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Physics

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Wednesday 15 July

Quantum Physics

Security Evaluation of Laser-Phase-Noise Quantum Random Number Generators with Intrinsic Correlations

Y. Gao, J.H Li, J.L. Liu et al. (+8 more)

Quantum random number generators are essential for achieving information-theoretical security in modern cryptographic systems. Among various implementations, laser phase noise schemes are widely favored for their simple architecture and high integration potential. However, the intrinsic correlations in the raw data are often neglected, which violates the independent and identically distributed assumption and potentially compromises system security. In this work, we establish an analytical model of correlation and formulate an analytical expression for the conditional min-entropy in the presence of intrinsic correlations to accurately quantify the genuinely extractable randomness. The validity of our theoretical model is confirmed by numerical simulations and experimental results, exhibiting excellent agreement. Under typical setups it is shown that neglecting intrinsic correlations leads to an overestimation of extractable randomness by approximately 46%. This work provides a valuable theoretical framework for designing compact, high-performance quantum random number generators with rigorous security analysis.
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All authors Y. Gao, J.H Li, J.L. Liu, M. Wu, L.J. Liu, H. Wang, Y. Pan, W. Huang, Y. Li, J. Yang, B.J. Xu

Quantum Physics

Basis-Independent Coherence Dynamics of Tripartite States under Pure Dephasing

Sovik Roy and Abhijit Mandal

Quantum coherence is a fundamental quantum resource whose preservation under environmental interactions is essential for quantum information processing. While most studies have focused on basis-dependent coherence measures, the dynamics of intrinsic coherence quantified by basis-independent measures remain largely unexplored. In this work, we investigate the dynamics of basis-independent quantum coherence for several representative tripartite pure and mixed states subjected to local and common dephasing environments in both Markovian and non-Markovian regimes. We show that Markovian local dephasing leads to state-dependent coherence degradation, whereas collective dephasing significantly enhances coherence preservation through decoherence-free sectors. More importantly, non-Markovian environments give rise to nearly frozen coherence dynamics for both pure and mixed states, demonstrating the remarkable robustness of intrinsic coherence against dephasing environment. A comparison with the measure of relative entropy of coherence reveals that basis-independent coherence measure exhibits substantially greater resilience and qualitatively different dynamical behaviour than its basis-dependent counterpart. These results provide new insights into the preservation of intrinsic multipartite coherence in open quantum systems and highlight basis-independent coherence as a robust quantum resource for realistic noisy quantum technologies.
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Space Physics

Influence of Magnetospheric Plasma Environment on Surface Charging of the Lunar South Pole

Yaqi Xiao, Xiaoman Wang and Ronghui Quan

The lunar south pole is a key candidate region for future lunar exploration and base construction, but its charging characteristics under real topographic conditions and dynamic plasma environments remain insufficiently understood. A high-fidelity terrain model of the lunar south pole spanning 86{\deg}S-90{\deg}S was constructed from optimized LRO/LOLA elevation data. Surface charging evolution over half a lunar orbital cycle was then simulated with a finite element-BP neural network scheme, using lunar-phase-dependent plasma inputs encompassing plasma parameters of solar wind and diverse Earth magnetospheric zones. The results show that south polar topography strongly regulates surface charging. Higher potentials appear on windward terrains, whereas lower potentials occur in shielded leeward regions, leading to enhanced local electric fields at the tops of uplands and crater floor-wall boundaries. Significant potential differences between the crests and the middle of the downstream walls of various craters indicate that these regions are highly terrain-sensitive. When the Moon passes through Earth's magnetosphere, surface potential and electric field are roughly symmetric around 0{\deg} lunar phase. From the solar wind to the plasma sheet, surface potential generally decreases while electric field magnitude rises. Only in the narrow magnetotail lobe adjacent to the plasma sheet does the potential temporarily increase and the electric field weaken. In the plasma sheet, the surface potential can decrease to approximately -1000 V, and the domain's peak electric field reaches about 5 V/m. These findings provide references for landing site selection, rover path planning, and electrostatic protection of lunar surface equipment.
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Computational Physics

$\lambda$PIC: A callback-centric particle-in-cell framework

Xuesong Geng, Yunwei Cui, Lingang Zhang et al. (+1 more)

We present $\lambda$PIC, a Python-based electromagnetic particle-in-cell framework built around a callback-centric architecture. Existing PIC codes typically tie high performance to static, pre-compiled timestep loops, hindering implementation of custom physics, diagnostics, or output logic. $\lambda$PIC breaks this coupling by exposing every stage of the loop as a named stage (hook), permitting attaching arbitrary Python functions that operate on the full simulation state, enabling custom algorithms and in-situ analysis without modifying the core algorithms. Under this flexible framework, performance-critical kernels are written in C extensions and Numba, fields and particles are stored in NumPy arrays, and MPI parallelism is paired with graph partitioning to support dynamic load balancing and non-rectangular domains. Although $\lambda$PIC is designed as general-purpose, it has special focus on intense laser-plasma interactions. Future work will extend the framework to GPU acceleration and additional physics modules including implicit solvers and nuclear physics.
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All authors Xuesong Geng, Yunwei Cui, Lingang Zhang, Liangliang Ji

Fluid Dynamics

Turbulent boundary layers altered by passively rotating discs

Max W. Knoop and Pierre Ricco

Turbulent boundary layers characterised by friction Reynolds numbers in the range $Re_{\tau} = 880 - 1460$ and flowing over flush-mounted passively rotating discs are investigated in a wind tunnel with the purpose of reducing the skin-friction drag. The test surface is composed of thirty-two rotating discs arranged in a staggered configuration and supported by bearings mounted in cylindrical cavities. As the discs are half covered by thin rigid plates, a steady rotation of the discs is sustained via the asymmetric distribution of the wall-shear stress exerted by the wall turbulence on the exposed halves of the discs. Direct force measurements reveal that the drag increases with respect to a flat-plate case because of the flow interaction with the disc housings and the covering plates. The effect of the disc motion is isolated and a 3% drag reduction is measured with respect to the flow over stationary discs. The skin-friction identity by \cite{Elnahhas_Johnson_2022} (J. Fluid Mech., vol. 940, 2022), extended herein to include the disc-flow effects, is utilised for the first time to analyse experimental data. This direct slip effect, quantified by using the measured disc angular velocities in the Elnahhas-Johnson identity, is negligible. Measurements obtained by particle image velocimetry disclose that a roughness mean-flow effect occurs between adjacent discs because of the clearance gaps around the discs and that a downwash secondary flow exists near the covering plates, analogous to flows over streamwise-elongated rectangular roughness elements. This downwash velocity is streamwise modulated because of the spanwise disc motion and alters the wall-normal transport term in the Elnahhas-Johnson identity, thus reducing the drag locally.
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General Relativity and Quantum Cosmology

Testing the Transverse Scalar Mode of Gravitational Quantum Field Theory with Taiji and LISA

Cong Xu, Yong Tang and Yue-Liang Wu

Space-based gravitational-wave (GW) detectors, including LISA and Taiji, offer unprecedented access to regimes where alternative theories of gravity may deviate from General Relativity (GR). Gravitational Quantum Field Theory (GQFT) provides a novel framework in which the Poincaré-type inhomogeneous spin symmetry of Weyl-type fermions in the Standard Model is elevated to a gauge symmetry. Within this construction, the fundamental gravitational field is identified with a gravigauge field which behaves as a Goldstone-type bi-covariant vector field. Unlike GR, GQFT predicts additional polarization states: one transverse scalar (breathing) mode and two vector modes. In this work, we focus on the transverse, isotropic scalar mode and investigate its detectability with Taiji. To isolate this mode, we employ the null-response channel (NRC), a specific interferometric combination designed to suppress contributions from other polarizations. We implement an analytical, dynamic orbital model to realistically simulate a triangular constellation. We compute the response functions and sensitivity curves for various interferometric channels, compare them with the standard Michelson channel, and demonstrate the effectiveness of the NRC approach. Our results show that the NRC provides a reliable, waveform-independent criterion for testing non-GR polarizations, and we anticipate that it will serve as a valuable tool for probing gravitational theories in future space-based GW missions.
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Nuclear Theory

Lorentz-Covariant Spectral Bounds from Thermal Quantum Field Theory: Retarded Green's Functions, Kubo Relations, and Holographic Constraints

Alisher Sanetullaev, Sarbinaz Bazarbaeva, Marhabo Beymamatova et al. (+1 more)

We extend the recently established framework of Lorentz-covariant relaxation bounds from linearized classical kinetic and rheological theories to the full quantum setting of thermal quantum field theory (QFT). Working directly with retarded two-point functions at finite temperature and density, we show that the analyticity and positivity properties of spectral functions – combined with Lorentz covariance and the Kubo–Martin–Schwinger (KMS) condition – impose rigorous frame-dependent constraints on the location of singularities in the complex frequency plane. Specifically, we prove that the non-hydrodynamic quasinormal spectrum in any boosted frame is confined to a strip whose width is determined solely by the rest-frame spectral weight at zero spatial momentum and the maximal group velocity of the theory. We derive covariant sum rules for the spectral density under Lorentz boosts and establish that the convergence radius of the hydrodynamic gradient expansion transforms in a manner dictated by the same rest-frame data. In holographic theories dual to Einstein gravity in asymptotically anti-de Sitter spacetime, we verify the bounds by an explicit quasinormal-mode computation: the leading boosted pole moves deeper into the complex plane – the observed relaxation rate increases with boost velocity, in sharp contrast to naive time dilation – while respecting the bound throughout; we further derive corrections from higher-derivative gravitational terms. Our results provide a first-principles, non-perturbative derivation of Lorentz-covariant spectral constraints applicable to the quark-gluon plasma, superfluid phases of neutron star matter, and strongly correlated electrons near quantum critical points.
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All authors Alisher Sanetullaev, Sarbinaz Bazarbaeva, Marhabo Beymamatova, Shokir Tursunov

Quantum Physics

Quantum memory advantage for quantum process tomography

Carlos Bravo-Prieto, Weiyuan Gong and Antonio Anna Mele

Quantum process tomography, the task of learning an unknown quantum channel from black-box access, is a central problem in quantum information. In this setting, protocols with quantum memory can coherently store and jointly process quantum information obtained from multiple channel uses, whereas protocols without quantum memory must measure after each use and retain only a classical transcript of the measurement outcomes. A fundamental open question is whether quantum memory provides a query-complexity advantage even when protocols without quantum memory may adapt their experiments based on all previous outcomes with unbounded classical computational power. In this work, we show that it does. We determine the optimal query complexity of quantum process tomography without quantum memory up to a constant factor to be $\Theta(d_{\mathrm{in}}^3 d_{\mathrm{out}}^3/\varepsilon^2)$, where $d_{\mathrm{in}}$ and $d_{\mathrm{out}}$ are the channel input and output dimensions, respectively, and $\varepsilon$ is the target diamond-norm accuracy. More precisely, we prove that any incoherent protocol for this task, including adaptive protocols, requires $\Omega(d_{\mathrm{in}}^3 d_{\mathrm{out}}^3/\varepsilon^2)$ queries, even when each channel use may be assisted by arbitrary fresh ancilla, and we present a non-adaptive, ancilla-free incoherent protocol achieving the matching upper bound $O(d_{\mathrm{in}}^3 d_{\mathrm{out}}^3/\varepsilon^2)$. Our results thereby generalize the optimal sample-complexity bounds for single-copy state tomography, recovered as the special case $d_{\mathrm{in}}=1$. By contrast, coherent protocols with quantum memory achieve query complexity $\Theta(d_{\mathrm{in}}^2 d_{\mathrm{out}}^2/\varepsilon^2)$. Hence, our results establish a rigorous learning separation between quantum process tomography with and without quantum memory.
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Materials Science

Physics-Informed Residual Deep Learning for Constitutive Modeling of Hot Deformation and Dynamic Recrystallization in a Mo-Rich $\alpha+\beta$ Titanium Alloy

Prashil S. Joshi, Diksha Mahadule and Rajesh K.Khatirkar

Accurate constitutive modeling of hot deformation behavior is essential for designing thermomechanical processes in advanced structural alloys. Conventional Arrhenius-type and empirical models do not adequately capture the combined effects of strain hardening, dynamic recovery (DRV), and dynamic recrystallization (DRX) across broad processing conditions. In this study, two Stacked Residual Physics-Informed Neural Networks (STAR-PINNs) were developed to simulate the hot deformation response of a Mo-rich $\alpha+\beta$ titanium alloy (Ti-6Al-4Mo-1V-0.1Si). The Enhanced STAR-PINN incorporated thermomechanical constitutive constraints, while the DRX-Aware STAR-PINN employed a dual-output architecture to account for recrystallization kinetics. Both models used a shared residual encoder trained on experimental flow stress data collected at temperatures from 800 to 1050 degrees C and strain rates between 0.01 and 10 per second. Physics-informed constraints, including thermal softening, strain-rate sensitivity, strain hardening, and post-peak softening, were enforced through automatic differentiation. The DRX-Aware model further integrated JMAK-Avrami regularization, DRX saturation constraints, and Arrhenius-based consistency with tunable parameters, directly linking the predicted DRX fraction to stress output via latent-feature fusion. The DRX-Aware STAR-PINN achieved RMSE = 11.62 MPa, MAE = 4.73 MPa, R^2 = 0.9852, and a cross-validated RMSE of 12.74 +/- 0.38 MPa. The learned JMAK parameters converged to k = 2.03 and n = 1.99, remaining close to the conventional values while being inferred directly from the data. The model effectively mirrored flow curves influenced by temperature, DRX development, and Zener Hollomon correlations under interpolation scenarios while preserving physically coherent constitutive behavior.
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Quantum Physics · Cross-listed from cs.LG

PQFA: Parallel Quantum Feature Augmentation of Fused Representations for Multimodal Classification

Mingzhu Wang and Yun Shang

Most multimodal learning methods improve how heterogeneous representations are aligned and fused, while post-fusion enhancement remains less explored. We propose Parallel Quantum Feature Augmentation (PQFA), a hybrid quantum-classical framework that applies multiple shallow variational quantum circuits to fused multimodal features. Text and image representations extracted by frozen RoBERTa and ViT encoders are processed through bidirectional cross-attention, attentive pooling, and adaptive gated fusion. The fused feature is then amplitude-encoded into parallel quantum circuits, whose measurement readouts are concatenated with the classical representation for prediction. We evaluate PQFA on MM-IMDb and N24News through controlled comparisons using the same encoders, fusion backbone, data splits, projection dimension, and augmentation output width. PQFA consistently outperforms both the fusion backbone without quantum augmentation and a width-matched MLP augmentation baseline, while using approximately 2.2K augmentation parameters compared with 24.0K for the MLP branch. Missing-modality experiments further show improved robustness when textual or visual inputs are incomplete, with particularly clear gains when the more informative textual modality is severely degraded. Controlled ablations and feature-space analyses indicate that the improvement cannot be reproduced by random feature mappings, increased classical width, or untrained quantum transformations. Quantum-state diagnostics additionally show stable predictive performance across the tested simulated noise levels and distinct branch-specific transformations of the encoded states. These results establish PQFA as an effective and parameter-efficient strategy for post-fusion augmentation in hybrid quantum-classical multimodal learning.
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Quantum Physics

Security evaluation of quantum distance-bounding protocols via semidefinite programming

Kevin Bogner, Aysajan Abidin, Dave Singelee et al. (+1 more)

Quantum distance-bounding (QDB) protocols let a verifier check that a prover is both genuine and physically nearby. During a timed fast phase of quantum communication, the verifier measures round-trip times to obtain an upper bound on the prover's distance. For a uniform comparison, we isolate the fast phase and study one-round distance-fraud (DF) and mafia-fraud (MF) games. For discrete-variable QDB, we show that these games reduce to convex optimization problems and can therefore be solved exactly with semidefinite programming; each MF value comes with an explicit attack achieving it and a matching certificate that no attack does better. This contrasts with quantum position verification, where an attack is split between two separated parties, so its optimization is nonconvex and analyses rely on relaxations. In our MF game, the cooperating pair collapses to a single sequential strategy, which keeps the game convex and its exact value computable. Across the discrete-variable protocols we examine, the best one-round DF attack succeeds with the same probability ($1/2$) for every protocol, whereas MF clearly separates the protocols. For continuous-variable QDB, we report estimated attack success probabilities from a calibrated Gaussian attack model. The benchmark covers protocols whose fast phase itself authenticates the prover; designs that follow Brands and Chaum and instead bind the fast phase with a final authenticated message, like the earliest QDB proposal, fall outside it and are treated separately. Of the four protocols studied, two had no previously known one-round attack values, and we report the first ones; for the other two, we find MF attacks with higher success probability than previously reported. Overall, one-round MF resistance depends on whether an attacker can use information revealed early by the prover to answer a fresh challenge from the verifier.
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All authors Kevin Bogner, Aysajan Abidin, Dave Singelee, Bart Preneel

Quantum Physics

Deterministic single-electron trapping on solid neon using engineered dielectric surface geometry

Kundan Surse, Eric Helgemo, Andrew Palmer et al. (+5 more)

Levitating electron qubit on the surface of solid neon has recently emerged as a promising and intrinsically noise-resilient platform for quantum information processing. Their ultra-clean, inert environment suppresses conventional decoherence pathways associated with lattice disorder, charge traps, and nuclear-spin baths that limit coherence in semiconductor qubits. Yet, uncontrolled surface features such as bumps, valleys, and electrode-defined gaps can bind electrons unintentionally, contributing charge noise and inducing spin-orbit coupling mediated decoherence. To address this challenge, we propose an engineered interface in which a dielectric layer is deposited beneath the solid neon to provide an atomically smooth template, eliminating surface-roughness induced trapping. By selectively etching this dielectric layer at desired qubit locations, deterministic potential minima can be engineered to reliably capture electrons while suppressing unwanted surface bound states. We perform large-scale Schrodinger and Poisson simulation to compare the existing and proposed strategies of electron trapping on neon, obtaining good agreement with recent experimental measurements.
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All authors Kundan Surse, Eric Helgemo, Andrew Palmer, Md Serajum Monir, Lukas Delventhal, Thanh Nguyen, Maja Cassidy, Rajib Rahman

Optics

Photonic Ising machines toward and beyond a million spins

A. Aadhi, Nayem Al-Kayed, Tristan Austin et al. (+8 more)

Combinatorial optimization problems are central to many challenges in logistics, finance, engineering, and the life sciences, yet they remain among the most computationally demanding. Many of these problems can be mapped onto the Ising model, in which binary spins interact through a network of couplings, and solutions correspond to low-energy, ideally ground-state, spin configurations. Photonic Ising machines have the potential to be fast and energy-efficient heuristic solvers of optimization problems by leveraging the low latency, high bandwidth, and inherent parallelism of optics. However, current photonic implementations remain limited in scalability, connectivity, reconfigurability, and time-to-solution, preventing their use in many practical applications. In this perspective, we examine the current landscape of photonic Ising machines, discuss the challenges and limitations of existing platforms, and identify the scientific and technological advances needed to realize large-scale systems. These developments could establish photonic Ising machines as useful hardware platforms for practical optimization.
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All authors A. Aadhi, Nayem Al-Kayed, Tristan Austin, Charles St-Arnault, Nir Rotenberg, Hitesh Ballani, David V. Plant, Edwin Ng, Yoshihisa Yamamoto, Peter L. McMahon, Bhavin J. Shastri

Physics and Society

Impacts of social and impact heterogeneity on social-climate outcomes

Amrita Punnavajhala, Brian Beckage, Madhur Anand et al. (+3 more)

Regional heterogeneity in social characteristics, temperature change, and vulnerability to climate impacts is likely to influence the magnitude of anthropogenic climate change, but has not been considered in coupled social-climate models, which seek to represent interactions between social and climate dynamics. Here, we examine how the projected mean global temperature anomaly and population support for mitigation respond to heterogeneity in these factors across five regions of the world, using a coupled social-climate model. We find that heterogeneity in climate impacts increases the temperature anomaly by 0.2$^\circ$C, while social heterogeneity increases it by an additional 0.1$^\circ$C. The projected temperature anomaly also increases with higher variability in climate impacts across regions, even for the same average global climate impact. Finally, we identify a social-climate tipping point, where low vulnerability to impacts under existing social conditions in one region can tip the system into an alternative slow-mitigation, high-temperature state. Our results show that heterogeneity in climate impacts leads to higher global mean temperatures and efforts to reduce global disparities could improve both social and climate outcomes.
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All authors Amrita Punnavajhala, Brian Beckage, Madhur Anand, Daniele Visioni, Jared Farley, Chris T. Bauch

Nuclear Theory

Further exploration of the machine-learning-based nuclear mass table

Liu Yaqi, Li Zhilong, Wang Yongjia et al. (+1 more)

The mass of the atomic nucleus, as one of the fundamental physical quantities of the atomic nucleus, plays an important role in understanding and researching the structure of the atomic nucleus and nuclear reactions, and the basic interactions between nucleons. However, accurately predicting the mass of nuclei far from the {\beta} stability line remains a huge challenge. Based on the machine-learning-refined mass model, we investigate the newly measured atomic nucleus masses since 2022, along with the residual proton-neutron interaction ({\delta}Vpn) and the {\alpha}-decay energy of heavy nucleus. It is found that: 1) For the 23 newly measured atomic nuclei, the root mean square deviations obtained by the machine-learning-refined mass models are between 0.51 and 0.58 MeV, which are significantly lower than 3.275, 1.058, 0.752, and 0.785 MeV given by the liquid droplet model (LDM), Weizsäcker-Skyrme-4 (WS4), finite-range droplet model (FRDM), and Duflo-Zucker (DZ), respectively. 2) The {\delta}Vpn of the atomic nucleus with N = Z obtained from machine-learning-refined mass models is consistent with the latest experimental data. 3) The root mean square deviations of the {\alpha}-decay energy of heavy nuclei obtained from the machine-learning-refined mass models have also been significantly reduced. Furthermore, by employing the Bayesian model average approach to combine the results from different machine-learning-refined mass models, we obtain more accurate predictions. These findings demonstrate that such models have good extrapolation capabilities and provide useful insight for further research. The datasets presented in this paper are openly available at https://doi.org/10.57760/sciencedb.j00213.00246.
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All authors Liu Yaqi, Li Zhilong, Wang Yongjia, Li Qingfeng Ma Chunwang

Strongly Correlated Electrons

Hubbard-assisted stability of Hatsugai-Kohmoto correlations in a one-dimensional open chain

Yan-Xiao Wang and Yin Zhong

The Hatsugai-Kohmoto (HK) model has recently been identified as a fixed-point description of Mottness that is stable against perturbing local interactions. This raises a natural question beyond the weak-perturbation regime: how does a finite local repulsion modify HK physics in real-space observables and local spectra? We address this question in a half-filled one-dimensional spinful fermion chain, where the HK interaction is supplemented by an onsite Hubbard repulsion. Using exact diagonalization in an open chain, we compute ground-state correlation functions and site-resolved local spectra. We find that the Hubbard term does not drive the system away from the HK-dominated regime. Instead, at moderate $U_{\rm HK}$, a finite $U_{\rm Hub}$ promotes the emergence of behavior characteristic of the pure HK chain at larger $U_{\rm HK}$. This Hubbard-assisted strong-HK response is reflected consistently in the development of positive spin correlations, the suppression of single-particle coherence, the impurity-induced redistribution of local spectral weight, and the evolution of pairing correlations. As a control perturbation, we replace the onsite Hubbard interaction by a nearest-neighbor (NN) density interaction. In contrast to the Hubbard case, the HK and NN interactions display competing tendencies and do not reproduce the same strong-HK behavior. These results provide a nonperturbative real-space complement to the fixed-point stability of HK physics and show that the effect of an additional repulsive interaction depends sensitively on its spatial structure.
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High Energy Physics (Experiment)

A Low-energy Threshold and Multi-messenger Trigger System for the JUNO Experiment

Thomas Adam, Fengpeng An, Costas Andreopoulos et al. (+565 more)

The Jiangmen Underground Neutrino Observatory (JUNO) is a 20-kiloton liquid scintillator neutrino detector, located 650 meters (1800 m.w.e.) underground in Jiangmen, Guangdong, China. JUNO is primarily designed for reactor neutrino measurements and has been taking data since 2025. With the largest mass of its kind and an excellent energy resolution, JUNO is a leading observatory for high-precision measurements of MeV neutrinos. The standard global trigger system serves as the primary trigger for JUNO. We present a newly developed multi-messenger trigger system that extends the capabilities of the global trigger by providing a lower energy threshold and an independent monitoring capability. During the 2025 operation, it achieved an effective energy threshold of approximately 110 +/- 10 keV, providing a lower threshold configuration suitable for low-energy event analysis. The system shows the potential to further reduce the threshold to well below 100 keV. Based on the multi-messenger trigger system, an astrophysical monitor has been developed to receive and process external alerts from other messengers, such as gravitational-wave observations. A Transient Neutrino Burst Monitor is integrated to detect short-time-scale neutrino burst events and enables real-time monitoring of transient astrophysical phenomena. The system is sensitive to neutrino bursts from core-collapse supernovae within a distance of about 250 kpc.
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All authors Thomas Adam, Fengpeng An, Costas Andreopoulos, Giuseppe Andronico, Nikolay Anfimov, Vito Antonelli, Tatiana Antoshkina, João Pedro Athayde Marcondes de André, Didier Auguste, Nikita Balashov, Andrea Barresi, Davide Basilico, Eric Baussan, Marco Beretta, Antonio Bergnoli, Nikita Bessonov, Daniel Bick, Lukas Bieger, Svetlana Biktemerova, Thilo Birkenfeld, Simon Blyth, Manuel Boehles, Anastasia Bolshakova, Mathieu Bongrand, Matteo Borghesi, Dominique Breton, Augusto Brigatti, Riccardo Brugnera, Riccardo Bruno, Antonio Budano, Jose Busto, Marcel Büchner, Anatael Cabrera, Barbara Caccianiga, Hao Cai, Xiao Cai, Yi-zhou Cai, Stéphane Callier, Antonio Cammi, Guofu Cao, Jun Cao, Yaoqi Cao, Rossella Caruso, Cédric Cerna, Vanessa Cerrone, Jinfan Chang, Yun Chang, Tim Charisse, Chao Chen, Haotian Chen, Jiahui Chen, Jian Chen, Jing Chen, Junyou Chen, Pingping Chen, Shaomin Chen, Shiqiang Chen, Yixue Chen, Yu Chen, Ze Chen, Zhangming Chen, Zhiyuan Chen, Zhongchang Chen, Jie Cheng, Yaping Cheng, Yu Chin Cheng, Alexander Chepurnov, Alexey Chetverikov, Davide Chiesa, Ziliang Chu, Artem Chukanov, Gérard Claverie, Catia Clementi, Barbara Clerbaux, Claudio Coletta, Marta Colomer Molla, Selma Conforti Di Lorenzo, Chenyang Cui, Lorenzo Vincenzo D'Auria, Christophe De La Taille, Luis Delgadillo Franco, Ziyan Deng, Xiaoyu Ding, Xuefeng Ding, Yayun Ding, Sergey Dmitrievsky, Dmitry Dolzhikov, Chuanshi Dong, Haojie Dong, Jianmeng Dong, Marcos Dracos, Frédéric Druillole, Ran Du, Katherine Dugas, Stefano Dusini, Hongyue Duyang, Jessica Eck, Andrea Fabbri, Ulrike Fahrendholz, Gaofeng Fan, Lei Fan, Liangqianjin Fan, Jian Fang, Wenxing Fang, Dmitry Fedoseev, Qichun Feng, Shaoting Feng, Giovanni Ferrante, Daniela Fetzer, Marcellin Fotzé, Amélie Fournier, Aaron Freegard, Ying Fu, Feng Gao, Alberto Garfagnini, Arsenii Gavrikov, Diwash Ghimire, Marco Giammarchi, Nunzio Giudice, Maxim Gonchar, Guanda Gong, Guanghua Gong, Yuri Gornushkin, Marco Grassi, Maxim Gromov, Vasily Gromov, Minhao Gu, Xiaofei Gu, Yu Gu, Mengyun Guan, Yuduo Guan, Nunzio Guardone, Rosa Maria Guizzetti, Cong Guo, Wanlei Guo, Caren Hagner, Hechong Han, Yang Han, Chuanhui Hao, Miao He, Wei He, Xinhai He, Ziou He, Patrick Hellmuth, Yuekun Heng, YuenKeung Hor, Shaojing Hou, Fatima Houria, Yee Hsiung, Bei-Zhen Hu, Jun Hu, Tao Hu, Guihong Huang, Jinhao Huang, Junlin Huang, Junting Huang, Kaixuan Huang, Lian-Chen Huang, Shengheng Huang, Tao Huang, Xin Huang, Xingtao Huang, Yongbo Huang, Jiaqi Hui, Cédric Huss, Ammad Ul Islam, Adrienne Jacobi, Arshak Jafar, Xiangpan Ji, Xiaolu Ji, Junji Jia, Cailian Jiang, Chengbo Jiang, Guangzheng Jiang, Junjie Jiang, Xiaoshan Jiang, Xiaozhao Jiang, Yijian Jiang, Yixuan Jiang, Xiaoping Jing, Cécile Jollet, Liam Jones, Amina Khatun, Khanchai Khosonthongkee, Denis Korablev, Alexey Krasnoperov, Sindhujha Kumaran, Chun-Hao Kuo, Nikolay Kutovskiy, Loïc Labit, Tobias Lachenmaier, Haojing Lai, Cecilia Landini, Lorenzo Lastrucci, Sébastien Leblanc, Matthieu Lecocq, Ruiting Lei, Rupert Leitner, Petr Lenskii, Demin Li, Fei Li, Gaosong Li, Jiajun Li, Meiou Li, Min Li, Nan Li, Ruhui Li, Rui Li, Shanfeng Li, Shuo Li, Teng Li, Weidong Li, Xiaonan Li, Yichen Li, Yifan Li, Yingke Li, Yufeng Li, Zhaohan Li, Zhibing Li, An-An Liang, Jiajun Liao, Minghua Liao, Yilin Liao, Ayut Limphirat, Bo-Chun Lin, Guey-Lin Lin, Shengxin Lin, Tao Lin, Xingyi Lin, Jiajie Ling, Xin Ling, Ivano Lippi, Caimei Liu, Fang Liu, Haidong Liu, Hongbang Liu, Hongjuan Liu, Jianglai Liu, Jiaxi Liu, Jinchang Liu, Kainan Liu, Min Liu, Qian Liu, Shenghui Liu, Shulin Liu, Ximing Liu, Xuewei Liu, Yankai Liu, Yiqi Liu, Zhipeng Liu, Zhuo Liu, Lorenzo Loi, Paolo Lombardi, Kai Loo, Haoqi Lu, Junguang Lu, Meishu Lu, Shuxiang Lu, Xianguo Lu, Bayarto Lubsandorzhiev, Sultim Lubsandorzhiev, Livia Ludhova, Arslan Lukanov, Fengjiao Luo, Guang Luo, Jianyi Luo, Shu Luo, Wuming Luo, Xiaojie Luo, Bangzheng Ma, Bing Ma, Qiumei Ma, Si Ma, Wing Yan Ma, Xiaoyan Ma, Xubo Ma, Jihane Maalmi, Jingyu Mai, Marco Malabarba, Yury Malyshkin, Roberto Carlos Mandujano, Fabio Mantovani, Stefano M. Mari, Agnese Martini, Johann Martyn, Matthias Mayer, Yue Meng, Anselmo Meregaglia, Lino Miramonti, Michele Montuschi, Cristobal Morales Reveco, Iwan Morton-Blake, Xiangyi Mu, Lakshmi Murgod, Massimiliano Nastasi, Dmitry V. Naumov, Elena Naumova, Igor Nemchenok, Elisabeth Neuerburg, Feipeng Ning, Zhe Ning, Yujie Niu, Lothar Oberauer, Juan Pedro Ochoa-Ricoux, Alexander Olshevskiy, Domizia Orestano, Fausto Ortica, Rainer Othegraven, Yifei Pan, Alessandro Paoloni, George Parker, Yatian Pei, Luca Pelicci, Anguo Peng, Yu Peng, Zhaoyuan Peng, Elisa Percalli, Willy Perrin, Frédéric Perrot, Fabrizio Petrucci, Oliver Pilarczyk, Pascal Poussot, Ezio Previtali, Fazhi Qi, Ming Qi, Sen Qian, Xiaohui Qian, Zhonghua Qin, Shoukang Qiu, Zhenning Qu, Gioacchino Ranucci, Thomas Raymond, Alessandra Re, Abdel Rebii, Bin Ren, Yuhan Ren, Barbara Ricci, Mariam Rifai, Mathieu Roche, Narongkiat Rodphai, Aldo Romani, Bedřich Roskovec, Félix Rosso, Peter Rudakov, Arseniy Rybnikov, Andrey Sadovsky, Ujwal Santhosh, Utane Sawangwit, Michaela Schever, Cédric Schwab, Konstantin Schweizer, Alexandr Selyunin, Andrea Serafini, Mariangela Settimo, Junyu Shao, Anurag Sharma, Vladislav Sharov, Hangyu Shi, Hexi Shi, Jingyan Shi, Yuan Shi, Dmitrii Shpotya, Yike Shu, Yuhan Shu, She Shuai, Vitaly Shutov, Randhir Singh, Apeksha Singhal, Chiara Sirignano, Jaruchit Siripak, Monica Sisti, Mikhail Smirnov, Oleg Smirnov, Sergey Sokolov, Julanan Songwadhana, Albert Sotnikov, Achim Stahl, Luca Stanco, Elia Stanescu Farilla, Hans Steiger, Jochen Steinmann, Tobias Sterr, Matthias Raphael Stock, Virginia Strati, Mikhail Strizh, Jun Su, Guangbao Sun, Mingxia Sun, Xilei Sun, Yongzhao Sun, Zhengyang Sun, Narumon Suwonjandee, Fedor Šimkovic, Akira Takenaka, Xiaohan Tan, Haozhong Tang, Jian Tang, Jingzhe Tang, Quan Tang, Xiao Tang, Vidhya Thara Hariharan, Yuxin Tian, Igor Tkachev, Tomas Tmej, Marco Danilo Claudio Torri, Andrea Triossi, Wladyslaw Trzaska, Andrei Tsaregorodtsev, Yu-Chen Tung, Cristina Tuve, Carlo Venettacci, Giuseppe Verde, Benoit Viaud, Vit Vorobel, Lucia Votano, Jiawei Wan, Caishen Wang, Chung-Hsiang Wang, En Wang, Hanwen Wang, Jiabin Wang, Jun Wang, Ke Wang, Meng Wang, Meng Wang, Mingyuan Wang, Ruiguang Wang, Sibo Wang, Tianhong Wang, Wei Wang, Wenshuai Wang, Wenyuan Wang, Xi Wang, Yangfu Wang, Yaoguang Wang, Yi Wang, Yifang Wang, Yuyi Wang, Zhe Wang, Zheng Wang, Zhimin Wang, Apimook Watcharangkool, Junya Wei, Jushang Wei, Wei Wei, Wei Wei, Yuehuan Wei, Zhengbao Wei, Liangjian Wen, Jun Weng, Rosmarie Wirth, Bi Wu, Chengxin Wu, Qun Wu, Wenjie Wu, Yinhui Wu, Zhaoxiang Wu, Zhi Wu, Michael Wurm, Jacques Wurtz, Dongmei Xia, Shishen Xian, Ziqian Xiang, Fei Xiao, Pengfei Xiao, Tianying Xiao, Xiang Xiao, Wei-Jun Xie, Yuguang Xie, Zhizhong Xing, Benda Xu, Cheng Xu, Chuang Xu, Donglian Xu, Fanrong Xu, Jiayang Xu, Jilei Xu, Jinghuan Xu, Meihang Xu, Shiwen Xu, Xunjie Xu, Dongyang Xue, Jingqin Xue, Baojun Yan, Qiyu Yan, Taylor Yan, Xiongbo Yan, Changgen Yang, Chengfeng Yang, Dikun Yang, Fengfan Yang, Jie Yang, Kaiwei Yang, Lei Yang, Pengfei Yang, Xiaoyu Yang, Xuhui Yang, Yifan Yang, Zekun Yang, Haifeng Yao, Jiaxuan Ye, Mei Ye, Ziping Ye, Frédéric Yermia, Jilong Yin, Weiqing Yin, Xiaohao Yin, Zhengyun You, Boxiang Yu, Chiye Yu, Chunxu Yu, Hongzhao Yu, Peidong Yu, Simi Yu, Zeyuan Yu, Cenxi Yuan, Chengzhuo Yuan, Noman Zafar, Vitalii Zavadskyi, Fanrui Zeng, Shan Zeng, Tingxuan Zeng, Liang Zhan, Bin Zhang, Feiyang Zhang, Han Zhang, Hangchang Zhang, Haosen Zhang, Honghao Zhang, Jiawen Zhang, Jie Zhang, Jingbo Zhang, Junwei Zhang, Lei Zhang, Ping Zhang, Qingmin Zhang, Rongping Zhang, Shiqi Zhang, Shuihan Zhang, Tao Zhang, Xiaomei Zhang, Xu Zhang, Xuantong Zhang, Yibing Zhang, Yinhong Zhang, Yiyu Zhang, Yongpeng Zhang, Yuanyuan Zhang, Yue Zhang, Yumei Zhang, Zhenyu Zhang, Zhicheng Zhang, Zhijian Zhang, Jie Zhao, Runze Zhao, Yangheng Zheng, Li Zhou, Lishui Zhou, Shun Zhou, Xiang Zhou, Xing Zhou, Jingsen Zhu, Kangfu Zhu, Kejun Zhu, Bo Zhuang, Honglin Zhuang, Ivan Zhutikov, Jiaheng Zou

Applied Physics

Chiral Landau levels induced by two in-plane pseudomagnetic fields in underwater acoustic metamaterials

Jiao Shen, Zhiyong Chang, Xinzong Wang et al. (+6 more)

The chiral zeroth Landau levels (LLs) constitute topologically protected bulk states that enable robust control of acoustic wave propagation. Given the central role of underwater acoustics in marine engineering, realizing such Landau-level physics in underwater acoustic systems is highly desirable. Nevertheless, existing studies have primarily been limited to airborne acoustic systems, and the implementation of chiral zeroth LLs in underwater acoustics remains a challenge due to the unavoidable fluid-solid interactions. In this study, we realize two kinds of chiral LLs in an open underwater spoof surface acoustic wave (SSAW) platform by introducing two perpendicular in-plane artificial pseudomagnetic fields (PMFs), oriented along the x and y directions, respectively, and reveal that scalar acoustic fields in water and vectorial elastic vibrations in solids can be jointly manipulated within a unified framework. Specifically, by strategically opening bandgaps at the Dirac points, position-dependent effective mass terms are introduced into the Dirac Hamiltonians, thereby synthesizing two in-plane PMFs. This results in the emergence of chiral LLs, which is confirmed both numerically and experimentally. The unidirectional propagation of the chiral LLs and their robustness against defects are also demonstrated. In addition, we achieve flexible manipulation of underwater ultrasonic energy carried by SSAWs, including beam splitting and arbitrary wave steering. Dual-band chiral LLs are also observed in small-scale underwater topological metamaterials. Our work provides a new route toward SSAW-based underwater ultrasonic control, opening opportunities for multiband underwater acoustic signal processing and detection, as well as underwater acoustic energy harvesting.
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All authors Jiao Shen, Zhiyong Chang, Xinzong Wang, Cheng Lin, Tuo Liu, Xiaoxiao Wu, Yifan Zhu, Haiyan Fan, Hui Zhang

Quantum Physics

Suppressing Detuning-Induced Bias in Ramsey Magnetometry with Composite Pulses

Shingo Kukita, Kento Nawata and Yuichiro Matsuzaki

Quantum sensing estimates a physical parameter encoded in the state of a probe; with independent spin probes the precision follows the standard quantum limit. Studies of sensing precision often assume that the parameters entering the model, such as the noise, are known. In practice these parameters are not always known, and a mismatch between the assumed and actual values induces a systematic error. Here we study single-qubit Ramsey magnetometry of a DC magnetic field under an unknown detuning between the actual and nominal spin frequencies: A first pulse puts the qubit into a superposition of its two states, the field to be sensed then adds a relative phase during an exposure stage, and a second pulse enables the readout. In our setting, the field acts only during the exposure stage, whereas the detuning acts throughout the whole protocol. We analyze how the detuning biases the estimate, preventing the total estimation error from following the standard quantum limit. We then construct a composite-pulse preparation and readout that exploits the difference in the intervals over which the field and the detuning act to cancel the detuning to first order. We evaluate the performance of this composite-pulse protocol and show that it suppresses the detuning-induced bias.
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Materials Science

Resistivity in Dilute Cu-3d Alloys Governed by Disorder-Induced Band Broadening

Kenji Yamaguchi

The mechanism governing the resistivity in dilute Cu-3d transition-metal alloys at ambient temperature – the regime relevant to most practical applications and distinct from the low-temperature, Kondo-screened regime addressed by earlier theoretical work – is investigated using first-principles calculations based on the Korringa–Kohn–Rostoker coherent potential approximation combined with the Kubo–Greenwood formalism. The paramagnetic state is described within the disordered local moment (DLM) framework, corresponding to a local-moment paramagnet rather than a Pauli paramagnet. We show that the experimentally observed resistivity trends are reproduced only within the DLM description, while nonmagnetic and ferromagnetic states fail to capture the correct element dependence. Contrary to conventional interpretations based on the density of states at the Fermi level, the resistivity exhibits a strong correlation with the full width at half maximum (FWHM) of the Bloch spectral function (BSF) on the Fermi surface. This correlation reflects the disorder-induced lifetime broadening of electronic states, directly related to the scattering rate that governs electrical resistivity. A common power-law scaling between resistivity and BSF broadening is identified across different magnetic states. These results demonstrate that the resistivity is governed by disorder-induced band broadening in momentum space rather than by local density-of-states effects, providing a unified microscopic interpretation of the breakdown of Linde's rule in Cu-based alloys.
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High Energy Physics (Theory)

An adaptive inverse-problem framework for one-loop five-gluon BCJ numerators

Lin Mai and Yaobo Zhang

An inverse problem comprises a matrix equation together with its unknown space, physical data, equivalence relation, and validation tests. We formulate Bern–Carrasco–Johansson (BCJ) numerator construction as an exact adaptive inverse problem. A fixed scientific specification determines the theory, graph conventions, coefficient field, locality and power counting, cut data, observable equivalence, and independent checks. Each finite working specification compiles to $\mathcal{P}_\sigma=(A,b;\mathcal{S};\mathcal{T})$, where $Ax=b$ reconstructs numerator coefficients, $\mathcal{S}$ classifies the solution fiber, and $\mathcal{T}$ tests it on held-out information. Left-null obstructions identify candidate numerator-basis directions needed for consistency, while the action of candidate measurements on the right kernel identifies informative new cut equations. We illustrate these steps by hand at four points and apply them to one-loop five-gluon pure Yang–Mills theory. After kinematic and graph-symmetry reduction, the candidate numerator basis contains 1127 independent coordinates. The combined maximal, box, triple, and double cuts have rank 920, giving a 207-dimensional affine solution fiber. Exact reconstruction determines a particular solution and the complete ordered kernel. The specified $R_{12345}$ color-ring readout $\mathcal{S}$ annihilates every kernel direction, so the full fiber represents one observable class. A published forward-limit numerator lies in this fiber, and fresh cuts, independent integral reductions, and helicity-amplitude benchmarks validate the result. Explicit search rules and agent interfaces can propose revisions. Deterministic compilation and exact evaluation assess each proposal.
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High Energy Astrophysical Phenomena

Inverse Transfer in Non-helical 2D Collisionless Magnetic Turbulence: Island-Merger Picture with Kinetic Effects

Yangyang Cai, Hongzhe Zhou and Yosuke Mizuno

Magnetic inverse transfer is often invoked to connect small-scale magnetic-field generation to larger coherence scales in high-energy and cosmological plasmas. The underlying magnetohydrodynamic (MHD) arguments combine two logically distinct ingredients: a bulk quantity that is asymptotically conserved in the limit of small resistivity, and a time scale determined by the decay dynamics. In this work, we explore whether this scenario still holds in decaying nonhelical turbulence formed by collisionless plasmas using particle-in-cell simulations. The simulations approximately satisfy $B^2\xi_B^2\simeq{\rm const}$ as in the MHD case, and the fitted exponents in $B^2\propto t^{-p}$ and $\xi_B\propto t^q$ obey $p\simeq2q$. Here $B^2\equiv\langle B_x^2+B_y^2\rangle$ is the average in-plane magnetic energy density, and $\xi_b$ is the magnetic integral scale. However, the decay time scale differs from the MHD case as inferred from the decay exponents. We found $p<1$ and $q<1/2$ in all cases with different initial magnetization $\sigma_0$, with both exponents lower than the MHD values and varying systematically with $\sigma_0$. The spectral peak also migrates toward lower wavenumber at a rate faster than the growth of $\xi_B$, indicating a broken self-similarity. The broken self-similarity is attributed to the appearance of kinetic scales in the magnetic energy spectrum due to pressure anisotropy and Larmor-scale magnetic structures. These results indicate that in astrophysical collisionless plasmas, including but not restrict to solar wind, pulsar-wind nebulae, interstellar medium, and cosmological plasmas, magnetic coherence can continue to grow by inverse transfer, but extrapolations based on MHD decay-time scaling can overestimate the rate of large-scale field growth.
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Quantum Physics

Deterministic Quantum Phase Estimation with Linear Circuit Complexity in a Photonic System

M. Midhuna, Ajay Jayachandran, Kanad Sengupta et al. (+2 more)

Quantum algorithms solve certain computational problems faster than the best known classical algorithms. Many algorithms, including Shor's for factoring, Grover's for unstructured search, and the HHL for solving linear systems, rely on quantum phase estimation (QPE) as a fundamental subroutine. The QPE protocol proceeds through the initialization of a control register in a uniform superposition, controlled unitary evolution encoding the eigenphase, and a final inverse quantum Fourier transform followed by measurement to extract the phase. Here, we address a special class of unitary operators that frequently appear in quantum Fourier transform-based protocols, cyclic group representations, and periodically evolving quantum systems. We introduce a QPE algorithm that successfully reduces the circuit complexity from $\mathcal{O}(n^2)$ to $\mathcal{O}(n)$ for a special class of unitary operators and implement it on a four-qubit photonic system. The four-qubit system is realised using a photon pair, with two qubits encoded in its polarization degree of freedom and the remaining two in its path modes. In contrast to previous photonic implementations of QPE based on dual-rail encoding and KLM protocol, where controlled operations are inherently probabilistic and thus reduce the overall success probability of phase estimation, our scheme is fully deterministic. Moreover, it is scalable to higher-dimensional unitaries, provided the underlying structure of the unitaries is preserved.
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All authors M. Midhuna, Ajay Jayachandran, Kanad Sengupta, Akshai T. Krishnan, C. M. Chandrashekar

Strongly Correlated Electrons

Dirac topology, anomalous Hall response, and giant magnetoresistance in carrier-compensated altermagnetic semimetal NiS

Shovan Gayen, Sk. Soyeb Ali and S K Panda

We combine first-principles density-functional theory, Berry-curvature analysis, semiclassical Boltzmann transport, and atomistic spin dynamics to establish hexagonal NiS as a compensated 3d altermagnetic semimetal in which topology, magnetism, and lattice dynamics are intrinsically intertwined. The rotational coset symmetry of the NiAs lattice produces momentum-dependent spin splitting characteristic of altermagnetism. With spin-orbit coupling, gapped Dirac-like crossings generate intense Berry-curvature hot spots and nearly compensated electron-hole pockets. This leads to a large and anisotropic intrinsic spin Hall conductivity comparable to that of several 4d, 5d metals, a symmetry-allowed anomalous Hall response despite zero net magnetization, and nonsaturating magnetoresistance exceeding 10000 percent. On the magnetic side, first-principles determination of the exchange tensor reveals dominant long-range superexchange and sizable anisotropic interactions, quantitatively reproducing the experimental Neel temperature. Our results identify NiS as a model 3d platform in which carrier compensation, altermagnetic symmetry, Berry-curvature driven transport, and lattice-sensitive magnetism coexist within a single symmetry framework, offering a design principle for multi-functional quantum responses in correlated transition-metal compounds.
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Mesoscale and Nanoscale Physics

On-chip quantum sensing of Kondo spins in a high-mobility quasi-one-dimensional nanoconstriction

Shun-Tsung Lo, Che-Cheng Wang, Sheng-Chin Ho et al. (+15 more)

The precise nature of Kondo spins has remained enigmatic when extended to multiple spin impurities or, more intriguingly, when the localized spin itself may already be the consequence of many-body interactions in a presumably-delocalized open nanoconstriction, such as a quantum point contact (QPC). It is experimentally challenging to distinguish the Kondo state from other coexisting many-body spin states in such a strongly correlated system. Here we lithographically define an all-on-chip electronic resonator (ER) and a QPC in a high-mobility GaAs/AlGaAs heterostructure transistor. Local Kondo screening of the QPC spin and nonlocal spin singlet across the ER-QPC integration are controllable in response to ER occupancy parity. We also show that the 0.7 anomaly, another strongly-correlated state in QPCs, not only has a different physical origin but furthermore counteracts the Kondo spin singlet. These results demonstrate a noninvasive quantum method for sensing spontaneous magnetic impurities within an open nanoconstriction.
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All authors Shun-Tsung Lo, Che-Cheng Wang, Sheng-Chin Ho, Jun-Hao Chang, Ming-Wei Chen, G. L. Creeth, L. W. Smith, Shih-Hsiang Chao, Yu-Chiang Hsieh, Pei-Tzu Wu, Yi-Cheng Wu, Chi-Te Liang, M. Pepper, J. P. Griffiths, I. Farrer, G. A. C. Jones, D. A. Ritchie, Tse-Ming Chen

Statistical Mechanics

The nonequilibrium statistical mechanics of Markov interacting particles

Dalton A R Sakthivadivel

We consider coupled stochastic systems decomposed into exterior, boundary, and interior variables, with the boundary variables sometimes carrying the directed structure of a sensor and actuator. The central question is when the conditional law of histories factorises, and how this path space statement is detected by log likelihoods, by Girsanov changes of measure, and by information theoretic quantities used in nonequilibrium statistical physics. The basic object is a regular conditional probability on a path space. Under domination by clamped reference laws, the boundary property becomes multiplicative separation of a Radon–Nikodym derivative, or equivalently additive separation of a path log likelihood. For Itō diffusions this log likelihood is computed by Girsanov's theorem; its expectation is the quadratic control energy appearing in the Föllmer entropy identity and in the stochastic control formulation of Schrödinger bridge problems. When exact factorisation fails, the remaining coupling is measured by conditional mutual information, namely the relative entropy between the true boundary-conditioned path law and the product of its conditional marginals. This gives a common language for boundary screening, path likelihood inference, controlled changes of path law, and the thermodynamic value of mutual information.
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Plasma Physics

Boronization-enabled I-mode on EAST tokamak with an expanded density window and favorable-configuration access

X.M. Zhong, X.L. Zou, A.D. Liu et al. (+19 more)

I-mode is a promising confinement regime for future fusion reactors because it combines enhanced energy confinement with L-mode-like particle transport and naturally ELM-free operation. Previous EAST I-mode studies were performed exclusively under lithium-conditioned wall conditions. Here we report the first systematic experimental investigation of I-mode under boronized wall conditions on EAST and compare it with an existing lithium-conditioned I-mode database at the same toroidal field, $B_t = 2.47$\,T. The boronized-wall dataset exhibits a substantially broader accessible density range, with the Greenwald fraction extending from $f_{\mathrm{GW}} = 0.26 - 0.77$ , compared with $f_{\mathrm{GW}} = 0.35 - 0.54$ under lithiation. A higher normalized $\mathrm{D}_\alpha$ emission suggests that enhanced edge recycling may contribute to this density extension. A striking increase in favorable-configuration I-mode is also observed: $51\%$ boronized-wall discharges are obtained in favorable-configuration, compared with only $8\%$ lithium-conditioned discharges. These favorable-configuration cases are concentrated at high density and exhibit a deeper radial electric-field($E_r$) well and stronger $\mathbf{E_r}\times\mathbf{B}$ velocity shear. When ETRO is present, the associated transition between electron and ion turbulence is similar under the two wall conditions, although ETRO occurs less frequently ($15\%$) under boronization. An empirical EAST I-mode energy confinement scaling at fixed $B_t$ is obtained, $\tau_E = 3.29 I_p^{0.51 \pm 0.10} P_{\mathrm{loss}}^{-0.53 \pm 0.05} \bar{n}_e^{0.08 \pm 0.07}$, indicating weaker power degradation than IPB98(y,2) H-mode scaling and a weak density dependence. These results show that boronization can broaden the operational space of EAST I-mode and support the development of reactor-relevant ELM-free scenarios.
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All authors X.M. Zhong, X.L. Zou, A.D. Liu, L.Q. Xu, B. Zhang, C. Zhou, J.P. Qian, X.Z. Gong, Y.T. Song, G. Zhuang, W.X. Shi, L.T. Gao, S.F. Wang, Y.H. Guan, G.Z. Zuo, T.Q. Jia, Y.X. Cheng, S.X. Wang, K.N. Geng, H.L. Zhao, EAST I-mode Working Group, EAST Team

High Energy Astrophysical Phenomena

Distinct Velocity Components in the Absorption Lines of the Neutron Star X-ray Binary AX J1745.6-2901

Kai Matsunaga, Maxime Parra, Yutaro Nagai et al. (+10 more)

Accretion disks in X-ray binaries regulate mass transfer onto compact objects and drive radiative and kinetic feedback to their surroundings. Here we report X-ray spectroscopy of the eclipsing neutron star low-mass X-ray binary AX J1745.6-2901 with XRISM/Resolve. The phase-averaged Fe XXVI Ly{\alpha} absorption profile exhibits two absorption minima with relative depths that are inconsistent with the theoretical Ly{\alpha}1/Ly{\alpha}2 doublet ratio expected from a single velocity component. We demonstrate that this profile is well described by two discrete velocity components: a blueshifted component at v~ -160 km/s and a redshifted component at v ~ +590 km/s. The significance of the redshifted component is more than 3 sigma based on a Monte-Carlo calculation. This velocity structure persists across orbital phases, disfavoring a localized origin such as a bulge or dip. The blueshifted component, well below the outer-disk escape velocity, is consistent with a slow outflow or disk atmosphere. The redshifted absorber can be explained either by infalling gas from a failed wind or by a gravitational redshift, and the present data cannot rule out either possibility. Regardless of its origin, the redshifted component is kinematically separate from the disk atmosphere and outflow. The absence of absorption at intermediate velocities further indicates a genuinely bimodal velocity distribution rather than the two ends of a single continuous flow, offering a new view of the absorbing-gas kinematics.
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All authors Kai Matsunaga, Maxime Parra, Yutaro Nagai, Teruaki Enoto, Yoshitomo Maeda, Takayuki Hayashi, Shifra Mandel, Kaya Mori, Hideki Uchiyama, Masayoshi Nobukawa, Hiroya Yamaguchi, Megumi Shidatsu, Ryota Tomaru

Statistical Mechanics

A Loewner-Theoretic Approach to the Nonlinear Generalized Langevin Equation: The Role of Entropy in Colored Noise Environment

Yusuke K. Shibasaki

In this study, the formal derivation of a one-dimensional nonlinear generalized Langevin equation is demonstrated using a decomposition method based on the conformal transformation governed by the chordal Loewner equation. Here, we used a modified Mori-Zwanzig method whose operator is substituted by that is derived from the discrete Loewner evolution. By this approach, the different types of fluctuation-dissipation relation (FDR) were reformulated using mathematical terms affected by the conformal maps. Dealing with a memory kernel that models the cell migration experiment, the numerical simulation was performed to obtain the specific scaling law of energy dissipation that is common among the two obtained types of FDRs. In addition, the concept of Loewner entropy is used for the estimation of the canonical ensemble in the colored noise environment throughout the theoretical analyses.
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Computational Physics · Cross-listed from math.NA

Residual-Christoffel Sampling for Random Feature Collocation of Linear PDEs

Jiale Linghu and Yangshuai Wang

Random feature collocation fixes a randomly generated trial space and determines its coefficients from a linear least-squares system. Stability then depends on whether the sampled residual equations represent the geometry induced by the differential operator. We construct an operator-aware discretization in which the operator-applied features determine both the collocation measure and a coefficient whitening map. The randomized scheme combines a residual-Christoffel density with inverse-density weights, while a deterministic scalar-row alternative maximizes successive regularized log-determinant increments. Conditional on the realized trial space, the sampled whitened interior Gram is a spectral approximation to the reference Gram on the retained residual space, with sample complexity linear in the retained dimension up to a logarithmic factor. For uniformly analytic residual kernels, the associated operator has stretched-exponentially decaying eigenvalues and ridge effective dimension that is polylogarithmic in the inverse ridge scale. Experiments on scalar and vector equations, varied geometries, and one to three spatial dimensions show that residual-space sampling and whitening produce numerically full-rank transformed systems with substantially smaller condition numbers and iteration counts. The deterministic construction attains the lowest errors at the smallest scalar sample sizes. Residual-space geometry therefore yields a principled design for stable strong-form random feature collocation.
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