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Monday 20 July

Quantum Physics

Single-atom sensor for low-frequency electric field

Quan Yuan, Shuang-Qing Dai, Tai-Hao Cui et al. (+8 more)

Precision measurement of low-frequency electric field (LFEF) signals with frequency from 30 kHz to 300 kHz is crucial for advancing both fundamental science and practical applications, owing to their unique frequency regime. For conventional electromagnetic antennas, the long wavelength (i.e., several kilometers) of the LFEF leads to a severe size constraint that efficient radiation becomes challenging to achieve when the antenna size is much smaller than the long wavelength of the LFEF signals, which in turn results in a reduction of measurement sensitivity and compromises antenna's performance. By exploiting the high intrinsic sensitivity of cold trapped ions to weak alternating electric signals via Coulomb interaction, we demonstrate a single-ion phonon laser sensor acted by an injection-locked 40Ca+ ion confined in a surface-electrode trap. Combining the beat frequency technique with the injection-locked phonon laser oscillation, we demonstrate a practical and efficient approach for simultaneous extraction of the frequency, phase, and amplitude from a single measurement, without the need for sideband cooling. This approach achieves precision detection for LFEF signals with the sensitivity of 404 uV/(m * Hz1/2) and the detection limit of 61.5 uV/m. Besides, this approach also shows remarkable robustness against noise. Our study helps realizing practical single-atom sensors in the low-frequency regime, opening avenues for applications in subsurface communication, precision metrology, mass spectrometry, and biomedical monitoring.
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All authors Quan Yuan, Shuang-Qing Dai, Tai-Hao Cui, Pei-Dong Li, Yuan-Zhang Dong, Zhuo-Zhu Wu, Ji Li, Fei Zhou, Jian-Qi Zhang, Liang Chen, Mang Feng

Astrophysics of Galaxies

The Intrinsic Multiphase Gas–Black Hole Connection across Scales in IllustrisTNG

Xiaoxia Zhang, Taotao Fang, Shulan Yan et al. (+2 more)

The relationship between supermassive black holes and the multiphase circumgalactic medium is central to understanding the co-evolution of galaxies and their central black holes. We investigate this relationship using the IllustrisTNG100 simulation with a sample of 5089 central galaxies at $z=0$, measuring the partial correlation between central black hole mass and the mass of cold ($T < 10^4$K), cool ($10^4 \le T < 10^5$K), warm ($10^5 \le T < 10^6$K), and hot ($T \ge 10^6$K) gas within $0.03R_{200}$, $0.15R_{200}$, and $R_{200}$, after accounting for stellar and dark matter halo mass. We find that after removing these confounding factors, black hole mass shows a significant negative partial correlation ($\rho \approx -0.37$) with cold gas within $R_{200}$ and $0.15R_{200}$, whereas warm and hot gas exhibit no substantial intrinsic correlation. The residual plane reveals a threshold pattern: galaxies with over-massive black holes show systematically reduced cold gas, consistent with the cumulative impact of AGN feedback. The anti-correlation persists across environments with a weak trend in local density, and varies with galaxy type (star-forming, green valley, and quenched). These results provide a quantitative multiphase diagnostic of AGN feedback in TNG and support a picture in which feedback progressively removes cold gas, offering testable predictions for future multiwavelength surveys.
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All authors Xiaoxia Zhang, Taotao Fang, Shulan Yan, Si-Yue Yu, Feng Yuan

High Energy Physics (Theory)

Geometric Approach to Quantum Theory. L-functionals

Albert Schwarz

This publication consists of slides from my talk at the Simons Center for Geometry and Physics in 2024. It contains a brief review of the L-functional formalism, along with a discussion of its possible applications to QED, linearized gravity, and quenched disorder. The most interesting part is the discussion of the infrared problem in QED and a conjecture on how to construct an infrared-finite perturbation theory for QED.
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Quantum Physics

Temporal Diffraction Grating for Engineered Superconducting Qubit Dissipation

Pratik J. Barge and Kater W. Murch

Parametric frequency modulation is a standard tool in superconducting circuits for activating tunable interactions and implementing quantum gates. Here, we engineer dissipation in a flux-tunable transmon qubit by using sideband modulation to bring it into resonance with a lossy resonator, opening an on-demand Purcell decay channel. We find that pulsing this channel on and off does not simply lower the time-averaged decay rate; instead, it reorganizes the dissipation spectrum into a structured interference pattern. A Chebyshev-propagator model for the repeated on/off block reproduces the measured spectra and reveals a close structural correspondence to N-slit Fraunhofer diffraction, with each on-window acting as a temporal aperture. By varying the pulse duration and duty cycle, we demonstrate control over the spacing, contrast, and envelope of the dissipation spectrum. These results establish pulsed parametric modulation as a direct method for shaping engineered dissipation in superconducting circuits and provide a new control knob for open quantum system dynamics.
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High Energy Astrophysical Phenomena

Beyond Spin: QCD Magnetars

Rachid Ouyed

We present a unified framework in which anomalous X-ray pulsars (AXPs), soft gamma-ray repeaters (SGRs), superluminous supernovae (SLSNe-I), luminous fast blue optical transients (LFBOTs), and fast radio bursts (FRBs) originate from quark deconfinement in the core of a massive neutron star (NS). Spontaneous ferromagnetism in the deconfined phase generates ~10^18 G core fields, producing a highly magnetized hybrid star (HS) - the "QCD magnetar" - whose surface field is set by NS mass, not birth spin. The Quark-Nova (QN) that forms the HS ejects ~0.01M_sun of neutron-rich outer layers, powering a kilonova and leaving the HS crustless for centuries. During this phase, magnetic instabilities at the hadron-quark interface release rising flux ropes that power X-ray-quiet FRBs; as the crust reforms, the source evolves into an X-ray-loud AXP&SGR. Two parameters govern the model: a critical mass M_dec triggering deconfinement, and a critical period P_fast separating fast and slow rotators. Fast rotators inject spin-down energy into the QN ejecta, producing an LFBOT - directly observable once the SN ejecta is optically thin, or via binary accretion with no preceding SN; otherwise the LFBOT is reprocessed by the SN ejecta into an SLSN-I. A Bayesian Monte Carlo population synthesis reproduces the observed rates of AXPs&SGRs, SLSNe-I, and LFBOTs with M_dec ~2.1M_sun and P_fast ~5.5 ms, and predicts non-merger r-process signatures and kilonovae from isolated NSs, with or without an LFBOT. The QN ejecta also carries its own DM and RM, independent of environment, predicted to appear as excess dispersion and rotation measure in FRBs once Galactic, host, and intergalactic contributions are removed. These provide direct observational tests of the hadron-quark phase transition and ferromagnetic ordering in dense quark matter.
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Quantum Physics

Lie-Group Mode Connectivity in Quantum Machine Learning from a Dynamical Lie Algebra Perspective

Hiroshi Ohno

Mode connectivity has been widely studied in classical machine learning as a geometric property of low-loss regions in parameter space. In quantum machine learning (QML), however, the physically relevant object is not the parameter vector itself but the unitary transformation implemented by a parameterized quantum circuit. In this study, we formulate mode connectivity on the reachable unitary Lie group generated by the dynamical Lie algebra of the generators. We show that, under a near-minimum connectedness assumption and the absence of critical values in a low-loss band, the corresponding low-loss sublevel set on the reachable Lie group is path-connected. This provides a geometric interpretation of mode connectivity in QML that is independent of a particular parameterization. We further discuss how overparameterization can enable the lifting of Lie-group paths to parameter space, thereby making Lie-group connectivity observable in parameter-space experiments. Finally, we present toy numerical experiments in which geodesic interpolations between trained unitaries exhibit nearly zero loss barriers, consistent with the proposed interpretation.
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Solar and Stellar Astrophysics

First double red giant Algol system with active mass transfer

Mikhail Kovalev, Hailiang Chen, Sufen Guo et al. (+7 more)

Double red giant stars are very important for studies of the stability of mass transfer, common-envelope evolution, and the formation of double white dwarfs with short orbital periods. However, no double red giant system undergoing mass transfer has yet been found. We present the discovery of a close Algol-type binary system composed of two red giant stars. This is the first known semi-detached system observed during the very short phase when the accretor has expanded into a red giant just before entering the common envelope phase. The $H_\alpha$ line suggests that the system has recently lost some material, which is now moving toward us. We present a consistent analysis of all the available spectroscopic and photometric observations of this system, constraining its orbital parameters and the fundamental properties of the components. Our findings are supported by a binary evolution model that successfully reproduces the currently observed parameters. The model suggests that the system will eventually merge into a single star.
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All authors Mikhail Kovalev, Hailiang Chen, Sufen Guo, Jiao Li, Hongwei Ge, Dengkai Jiang, Marina Burlak, Natalia Ikonnikova, Xuefei Chen, Zhanwen Han

Soft Condensed Matter

Universal Jamming Criticality and Self-Organizing Principles from Disorder to the Limit of Perfect Crystalline Order

Jianhua Zhang, Jiaqi Si, Ning Xu et al. (+1 more)

While crystals are defined by periodic order, the nature of amorphous solids remains elusive due to their disordered, diverse, and nonequilibrium structures. Here, we focus on jammed elastic packings and systematically tune structure from crystalline to fully disordered to unveil the universal underlying characteristics. We demonstrate that their mechanical properties are universally governed by jamming criticality, featuring characteristic scaling behaviors near the jamming transition, excepting the singular close-packed point. This is facilitated by random nonaffine elasticity arising from contact-level disorder. Consequently, the jamming density can approach close packing, suggesting a fundamental decoupling between jamming criticality and the glass transition physics. Moreover, we uncover a universal coordination-number distribution and contact hyperuniformity in marginally jammed states, independent of particle-level structure. These findings suggest a general organizing mechanism for emergent rigidity in disordered solids, underscore the broad relevance of jamming physics, and complement principles of mechanical self-organization.
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All authors Jianhua Zhang, Jiaqi Si, Ning Xu, Hua Tong

Superconductivity

Interface-Confined Superconductivity with Thickness-Independent Superfluid Stiffness in (Pb,Sn)Te/FeTe Bilayers

Zi-Jie Yan, Hongtao Rong, Yiyuan Luo et al. (+12 more)

Interface-induced superconductivity in FeTe-based heterostructures provides a promising route toward topological superconductivity, yet the roles of the neighboring layers topology, symmetry, and electronic structure remain unresolved. In this work, we employ molecular beam epitaxy to grow Pb1-xSnxTe/FeTe bilayers and use angle-resolved photoemission spectroscopy to track the evolution of the Pb1-xSnxTe layer from a trivial insulator to a topological crystalline insulator hosting multiple Dirac surface states. Electrical transport measurements reveal robust superconductivity throughout the entire composition range, with a nearly constant superconducting transition temperature of ~12 K despite substantial changes in the electronic structure and topology of Pb1-xSnxTe. Double-coil mutual-inductance measurements further reveal comparable superfluid stiffness across the topological phase transition and nearly thickness-independent superfluid stiffness despite large variations in the constituent-layer thicknesses, demonstrating that superconductivity is confined near the interface. These results establish that superconductivity in FeTe-based heterostructures is largely insensitive to the topology, crystal symmetry, and detailed electronic structure of the neighboring layer, supporting a primary origin in modifications to the FeTe layer. The coexistence of interface-confined superconductivity and tunable multiple Dirac surface states in Pb1-xSnxTe/FeTe bilayers provides a versatile platform for exploring topological superconductivity and interactions among multiple Majorana zero modes.
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All authors Zi-Jie Yan, Hongtao Rong, Yiyuan Luo, Yufei Zhao, Pu Xiao, Zihao Wang, Lok-Kan Lai, Annie G. Wang, Zhiyuan Xi, Yanxing Li, Xiaoyu Wei, Ke Wang, Binghai Yan, Chih-Kang Shih, Cui-Zu Chang

Chemical Physics

Multireference Density Matrix Embedding for Spin-Phonon Relaxation

Shreya Verma, Antonio L. Mariano, Matthew R. Hermes et al. (+3 more)

Spin-phonon coupling governs magnetic relaxation in numerous systems including single-molecule magnets and molecular spin qubits. In most cases, the accurate prediction of spin relaxation rates requires multireference electronic structure methods, but their computational cost has largely restricted such calculations to isolated molecules. Here we show that spin-phonon relaxation rates can be computed within a multireference density matrix embedding framework. We apply the approach to three cobalt- and two dysprosium-based single-molecule magnets and to a cobalt-based molecular crystal. Across all systems, treating only the first coordination sphere of the magnetic center at the multireference level reproduces spin relaxation rates in good agreement with non-embedded CASSCF calculations while reducing the correlated problem to 10-68% of the total basis functions. Periodic calculations further demonstrate that spin relaxation rates can be computed for a molecular crystal using an embedded active space of only 259 basis functions out of a total of 2569. These results show that multireference density matrix embedding extends quantitative spin-phonon relaxation calculations from isolated molecules to molecular crystals.
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All authors Shreya Verma, Antonio L. Mariano, Matthew R. Hermes, Alessandro Lunghi, Giulia Galli, Laura Gagliardi

Quantum Physics

Neural Gauge-P Representation for Open Quantum Dynamics of Interacting Bosons

Xiaodong Cao and Zhicheng Zhong

Simulating the nonequilibrium dynamics of interacting open quantum systems remains challenging beyond small system sizes. Quantum phase-space representations provide a scalable approach, but their useful simulation time can be limited by broad distribution tails and the associated boundary terms. We introduce the neural gauge-$P$ representation for open bosonic systems, in which stochastic gauges are parameterized by neural networks and optimized using exact moment equation residuals. For the driven-dissipative Bose–Hubbard model in both single-site and square-lattice settings, the neural gauge-$P$ representation remains accurate during long-time evolution toward the steady state, whereas the corresponding ungauged representation becomes unreliable at substantially earlier times. These results demonstrate the potential of the neural gauge-$P$ representation for accurate simulations of nonequilibrium open quantum many-body dynamics.
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Materials Science

Non-equilibrium Effects in Vibrational Modes Pumped by Inelastic Tunneling

Chi Ming Yim, Owain T. Beynon, Seunghyun Khim et al. (+2 more)

The properties of strongly correlated electron materials exhibit a surprising sensitivity to small lattice distortions, providing an opportunity for their tuning by selective distortion driving, usually achieved by optical excitations. Using inelastic electron tunneling in scanning tunneling microscopy, we demonstrate that at the surface of a strongly correlated electron material, we can drive vibrational excitations out of equilibrium, by studying the dynamics of localized modes on the Pd-terminated surface of the delafossite oxide PdCrO2. This surface forms a tiling of hydrogen clusters of varying sizes and shapes upon hydrogen adsorption. Our findings reveal that vibrational excitations in the clusters exhibit longer lifetimes than on typical metal surfaces. Detailed analysis of the spectroscopy data reveals signatures of non-equilibrium effects in the excitations which we attribute to the extended lifetimes of these modes. Theoretical calculations support that the long-lived nature of the excitations is related to the unique properties of the substrate.
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All authors Chi Ming Yim, Owain T. Beynon, Seunghyun Khim, Chiara Gattinoni, Peter Wahl

Astrophysics of Galaxies

Anomalously high deuterium fractionation in a galactic translucent cloud: a challenge to chemical models

Gan Luo, Zhi-Yu Zhang, Thomas G. Bisbas et al. (+8 more)

Deuterated (D-) species have long been proposed to diagnose the physical conditions and chemical evolution of cold dense molecular clouds. While deuterium fractionation has been extensively measured in dense cores, observations in diffuse and translucent clouds remain rare. We report here the detection of DCN and DNC toward a translucent cloud ($A_{\rm V} =1.2\pm0.2$ mag, $n_{\rm H_2}$ = $3.9\pm0.2\times10^2$ cm$^{-3}$) through sensitive absorption observations with the IRAM NOrthern Extended Millimeter Array (NOEMA). This detection reaches the lowest column-density and volume-density regime in which deuteration has been observed so far. Interestingly, the observed DCN/HCN and DNC/HNC abundance ratios ($3.3\pm0.6\times10^{-3}$ and $3.6\pm1.2\times10^{-3}$, respectively), which are more than two orders of magnitude higher than the element abundance [D]/[H] (1.5$\times$10$^{-5}$), suggest an unexpected enhancement of deuterium fractionation in the translucent cloud. These results represent a significant departure from established chemical models considering deuterium fractionation, which predict negligible formation of D-molecules in such environments. Although it remains unclear how D-molecules built up their abundances in translucent gas, a dispersed dense core scenario could potentially explain the observed high deuterium fraction. This interpretation is consistent with the idea proposed by Price et al. (2003) more than two decades ago: a translucent cloud may be a transient, dynamically evolving structure formed through the dissipation of a dense molecular cloud.
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All authors Gan Luo, Zhi-Yu Zhang, Thomas G. Bisbas, Di Li, Serena Viti, Roberto Neri, Junzhi Wang, Siyi Feng, Ningyu Tang, Daniel R. Rybarczyk, Lingrui Lin

General Relativity and Quantum Cosmology

Hawking evaporation and the possibility of remnant formation for covariant quantum black holes

Li-Shuai Wang and Xiangdong Zhang

Covariant quantum black holes (BHs) are an important development in loop quantum gravity (LQG), and investigations of their evaporation may offer a possible avenue for testing LQG. In this paper, we investigate the evaporation of covariant quantum BHs and the possibility of remnant formation. Our results show that covariant quantum BHs can leave remnants, calculated by analytical greybody factors for a massless scalar field. Nevertheless, the fully numerical results indicate mass loss rates of covariant quantum BHs are spin-dependent and differ from those of Schwarzschild BHs, due to spin-dependent greybody factors. In particular, these BHs evaporate faster than Schwarzschild BHs in the low-mass regime, with the evaporation being dominated by massless neutrino emission rather than scalar field emission, contrary to the scalar field dominance commonly assumed in previous studies. Therefore, considering only BH evaporation in the massless scalar field case may be insufficient and may even lead to misjudging BH fate. In addition, these results may provide a way to test LQG in the future.
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High Energy Astrophysical Phenomena

Optical observations on the young Type Ia SN 2021fxy with detached high velocity features

Liping Li, Jujia Zhang, Zhenyu Wang et al. (+5 more)

We present optical observations on the young type Ia supernova (SN Ia) SN 2021fxy obtained within a few days after the explosion, with a focus on its prominent high-velocity features (HVFs). It reached a $B$-band maximum of $M_{\rm max}(B) = -19.36\pm0.31$ mag, corresponding to a bolometric luminosity of $\sim 1.3\times10^{43}~\rm{erg~s^{-1}}$ with a synthesized $^{56}$Ni mass of $0.58\pm0.14$ M$_{\odot}$. The early spectra exhibit strong HVFs of intermediate-mass elements that are significantly detached from the photospheric components. In particular, the velocity of the Si II $\lambda6355$ HVFs follows a power-law evolution ($\beta \approx 0.1$), shallower than the expected photospheric velocity evolution expected for an assumed $n=10$ density profile ($\beta \approx 0.22$) under homologous expansion. This behavior is consistent with the HVFs forming in intrinsic ejecta structures at least partially decoupled from the bulk outer ejecta, providing a possible constraint on the explosion physics of SNe Ia.
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All authors Liping Li, Jujia Zhang, Zhenyu Wang, Xiaofeng Wang, Qian Zhai, Shengyu Yan, Bo Wang, Jinming Bai

Instrumentation and Detectors

Final assessment of radioactive impurities in the JUNO detector

Thomas Adam, Fengpeng An, Costas Andreopoulos et al. (+571 more)

The Jiangmen Underground Neutrino Observatory (JUNO) collaboration has completed the construction of the 20,000-ton liquid scintillator detector and the associated muon veto detector system. To meet the physics objectives, the materials used in the detector must exhibit low radioactive contamination. The single-event rate in the fiducial volume (R $<$ 17.2 m) of the scintillator is required to be approximately 7 Hz for energies above 0.7 MeV, resulting in an accidental coincidence background of about 1 event per day for reactor neutrino physics analyses. Since the beginning of the construction phase, we have screened the natural radioactivity content of thousands of materials, to select those that meet the design background budget. The radioactive impurity concentrations of the materials ultimately used in the JUNO detector are summarized in this paper. The construction of the entire detector and the subsequent filling of the liquid scintillator were completed in August 2025. From the initial data, the total count rate of natural radioactivity within the detector's fiducial volume has met the requirements and is sufficient to support the reactor antineutrino analysis.
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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 Böhles, 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, Shuxian 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, Lian-Chen Huang, Guihong Huang, Jinhao Huang, Junlin Huang, Junting Huang, Kaixuan Huang, Shengheng Huang, Tao Huang, Xin Huang, Xingtao Huang, Yongbo Huang, Jiaqi Hui, Lei Huo, 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, Zi-Ming 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, Manhao Qu, 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, Sahar Safari, Ujwal Santhosh, Utane Sawangwit, Michaela Schever, Cédric Schwab, Konstantin Schweizer, Alexandr Selyunin, Andrea Serafini, Mariangela Settimo, Junyu Shao, Anurag Sharma, Vladislav Sharov, Hangyu Shi, Jingyan Shi, Yuan Shi, Hexi 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, Aoqi Su, 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, Li 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, 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, Shujun Zhao, Yangheng Zheng, Li Zhou, Lishui Zhou, Shun Zhou, Xiang Zhou, Xing Zhou, Jingsen Zhu, Kangfu Zhu, Kejun Zhu, Bo Zhuang, Honglin Zhuang, Jiaheng Zou

Cosmology and Nongalactic Astrophysics

Simultaneous inference of isotropic and anisotropic polarization rotation angles for next-generation cosmic microwave background experiments

Yue Zhang, Chang Feng, Sen Li et al. (+1 more)

The ultrahigh-sensitivity polarization imaging of the cosmic microwave background (CMB) is a treasure trove for new physics. Searching for a predicted polarization angle rotation known as the cosmic birefringence effect is a pursuit of the next-generation CMB experiments, and this new polarization signal would be important for testing fundamental physics theories. However, such a delicate rotation effect can be confused by different mechanisms including polarized Galactic foregrounds and instrumental calibration effects. Also, the cosmological rotation effects may arise from both the background evolution and spatial fluctuations of axion-like particles, leaving complicated imprints on CMB polarization fluctuations. In this work, we establish a comprehensive modeling of cosmological rotation effects, the instrumental miscalibration of polarization angles and complex foreground polarization with higher-order fluctuations, and perform a Bayesian analysis to infer both isotropic and anisotropic rotation angles simultaneously for foreground-mitigated polarization datasets from submillimeter to millimeter wavelengths. We find that such a Bayesian formalism can effectively extract the rotation effects for the next-generation CMB experiments and investigate the impact of the known sources including Galactic foregrounds and lensing on the inferred cosmological signals. The method in this work is well suited for future polarization data analyses, and the inferred rotation effects may shed light on the nature of the axion-like particles.
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All authors Yue Zhang, Chang Feng, Sen Li, Filipe B. Abdalla

Quantum Physics

LLM-Driven Cross-Paradigm Design for Quantum Optimal Control

Yu-Qin Chen and Shi-Xin Zhang

Quantum optimal control (QOC) underpins adiabatic quantum computation, quantum annealing, and quantum state engineering, yet practical deployment is fundamentally bottlenecked by strict hardware constraints and substantial expert effort required to design protocols for each problem instance. To overcome this, we introduce QOC-Workbench, an auditable, large language model (LLM)-driven workflow that acts as an automated quantum co-scientist for cross-paradigm protocol design. Going beyond traditional numerical optimizers that merely tune parameters within a fixed formula, the LLM autonomously parses physics literature, proposes structural hypotheses, and writes code to validate them by direct simulation. This workflow supports cross-paradigm design by accumulating control motifs across tasks. We demonstrate this approach across three distinct settings: Case 1, Rydberg-atom maximum-independent-set arrays; Case 2, interacting XXZ spin chains; and Case 3, random transverse-field Ising models. In Cases 1 and 2, the workflow autonomously discovers hardware-compliant auxiliary controls, target catalysts, and schedule deformations that outperform literature baselines. In Case 3, it addresses the computational bottleneck of variational counterdiabatic driving by escalating from per-instance optimization to an amortized graph-neural-network generator, successfully transferring learned coefficient paths to larger unseen systems. By actively bridging the gap between theoretical algorithms and experimental restrictions across distinct control paradigms and Hamiltonian families, QOC-Workbench establishes a continuously evolving, cross-paradigm methodology for autonomous quantum control.
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High Energy Physics (Phenomenology)

Vector mesons leading-twist longitudinal distribution amplitudes and related semi-leptonic decays within QCD sum rules

Wan-Bing Luo, Ru-Meng Pan, Ya-Xiong Wang et al. (+1 more)

In this work, we focus on the light vector meson leading-twist longitudinal distribution amplitudes (DAs) $\phi^\parallel_{2;V}(x,\mu)$ with $V = \rho, K^\ast, \phi$. A new scheme of QCD sum rule research with respect to DA suggested in 2021 by us is adopted. With an improved sum rule formula, the $\xi$-moments $\langle\xi^n\rangle_{2;V}^\parallel$ up to tenth order are calculated. In which, $\langle\xi^2\rangle^\parallel_{2;\rho}=0.225^{+0.013}_{-0.012}$, $\langle\xi^1\rangle^\parallel_{2;K^\ast}=-0.0228^{+0.0042}_{-0.0040}$, $\langle\xi^2\rangle^\parallel_{2;K^\ast}=0.217^{+0.007}_{-0.007}$, $\langle\xi^2\rangle^\parallel_{2;\phi}=0.209^{+0.020}_{-0.020}$, and the corresponding Gegenbauer moments $a^{2;\parallel}_{2;\rho}=0.074^{+0.039}_{-0.036}$, $a^{1;\parallel}_{2;K^\ast}=-0.038^{+0.007}_{-0.007}$, $a^{2;\parallel}_{2;K^\ast}=0.050^{+0.020}_{-0.019}$, $a^{2;\parallel}_{2;\phi}=0.027^{+0.058}_{-0.058}$ at the scale $\mu = 1~{\rm GeV}$, respectively. By fitting those $\langle\xi^n\rangle^\parallel_{2;V}(n = 1,2,\cdots,10)$ with the least squares method, the behaviors of leading-twist longitudinal DAs for $\rho, K^\ast, \phi$ are determined. In addition, we also analyze the impact of incorporating different numbers of $\xi$-moments into the fitting on the stability and reliability of the obtained DAs. Be different from the pion leading-twist DA, we find that the higher-order moments do not significantly change the reconstructed shapes of $\phi^\parallel_{2;V}(x,\mu)$. Further, we recalculate the transition form factors and branching ratios of the $D\to(\rho,K^\ast)$, $D_s\to\phi$ semi-leptonic decay processes.
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All authors Wan-Bing Luo, Ru-Meng Pan, Ya-Xiong Wang, Tao Zhong

High Energy Physics (Phenomenology)

Analysis of the hidden-charm pentaquark candidates in the $J/\psi \Sigma^*$ mass spectrum via the QCD sum rules

Zhi-Gang Wang and Yang Liu

In this work, we study the diquark-diquark-antiquark type $uusc\bar{c}$ pentaquark states in the light-flavor $\mathbf{10}$ representation via the QCD sum rules in details. We exhaust the lowest five-quark configurations and obtain the spectroscopy of the $uusc\bar{c}$ pentaquark states with the quantum numbers $IJ^{P}=1{\frac{1}{2}}^-$, $1{\frac{3}{2}}^-$, $1{\frac{5}{2}}^-$, and suggest to investigate them in the decay chain $\Sigma_b^+\to P_{cs}^+\,\phi \to J/\psi \Sigma^{*+}\, \phi$ experimentally.
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Mathematical Physics · Cross-listed from math.AP

Finite Potential Energy for Entire Solutions of the Planar Ginzburg–Landau Equation

Hongge Chen, Juncheng Wei, Haicheng Yan et al. (+1 more)

We prove that every smooth entire solution $ u\colon\mathbb{R}^2\to\mathbb{R}^2 $ of the Ginzburg–Landau equation $ -\Delta u=u(1-|u|^2) $ with $ |u(x)|\to1 $ as $ |x|\to\infty $ has finite potential energy, i.e., \begin{equation*} \int_{\mathbb{R}^2}(1-|u|^2)^2 \mathrm{d}x<+\infty, \end{equation*} thereby resolving Brezis' Open Problem 2.5 in [4]. The main difficulty stems from the possible presence of a curl-free mode that carries nonzero circulation and decays only like $ |x|^{-1} $; such a mode lies outside $ L^2 $ and does not admit a single-valued potential. By minimizing over $ L^2 $ gradient corrections, we construct a comparison field that solves the homogeneous equation and inherits the same circulation. The Kelvin inversion, combined with the De Giorgi–Nash–Moser theory for quasilinear elliptic equations, then produces the optimal decay $ O(|x|^{-1}) $. For a Ginzburg–Landau solution, the Bernstein estimate and the coercivity of the Jacobi form produce an $ L^2 $ forcing term in the exterior phase equation. The resulting $ L^4 $ bound on the phase field implies $1-|u|^2\in L^2(\mathbb{R}^2)$, and therefore the potential energy is finite.
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All authors Hongge Chen, Juncheng Wei, Haicheng Yan, Wen Yang

Solar and Stellar Astrophysics

Surrogate models for type II supernovae: Probing low-energy explosions and interaction-free regimes

Zhengyang Zhang, Shuai Zha, Nikhil Sarin et al. (+3 more)

To address the computational bottleneck of analyzing type II supernova samples from surveys such as the Legacy Survey of Space and Time, we present two STELLA-based neural-network surrogates: an interaction model for low-energy explosions with possible circumstellar-material (CSM) interaction and a photospheric model for standard interaction-free SNe IIP. Each uses an autoencoder to compress spectral energy distributions and an emulator to map physical parameters to the latent space. Latent-mixup regularization improves latent-space continuity, with ResNet blocks used for the interaction model and 2D CNNs for the photospheric model. Their normalized test-set reconstruction MSEs are approximately 9.1e-5 and 1.0e-4, respectively. Applied to SN 2005cs, the interaction model favors a low-mass progenitor, M_ZAMS = 10.40(+0.04/-0.05) M_sun, and confined dense CSM, providing a scenario consistent with direct imaging and helping resolve the historical mass discrepancy. For SN 2012aw, it recovers M_ZAMS = 11.05(+0.06/-0.06) M_sun, consistent with previous studies. For SN 1999em, the photospheric model gives M_ZAMS = 10.05(+0.07/-0.04) M_sun, broadly consistent with preexplosion imaging limits without explicit CSM modeling. These surrogates reduce full Bayesian inference from days to minutes and enable rapid physical characterization of large supernova samples.
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All authors Zhengyang Zhang, Shuai Zha, Nikhil Sarin, Takashi J. Moriya, Chengyuan Wu, Bo Wang

Solar and Stellar Astrophysics

Parker Solar Probe Observations of Preferential Heating of Protons over Alpha Particles near Turbulent Coherent Structures

Jiayang Xi, Tieyan Wang, Daniel Verscharen et al. (+15 more)

Solar wind alpha particles exhibit preferential heating and acceleration relative to protons; however, their behavior in the vicinity of turbulent coherent structures remains less understood. We report the first evidence of localized alpha particle and proton heating within coherent structures identified using the Partial Variance of Increments (PVI) method, based on Parker Solar Probe (PSP) observations. Our results show that high-PVI events are associated with significant, species-dependent temperature enhancements: protons undergo a relative larger temperature increase than alpha particles. This preferential proton heating produces a localized decrease in the alpha-to-proton temperature ratio, indicating that the plasma is driven toward thermal equilibration between species. The heating is also anisotropic, being dominated by enhancements in the perpendicular temperature. These temperature-signatures coincide with a pronounced reduction in the normalized alpha-proton differential flow speed and a localized minimum in the Coulomb collision age, suggesting that the relaxation is affected primarily by collisionless kinetic effects. These findings provide new insight into the intermittent energy conversion and ion thermodynamics in the solar wind.
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All authors Jiayang Xi, Tieyan Wang, Daniel Verscharen, Yan Yang, Luca Sorriso-Valvo, Xinyi Wang, Wenhao Chen, Zuzheng Chen, Zeren Zhima, Chao Xiao, Xiangcheng Dong, Jin Liu, Xiang Li, Guoqi Liu, Naifei Gou, Xiaoxiao Qin, Malcolm Dunlop, Jinbin Cao

General Relativity and Quantum Cosmology

Shadow of the generalized Vaidya black hole

Vitalii Vertogradov and Ali Övgün

In this paper, we investigate the shadow of the generalized Vaidya black hole described by the Husain solution. Assuming a barotropic equation of state for the additional matter sector, we first identify the self-similar class admitting a homothetic Killing vector and transform the geometry to a conformally static form. This allows us to derive the effective potential for null geodesics in the conformally static representative, determine the corresponding homothetic photon surface, and then transform the result back to the original generalized Vaidya coordinates. We show that, within the weak-energy-condition branches, the parameter $\alpha$ controlling the equation of state determines whether the shadow is enlarged or reduced relative to the Vaidya case: the branch $0\leq\alpha<1/2$ increases the photon-sphere and shadow radii, whereas the branch $1/2<\alpha\leq 1$ decreases them. We then turn to the genuinely time-dependent Husain metric and derive quasistatic slow-evolution equations for the instantaneous photon surface and critical impact parameter. In particular, we show that the growth or contraction of the shadow is governed by the local effective influx in the photon region rather than by the signs of $\dot M$ and $\dot N$ separately. For the charge-like branch, this yields a transparent criterion for when accretion enlarges the shadow and when rapid charge growth instead causes it to shrink.
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Nuclear Theory

Trace anomaly and isospin splitting in inverse-mapped relativistic mean-field theory

Wen-Jie Xie and Jun-Hua Guo

Trace anomaly and sound speed provide EOS-level probes of dense-matter nonconformality, but do not by themselves identify the microscopic channels responsible for the response. We study this question with a uniform-matter inverse-mapped relativistic mean-field ensemble constrained by chiral effective field theory, heavy-ion flow information, and neutron-star mass-radius data. The ensemble reproduces the flow-based trace trend in symmetric nuclear matter, while beta-equilibrated matter approaches the neutron-star trace bands more slowly. The resulting splitting, \(\Delta_{\SNM}-\Delta_{\betaeq}\), remains positive over \(2--5\nzero\) and is most strongly correlated with the density derivative of the isovector-vector coupling, with bootstrap-stable Spearman coefficients \(r_s\simeq0.91--0.92\) at \(2--3\nzero\). Its correlation with the beta-equilibrium proton fraction is much weaker. The sound-speed splitting changes sign near \(3.38\nzero\), and the derivative term \(-\dd\Delta/\dd\ln\varepsilon\) becomes sensitive to both scalar-vector and isovector responses above \(4\nzero\). Data-combination and controlled-isovector tests show that this channel separation is resolved only when laboratory and astrophysical projections are combined. Thus, within the present inverse-mapped RMF space, the SNM–beta trace splitting acts as a thermodynamic probe of the high-density symmetry sector rather than as a unique signal of exotic degrees of freedom. A finite-nucleus-calibrated extension will be needed to test how much of this channel diagnostic survives in predictive covariant density functionals.
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High Energy Physics (Phenomenology)

Heavy quark mass dependence of the $\Lambda_Q$ light-cone distribution amplitude in QCD

Yu-Ji Shi, Ji Xu and Shuai Zhao

We study the heavy quark mass dependence of the leading-twist light-cone distribution amplitude (LCDA) of the $\Lambda_Q$ baryon in QCD. Starting from the factorization formula that relates the QCD LCDA to the boosted heavy-quark effective theory (bHQET) LCDA, we derive a first-order partial differential equation governing this mass dependence in the peak region. The equation is solved analytically, and the explicit factor connecting LCDAs at different heavy quark masses is presented. We further incorporate Borel-resummed perturbative corrections from a renormalon model into the factorization. The impact of these renormalon corrections on the mass dependence is studied, and a numerical analysis using a simple LCDA model is performed to illustrate the behavior and to assess the uncertainties arising from the corrections, thereby providing a numerical estimate of the associated power corrections to the mass dependence. Our results provide an essential tool for extrapolating lattice QCD calculations of heavy-baryon LCDAs from smaller simulated masses to the physical bottom quark mass.
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Statistical Mechanics · Cross-listed from cs.CC

Local Search with Correlated Randomness

Yunbei Xu

The running-time distribution of a randomized algorithm is computed under independent randomness, but independence is rarely what a source guarantees. We study sources $\nu$ with $\nu[w]\le DP[w]^s$ for every finite prefix $w$ of the tape, where $P$ is an independent reference law, $0<s\le1$, and $D\ge1$; individual choices may be predictable, even determined by the past. The worst-case probability of any closed tape event $E$ is exactly $\min\{1,DC_s(E)\}$, where $C_s(E)$ is the infimum cost of covering $E$ by prefixes of varying depth. This tree max-flow/min-cut identity makes worst-case probabilities exact and optimizable. Three applications follow. In scheduling, $n$ tasks on one machine are each retried until the next random symbol lies in its success set; every schedule has the same makespan distribution under independent randomness, yet under our constraint two fixed orders miss a linear deadline with worst-case probabilities $1$ and $\exp[-\Theta(n)]$, and a static priority rule is optimal at every deadline. For the standard local walk on a $k$-CNF with an assignment satisfying a majority of each clause, we find the sharp source threshold $s_*$: below it, on some instances one admissible source forces nontermination for every clause selection; at it, with fixed $D$, the expected number of flips is at most cubic in the initial distance, against linear under independence, with matching instances at distances up to a constant fraction of the number of variables; a fixed margin above it restores linear dependence. For noisy predecessor search with prefix-bounded comparison errors, verified backtracking attains any prescribed error probability at or above a source threshold whose sharpness we leave open, with the same cubic-to-linear query bounds. Restarting on the shared tape restores exponential tails exactly when the nontermination event has a prefix cover of cost below one.
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Mathematical Physics · Cross-listed from math.AP

Couette Flow with Robin Boundary Condition (I): the viscosity-independent friction

Siming He, Binqian Niu and Weiren Zhao

This article is the first paper in the series. In this series of articles, we will examine the influence of the friction factor $\alpha$ at the solid–fluid boundary on the stability of Couette flow. Specifically, we consider the stability of Couette flow in a bounded periodic channel $\mathbb{T} \times [-1,1]$ under Robin-type boundary conditions ($u^2|_{y=\pm 1} = 0$, $[\alpha \partial_n u^1 + u^1]|_{y=\pm1} = f $), where $\alpha$ is the friction factor and $n$ is the unit outer normal vector. In this article, we prove that for a given friction factor $\alpha$, as long as the fluid viscosity coefficient $\nu\ll \alpha$ is sufficiently small, the system is asymptotically stable if the initial perturbation satisfies $\|\omega_{\rm in}\| \leq \epsilon \nu^{1/3}$. Moreover, inviscid damping and enhanced dissipation hold.
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Quantum Physics

The finite key effect of side-channel-secure quantum key distribution beyond post-selection technique

Cong Jiang, Zong-Wen Yu and Xiang-Bin Wang

By applying the framework of entropic uncertainty relation (EUR) and the Quantum Leftover Hash Lemma (QLHL), we introduce a security-proof method for variable-length side-channel-secure (SCS) quantum key distribution (QKD) against coherent attacks. This method reframes composable security as a statistical fluctuation problem of phase errors, enabling direct proofs against coherent attacks through observables and virtual observables. It yields tight key rates for the SCS protocol and reduces pulse requirements by over two orders of magnitude compared to prior works that employ the post-selection technique. {Utilizing the characteristic of the SCS protocol that it has no untagged-bit bit-flip errors, we prove that the secure key length for the SCS protocol can be determined after Cascade error correction, using its actual parity disclosures. We also explain how the same argument extends to protocols with compatible bit-error-pattern and phase-error measurements.} We further identify sufficient conditions under which the final key length may be determined after error correction in a broader class of QKD protocols. Under the framework of EUR and QLHL, we clarify the applicability of several commonly used concentration bounds to variable-length QKD and the appropriate manner of their implementation. This work enhances the practical value of the SCS protocol and clarifies the security justification of key-rate formulas used in practical variable-length QKD implementations.
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Materials Science

Going Beyond the d-band Center to Design Intermetallic Catalysts for Nitrogen Reduction: A High-Throughput DFT and Machine Learning Study

Parastoo Agharezaei and Kulbir Kaur Ghuman

This study combines high-throughput density functional theory (DFT) calculations with machine learning (ML) to uncover the key descriptors governing the nitrogen reduction reaction in 47 intermetallic compounds (IMCs) composed of Co, Ni, Al, Zn, V, Fe, Cu, and Pt, and the adsorption energies of key intermediates (*N2, *N2H, and *NH3) were systematically evaluated across all accessible surface sites, yielding approximately 1,200 data points. Among the IMCs studied, Fe9Co7 and Fe3Co emerge as the most balanced catalysts, exhibiting favorable adsorption energies across all three intermediates. By incorporating intrinsic material properties along with local and global electronic descriptors including s-, p- and d-band centers and fillings, as well as Bader charges of atoms neighboring the adsorbate, predictive ML models were developed with mean absolute errors (MAEs) of 0.27 eV for *N2, 0.39 eV for *N2H, and 0.17 eV for *NH3 adsorption. Importantly, accurate adsorption-energy predictions were achieved using only 20 key features for *N2H and *NH3 and 38 features for *N2, enabling the use of simple and computationally efficient ML models. SHAP analysis indicates that p-band and s-band characteristics play a more prominent role in determining adsorption strength than the traditionally used d-band center, particularly for *N2. Beyond their established importance in systems containing p-block elements or nearly filled d-band metals, s- and p-orbitals are also found to contribute significantly to transition metal alloy activity such as Fe-Co. By challenging the d-band-centric paradigm and identifying s- and p-band descriptors as critical yet overlooked contributors, this work redefines the electronic descriptor space for intermetallic NRR catalysts and lays the groundwork for DFT-ML-guided discovery of non-noble, compositionally complex materials for sustainable ammonia synthesis.
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