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arXiv 2023年

作者： Yang, Teng Cai, Zefeng Huang, Zhengtao Tang, Wenlong Shi, Ruosong Godfrey, Andy Liu, Hanxing Lin, Yuanhua Nan, Ce-Wen Ye, Meng Zhang, LinFeng Wang, Han Xu, Ben Graduate School of China Academy of Engineering Physics Beijing100088 China School of Materials Science and Engineering Tsinghua University Beijing100084 China International School of Materials Science and Engineering Wuhan University of Technology Wuhan430070 China AI for Science Institute Beijing100080 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Fenghao East Road 2 Beijing100094 China HEDPS CAPT College of Engineering Peking University Beijing100871 China

Atomistic simulations hold significant value in clarifying crucial phenomena such as phase transitions and energy transport in materials science. Their success stems from the presence of potential energy functions capable of accurately depicting the relationship between system energy and lattice changes. In magnetic materials, two atomic scale degrees of freedom come into play: the lattice and the spin. However, accurately tracing the simultaneous evolution of both lattice and spin in magnetic materials at an atomic scale is a substantial challenge. This is largely due to the complexity involved in depicting the interaction energy precisely, and its influence on lattice and spin-driving forces, such as atomic force and magnetic torque, which continues to be a daunting task in computational science. Addressing this deficit, we present DeepSPIN, a versatile approach that generates high-precision predictive models of energy, atomic forces, and magnetic torque in magnetic systems. This is achieved by integrating first-principles calculations of magnetic excited states with deep learning techniques via active learning. We thoroughly explore the methodology, accuracy, and scalability of our proposed model in this paper. Our technique adeptly connects first-principles computations and atomic-scale simulations of magnetic materials. This synergy presents opportunities to utilize these calculations in devising and tackling theoretical and practical obstacles concerning magnetic materials. Copyright © 2023, The Authors. All rights reserved.

关键词： Degrees of freedom (mechanics)

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Target Density Effects on Charge Transfer of Laser-Accelerated Carbon Ions in Dense Plasma

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Physical Review Letters 2023年第9期130卷 095101-095101页

作者： Jieru Ren Bubo Ma Lirong Liu Wenqing Wei Benzheng Chen Shizheng Zhang Hao Xu Zhongmin Hu Fangfang Li Xing Wang Shuai Yin Jianhua Feng Xianming Zhou Yifang Gao Yuan Li Xiaohua Shi Jianxing Li Xueguang Ren Zhongfeng Xu Zhigang Deng Wei Qi Shaoyi Wang Quanping Fan Bo Cui Weiwu Wang Zongqiang Yuan Jian Teng Yuchi Wu Zhurong Cao Zongqing Zhao Yuqiu Gu Leifeng Cao Shaoping Zhu Rui Cheng Yu Lei Zhao Wang Zexian Zhou Guoqing Xiao Hongwei Zhao Dieter H. H. Hoffmann Weimin Zhou Yongtao Zhao MOE Key Laboratory for Nonequilibrium Synthesis and Modulation of Condensed Matter School of Physics Xi’an Jiaotong University Xi’an 710049 China Science and Technology on Plasma Physics Laboratory Laser Fusion Research Center China Academy of Engineering Physics Mianyang 621900 China Advanced Materials Testing Technology Research Center Shenzhen University of Technology Shenzhen 518118 China Institute of Applied Physics and Computational Mathematics Beijing 100094 China Graduate School China Academy of Engineering Physics Beijing 100088 China Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China School of Nuclear Science and Technology University of Chinese Academy Sciences Beijing 101408 China

We report on charge state measurements of laser-accelerated carbon ions in the energy range of several MeV penetrating a dense partially ionized plasma. The plasma was generated by irradiation of a foam target with laser-induced hohlraum radiation in the soft x-ray regime. We use the tricellulose acetate (C9H16O8) foam of 2 mg/cm3 density and 1 mm interaction length as target material. This kind of plasma is advantageous for high-precision measurements, due to good uniformity and long lifetime compared to the ion pulse length and the interaction duration. We diagnose the plasma parameters to be Te=17 eV and ne=4×1020 cm−3. We observe the average charge states passing through the plasma to be higher than those predicted by the commonly used semiempirical formula. Through solving the rate equations, we attribute the enhancement to the target density effects, which will increase the ionization rates on one hand and reduce the electron capture rates on the other hand. The underlying physics is actually the balancing of the lifetime of excited states versus the collisional frequency. In previous measurement with partially ionized plasma from gas discharge and z pinch to laser direct irradiation, no target density effects were ever demonstrated. For the first time, we are able to experimentally prove that target density effects start to play a significant role in plasma near the critical density of Nd-glass laser radiation. The finding is important for heavy ion beam driven high-energy-density physics and fast ignitions. The method provides a new approach to precisely address the beam-plasma interaction issues with high-intensity short-pulse lasers in dense plasma regimes.

关键词： Electronic excitation & ionization High-energy-density plasmas Plasma fusion Plasma-beam interactions laboratory plasma Near-critical & underdense plasmas Ab initio molecular dynamics First-principles calculations in plasma physics Particle plasma measurements

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Multi-Scale Electromagnetic Simulation Through Parallel Adaptive Mesh Refinement FDTD Method with Symmetric Positive Semi-Definite Subgridding Scheme

Multi-Scale Electromagnetic Simulation Through Parallel Adap...

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International applied computational Electromagnetics Society Symposium (ACES)

作者： Hanyu Li Haijing Zhou Xianfeng Bao Xiaojie Chen School of Physical Science and Technology Southwest Jiaotong University Chengdu China Institute of Applied Physics and Computational Mathematics Beijing China Software Center for High Performance Numerical Simulation CAEP Beijing China

FDTD method is a common approach for electromagnetic propagation, scattering and coupling simulation. Conventional FDTD with universal mesh requires numerous computations to represent solve problems with multi-scale structures. In this paper, adaptive mesh refinement (AMR) strategy is performed to reduce the calculations along with symmetric positive semi-definite subgridding scheme to guarantee stability. Numerical example of a missile seeker coupling simulation shows that the computation time decrease down to 2% while preserving excellent precision.

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Sumanene monolayer of pure carbon: a two-dimensional Kagome-analogy lattice with desirable band gap, ultrahigh carrier mobility and strong exciton binding energy

arXiv

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arXiv 2023年

作者： Shi, Xiaoran Gao, Weiwei Liu, Hongsheng Fu, Zhen-Guo Zhang, Gang Zhang, Yong-Wei Gao, Junfeng Zhao, Jijun Key Laboratory of Materials Modification by Laser Ion and Electron Beams Dalian University of Technology Ministry of Education Dalian116024 China Institute of Applied Physics and Computational Mathematics Beijing100088 China Institute of High Performance Computing A*STAR Singapore138632 Singapore

Design and synthesis of novel two-dimensional (2D) materials that possess robust structural stability and unusual physical properties may open up enormous opportunities for device and engineering applications. Herein we propose a 2D sumanene lattice that be regarded as a derivative of the conventional Kagome lattice. Our tight-binding analysis demonstrates sumanene lattice contains two sets of Dirac cones and two sets of flat bands near the Fermi surface, distinctively different from the Kagome lattice. Using first-principles calculations, we theoretically suggest two possible routines for realization of stable 2D sumanene monolayers (named as α phase and β phase), and α-sumanene monolayer can be experimentally synthesized with chemical vapor deposition using C21H12 as a precursor. Small binding energies on Au(111) surface (e.g. -37.86 eV/Å2 for α phase) signify the possibility of their peel-off after grown on the noble metal substrate. Importantly, our GW plus Bethe-Salpeter equation calculations demonstrate both monolayers have moderate band gaps (1.94 eV for α) and ultrahigh carrier mobilities (3.4×104 cm2V−1s−1 for α). In particular, αsumanene monolayer possesses a strong exciton binding energy of 0.73 eV, suggesting potential applications in optics. Copyright © 2023, The Authors. All rights reserved.

关键词： Monolayers

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Unscreened forces in the quark-gluon plasma?

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Physical Review D 2024年第7期109卷 074504-074504页

作者： Alexei Bazavov Daniel Hoying Rasmus N. Larsen Swagato Mukherjee Peter Petreczky Alexander Rothkopf Johannes Heinrich Weber Department of Computational Mathematics Science and Engineering and Department of Physics and Astronomy Michigan State University East Lansing Michigan 48824 USA Albert Einstein Center Institute for Theoretical Physics University of Bern CH-3012 Bern Switzerland Department of Mathematics and Physics University of Stavanger 4021 Stavanger Norway Physics Department Brookhaven National Laboratory Upton New York 11973 USA Institut für Physik and IRIS Adlershof Humboldt-Universität zu Berlin D-12489 Berlin Germany

We study the correlator of temporal Wilson lines at nonzero temperature in 2+1 flavor lattice QCD with the aim to define the heavy quark-antiquark potential at nonzero temperature. For temperatures 153 MeV≤T≤352 MeV the spectral representation of this correlator is consistent with a broadened peak in the spectral function, position, or width of which then defines the real or imaginary parts of the heavy quark-antiquark potential at nonzero temperature, respectively. We find that the potential’s real part is not screened contrary to the widely held expectations. We comment on how this fact may modify the picture of quarkonium melting in the quark-gluon plasma.

关键词： Color confinement Heavy quark effective theory Lattice QCD Quark-gluon plasma Lattice field theory

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Stimulated Emission of Signal Photons from Dark Matter Waves

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Physical Review Letters 2024年第14期132卷 140801-140801页

作者： Ankur Agrawal Akash V. Dixit Tanay Roy Srivatsan Chakram Kevin He Ravi K. Naik David I. Schuster Aaron Chou James Franck Institute University of Chicago Chicago Illinois 60637 USA Department of Physics University of Chicago Chicago Illinois 60637 USA Kavli Institute for Cosmological Physics University of Chicago Chicago Illinois 60637 USA Department of Physics and Astronomy Rutgers University Piscataway New Jersey 08854 USA Computational Research Division Lawrence Berkeley National Laboratory Berkeley California 94720 USA Pritzker School of Molecular Engineering University of Chicago Chicago Illinois 60637 USA Department of Applied Physics Stanford University Stanford California 94305 USA Fermi National Accelerator Laboratory Batavia Illinois 60510 USA

The manipulation of quantum states of light has resulted in significant advancements in both dark matter searches and gravitational wave detectors. Current dark matter searches operating in the microwave frequency range use nearly quantum-limited amplifiers. Future high frequency searches will use photon counting techniques to evade the standard quantum limit. We present a signal enhancement technique that utilizes a superconducting qubit to prepare a superconducting microwave cavity in a nonclassical Fock state and stimulate the emission of a photon from a dark matter wave. By initializing the cavity in an |n=4⟩ Fock state, we demonstrate a quantum enhancement technique that increases the signal photon rate and hence also the dark matter scan rate each by a factor of 2.78. Using this technique, we conduct a dark photon search in a band around 5.965 GHz (24.67 μeV), where the kinetic mixing angle ε≥4.35×10−13 is excluded at the 90% confidence level.

关键词： Dark matter Machine learning Particle dark matter Quantum circuits Quantum coherence & coherence measures Quantum control Quantum feedback Quantum measurements Quantum metrology Quantum protocols Quantum state transfer Weak values & weak measurements

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Thermalization dynamics in photonic lattices of different geometries

arXiv

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arXiv 2024年

作者： Yang, Guowen Bongiovanni, Domenico Song, Daohong Morandotti, Roberto Chen, Zhigang Efremidis, Nikolaos K. MOE Key Laboratory of Weak-Light Nonlinear Photonics TEDA Applied Physics Institute School of Physics Nankai University Tianjin300457 China INRS-EMT 1650 Blvd. Lionel-Boulet VarennesQCJ3X 1S2 Canada Collaborative Innovation Center of Extreme Optics Shanxi University Shanxi Taiyuan030006 China Department of Mathematics and Applied Mathematics University of Crete Crete Heraklion70013 Greece Institute of Applied and Computational Mathematics FORTH Crete Heraklion70013 Greece

The statistical mechanical behavior of weakly nonlinear multimoded optical settings is attracting increased interest during the last few years. The main purpose of this work is to numerically investigate the main factors that affect the thermalization process in photonic lattices. In particular, we find that lattices with identically selected properties (such as temperature, coupling coefficient, lattice size, and excitation conditions) can exhibit very different thermalization dynamics and thus thermalization distances. Our investigation is focused on two different two-dimensional lattices: the honeycomb lattice and the triangular lattice. Our numerical results show that, independently of the excitation conditions, the honeycomb lattice always thermalizes faster than the triangular lattice. We mainly explain this behavior to the quasilinear spectrum that promotes wave-mixing in the honeycomb lattice in comparison to the power-like spectrum of the triangular lattice. In addition, we investigate the combined effects of temperature as well as the sign and magnitude of the nonlinearity. Switching either the sign of the Kerr nonlinear coefficient or the sign of the temperature can lead to significant differences in the thermalization dynamics, a phenomenon that can be physically explained in terms of wave instabilities. Larger absolute values of the temperature |T| result in more uniform distributions for the power occupation numbers and faster thermalization speeds. Finally, as expected, increasing the magnitude of the nonlinearity results in accelerated thermalization. Our findings provide valuable insights into optical thermalization in discrete systems where experimental realization may bring about new possibilities for light manipulation and applications. Copyright © 2024, The Authors. All rights reserved.

关键词： Optical lattices

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Development of a Hybrid Parallelism Monte Carlo Transport Middleware on Mesh Geometry

SSRN

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SSRN 2023年

作者： Wang, Xin Yu, Yi Li, Xunzhao Feng, Jingchao Zhang, Baoyin Yan, Congchong Fu, Yuanguang Xu, Jingjie CAEP Software Center for High Performance Numerical Simulation Beijing100088 China Institute of Applied Physics and Computational Mathematics Beijing100088 China University of Nevada Las Vegas89154 United States

Mesh-based Monte Carlo particle transport is suitable for complex geometry modeling and for multi-physics coupling calculations. Parallel computing is crucial because Mesh-based Monte Carlo transport requires a quite large amount of computation and memory space. In this study, a hybrid parallelism Monte Carlo transport middleware on mesh geometry was developed. The middleware provides the capability of hybrid parallelism of domain decomposition and particle parallelism, and implements efficient particle tracking method. Base on the middleware, the serial particle tracking efficiency of JMCT was 6.56 times as high as that of MCNP6 in the calculation of an unstructured mesh model. The parallel efficiency of domain decomposition was higher than that of JMCT based on CSG. In the calculations of shielding problem of the Qinshan No. 1 reactor, the results were in good agreement with the experimental data, and the hybrid parallel efficiencies were higher than 65% on 4000 CPU cores. © 2023, The Authors. All rights reserved.

关键词： Middleware

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Hilbert band complexes and their applications

arXiv

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arXiv 2024年

作者： Zhang, Zeying Zhao, Y.X. Yao, Yugui Yang, Shengyuan A. College of Mathematics and Physics Beijing University of Chemical Technology Beijing100029 China Department of Physics HKU-UCAS Joint Institute for Theoretical and Computational Physics at Hong Kong The University of Hong Kong Pokfulam Road Hong Kong Beijing Institute of Technology Beijing100081 China Research Laboratory for Quantum Materials IAPME FST University of Macau Macau China

The study of band connectivity is a fundamental problem in condensed matter physics. Here, we develop a new method for analyzing band connectivity, which completely solves the outstanding questions of the reducibility and decomposition of band complexes. By translating the symmetry conditions into a set of band balance equations, we show that all possible band structure solutions can be described by a positive affine monoid structure, which has a unique minimal set of generators, called Hilbert basis. We show that Hilbert basis completely determine whether a band complex is reducible and how it can be decomposed. The band complexes corresponding to Hilbert basis vectors, termed as Hilbert band complexes (HBCs), can be regarded as elementary building blocks of band structures. We develop algorithms to construct HBCs, analyze their graph features, and merge them into large complexes. We find some interesting examples, such as HBCs corresponding to complete bipartite graphs, and complexes which can grow without bound by successively merging a HBC. Copyright © 2024, The Authors. All rights reserved.

关键词： Graph theory

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A Chemical Compiler for the Synthesis of Branched Oligomers on Standardized Chemical Reaction Structures

A Chemical Compiler for the Synthesis of Branched Oligomers ...

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Conference on Artificial Life, ALIFE 2023

作者： Weyland, Mathias S. Flumini, Dandolo Schneider, Johannes J. Faggian, Alessia Diaz, Aitor Patiño Füchslin, Rudolf M. Institute of Applied Mathematics and Physics School of Engineering Winterthur8401 Switzerland Laboratory for Artificial Biology Dept. of Cellular Computational and Integrative Biology University of Trento Povo 38123 Italy European Centre for Living Technology Venice30124 Italy

This research paper presents a chemical compiler developed to find optimal configurations of a platform for synthesizing specific branched oligomers in an artificial chemistry, along with exemplary compiler output and benchmarks where the platform configuration suggested by the compiler is compared to other configurations in simulation. The compiler operates as a pipeline with two stages: labelling and optimization. The report explains the structure of the compiler target and its interpretation, followed by a code walk-through of the compiler stages with code snippets and examples. The compiler can be used as a code generator for reactions in a chemical simulator and to derive loading schemes for multilevel droplets. The results obtained in simulations suggest that the container system can efficiently optimize the yield of coupled reaction networks and that multi-level droplets can lead to significant improvements. © 2023, Massachusetts institute of Technology. All rights reserved.

关键词： Synthesis (chemical)

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