Data Analysis and Statistics · Cross-listed from cs.NI
Link-adaptive digital twin for robust physical-layer modeling in hybrid-amplified ultra-wideband optical networks
Xiaoxuan Gao, Rentao Gu, Yingchun Wang et al. (+3 more)
Accurate physical-layer modeling is increasingly essential for reliable ultra-wideband operation and capacity optimization, especially under the intensified inter-channel stimulated Raman scattering (ISRS) effect. This paper proposes the link-adaptive digital twin (LA-DT) for hybrid-amplified ultra-wideband links to overcome the generalization and speed limitations of existing methods, achieving accurate modeling and robust generalized signal-to-noise ratio (GSNR) estimation across diverse links. First, to address EDFA heterogeneity, the GSNR modeling task is decomposed into three key power predictions: ASE, NLI, and signal powers before EDFA entry. Second, to enhance cross-scenario generalization, three dedicated DT models are developed using a novel neural architecture with linear modulation layers (LMLs). Third, for rapid adaptation to unseen scenarios with limited data, three domain discriminators guide few-shot fine-tuning of the LMLs. Fourth, the LA-DT explicitly accounts for Raman amplifier (RA) insertion loss, improving practical deployment reliability. Results across 35 scenarios show that LA-DT reduces RMSE for NLI, ASE, and signal power predictions to 0.151, 0.111, and 0.113 dBm with improvements of 56.0%, 58.4%, and 52.7% over the baseline,and achieves an average GSNR estimation RMSE of 0.114 dBm (55.8% improvement). For 12 unseen scenarios, the LA-DT maintains high accuracy through few-shot fine-tuning with only 20 samples per scenario, achieving an average GSNR RMSE of 0.159 dB and demonstrating strong adaptability and robustness.
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All authors Xiaoxuan Gao, Rentao Gu, Yingchun Wang, Xinyi Liu, Junshi Gao, Yuefeng Ji
Mathematical Physics · Cross-listed from math.PR
Limiting Law of Local Fields for the Mean Field Ghatak-Sherrington Model
Yunhui Chen and Keaton Fierro
We study the limiting law of local field in the mean field Ghatak-Sherrington model with
spin values $\{0,\pm1,\ldots,\pm S\}$ in the high-temperature regime. Using the cavity method and the quantitative overlap and self-overlap estimates of Sheng-Wu~\cite{SW24}, we prove a central limit
theorem for the non-centered cavity field. As a result, we then identify the local field limiting law as a random finite mixture of Gaussian distributions. The proof is based on moment method and gives a quantitative error bound.
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Optics
730-nm optical parametric conversion from near- to short-wave infrared band
J. M. Chavez Boggio, J. R. Windmiller, M. Knutzen et al. (+6 more)
A record 730 nm parametric conversion in silica fiber from the near-infrared to the short-wave infrared band is reported and analyzed. A parametric gain in excess of 30 dB was measured for a signal at 1300 nm (with corresponding idler at 2030 nm). This conversion was performed in a travelling single-pass one-pump parametric architecture and high efficiency is achieved by a combination of high peak power and a nonlinear fiber with a reduced fourth-order dispersion coefficient.
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All authors J. M. Chavez Boggio, J. R. Windmiller, M. Knutzen, R. Jiang, C. Bres, N. Alic, B. Stossel, K. Rottwitt, S. Radic
High Energy Astrophysical Phenomena
Electromagnetic responses driven by gravitational-wave memory in magnetar-flare outflows
Wen-Biao Han
An asymmetric relativistic
outflow from a magnetar
giant flare produces a step-like gravitational-wave (GW)
memory. In the magnetized pair
plasma surrounding the
star, such GW
memory drives transverse electromagnetic (EM) X-mode/fast-magnetosonic responses at the corresponding frequencies. We use this GW-
memory spectrum to drive a global wave equation for a cold electron–positron pair
plasma. With radiative boundary conditions excluding incoming waves, the driven response forms an outgoing EM mode that reaches the outer boundary of the source region. For central-engine energy-release timescales of $10$, $1$, and $0.15\,\mu\mathrm{s}$, 90% of the integrated response energy lies below 23.3 kHz, 233 kHz, and 1.51 MHz, respectively. The principal response occupies the 10 kHz–1 MHz frequency band; a substantial extension into the 1–3 MHz frequency band also appears when a submicrosecond asymmetric-energy component is present. The electromagnetic response can escape from the source region and potentially propagate in the interstellar medium.
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Optics
Toward a Thermodynamic Framework for Dissipative Solitons: From Photonics to Turbulence and Bose–Einstein Condensate Analogies
Vladimir L. Kalashnikov and Irina T. Sorokina
# Abstract Thermodynamic concepts are increasingly used in nonlinear photonics to describe Rayleigh–Jeans thermalization, optical wave
turbulence, condensation, negative-temperature states, and statistical mode locking. This raises a broader question: how far can thermodynamic
reasoning be extended to localized structures maintained far from
equilibrium by a balance of gain, loss, dispersion, and nonlinearity? We address this question using strongly chirped dissipative
solitons (DSs) of the complex cubic–quintic Ginzburg–Landau equation (CQGLE) as a model system. Their internal energy flows and separation of correlation scales connect coherent solitary waves with semi-incoherent wave kinetics, driven open systems, and Bose–Einstein-condensation analogies. We review thermodynamic-like descriptions based on spectral
entropy, internal energy, effective temperature, and condensation-like spectral restructuring, relating them to dissipative-
soliton resonance (DSR),
stochastic mode-locking self-start, and redistribution between single- and multipulse attractors. Normal and anomalous group-delay dispersion (NGD and AGD) provide complementary realizations: in NGD, DSR is accompanied by spectral localization, scale separation, and increasing accessibility of multipulse states; in AGD, the spectrum has extended wings and dynamical robustness occupies only part of the existence domain. These results distinguish general features of nonequilibrium state selection from effects tied to a particular localization mechanism. We argue that thermodynamic-like observables are best viewed as coarse-grained structural diagnostics rather than
equilibrium state variables, while DSs provide a photonic platform linking nonequilibrium thermodynamics, wave
turbulence, driven condensates, and statistical phase-transition concepts.
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Chemical Physics
Benchmark measurements of absolute frequencies and collisional line-shape parameters in the CO-Ar system using comb-based FTS
Akiko Nishiyama, Grzegorz Kowzan, Dominik Charczun et al. (+2 more)
We report absolute frequency measurements of the CO fundamental band, together with high-precision Ar-induced collisional line-shape parameters using comb-based
Fourier-transform spectroscopy. High-quality spectra were obtained with a stable mid-IR optical frequency comb source and careful suppression of technical noise. By applying analysis methods that fully exploit the advantages of optical frequency comb spectroscopy, precise frequency calibration and robust multi-line fitting were achieved, resulting line-center fitting errors below 0.00001 cm$^{-1}$ for most transitions. The measured transition frequencies agree with HITRAN within 0.0001 cm$^{-1}$, supporting the reliability of the semi-empirical database. Multi-line fits using a speed-dependent Voigt profile yield collisional parameters for approximately 40 P- and R-branch lines, providing a reliable experimental
benchmark for CO-Ar line-shape modeling.
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All authors Akiko Nishiyama, Grzegorz Kowzan, Dominik Charczun, Roman Ciuryło, Piotr Masłowski
Fluid Dynamics
Low-dimensional structure and online tracking of POD subspaces on the Grassmann manifold: application to flow around an airfoil
Shintaro Sato, Yoshitsugu Naka, Rei Sasaki et al. (+2 more)
Representing flow states over a wide range of flow parameters and control inputs in a low-dimensional state space is a central challenge in fluid mechanics. Rather than representing the instantaneous flow field in a fixed subspace spanned by the leading proper orthogonal decomposition (POD) modes, this study regards the POD subspace itself as the flow state at each flow condition. The set of POD subspaces associated with flow conditions defines a state space on the Grassmann
manifold.
Diffusion maps identify the intrinsic low-dimensional structure of the family of POD subspaces, while Grassmannian rank-one update subspace estimation tracks the temporal
evolution of a POD subspace online. The framework is experimentally demonstrated for flow around an airfoil. POD subspaces are extracted from wall-pressure fluctuations measured by a microphone array over a range of angles of attack and under different control inputs. The subspaces are found to lie on a one-dimensional submanifold of the Grassmann
manifold. Moreover, the transition from separated to attached flow, induced by a
plasma actuator, follows a reproducible trajectory along the same submanifold identified from statistically stationary flow data. The temporal
evolution of the subspace is consistent with the transient
evolution of the flow field observed using particle image velocimetry. These results show that POD subspaces can serve as representative flow states, enabling their temporal
evolution across a wide range of flow conditions to be tracked online in a low-dimensional space based on wall-pressure fluctuations. This low-dimensional representation provides a basis for real-time flow-state estimation and feedback control.
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All authors Shintaro Sato, Yoshitsugu Naka, Rei Sasaki, Rion Handa, Naofumi Ohnishi
High Energy Physics (Phenomenology)
Event-by-event analysis of chiral charge separation in $p^{\uparrow}+$Au collisions within an improved AMPT model
Chen Gao, Gui-Zhen Wu, Yi Xu et al. (+1 more)
We study the charge separation induced by
chiral magnetic effect (CME) in $p^{\uparrow}$+Au collisions at $\sqrt{s_{NN}}=200$ GeV event-by-event with an improved string-melting AMPT model. In this model, an impact-parameter-dependent formation-time delay is introduced to reduce the peak Bjorken energy density from $\sim$2 to $\sim$0.3 GeV/fm$^3$ and reproduces the illiptic flow $v_2(p_T)$ measured by PHENIX in $p+$Au simultaneously. The event-by-event CME source, whose
quark momentum-exchange fraction scales with $|\mathbf{B}|_{\mathrm{event}}/|\mathbf{B}|_{\mathrm{max}}$ and is capped at the 7% value from Au+Au, transmits the field geometry directly to the observable. We find that the initial correlator shows a clear scheme hierarchy tracking $B^2$. The parton cascade preserves $\sim$80–90% of the signal, while coalescence and ART hadronic rescattering dissipate the bulk, leaving $\sim$10–30% in the final state. The $\gamma_{OS}/\gamma_{SS}$ splitting remains visible. These results support the use of the inter-scheme difference $\Delta\gamma_{\mathrm{IV}}-\Delta\gamma_{\mathrm{II}}$ as an essentially background-free CME observable as we proposed in previous work.
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All authors Chen Gao, Gui-Zhen Wu, Yi Xu, Wei-Tian Deng
General Relativity and Quantum Cosmology
The generalized second law as a thermodynamic selection criterion for dynamical dark energy
Marcos H. Cruz, Miguel Cruz, Joel Saavedra et al. (+1 more)
The growing number of generalized horizon
entropy proposals has led to a wide variety of modified cosmological models, yet there is currently no general physical principle capable of discriminating among them. We show at the level of an homogeneous background that the generalized second law (GSL) of thermodynamics provides such a criterion. Considering a general modified Friedmann framework described by an arbitrary function $f(H)$ of the Hubble parameter, and allowing the apparent horizon and the
cosmic fluid to evolve out of thermal
equilibrium, we derive model-independent constraints on the asymptotic scaling of the horizon
entropy, $S_A\propto A^k$. We find that phantom
evolution requires $k\ge(3\omega-1)/(2\omega)$, with $\omega$ the total fluid equation of state, whereas quintessence imposes the complementary upper bound. Additionally, in the exact thermal
equilibrium limit, the dynamical coupling strictly enforces $k \le 2$, recovering the non-
equilibrium quintessence bound. The two bounds converge to the unique value $k=2$ as the phantom divide is approached, indicating that a smooth crossing of the phantom divide is thermodynamically associated with a quadratic
entropy-area scaling, where the effective theory degenerates into a logarithmic
gravity framework. Applying this criterion to representative generalized
entropy models shows that many commonly used proposals are constrained by the generalized second law, whereas multiparameter constructions are naturally compatible with the required asymptotic behavior. Finally, we demonstrate that the same thermodynamic selection principle extends to derivative-dependent cosmologies described by $f(H,\dot H)$, highlighting its robustness beyond
entropy functionals that depend only on the horizon area.
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All authors Marcos H. Cruz, Miguel Cruz, Joel Saavedra, Emmanuel N. Saridakis
Quantum Physics
Simultaneous Heisenberg-Limited Multiparameter Metrology via Indefinite Evolution
Hang Xu, Tailong Xiao, Ze Zheng et al. (+4 more)
Quantum metrology achieves Heisenberg-limited precision in single-parameter estimation, but its multiparameter extension is fundamentally constrained by both parameter-encoding and measurement incompatibility. Noncommuting signal generators may cause incompatible parameter-encoding, preventing the
quantum Fisher information
matrix from simultaneously achieving the Heisenberg scale for all parameters. Due to incompatible optimal measurements, the classical Fisher information
matrix represents the practical attainable precision. Here, we introduce a multiparameter metrology framework based on indefinite
evolution (IE), in which different control operations and signal reversal are placed in a coherent superposition. For a single-
qubit probe with mutually orthogonal signal generators, IE enables compatible parameter encoding and optimal measurement without the signal reversal. For parallel generators, where only signal reversal realized by its generator is available, IE can achieve the same performance. We further extend this mechanism to noisy, many-body, and high-dimensional probes, and establish general conditions for achieving the simultaneous Heisenberg-limit. In contrast, definite
evolution cannot achieve the same performance under compatible optimal measurements, even when signal reversal is available. Our results identify IE as an operational resource for overcoming multiparameter incompatibility and open a route toward attainable Heisenberg-limited sensing in interferometric platforms.
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All authors Hang Xu, Tailong Xiao, Ze Zheng, Xiaoyang Deng, Jinfeng Zheng, Jingzheng Huang, Guihua Zeng
Mesoscale and Nanoscale Physics
Dynamics of amorphous membranes in the two-dimensional limit
Liga Jasulaneca, Alberto Martín-Pérez, Hongji Zhang et al. (+7 more)
Atomically thin mechanical resonators have been realized predominantly in crystalline two-dimensional (2D) materials, such as
graphene, where long-range crystalline order sets their elastic properties and defines their nonlinear resonant behavior. Extending these concepts to the amorphous 2D limit has remained largely unexplored. Here, we demonstrate that monolayer amorphous carbon (MAC) forms suspended membranes that support optothermal actuation and sensitive interferometric readout across both linear and nonlinear regimes of its resonant motion. We resolve thermomechanical motion, driven resonances, and multimode spectra in MAC nanodrums. The frequencies of fundamental vibration modes correspond to unusually low pretensions, placing monolayer MAC nanodrums in a regime where
geometric nonlinearities, stress heterogeneity, and mode coupling emerge at comparatively low drive powers. Consistently, we observe pronounced nonlinear dynamics, including hardening, softening, and mixed Duffing responses, nonlinear damping, parametrically excited modes, and signatures of intermodal coupling. These results establish MAC as a robust nanoelectromechanical platform and open an experimental route to disorder-governed nanomechanics in the 2D amorphous limit.
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All authors Liga Jasulaneca, Alberto Martín-Pérez, Hongji Zhang, Prertahn Munireternam, Natalia A. Mamchik, Chee-Tat Toh, Artem K. Grebenko, Barbaros Özyilmaz, Makars Šiškins, Farbod Alijani
Materials Science · Cross-listed from cs.AI
Predicting Space Groups of Double Perovskites by LLM with Dynamic Few-Shot Learning
Jongwon Park, Inhyo Lee, Junhyeong Lee et al. (+1 more)
Double perovskites (DPs) offer broad compositional tunability, but predicting the space groups (SGs) of stable structures remains difficult because available
datasets are often strongly imbalanced toward dominant SG classes. We refer to dominant SG classes as major SGs and underrepresented classes as minor SGs. We introduce Dynamic and Diversity-enhanced Few-shot
Retrieval and Rule-Guided Inference for Space-Group Prediction (DyRIS), an LLM-
agent-based framework that predicts ranked SG candidates from a given DP composition. DyRIS uses diversity-enhanced dynamic few-shot prompting to retrieve relevant in-context examples while limiting the dominance of frequently represented SGs. It further incorporates rule-guided inference based on B/B' cation ordering, quantitative indicators, and major-SG bias control to refine and rank the final Top-3 SG candidates. We evaluate DyRIS on 3,528 thermodynamically filtered DP entries and compare it with composition-based and descriptor-based baselines. At a training-data ratio of 0.5, DyRIS achieves competitive overall accuracy while obtaining the best Overall Top-1 macro-F1 score and the best performance across all Minor-SG metrics. DyRIS improves Minor-SG Top-1 accuracy by 3.26 percentage points relative to CrabNet and achieves higher Minor-SG Top-3 accuracy than the strongest PyCaret-based baseline. Ablation studies show that diversity-enhanced
retrieval, quantitative indicators, major-SG bias control, and B/B' ordering information each contribute to prediction performance. Additional experiments show that the final rule-guided inference step is not easily replaced by conventional classifier- or ranker-based models. These findings demonstrate the potential of combining
retrieval-based LLM
reasoning with crystallographic domain knowledge for SG prediction in imbalanced materials
datasets.
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All authors Jongwon Park, Inhyo Lee, Junhyeong Lee, Seunghwa Ryu
General Relativity and Quantum Cosmology
Quantum-Corrected Entropy Bounds on Black Hole Merger Efficiency
Jiswin Varghese
We examine the
entropy balance of black hole mergers in the presence of
quantum gravity corrections described by the Generalized Uncertainty Principle (GUP). Focusing on the coalescence of two non-spinning Schwarzschild black holes with unequal masses, we analyze the thermodynamic
evolution from the initial binary system to the final merger remnant, explicitly accounting for energy loss through gravitational-wave emission. Using a logarithmically corrected
entropy motivated by a quadratic GUP, we derive a generalized
entropy change as a function of the gravitational-wave efficiency and the mass ratio of the merging components. The classical area
theorem is recovered in the appropriate limit, while the GUP correction introduces a
quantum-modified
entropy bound that constrains the maximum allowed gravitational-wave energy emission. This bound is most restrictive for nearly equal-mass mergers, indicating an enhanced sensitivity of symmetric systems to
quantum gravity effects.
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General Relativity and Quantum Cosmology
Probing scalarized wormholes through quasi-periodic oscillations and spinning particle dynamics
Asalkhon Alimova, Akbar Davlataliev, Farruh Atamurotov et al. (+3 more)
We investigate the dynamics of test particles in a three-parameter scalarized wormhole spacetime within Einstein-scalar field theory. For spinless particles, we derive the orbital and epicyclic frequencies and compute twin-peak QPO spectra using the ER3 and ER4 resonance models. The scalar coupling parameter $g_s$ shifts the innermost stable circular orbit to larger radii and systematically modifies the characteristic 3:2 resonance condition. Extending to spinning particles via the Mathisson-Papapetrou-Dixon formalism, we find that
spin-
curvature coupling significantly alters the effective potential and innermost stable circular orbit parameters. The maximum physically admissible
spin increases monotonically with the scalar coupling. Analysis of particle collisions near the wormhole throat reveals that both scalar coupling and relative
spin orientation determine collision energetics, with anti-aligned
spin configurations producing substantially higher energies. Our results suggest that the combined effects of scalar coupling and
spin-
curvature interaction leave distinct imprints on QPO frequencies and collision processes, potentially providing observable signatures for distinguishing scalarized wormholes from standard black holes.
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All authors Asalkhon Alimova, Akbar Davlataliev, Farruh Atamurotov, Ahmadjon Abdujabbarov, Phongpichit Channuie, Chengxun Yuan
Materials Science
Machine-learning approach for the phase stability and mechanical properties of disordered alloys at finite temperature
Rutchapon Hunkao, Urvesh Patil and Stefano Sanvito
The prediction of stable
alloys forming solid-state solutions across large portions of the composition space is a serious theoretical challenge, since one has to evaluate the Gibbs free energy, including both configurational and vibrational contributions. This requires an energy theory capable of extremely high throughput. By taking the Ni-Pd system as prototype, we construct an efficient Jacobi-Legendre machine-learning potential based on density-functional-theory data, which provides accurate energies and forces across the entire composition space. Based on a cluster expansion up to three-body terms and only 873 trainable parameters, this allows us to compute the partition function by directly integrating all accessible microstates, differing for composition, atomic configuration and thermal agitation. We confirm that Ni and Pd are fully miscible, forming an $fcc$ solid-state solution. This is only metastable at room temperature, while becomes thermodynamically stable at around 600~K, with the stability achieved first at the Pd-rich end of the composition range. Interestingly,
entropy and heat capacity analysis reveal a competition between the solid-state solution and two intermetallic phases with long-period L1$_0$ structure for NiPd and NiPd$_3$. All in all, our approach offers a powerful and high-throughput workflow for the study of disordered
alloys, an approach that can be extended to multi-component systems such as high-
entropy alloys.
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Lattice Field Theory
Approximating Grassmann valued path integrals with radial basis function neural networks
Gábor Balassa
Solving path integrals in
quantum field theories often involves the numerical handling of noncommuting Grassmann fields, which is in many cases a highly nontrivial and numerically inefficient task, especially in large systems and at higher dimensions. In this paper a radial basis function type neural network construction is used to approximate fermionic path integrals that include local couplings in their hopping terms. By isolating the interaction terms from the purely fermionic components using a radial basis function expansion, the path integral can be approximated by a few percent accuracy even for very large
lattice sizes. The method has been developed and tested using staggered
fermions in one, and in two dimensions, through calculating the partition functions, and expectation values.
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Lattice Field Theory
Vacuum polarization in QED with an electromagnetic background from the lattice
En-Hung Chao
We propose a framework to determine the
vacuum polarization functions in QED in the presence of an electromagnetic background field in the spacelike region on the
lattice. This method consists in reweighting
lattice Monte Carlo data generated without the background with the
fermion determinant ratio evaluated in the continuous spacetime using worldline formalism. This proposal can be further extended to other applications in
lattice gauge theory, such as QCD in finite chemical potential.
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High Energy Astrophysical Phenomena
Two new highly scattered fast radio bursts: evidence for scatter broadening by the circumsource medium
Joscha N. Jahns-Schindler, Keith W. Bannister, Adam T. Deller et al. (+17 more)
We found two highly scattered Fast
Radio Bursts (FRBs) during commissioning of the Commensal Realtime ASKAP Fast Transient COherent (CRACO) backend. FRB 240210D and FRB 240312D have scattering times of $34\pm6$ and $300\pm48$ ms, respectively, when scaled to 1 GHz. FRB 240312D originates near a spiral arm of a face-on
galaxy at a
redshift of only 0.05. Scintillation from a Milky Way screen constrains the distance of the scattering screen to $\sim 10$ pc from the source. FRB 240312D is therefore the first highly scattered FRB where scattering screens in the host
galaxy centre, a background
galaxy, or intervening structures can all be excluded, leaving only the circumsource medium. Integral field spectroscopy of the host reveals a Milky Way-like
galaxy with a
star-formation region at the FRB position. We find refractive scattering in a
pulsar wind nebula as the most likely scattering origin. However, the explanation is not completely satisfactory as it requires a fine-tuned orientation. Hence, additional theoretical studies under different FRB progenitor models are needed. From the two FRBs, we calculate a total rate of $R_\mathrm{tot}=210^{+460}_{-180}\,\mathrm{events}\,\mathrm{sky}^{-1}\mathrm{day}^{-1}$ with durations between 55.2 ms and 1 s and above a fluence of 9 Jy ms consistent with the rate of shorter FRBs. This elevated rate suggests that the strong scattering seen in other FRBs likewise does not arise from chance-aligned sightlines, but is instead causally linked to the FRB sources.
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All authors Joscha N. Jahns-Schindler, Keith W. Bannister, Adam T. Deller, Xinping Deng, Marcin Glowacki, Alexa C. Gordon, Vivek Gupta, Akhil Jaini, Clancy W. James, Ilya S. Khrykin, Yu Wing Joshua Lee, J. Xavier Prochaska, Hao Qiu, Hugh Roxburgh, Stuart D. Ryder, Ryan M. Shannon, Tim Sprenger, Nicolas Tejos, Yuanming Wang, Ziteng Wang
High Energy Astrophysical Phenomena
JWST Spectroscopy of Type Ia Supernova 2025rbs from Maximum Light to the Nebular Phase
Lindsey A. Kwok, Stéphane Blondin, Adam A. Miller et al. (+53 more)
We present JWST observations of the Type Ia
supernova (SN Ia) 2025rbs ($D=$14.5 Mpc) at +1, +23, and +84 days after B-band maximum, spanning peak light through a wavelength-dependent transition toward the nebular phase. Combined with ground-based optical and near-infrared (NIR) data, our panchromatic spectra (0.4-14 $\mu$m) include the first maximum-light mid-infrared (MIR) spectrum and the earliest MIR spectroscopic sequence of an SN Ia to date. At peak light, the MIR spectrum exhibits a continuum with permitted and forbidden features, including Si II, Ni II, and early-emerging [Ni III-IV] and [Ar II-III]. By +23 days the MIR is dominated by forbidden lines with a weak continuum, and by +84 days it is fully nebular, whereas the optical/NIR spectra remain transitional. The nebular spectrum reveals strongly stratified ejecta, with stable Ni concentrated at the lowest velocities, radioactive Co at intermediate velocities but absent within ~2000 km s$^{-1}$, and Ar occupying an outer shell. We detect small-scale substructure in [Ca IV] 3.21 $\mu$m with fractional amplitudes of a few percent and a characteristic velocity scale of ~800 km s$^{-1}$, which may reflect compositional structure, ionization variations, or both. Radiative-transfer calculations substantially underpredict these MIR Mg II features despite approximately reproducing the NIR Mg II 1.0927 $\mu$m line, suggesting that the relative strengths of these transitions are sensitive to the treatment of Mg ionization and excitation. These observations demonstrate that MIR spectroscopy beginning near maximum light simultaneously probes the emerging inner ejecta and rapidly fading outer burning products, providing new constraints for explosion and radiative-transfer models.
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All authors Lindsey A. Kwok, Stéphane Blondin, Adam A. Miller, Saurabh W. Jha, Willem B. Hoogendam, Cameron M. Pfeffer, Eyouel Z. Abate, Jennifer E. Andrews, Moira Andrews, Chris Ashall, Katie Auchettl, K. Azalee Bostroem, Thomas G. Brink, Fionntan P. Callan, Collin T. Christy, Joseph R. Farah, Alexei V. Filippenko, Andreas Flörs, Ryan J. Foley, Eli Gendreau-Distler, Or Graur, Jason T. Hinkle, D. Andrew Howell, David O. Jones, Rinon Kageyama, Miho Kawabata, Cristine Koelln, Conor Larison, Chang Liu, Keiichi Maeda, Kate Maguire, Curtis McCully, Kyle Medler, Nicolas E. Meza-Retamal, Ann Mina, Rüdiger Pakmor, Riley Patlak, Jeniveve Pearson, Aravind P. Ravi, Nabeel Rehemtulla, Armin Rest, David J. Sand, Huei Sears, Benjamin J. Shappee, Manisha Shrestha, Mridweeka Singh, Tamás Szalai, Kenta Taguchi, Tea Temim, Jacco H. Terwel, Stefano Valenti, József Vinkó, J. Craig Wheeler, Kathryn Wynn, Yi Yang, WeiKang Zheng
Materials Science
Universal Density Control of Surface Reconstruction in Two-Dimensional Metals
Jinyuan Yang and Xiaoliang Zhong
We identify a unified thickness criterion for surface reconstruction in ultrathin metal sheets. The critical thickness is governed by the change in surface atomic density upon reconstruction: thinning always favors structural changes that increase this density. Thus, thinning suppresses the (1x2) reconstruction of 5d noble metal (110) sheets but promotes the quasi-hexagonal reconstruction of 4d noble metal (001) sheets. Density functional calculations validate these trends and show only minor corrections from surface stress and
quantum-oscillation effects.
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Medical Physics · Cross-listed from cs.CV
Lesion-Aware Adaptive Fourier Neural Operator for CT-to-PSMA PET Synthesis in Prostate Cancer
Rashmi Bhaskara, Waleed M. Almutairi, Matthew Gopaulchan et al. (+5 more)
Deep learning models that synthesize PET from CT or MRI can reduce patient dose and scanner demand, but are typically optimized with global losses such as L1 or mean squared error (MSE) that treat all voxels similarly. In whole-body PSMA-PET, tumor voxels occupy only a small fraction of the volume, yet carry the clinically relevant activity signal; as a result, models can achieve high structural similarity index measure (SSIM) and peak signal-to-noise ratio (PSNR) while still underestimating lesion activity or failing to preserve tumor-specific structure. Radiomics provides biologically meaningful descriptors of tumor intensity and texture, but direct radiomics conditioning is time-consuming because it requires feature extraction from delineated lesion regions. We propose LAFNO, a Lesion-Aware Adaptive
Fourier Neural Operator for CT-to-PSMA-PET synthesis that replaces high-dimensional radiomics conditioning with two efficient CT-derived proxy channels. Motivated by radiomics analysis of PSMA-avid tumor core and peritumoral regions, LAFNO uses a contrast proxy for local density variation and a disorder proxy for local texture heterogeneity, both injected into the model bottleneck. LAFNO combines whole-volume reconstruction with lesion-level total lesion activity (TLA), tumor-core contrast, and peritumoral supervision. We evaluated LAFNO against four baseline architectures on the TCIA PSMA-PET-CT-Lesions
dataset. LAFNO remained competitive on whole-volume image quality, achieving SSIM of 0.960 and 0.938 for 18F- and 68Ga-PSMA, respectively, while reducing per-patient TLA error to 48.3% and 64.0% for 18F- and 68Ga-PSMA, respectively, and achieving the highest tumor-core radiomics reproducibility across all feature classes for both tracers. Peritumoral reproducibility remained tracer-dependent, indicating that biological fidelity in synthetic PSMA-PET remains challenging.
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All authors Rashmi Bhaskara, Waleed M. Almutairi, Matthew Gopaulchan, Maram Musaad Alqurashi, Francis Asamoah, Alex Ocana, Clinton D. Bahler, Oluwaseyi M. Oderinde
Superconductivity
Quadrupolar phase transition in superconducting lanthanum hydride
Abhishek Raghav, Kousuke Nakano, Marco Cherubini et al. (+2 more)
Lanthanum hydride (LaH$_{10}$) has been widely studied for its high superconducting critical temperature of 250 K at about 170 GPa pressure. Although the structural ${R\bar{3}m}$-to-${Fm\bar{3}m}$ transition under pressure connected to the emergence of the superconducting phase in this material is broadly understood, the detailed characterization of its nature and its order parameter are still missing. By applying the cluster multipole moment analysis to the hydrogen sublattice, we reveal that this transition is triggered by a quadrupolar $T_{2g}$ order parameter, and we provide evidence for its weak first-order nature. By performing path integral molecular dynamics coupled to a message-passing atomic cluster expansion (MACE) neural network potential, trained on Perdew-Burke-Ernzerhof (PBE) density functional theory configurations, we show that the collapse of the order parameter at the transition is simultaneously associated with the discontinuous softening of the optical $T_{2g}$
phonons. Their
symmetry lets them carry a non-negligible electron-
phonon coupling in LaH$_{10}$, while the weak first-order nature of the transition makes them soft. The presence of structural instabilities with low-frequency quadrupolar distortions can be a key ingredient to enhance superconductivity in superhydrides and provides guidance for the discovery of new high-$T_c$
superconductors in hydrogen-rich compounds.
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All authors Abhishek Raghav, Kousuke Nakano, Marco Cherubini, Ryotaro Arita, Michele Casula
Optics
Causality Sum Rules in Conventional Scattering Matrices
Ning Han, Rui Zhao, Shuxing Yang et al. (+3 more)
Scattering
matrices are the standard experimental and computational description of photonic and electromagnetic devices. Passivity is explicit in the conventional incoming-outgoing
matrix, whereas causality sum rules are usually formulated only after transforming the response into auxiliary variables. Here we show that these rules can be written directly in the conventional scattering
matrix by removing the time advance introduced by the reference domain. Using the earliest-arrival delay of each channel, we define a domain-delayed
matrix that preserves real-frequency passivity while restoring the causal time origin. Under explicit analyticity, transparency, and regularity assumptions, this
matrix becomes a Schur function, enabling a Cayley-Herglotz construction. The resulting projected and determinant bounds constrain coherent channel superpositions and aggregate multichannel loss. The framework recovers Rozanov's absorber limit and spherical-multipole sum rules, while extending causality bounds to measurable quantities including insertion loss, suppressed singular-value channels, and conditional lossless delay-bandwidth trade-offs. Our work directly connects fundamental causality theory with experimentally accessible scattering data. The initial theoretical route is autonomously explored by Qiushi Engine, an AI research system for open-ended scientific discovery, and subsequently verified, refined, and developed by the authors, demonstrating a hybrid AI-human discovery workflow.
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All authors Ning Han, Rui Zhao, Shuxing Yang, Mingzhu Li, Hongsheng Chen, Yihao Yang
Accelerator Physics
Realizing A Hard X-Ray Storage Ring Free Electron Laser Oscillator at the APS-U
Emmanuel Aneke, Kent Wootton, Ryan Lindberg et al. (+1 more)
We show that the APS-U could support a hard X-ray storage ring free electron
laser oscillator, providing a promising avenue toward high repetition rate, narrow bandwidth coherent light sources. The results of our numerical simulations demonstrate that a transverse gradient undulator yields ~8% and ~6% single-pass gain at 8.05 keV and 10 keV respectively. We further identify a configuration at 5 keV that does not require a TGU but still exceeds a 5% gain threshold despite the relatively short 5-meter long insertion device. All cases presented retain spectral purity on the order of meV and reach a steady-state output whose
equilibrium is consistent with the Renieri Saturation Limit. We have calculated the 5 keV case to have an average brightness of ~10^26
photons/(s * mm2 * mrad2 * 0.1% BW), representing an increase in more than four orders of magnitude from the standard APS-U undulator. These results indicate that a storage ring free electron
laser oscillator at multi-keV
photon energies is feasible with nominal APS-U parameters and standard x-ray cavity optics.
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All authors Emmanuel Aneke, Kent Wootton, Ryan Lindberg, Chris Jacobsen
Earth and Planetary Astrophysics
PDS 70 c and SR 12 c: Observational Constraints on Giant-Planet and Satellite Formation
Ignacio Mosqueira
PDS~70~c and SR~12~c are the only bound planetary-mass objects with secure cold submillimeter disk detections. Together, these systems constrain
giant-
planet growth and satellite formation. The PDS~70
planets exhibit remarkable parallels to the Jupiter–Saturn pair in our
Solar System. Both PDS~70
planets accrete within one shared gap, which links their final masses, the material reaching each Hill sphere, and the properties of the circumplanetary disk. Planetary torques deplete the finite interplanetary reservoir, causing circumplanetary supply to decline as the protoplanets open a circumstellar gap. SR~12~c separates the planetary-growth and satellite-formation timescales: gas and solids survive even though its current mass-growth timescale is $(1.9\pm0.6)\times10^9$~yr. For PDS~70~c, the 855-$\mu$m flux implies $0.007$–$0.031\,\Mearth$ of
dust at 26~K in the optically thin limit. A fully
dust-dominated, uniform 22–26-K optically thick emitter has an equivalent coplanar radius of $0.58$–$0.66$~au, while a fiducial radial temperature profile yields an equivalent radius of approximately 0.46~au. The continuum constraints overlap the 0.5–1.5~au circularization range estimated by ballistic calculations of late-stage gap-fed inflow. We find that the PDS~70 constraints are consistent with our \SEMM{} satellite-formation model (Mosqueira & Estrada 2003a,b, submitted in 2001). Thus the observations provide strong support for a quiescent, solids-enhanced satellite-forming environment, coupled in the early stages to planetary-gap
evolution.
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Atmospheric and Oceanic Physics
Observational Evidence Revises Presumed Large Ozone Worsening from Nitrogen Oxides Cuts
Xiang Weng, Xiao Lu, Jiawei Li et al. (+8 more)
Many air quality models indicate that rapid reductions in nitrogen
oxides (NOx), without comparable controls on volatile organic compounds, have worsened summertime ozone pollution in urban China, producing a short-term strong ozone penalty. Other models, however, simulate the opposite response, suggesting that cutting down NOx has already helped mitigate ozone pollution. This contradiction obscures understanding of atmospheric chemistry and weakens guidance on control policy design. Here, we reconcile this disagreement and reveal the underestimated benefits of NOx emission reductions using a machine learning framework integrated with an observational constraint. We first constrain ozone responses under a 30% NOx reduction, comparable to the magnitude of NOx emission declines across major Chinese city clusters between 2015 and 2023. The constrained results indicate that ozone decreases prevail across urban China, with only small increases mainly in July 2015. This challenges the widespread ozone worsening that many models predict. We then extend the constraint across 10-60% NOx reductions, establishing its use for rapid ozone sensitivity diagnosis without exhaustive scenario modeling. This diagnosis shows that sustained NOx control increasingly favored ozone mitigation during 2015-2023, benefiting a growing share of China's population. These results underscore that continued NOx reductions can deliver larger ozone mitigation benefits than many models suggest.
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All authors Xiang Weng, Xiao Lu, Jiawei Li, Grant Forster, Jessica Chapman, Beckie George, Yunbo Lu, Guowen He, Haofan Wang, Jingcheng Lai, Peer Nowack
High Energy Astrophysical Phenomena
An Optically Motivated Gamma-ray Study of Fermi-LAT Novae
Owen K. Henry, Timothy A.D. Paglione, David Zurek et al. (+1 more)
High-energy (GeV) gamma-ray emission from nova eruptions was a surprise detection by the
Fermi-LAT in 2010. Since then, it has been suggested that the gamma-rays from these systems are generated in collisionless non-relativistic shocks. In this theory, the observed correlation between optical and gamma-ray nova lightcurves naturally arises if a portion of the optical luminosity is reprocessed shock power. In this work, we investigate this scenario by analyzing
Fermi-LAT-detected novae in varied time bins and then correlating the bin size that maximizes the nova's significance (tgam) with the nova's optical eruption data. Furthermore, we investigate whether there is a common optical decay across the sources' measured tgam values in the population. We find that across our population, a nova's $t_3$ (the time it takes the nova V band brightness to decay 3 magnitudes) appears to be the favored analysis bin that optimizes the
Fermi-LAT detection significance, although there is significant spread. Additionally, we report V679 Car, a source previously noted as a marginally detected gamma-ray nova, as a $>5 \sigma$ detection in this work. We perform cross-correlation analysis of gamma-ray and optical lightcurves.
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All authors Owen K. Henry, Timothy A.D. Paglione, David Zurek, Joshua Tan
Quantum Physics
A Single Atom in Front of a Mirror is a Universal Reservoir Computer
Peter J. Ehlers, Phi Hung Nguyen, Kanu Sinha et al. (+4 more)
Universal approximation in reservoir computing is typically associated with a class of reservoirs. We show that universality can be associated with a single reservoir, considering a minimal setup of a single atom in front of a mirror. In its linear-transducer limit, our reservoir is a universal approximator of fading-
memory maps under an operating class of checkable conditions, with a rate constant measured at the operating point. A given reservoir can reach arbitrary accuracy by changing measurement settings. The proof gives an explicit recipe: for a target accuracy, it specifies the required physical resources and resonator modes. Enlarging the number of accessible modes increases the matchable kernel span without reducing capability. Beyond the linear limit, the atom's saturation replaces high-order
polynomial readouts, and the device operates on real-world tasks alongside classical baselines. Our results highlight an example of universality with a minimal
quantum setup.
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All authors Peter J. Ehlers, Phi Hung Nguyen, Kanu Sinha, Noelle Daigle, Travis W. Sawyer, Hendra I. Nurdin, Daniel Soh
Quantum Physics
Private Correlations Certify Sensing Capability
Yunkai Wang, Peixue Wu, Graeme Smith et al. (+1 more)
We show that private correlations in a bipartite
quantum state constitute a metrological resource for distributed sensing assisted by a possibly noisy channel from one party to the other. We begin with an example with distillable secret key but poor locally accessible sensing performance and show that an assisting channel substantially improves its performance. We then show that any shared state yielding positive private information can serve as a sensing resource after appropriate local coherent processing, and derive a quantitative lower bound on the locally accessible sensing capability after assistance. We further show that classical correlations alone provide no analogous guarantee. Finally, in a channel formulation, we show that a channel with positive private information allows nonzero locally accessible sensitivity when paired with a suitable assisting channel.
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All authors Yunkai Wang, Peixue Wu, Graeme Smith, Sisi Zhou
Mesoscale and Nanoscale Physics
Moving Analogue Horizons in Stationary Ferroelectrics
David Galvez-Poblete, Rubén M. Otxoa, Alvaro S. Nunez et al. (+1 more)
We show that a traveling modulation of the polarization-gradient stiffness in a ferroelectric material induces an effective flow in its collective polarization dynamics. Within a controlled local approximation, small polarization fluctuations, or ferrons, obey a massive Klein-Gordon equation with flow. Unlike conventional analogue-
gravity platforms, the effective flow originates from the modulation of the material parameters rather than from the physical transport of the medium. This mechanism enables mobile analogue horizons separating sub-ferronic and super-ferronic regions, the latter supporting negative-norm antiferron modes. Their coupling to positive-norm ferrons gives rise to superradiant-like amplification, while the effective mass gap can be tuned independently through an external electric field. Ferroelectric systems therefore provide a novel and experimentally controllable platform for analogue
gravity with massive scalar excitations.
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All authors David Galvez-Poblete, Rubén M. Otxoa, Alvaro S. Nunez, Sebastian Allende