell
It has been observed that the mutual scalar products of the vectors in a SIC-POVM are given by algebraic units, and at least in some cases by square roots of Stark units. The full picture is somewhat more complicated, especially if non-minimal SIC-POVMs are considered. We present a mixture of exact and numerical evidence suggesting that the overlap units are always products of integral powers of square roots of Stark units from ray class fields all of which are attached to the maximal ring of integers in the base field. In the non-minimal case a
lattice of such ray class fields is involved. In every second dimension (counted in a certain way) some of the overlap units equal $\pm 1$, and we show that this follows from a special property of the ray class fields. Our observations are complementary to but consistent with the claim that the overlap units can be calculated directly from the Shintani–Faddeev modular cocycle.
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Physics and Society · Cross-listed from cs.SI
Direct and Indirect Influence on Likes in Social Media
Ivan Kozitsin and Anton V. Proskurnikov
The present study investigates direct and indirect social contagion mechanisms in an online social network environment. Using a large-scale
dataset comprising approximately 290,000 users from the VKontakte platform, we examine the factors associated with the probability that a user likes a post. Our analysis shows that, while demographic and structural characteristics of individual nodes, such as gender and degree, contribute to the observed dynamics, the strongest associations arise from activity in the user's local network. In particular, active nodes (users who have already liked the post) at distances d = 1 and d = 2 play a central role in shaping liking behavior. We find a substantial association between second-order activity and liking probability, which persists even in the absence of active direct neighbors and is consistent with indirect influence pathways in the network. No significant association is detected for nodes at distance three or beyond. The results also support the structural diversity hypothesis: the number of connected components among active friends is a significant predictor of liking.
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General Relativity and Quantum Cosmology · Cross-listed from math.DG
Riemannian Positive Mass Theorem in All Dimensions in the Presence of Low-Codimension Singularities
Marcus Khuri, Jian Wang and Jinmin Wang
We prove the Riemannian positive mass
theorem in all dimensions for asymptotically flat $L^\infty$-metrics with subcritical singular sets. More precisely, we consider complete asymptotically flat
manifolds whose metrics are smooth away from a compact singular set of Minkowski dimension less than $n-3+\frac{2}{n}$, and whose scalar
curvature is nonnegative on the regular set. We show that the ADM mass of each asymptotically flat end is nonnegative, and that the mass vanishes in some end only in the Euclidean case. For the
rigidity statement, we require additionally that the Minkowski dimension of the singular set is not larger than $n-3+\frac{1}{n-1}$. This gives an asymptotically flat analogue of Schoen's codimension-three
conjecture for positive scalar
curvature. The proof combines a density
theorem for singular asymptotically flat metrics, capacity estimates across the singular set, conformal blow-up inspired by Bi-Hao-He-Shi-Zhu [3], and a $\mu$-bubble dimension-descent argument adapted from Brendle-Wang [6].
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Quantum Gases
A dipolar Bose-Bose mixture of Dysprosium isotopes with controllable interspecies interactions
M. Duerbeck, L. Reihs, J.P. Marulanda-Serna et al. (+5 more)
We report on the realization of a
quantum-degenerate Bose-Bose mixture of 162Dy and 164Dy. Owing to the near-identical mass and polarizability of the two isotopes, the mixture thermalizes efficiently, with evaporation trajectories closely following those of the single-isotope case. Using a broad interspecies Feshbach resonance, we explore a miscible-immiscible transition between the two Bose-Einstein condensates. The tunability of the interspecies interaction, combined with the large
magnetic dipole moment of Dy, makes this platform well suited for exploring dipolar effects in ultracold mixtures, including multi-component supersolidity.
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All authors M. Duerbeck, L. Reihs, J.P. Marulanda-Serna, B. Choudhari, J. Seifert, N. Werum, G. Meijer, G. Valtolina
Optics
System-Level Limits of Higher-Order QAM in Hollow-Core Fiber Systems
Md Ghulam Saber and Zhiping Jiang
Hollow-core fiber (HCF) is widely expected to enable higher-order quadrature amplitude modulation (QAM) because of its near-
vacuum Kerr nonlinearity and higher launch power. We develop a per-channel effective signal-to-noise ratio (SNR) budget that combines, in reciprocal form, optical-link impairments including amplified spontaneous emission, Kerr nonlinear interference (NLI), inter-modal interference (IMI), pigtail NLI, and CO2 gas absorption; a parameterized, symbol-rate-dependent transceiver back-to-back SNR ceiling determined by effective-number-of-bits at rate, analog bandwidth, and Tx/Rx nonlinearity; and the remaining transceiver and line impairments, including
laser phase noise, equalization-enhanced phase noise, timing jitter, polarization-dependent loss, and amplifier gain ripple with filter narrowing, each expressed as an equivalent SNR floor. The central result, at a representative 64GBaud system with 75GHz channel spacing over 6THz, is that once HCF removes the fiber limits, the transceiver ceiling rather than the fiber sets the achievable modulation order: a roughly 25dB ceiling at 64GBaud makes 1024-QAM and above infeasible on either fiber, confining ultra-high-order QAM to low baud rates. HCF therefore provides its main advantage in reach and achievable baud rate at a given modulation order: at an IMI coefficient of kappa=-55dB/km, 256-QAM reach increases from about 45km to about 170km and 64-QAM reach from about 415km to about 2275km when moving from single-mode fiber to HCF. In the C-band, CO2 absorption lines are weak and sparse, so channels placed away from the lines follow the gas-free baseline, while only worst-case placements lose reach at long distances. In the L-band, the stronger absorption bands are denser than the channel bandwidth, making line avoidance spectrally costly, and a channel placed on a line loses one to two QAM orders.
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High Energy Physics (Theory)
One-loop contributions in Lorentz-violating scalar QED with nonminimal coupling
F. M. Belchior, J. R. Nascimento, A. Yu. Petrov et al. (+1 more)
In the context of pertubative aspects of Lorentz-violating theories, we study the divergent one-loop two-point functions of a Lorentz-violating (LV) extension of scalar QED containing a dimension-five CPT-odd nonminimal coupling. The model is defined through a generalized covariant derivative involving a constant background vector and the dual electromagnetic field strength. After expanding the action, we derive the full set of vertices relevant for the
photon and scalar self-energies, including the mixed minimal-nonminimal seagull interaction diagram required by the gauge invariance. Using dimensional regularization, we compute the divergent parts of the
vacuum polarization and scalar self-energy. The complete
photon two-point function is shown to be transverse since the mass-dependent pieces generated by the mixed and purely nonminimal bubble graphs cancel against the corresponding seagull graphs, leaving higher-derivative CPT-odd and CPT-even LV gauge counterterms. The scalar self-energy generates LV kinetic and higher-derivative counterterms. The calculation confirms that gauge invariance is preserved, while the nonminimal interaction should be understood within an effective-field-theory expansion.
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All authors F. M. Belchior, J. R. Nascimento, A. Yu. Petrov, P. Porfirio
High Energy Physics (Theory)
Microscopic entropy of de Sitter spacetime and entropic solution to the old cosmological constant problem
Mariano Cadoni, Lorenzo Herres, Lorenzo Orlando et al. (+1 more)
We study the role of Weyl
symmetry breaking in conformal
gravity and the residual scale
symmetry of Einstein
gravity. The corresponding action is characterized by a dimensionless coupling $\alpha$, determined by the ratio between the de Sitter and Planck scales. We show that this quantity admits a natural interpretation as the Bekenstein-Hawking
entropy of de Sitter spacetime. Combining ideas from the functional renormalization group, holography, and emergent
gravity, we propose a microscopic interpretation of $\alpha$ as a measure of the degrees of freedom associated with the de Sitter horizon. In this framework, the renormalization group flow of $\alpha(k)$ encodes the scale dependence of these microscopic degrees of freedom. Requiring this flow to be monotonically increasing toward the infrared leads to a cosmological constant of the same order as the observed one, suggesting an entropic solution to the old cosmological constant problem. This remarkably small value can therefore be understood as a direct consequence of the extraordinarily large number of degrees of freedom in our de Sitter universe.
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All authors Mariano Cadoni, Lorenzo Herres, Lorenzo Orlando, Mirko Pitzalis
Fluid Dynamics
Scaling patch analysis of turbulent kinetic energy budget equation in wall-bounded flows
Tie Wei, Zhaorui Li and Sergio Pirozzoli
The scaling patch approach is applied to analyze the turbulent kinetic energy (TKE) budget equation in wall-bounded turbulent flows. The balance of the TKE equation is divided into several distinct regions, or scaling patches, each characterized by a dominant balance among the governing terms and its own appropriate scaling parameters. In the near-wall viscous sublayer, the TKE balance is primarily between viscous
diffusion and dissipation, and the characteristic scales are set by the kinematic viscosity and the wall dissipation rate. The thickness of this sublayer is on the order of the Kolmogorov length scale. Moving away from the wall, the peak TKE production provides a natural reference scale for the inner layer, yielding the traditional inner scaling. Grouping the viscous
diffusion and dissipation terms in the inner layer enhances the collapse across different Reynolds numbers. In the outer region, Prandtl's mixing-length model is used to derive a characteristic scale for TKE production. A new meso-scaling is further introduced to describe the intermediate region, ensuring a smooth transition between the inner and outer layers. The scaling patch framework offers a unified interpretation of the structure and scaling behavior of the TKE budget across all regions of wall-bounded
turbulence.
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Cosmology and Nongalactic Astrophysics
DSWIM:Efficient and Stable Deterministic Computation of Warm Inflation Perturbations
Umang Kumar
Warm inflation perturbations are sourced by both thermal and
quantum fluctuations and are commonly computed through
stochastic realizations of the perturbation equations, as implemented in the publicly available code SWIM. Deterministic formulations based on correlation
matrix evolution provide a computationally efficient alternative, but can become numerically ill-conditioned when the perturbation variables evolve over widely different scales. In this work, we extend SWIM by introducing a deterministic module, DSWIM, based on correlation
matrix evolution. We introduce a physically motivated scaling
matrix transformation derived from the effective Hubble scaling of the perturbation variables. The transformed system preserves the
primordial curvature power spectrum exactly while substantially improving the numerical conditioning of the deterministic
evolution equations. Using representative warm inflation models, we show that the scaled framework suppresses numerical artifacts, improves the robustness of the deterministic
evolution, and yields substantial computational speedups while preserving accuracy. We further show that correlated thermal noise contributions arise naturally through the
diffusion matrix structure, resolving previously observed discrepancies between
stochastic and deterministic implementations. Our results establish DSWIM as a numerically robust and computationally efficient framework for computing warm inflation scalar perturbations.
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Optics
Hollow-Core Fiber in Direct-Detection Optical Networks: Technology Readiness, Deployment Drivers, and Adoption Outlook
Md Ghulam Saber and Zhiping Jiang
This paper presents a comprehensive analysis of hollow-core fiber (HCF) for intensity-modulation and direct-detection (IMDD) optical networks, covering fiber-level physics, system-level performance, and deployment economics. We quantify the three principal advantages of anti-resonant HCF over standard single-mode fiber (SMF) for IMDD: (i) chromatic dispersion of 2-4 ps/(nm km) versus 17 ps/(nm km), which shifts the first dispersion-induced power-fading null from about 10 GHz to 20-28 GHz at 40 km, extending the dispersion-limited reach by 4-8x; (ii) a nonlinear coefficient approximately 1,000x lower than silica, permitting launch powers of +10 to +20 dBm and yielding 7-17 dB of additional link budget; and (iii) a group index near unity (ng about 1.003), reducing propagation latency by 31%. We further analyze inter-modal interference (IMI) as the dominant impairment for HCF-based IMDD. We show that differential modal attenuation (DMA) exceeding 12 dB/km suppresses IMI-induced crosstalk below the -30 dB multipath interference threshold required for PAM4. The reduced dispersion also lowers the required feed-forward equalizer (FFE) tap count by 3-6x, directly decreasing noise enhancement penalty and DSP complexity. A deployment cost model across five application scenarios - intra-data center, campus DCI, metro DCI, 5G fronthaul, and PON - reveals that fiber cable constitutes only 5-10% of outside-plant deployment cost, and that coherent transceiver avoidance savings of $1000 to $2000 per transceiver can offset the current HCF premium at metro distances. We provide a technology adoption roadmap indicating that HCF is economically justified now for intra-DC and campus DCI, with metro DCI following in 2027-2030 as manufacturing costs continue to decline.
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Materials Science
Atomic-scale theory of robust out-of-plane ferroelectricity in ultrathin films
Fengbo Yuan, Yujia Teng, Karin M. Rabe et al. (+1 more)
Ferroelectricity in ultrathin films, characterized by robust switchable out-of-plane polarization, is key to next-generation nanoelectronics. Although the macroscopic theory of ferroelectricity suggests that ferroelectricity is inevitably suppressed as the film thickness decreases, recent studies have demonstrated robust ultra thin-film ferroelectricity, for certain ferroelectric materials, specifically HfO$_2$-based
oxides and bismuth-based
oxides. In this work, we develop an atomic-scale theoretical framework for understanding ferroelectricity in this limiting regime. By considering the work function of the termination layers of the film, we find that robust ferroelectricity arises from “self-polarizing” and “switchable role of the termination layer” effects strongly correlated to the “characteristic structure.” This theory also provides further insights on the importance of top electrodes in stabilizing ferroelectricity for this class of materials in the ultrathin limit. This work aims to develop a comprehensive theoretical framework for thin-film ferroelectricity, providing fundamental insights that can guide the design of next-generation nanoscale devices.
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All authors Fengbo Yuan, Yujia Teng, Karin M. Rabe, Yubo Qi
Physics Education
Analysis of quantum-related courses and textbooks for potential integration of quantum sensing
Namitha Pradeep and Ben Zwickl
The second
quantum revolution is driving advancements in
quantum computing, communication, and sensing. While
quantum computing has gained significant
attention in education,
quantum sensing remains largely overlooked. In order to find ways of integrating sensing into existing
quantum-related curricula, we performed an analysis of six of the most commonly used textbooks in modern physics,
quantum mechanics, and
quantum computing. We identified a set of keywords related to
quantum sensing and tagged all excerpts in which these concepts appeared. For each excerpt, we also recorded the context in which it was presented within the textbook. Network maps were constructed to visualize which keywords appeared in which contexts and the frequency of these occurrences within each subject area. We then developed an analytic rubric to evaluate the conceptual and mathematical depth of these excerpts as well as the extent of sensing-related discussions. Our results show that there is significant variation in how different subjects address these concepts, both in the nature of the content covered and the depth of coverage. We also observe notable differences in how
spin-first and position-first textbooks discuss these keywords, particularly in the coverage and contexts in which core concepts such as superposition and
entanglement appear. Additionally, we analyzed course titles and descriptions from a database of over 8,000
quantum-related courses, focusing on those that mentioned “sensing” or “sensor”. Together, these analyses of textbook content and course descriptions inform the
quantum information science and engineering education community about potential opportunities to integrate
quantum sensing topics into
quantum-related courses in physics and adjacent disciplines.
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Optics
Fractality-induced photonic topological insulators
Shuming Zhang, Zhaoxin Wu, Lumen Eek et al. (+2 more)
Fractal
lattices have recently emerged as a promising setting for topological wave physics, but in most realizations the topological character is inherited from externally engineered couplings, gauge fields, or temporal modulation rather than from the fractal geometry itself. Here, we experimentally realize a photonic higher-order topological
insulator in which the
topology is induced solely by the self-similar geometry of a Sierpiński-gasket
lattice. Following the isospectral reduction method recently proposed by Eek et al.~\cite{Eek2025}, we show that the fractal waveguide array with uniform nearest-neighbor couplings can be mapped onto an effective breathing Kagome model that supports corner states. We selectively excite these modes with a weakly coupled detuned auxiliary waveguide and directly observe robust corner localization in real space, whereas an otherwise equivalent uniform triangular
lattice exhibits only bulk diffraction under the same protocol. Spectral analysis and open-boundary calculations associate the observed states with nontrivial $C_3$ rotational
topology, and disorder measurements further show that the corner localization persists over a finite range of random and
symmetry-preserving disorder. Our results establish fractal geometry itself as a mechanism for generating topological boundary states in photonic
lattices.
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All authors Shuming Zhang, Zhaoxin Wu, Lumen Eek, Cristiane Morais Smith, Zhaoju Yang
Computational Physics · Cross-listed from math.NA
Projection-Based Reconstruction for Achieving High-Order Accuracy from Low-Order DGSEM Simulations
Xukun Wang, Suyash Shrestha, Oscar A. Marino et al. (+1 more)
High-order discontinuous Galerkin spectral element methods (DGSEM) based on Legendre-Gauss-Lobatto (LGL) nodes provide accurate and efficient discretizations for conservation laws. However, their cost,
memory footprint, and time-step restrictions increase rapidly when the degree of the
polynomial increases. This paper develops a corrected $\mathbb{P}_n\mathbb{P}_m$ ($c\mathbb{P}_n\mathbb{P}_m$) approach for DGSEM-LGL discretizations that aims to recover the accuracy of an $m^{th}$-order approximation while evolving only the degrees of freedom associated with an $n^{th}$-order representation, with $n<m$. The projected
evolution of the high-order components is derived first at the continuous level and then in the fully discrete DGSEM-LGL setting. The discrete analysis shows that because LGL quadrature is not exact for the highest Legendre mode, a correction term for that mode is required to preserve the order of convergence. A compact projection-based reconstruction operator is then introduced to recover high-order components without solving the enlarged constrained least-squares systems used in standard reconstruction procedures. For sufficiently smooth solutions, the resulting $c\mathbb{P}_n\mathbb{P}_m$ scheme is shown to achieve the expected $m+1^{th}$ convergence order. Numerical experiments for one- and two-dimensional conservation laws, including Euler, viscous Burgers, and 2D decaying homogeneous isotropic
turbulence, confirm theoretical convergence behavior and demonstrate competitive accuracy relative to computational cost, with particularly clear efficiency gains for viscous flows.
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All authors Xukun Wang, Suyash Shrestha, Oscar A. Marino, Esteban Ferrer
Chaotic Dynamics
Recurrence time entropy and weak chaos in Hamiltonian flows
Matheus Rolim Sales, Leonardo Costa de Souza, Iberê Luiz Caldas et al. (+2 more)
Stickiness in mixed
Hamiltonian systems causes chaotic trajectories to remain temporarily trapped near regular structures, making it difficult to distinguish regular, weakly chaotic, and strongly chaotic motion over finite times. We show that the recurrence time
entropy (RTE), previously used in discrete maps, also characterizes weak chaos in
Hamiltonian flows. In the Hénon-Heiles system, the RTE reproduces the structures identified by the largest Lyapunov exponent, taking intermediate values in the sticky layers, and yields a proportion of chaotic trajectories consistent with the smaller
alignment index. The finite-time RTE identifies low-
entropy episodes near regular islands, whose durations decay algebraically, whereas high-
entropy episodes decay exponentially. The same characterization holds for a periodically driven system and for a
Hamiltonian system with three degrees of freedom, whose section is four-dimensional. The RTE is thus an effective diagnostic of weak chaos and stickiness in
Hamiltonian flows.
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All authors Matheus Rolim Sales, Leonardo Costa de Souza, Iberê Luiz Caldas, Edson Denis Leonel, José Danilo Szezech Jr
High Energy Astrophysical Phenomena
Spectral and timing variability of the transient ultraluminous X-ray source NGC 4631 X-4
Sinan Allak, Wei Yu, Lorenzo Ducci et al. (+4 more)
Ultraluminous X-ray sources (ULXs) are among the best laboratories for studying super-Eddington
accretion onto compact objects. We present a detailed spectral and timing analysis of the transient ULX NGC 4631 X-4 using archival Chandra, XMM-Newton, and Swift/XRT observations. The source exhibits pronounced spectral and flux variability on both short and long timescales, with luminosity variations exceeding two orders of magnitude. Its X-ray spectra are well described by absorbed multicolor disk blackbody and power-law models, with characteristic inner disk temperatures of 0.9-1.4 keV and
photon indices of 2.0-2.4. The source does not follow the standard luminosity-temperature relation expected for a geometrically thin, optically thick
accretion disk. No coherent pulsations or quasi-periodic oscillations are detected, while the short-term variability is dominated by aperiodic fluctuations and kilosecond peak-like structures, consistent with clumpy winds and
geometric effects in a super-Eddington
accretion flow. Overall, the spectral and timing properties support super-Eddington
accretion onto a
stellar-mass compact object, although the current data do not allow us to distinguish uniquely between a
neutron star and a
stellar-mass black hole accretor.
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All authors Sinan Allak, Wei Yu, Lorenzo Ducci, Andrea Santangelo, Aysun Akyuz, Faruk Soydugan, Valery Suleimanov
Materials Science
High-quality single crystals of the kagome metals Ni$_3$In and Ni$_3$Sn grown from Pb flux
Fabian Garmroudi, Jennifer Coulter, Caitlin S.T. Kengle et al. (+4 more)
The
bilayer kagome metal Ni$_3$In has recently attracted
attention due to the presence of a flat band located near the
Fermi level, which has been associated with unconventional thermodynamic and electronic transport properties [Ye et al., Nat. Phys. 20, 610-614 (2024)]. However, further investigation of the intrinsic properties of this system has been hindered by the lack of large, high-quality single
crystals. Here, we report the successful growth of Ni$_3$(In, Sn) single
crystals using a Pb-flux technique. By optimizing the growth conditions, competing binary phases can be effectively suppressed, enabling the synthesis of single
crystals with dimensions reaching several millimeters. We compare the physical properties of our Pb-flux-grown
crystals to previously reported samples prepared by iodine-assisted chemical vapor transport and molecular beam epitaxy as well as to first-principles resistivity calculations. We find a significantly lower electrical resistivity in our
crystals, in excellent agreement with calculations of resistivity from electron-
phonon scattering, a sizeable non-saturating magnetoresistance, and a reduced Sommerfeld coefficient and
magnetic susceptibility compared to previous experimental findings, which are likely related to differences in the
Fermi level position. Our results establish Pb-flux growth as a reliable route for obtaining large single
crystals of the
bilayer kagome metals Ni$_3$(In, Sn) that are suitable for further thermodynamic and spectroscopic investigations of their intrinsic electronic and
magnetic properties.
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All authors Fabian Garmroudi, Jennifer Coulter, Caitlin S.T. Kengle, Joe D. Thompson, Eric D. Bauer, Sean M. Thomas, Priscila F.S. Rosa
Superconductivity
Anomalous charge density wave in a two-dimensional superatomic superconductor
Boqin Song, Shuaishuai Sun, Zhongxu Wei et al. (+12 more)
The spatial modulation of electron density into a wave-like pattern, known as charge density wave (CDW), represents a fundamental
quantum state that often coexists with superconductivity,
quantum Hall states,
axion insulating phases and etc. Conventional CDWs are mediated by longitudinal acoustic
phonons, exhibit picometer-scale
lattice distortions ($10^{-12}$–$10^{-11}$ m), and typically vanish approaching the atomic limit. Here, we report a series of anomalous CDW behaviors in the 2D superatomic
superconductor Au$_6$Te$_{12}$Se$_8$. Remarkably, its CDW is governed by transverse
phonons, accompanied by an extraordinarily high real-space displacement of $\sim 4$ Ångström. Furthermore, we observe an exotic dimensional response persisting up to micrometer-scale thickness, a regime where other materials are already considered as bulk. Through
liquid helium-temperature transmission electron microscopy, ultrafast pump-probe spectroscopy and transport measurements, we demonstrate a dramatic enhancement of the CDW transition temperature ($T_{\text{CDW}}$) from $<2$ K in the bulk to 110 K in approaching the “superatomic limit”. Our findings not only reveal novel facets of both CDW and superatomic materials, but the competition between this anomalous CDW and superconductivity opens avenues for exploring unconventional electron-
phonon interactions.
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All authors Boqin Song, Shuaishuai Sun, Zhongxu Wei, Xinbo Wang, Xiaoping Ma, Kaifa Luo, Lei Wang, Jun Deng, Xu Chen, Tian Qian, Shuya Xing, Zhihai Cheng, Jiangang Guo, Tianping Ying, Xiaolong Chen
High Energy Astrophysical Phenomena
A Tentative Double Excess in the Gamma-Ray Spectrum of the Fermi Blazar 4FGL J0604.9-0000
Shi-Ju Kang
Based on 17.75 years of
Fermi-LAT observations, we report a tentative double excess in the gamma-ray spectrum of the blazar 4FGL J0604.9-0000, with peak energies at approximately 1.5 GeV and 11 GeV. The two excesses are modeled as double Gaussian components. For the lower-energy excess, the best-fit centroid is $E_1 = 1.59\pm0.07$ GeV with a width fixed to the instrumental resolution ($\sigma_1 = 0.145$ GeV). For the higher-energy excess, the centroid is $E_2 = 11.15\pm0.61$ GeV and the width is constrained to $\sigma_2 = 1.185$ GeV (about 10% of the peak energy), which is comparable to the
Fermi-LAT energy resolution at that energy. The two features have local significances of $2.6\sigma$ and $3.7\sigma$ (3 dof), respectively. A joint likelihood analysis yields a combined test statistic of TS $\simeq 27$, corresponding to a local significance of approximately $4.3\sigma$ (4 dof, without correction for trials and the look-elsewhere effect) or about $4.8\sigma$ (2 dof). To our knowledge, no other active
galactic nucleus has been reported to show a similar double-excess candidate. The observed energy ratio of $\sim$1:7 is difficult to explain with standard astrophysical emission processes. However, the energies and their ratio are consistent with dark matter annihilation (e.g., $\chi\chi\to\gamma\gamma$ and $\chi\chi\to\gamma\gamma'$) for a particle mass near 11 GeV, making this source a promising target for follow-up observations with next-generation gamma-ray
telescopes.
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High Energy Physics (Theory)
Geometric and Statistical Thermo Field Dynamics in de Sitter Spacetime
D. S. Cabral, L. A. S. Evangelista, J. C. R. de Souza et al. (+1 more)
The dynamics of a massive scalar field non-minimally coupled to
gravity in an expanding de Sitter universe are investigated. It is shown that a comoving observer identifies the Bunch–Davies state as the
vacuum, whereas a static observer perceives the same state as a thermal bath at the Gibbons–Hawking temperature. Motivated by this observer dependence, a thermal formulation based on Thermo Field Dynamics is developed by combining the
geometric doubling associated with the cosmological horizon with the statistical doubling induced by a intrinsec thermal bath. The resulting construction reveals that the doubling procedure is not merely a mathematical artifact, but rather a manifestation of the global causal structure of spacetime together with finite-temperature effects. The temporal
evolution of the Bogoliubov angle is analyzed and the corresponding particle number densities are evaluated in both comoving and static frames. In the radiation limit, the comoving number density remains conserved, providing a thermodynamic
evolution consistent with that of the
Cosmic Microwave Background, whereas in the static frame finite-temperature effects sti\-mulate Parker particle creation. For massive and non-minimally coupled fields, the interplay between
geometric and statistical temperatures gives rise to a characteristic thermal scale and a nontrivial dependence on the initial conditions. These results provide a unified framework for describing
quantum fields in de Sitter spacetime in the presence of both apparent horizon-induced and intrinsec thermal effects.
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All authors D. S. Cabral, L. A. S. Evangelista, J. C. R. de Souza, A. F. Santos
Earth and Planetary Astrophysics
Energy-Limited Radiolytic Habitability in the Shallow Martian Subsurface: Implications for ExoMars Rosalind Franklin and Tianwen-3
Dimitra Atri
The surface of Mars is sterilized by ionizing radiation and pervasive oxidants; its shallow subsurface, shielded from ultraviolet light and the most reactive oxidation, may instead preserve habitable conditions. The radiolytic habitable zone (RHZ) hypothesis holds that
galactic cosmic rays can drive water and oxychlorine radiolysis there, generating H2 and oxidants that support chemolithotrophy without sunlight or geothermal heat. We develop a quantitative framework coupling Monte Carlo GCR transport, phase-resolved radiolysis chemistry, water-activity and H2-retention treatments, and microbial maintenance-power constraints for Gale Crater, Oxia Planum, southern Utopia, and Arabia/Mawrth, expressing radiolytic chemical energy as a depth-resolved redox power comparable to the power requirements of life. H2 retention is the dominant control. Sorbed or mineral-associated retention yields 4-6 x 10^-13 W kg^-1 at protected depth (>=10 cm), whereas connected-pore free-gas escape lowers redox power by two to four orders of magnitude. Gale remains inactive under both retention assumptions, consistent with published SAM evolved-gas analyses. Even in retained-H2 active terrains, supported
cell density reaches only 10^3-10^5
cells cm^-3 at subseafloor maintenance powers. The framework predicts a spatially restricted, low-density RHZ, testable by stepped H2 evolved-gas analysis of protected-depth samples from ExoMars Rosalind Franklin, Tianwen-3, or Mars Sample Return.
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Solar and Stellar Astrophysics
Sergey A. Belov, Dmitrii Y. Kolotkov, Akshay V. Mehta et al. (+1 more)
The temporal morphology of
flare light curves encodes the underlying
flare physics, and deviations from the typical
flare profile may indicate the presence of mechanisms not captured by a standard
flare model. To search for such time-domain deviations from a "standard"
flare, we develop an unsupervised Deep Support Vector Data Description (Deep SVDD) model, which learns a compact representation of normal
flares, against which unseen anomalous
flares are identified. The model is trained on synthetic light curves with a "normal"
flare morphology, generated from existing analytical
flare trend models with noise. Using the distribution of normal
flare data, we introduce a probabilistic
Flare Anomaly Index (FLAI) which allows for separating
flare light curves into three distinct classes: normal data (ND), weak anomalies (WA), and strong anomalies (SA). Application of FLAI to the Kepler
flare catalogue (white light) reveals that 36% and 30% of events belong to the WA and SA classes, respectively. For M- and X-class
solar flares from the STIX
flare list, 25% and 32% of events in the 15-25 keV channel are classified as WA and SA, respectively, versus 15% for both WA and SA classes in the 4-10 keV channel. Thus, anomalous
flares appear more frequently in the STIX high-energy channel. These results show that both
solar and
stellar flares often deviate from the normal
flare population used for model training, suggesting departures from the standard
flare scenario, such as modified energy release and dissipation, or the development of wave and oscillatory processes in
flare sites.
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All authors Sergey A. Belov, Dmitrii Y. Kolotkov, Akshay V. Mehta, Laura A. Hayes
Fluid Dynamics
Continuity equations in the Generalised Lagrangian Mean theory
Vladimir A. Vladimirov
Generalised Lagrangian Mean (GLM) theory describes the joint
evolution of the mean flow and its perturbations. This paper analyses the exact GLM continuity equations (GLM-CEs), presents them in new forms, and adds new equations to complete them. Our three-dimensional results include: (i) A modified approach to GLM theory that uses only the basic notions of classical fluid dynamics. The only tools used are Lagrangian X, Eulerian x, averaged (mean) Eulerian x' coordinates of fluid particles, and an averaging parameter a. The targeted forms of GLM-CEs are expressed with functions x(x',t, a) and r(x',t, a), where r is the fluid density. (ii) Actual velocity divergence div u expressed through div'u', where u and u' are the actual and mean fluid velocities. (iii) Three new forms of GLM-CEs. Each version represents a sum of a mean and an a-dependent (tilde) part. The latter addition makes each form mathematically complete. (iv) The original Andrews-McIntyre transformation (AMT) is also complemented by its tilde part. Then it also gives the full version of the exact GLM-CEs. However, it works only for a special class of fluid flows. Its structure explains why the tilde equations have been overlooked. (v) Our generalisation of AMT, which repeats the results (i)-(iii) but requires a more complex derivation. (vi) Examples of flows with small but finite Lagrangian perturbations, linking our exposition to the classical GLM theory. Keywords: continuity equations, general Lagrangian mean theory, average (mean) coordinates, Eulerian description, tilde equations, Andrews-McIntyre transformation.
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Earth and Planetary Astrophysics
A Multiband Study of the HR 4796A Disk in the Optical Using MagAO-X
Jay K. Kueny, Alycia J. Weinberger, Zhe-Yu Daniel Lin et al. (+18 more)
We present total intensity images of the debris disk around HR 4796A from observations spanning 2023 to 2025 with the Magellan extreme adaptive optics instrument (MagAO-X). We detected the disk at high signal-to-noise ratios at $g' (527$ nm), $r' (615$ nm), $i' (762$ nm), and $z' (909 $ nm). Additionally, we present images collected using the "
star-hopping" technique that show the entirety of the disk, including the dramatic forward-scattering at the minor axis. We subjected our images to a battery of modeling techniques to constrain the geometry and photometry of the disk. Leveraging our clear detections of the disk's minor axis, we modeled the scattering phase function (SPF) using a basis of the Legendre
polynomials. To mitigate self-subtraction artifacts in our angular differential imaging, we implemented a forward-modeling pipeline that generates a pixel-based freeform disk forward model leading to a deconvolved image of the disk. Our best-fit disk models reveal: (1) highly forward-scattering SPFs with a minimum at the $\sim65^{\circ}$ scattering angle, (2) a faint
halo of
dust just exterior to the spine of the disk that is not well-described by a broken power law density profile, (3) a red spectral slope for the
dust, and finally (4) a compact, clump-like feature in the freeform disk models. Our empirically-measured SPFs suggest that the scattering is dominated by large, highly-absorptive grains. However, we emphasize the need for testing advanced irregular grain models using our SPFs to learn more about the physical and chemical properties of this complex system.
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All authors Jay K. Kueny, Alycia J. Weinberger, Zhe-Yu Daniel Lin, Joseph D. Long, Jared R. Males, Joshua Liberman, Jialin Li, Sebastiaan Haffert, Laird M. Close, Eden McEwen, Maggie Y. Kautz, Olivier Guyon, Logan Pearce, Parker T. Johnson, Katie Twitchell, Alex Hedglen, Avalon Gower, Warren Foster, Jhen Lumbres, Lauren Schatz, Elena Tonucci
Superconductivity
Magnetic-Free Quantum Interference and Universal Josephson Diode Effect Driven by a Supercurrent Gauge Field
Haowei Ye, Wenxue He, Kaixuan Fan et al. (+8 more)
The Josephson effect, a hallmark of superconducting phase coherence, drives modern
quantum technologies. However, Josephson-based
quantum interference has hitherto been tethered to
magnetic fields, despite phase coherence being a quintessential, intrinsic trait of superconductivity. Moreover, the Josephson diode effect (JDE) is typically viewed as an anomalous phenomenon indicative of broken
symmetries in exotic phases of matter. Here, in planar Josephson junctions made with $\mathrm{Bi}_2\mathrm{O}_2\mathrm{Se}$ and
bilayer graphene, we demonstrate that the JDE is a missing universal property of the Josephson effect. Simultaneously, we present an all-electric technology that replaces
magnetic flux for controlling and measuring supercurrent interference. Central to our approach is a supercurrent gauge field (SGF), generated and amplified through high-kinetic-inductance
superconductors and novel device architectures. By establishing the physical equivalence between the SGF and a
magnetic field, we eliminate the reliance on external fields in
quantum interference and reveal a universal, field-free JDE mechanism with broad implications for detecting broken-
symmetry states. Finally, we show that the SGF offers capabilities beyond those of a conventional
magnetic field by experimentally demonstrating a
magnetic-free, phase-sensitive technique to construct and characterize finite-momentum superconductivity, opening new frontiers for exploring novel phases of matter and superconducting
quantum architectures.
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All authors Haowei Ye, Wenxue He, Kaixuan Fan, Yingpeng Zhang, Shijin Li, Yu Pan, Dechao Geng, Fan Yang, Kenji Watanabe, Takashi Taniguchi, Hechen Ren
Instrumentation and Methods for Astrophysics
ffortissimo: A Freeform Forward-Modeling Pipeline for High-Contrast Images of Circumstellar Disks Based on Automatic Differentiation
Jay K. Kueny, Joseph D. Long, Jared R. Males et al. (+16 more)
Modeling circumstellar disks in the traditional sense carries the assumption that the
dust density distribution can be accurately described with a fixed parametric form. Furthermore, commonly-used
algorithms for subtracting the
stellar point-spread function (PSF) distort the true morphology of the faint underlying disk structure, especially dusty features that are located at small angular separations. These phenomena often lead to significant residuals with parametric disk models and make it difficult to measure the full realizable range of the scattering function of the
dust. We address these challenges with ffortissimo, a novel, pixel-based freeform forward modeling pipeline designed to characterize extended objects in KLIP-reduced images. We built this pipeline within the framework of JAX, which is a machine learning library in Python that enables efficient optimization through automatic differentiation ("autodiff") and GPU-accelerated array computations. Using visible light images of the disk around HR 4796A taken by the "extreme" Magellan Adaptive Optics instrument (MagAO-X), we show that our data-driven freeform models excel at fitting a complex
dust distribution and can infer the
dust scattering properties even through PSF subtraction artifacts. Additionally, we demonstrate the potential for retrieving spatial
dust features beyond the diffraction limit of the
telescope. We note that there are remaining challenges to address before precision photometry using these freeform models is advised. These include better background, wind-driven
halo, and speckle characterization as preventing the freeform models from learning these noise artifacts is currently difficult.
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All authors Jay K. Kueny, Joseph D. Long, Jared R. Males, Alycia J. Weinberger, Laird M. Close, Joshua Liberman, Sebastiaan Haffert, Eden McEwen, Maggie Y. Kautz, Olivier Guyon, Logan Pearce, Parker T. Johnson, Katie Twitchell, Jialin Li, Alex Hedglen, Avalon Gower, Warren Foster, Jhen Lumbres, Lauren Schatz
High Energy Astrophysical Phenomena
TeV-PeV Gamma-ray and Neutrino Emission in the Galactic Plane
Saikat Das, Nayantara Gupta and Siyao Xu
We model the LHAASO observation of diffuse TeV–PeV $\gamma$ rays in the
Galactic plane as the sum of unresolved leptonic emission from
pulsar wind nebulae and hadronic emission from
supernova-injected
cosmic-ray (CR)
protons. We investigate uncertainties in the radial distribution of the infrared component of the interstellar radiation field (ISRF), using profiles with enhanced
photon densities in the inner
Galaxy. We quantify their effects on $\gamma\gamma$ attenuation of the diffuse $\gamma$-ray emission. The alternative ISRF models affect the LHAASO diffuse fit only modestly, as the analysis excludes the
Galactic center direction and applies source masks in the
Galactic plane. Using the hadronic normalization inferred from the LHAASO fit for various ISRF models, the associated $pp$
neutrino emission remains consistent with the IceCube all-sky measurement, while the flux from the
Galactic Ridge region remains compatible with current ANTARES and KM3NeT constraints. Since the modified infrared profiles differ most strongly toward the inner
Galaxy, we also examine their impact on inverse-Compton emission from point sources near the central molecular zone. These same models can noticeably modify the hadronic and inverse-Compton $\gamma$-ray emission above $\sim\!10$ TeV from sources in the central region. Future KM3NeT observations, combined with $\gamma$-ray measurements of individual sources, can probe the inner-
Galaxy CR population and constrain the radial distribution of the ISRF near the
Galactic Center.
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Applied Physics
High performance construction materials fracture and high cycle fatigue assessment based on accelerated PF-CZM
Jiaqi Li, Zhihua Xiong, Xuyao Liu et al. (+1 more)
Given the widespread application of high-performance materials in cyclic loaded infrastructure, a thorough understanding of the fracture and high-cycle fatigue behavior of high-performance materials is of critical importance. However, these behaviors predominantly rely on experimental methods, which are often costly, time-consuming and limited in generalizability. To address these issues, this paper proposes the constitution and high-cycle fatigue of Ultra-High Performance Concrete (UHPC) and High Strength Steel (HSS) within the Phase-Field Cohesive Zone Model (PF-CZM) framework. A generic stress-based failure criterion for UHPC is derived from the biaxial tensile test results to calculate crack driving force. Furthermore, a fatigue degradation function and an acceleration
algorithm are integrated into the PF-CZM framework to enable efficient high-cycle fatigue simulations. In the acceleration
algorithm, the envelope load is used to approximate the real cyclic load to avoid the simulation of each cycle, and the three-stage fatigue process is simulated through adjusting the cyclic increment adaptively. The proposed model successfully captures mixed-mode fracture and high-cycle fatigue behavior of UHPC and HSS, with validation provided through relevant experimental comparisons.
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All authors Jiaqi Li, Zhihua Xiong, Xuyao Liu, Hongyu Liu