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Coherent-State Approach for Majorana Representation

Communications in Theoretical physics 2017年第6期67卷 611-618页

作者：刘昊迪傅立斌王晓光 Beijing Computational Science Research Center Center for Quantum Sciences and School of Physics Northeast Normal University National Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics Zhejiang Institute of Modern Physics Department of PhysicsZhejiang University

By representing a quantum state and its evolution with the Majorana stars on the Bloch sphere, the Majorana representation provides us an intuitive way to study a physical system with SU(2) symmetry. In this work,based on coherent states, we propose a method to establish the generalization of Majorana representation for a general symmetry. By choosing a generalized coherent state as a reference state, we give a more general Majorana representation for both finite and infinite systems and the corresponding star equations are given. Using this method, we study the squeezed vacuum states for three different symmetries, Heisenberg–Weyl, SU(2) and SU(1,1), and express the effect of squeezing parameter on the distribution of stars. Furthermore, we also study the dynamical evolution of stars for an initial coherent state driven by a nonlinear Hamiltonian, and find that at a special time point, the stars are distributed on two orthogonal large circles.

关键词： majorana representation coherent state squeezed states SU(1,1) symmetry

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A One-Dimensional Discrete Boltzmann Model for Detonation and an Abnormal Detonation Phenomenon

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Communications in Theoretical physics 2019年第1期71卷 117-126页

作者： Yu-Dong Zhang Ai-Guo Xu Guang-Cai Zhang Zhi-Hua Chen Key Laboratory of Transient Physics Nanjing University of Science and Technology Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Center for Applied Physics and Technology MOE Key Center for High Energy Density Physics Simulations College of Engineering Peking University

A one-dimensional discrete Boltzmann model for detonation simulation is presented. Instead of numerical solving Navier-Stokes equations, this model obtains the information of flow field through numerical solving specially discretized Boltzmann equation. Several classical benchmarks including Sod shock wave tube, Colella explosion problem,and one-dimensional self-sustainable stable detonation are simulated to validate the new model. Based on the new model,the influence of negative temperature coefficient of reaction rate on detonation is further investigated. It is found that an abnormal detonation with two wave heads periodically appears under negative temperature coefficient *** causes of the abnormal detonation are analyzed. One typical cycle of the periodic abnormal detonation and its development process are discussed.

关键词： detonation discrete Boltzmann model negative temperature coefficient abnormal detonation

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A conservative local discontinuous Galerkin method for the solution of nonlinear Schrdinger equation in two dimensions

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science China Mathematics 2017年第12期60卷 2515-2530页

作者： ZHANG RongPei YU XiJun LI MingJun LI XiangGui School of Mathematics and Systematic Sciences Shenyang Normal University Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics School of Mathematics and Computational Science Xiangtan University School of Applied Science Beijing Information Science and Technology University

In this study, we present a conservative local discontinuous Galerkin(LDG) method for numerically solving the two-dimensional nonlinear Schrdinger(NLS) equation. The NLS equation is rewritten as a firstorder system and then we construct the LDG formulation with appropriate numerical flux. The mass and energy conserving laws for the semi-discrete formulation can be proved based on different choices of numerical fluxes such as the central, alternative and upwind-based flux. We will propose two kinds of time discretization methods for the semi-discrete formulation. One is based on Crank-Nicolson method and can be proved to preserve the discrete mass and energy conservation. The other one is Krylov implicit integration factor(IIF) method which demands much less computational effort. Various numerical experiments are presented to demonstrate the conservation law of mass and energy, the optimal rates of convergence, and the blow-up phenomenon.

关键词： discontinuous Galerkin method nonlinear Schrdinger equation conservation Krylov implicit integration factor method

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Diabatic error and propagation of Majorana zero modes in interacting Quantum Dots systems

arXiv

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arXiv 2025年

作者： Pandey, Bradraj Gupta, Gaurav Kumar Alvarez, Gonzalo Okamoto, Satoshi Thomale, Ronny Dagotto, Elbio Department of Physics and Astronomy The University of Tennessee KnoxvilleTN37996 United States Materials Science and Technology Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Texas Center for Superconductivity Department of Physics University of Houston HoustonTX77204 United States Computational Sciences and Engineering Division Oak Ridge National Laboratory Oak RidgeTN37831 United States University of Würzburg Am Hubland Deutschland Würzburg97074 Germany

Motivated by recent experimental progress in realizing Majorana zero modes (MZMs) using quantum dot systems, we investigate the diabatic errors associated with the movement of those MZMs. The movement is achieved by tuning time-dependent gate potentials applied to individual quantum dots, effectively creating a moving potential wall. In order to probe the optimized movement of MZMs, we calculate the experimentally accessible time-dependent fidelity and local density-of-states using many-body time-dependent numerical methods. Our analysis reveals that an optimal potential wall height is crucial to preserve the well-localized nature of the MZM during its movement. Moreover, for the first time, we analyze diabatic errors in realistic quantum-dot systems, incorporating the effects of repulsive Coulomb interactions and disorder in both hopping and pairing terms. Additionally, we provide a comparative study of diabatic errors arising from the simultaneous versus sequential tuning of multiple gates during the MZMs movement. Finally, we estimate the time scale required for MZM transfer in a six-quantum-dot system, demonstrating that MZM movement is feasible and can be completed well within the qubit’s operational lifetime in practical quantum-dot setups. © 2025, CC BY-NC-SA.

关键词： Semiconductor quantum dots

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Magnon thermal conductivity in multiferroics with spin cycloids

arXiv

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arXiv 2025年

作者： Park, Hyeon Woo Zhang, Shu Meisenheimer, Peter Ramesh, Maya Husain, Sajid Harris, Isaac Íñiguez-González, Jorge Yao, Zhi Ramesh, Ramamoorthy Kim, Se Kwon Department of Physics Korea Advanced Institute of Science and Technology Daejeon34141 Korea Republic of Institute for Theoretical Solid State Physics IFW Dresden Helmholtzstrasse 20 Dresden01069 Germany Department of Materials Science and Engineering University of California BerkeleyCA94720 United States Department of Materials Science and Engineering Cornell University IthacaNY14853 United States Materials Science Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Department of Physics University of California BerkeleyCA94720 United States Esch-sur-Alzette Luxembourg Department of Physics and Materials Science University of Luxembourg Belvaux Esch-sur-Alzette1511 Luxembourg Applied Mathematics and Computational Research Division Lawrence Berkeley National Laboratory BerkeleyCA94720 United States Departments of Physics and Astronomy and Materials Science and Nano Engineering Rice Advanced Materials Institute Rice University HoustonTX77005 United States

Multiferroic materials, characterized by the occurrence of two or more ferroic properties, hold potential in future technological applications and also exhibit intriguing phenomena caused by the interplay of multiple orders. One such example is the formation of spin cycloid structures within multiferroic materials, which we investigate in this work by focusing on their magnon excitations and transport based on a general multiferroic Hamiltonian with an antiferromagnetic order. More specifically, we identify the ground state and explore the dynamics of magnon modes, revealing distinct in-plane and out-of-plane modes with anisotropic dispersion relations. The magnon modes include a massless excitation, known as the Goldstone boson, originating from the spontaneous breaking of the translational symmetry by the formation of the cycloid structures. By employing the Boltzmann transport formalism, the magnonic thermal conductivity with spin cycloids and low-temperature anisotropic behaviors is discussed. This work provides pathways to envision the spin-textured multiferroics, which may serve as a fertile ground to look for novel thermal and spin transport with the rich interplay of quasiparticles such as magnons and phonons. Copyright © 2025, The Authors. All rights reserved.

关键词： Anisotropy

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Machine learning interatomic potential for irradiation damage simulations of ZrC

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Journal of Materials science & technology 2025年

作者： Chang-jie Ding Xiao-yang Wang Xiang-yan Li Wei-shu Yang Xiao-lin Li Yan-ge Zhang Yi-chun Xu Chang-song Liu Xuebang Wu Institute of Solid State Physics Hefei Institutes of Physical Science Chinese Academy of Sciences Hefei 230031 China University of Science and Technology of China Hefei 230026 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China

Molecular dynamics simulation of irradiation damage is critical for understanding microstructural evolution and defect formation in zirconium carbide (ZrC). However, the absence of a suitable interatomic potential remains a challenge. Here, we develop a precise deep-neural-network based machine learning interatomic potential tailored for investigating irradiation damage in ZrC. Our model accurately reproduces the energetics and kinetics of native point defects, thermodynamics properties, surface energies, and generalized stacking fault energies. We further explore collision cascades spanning a range of primary knock-on atom energies (from 1 keV to 40 keV), types (C and Zr), and directions (<100>, <010>, and <111>) at 300 K. The results reveal carbon interstitial atoms and vacancies as the dominant point defects, consistent with first-principles calculations, with the notable formation of carbon-rich clusters within collision cascades. These carbon-rich defect clusters, resembling “black-dot” structures in experimental observations, emerge directly in collision cascades and remain thermodynamically stable at low temperatures due to the low mobility of Zr interstitial atoms. In contrast to the absence of dislocation loops in the collision cascade simulations, our results suggest a thermally-driven mechanism for the formation and transformation of 1/3 <111> and 1/2 <110> dislocation loops. This work enriches our understanding of the irradiation damage mechanism in ZrC and other carbide ceramics.

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Qudit Dynamical Decoupling on a Superconducting Quantum Processor

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Physical Review Letters 2025年第5期134卷 050601-050601页

作者： Vinay Tripathi Noah Goss Arian Vezvaee Long B. Nguyen Irfan Siddiqi Daniel A. Lidar Department of Physics and Astronomy University of Southern California Los Angeles California 90089 USA Center for Quantum Information Science and Technology University of Southern California Los Angeles California 90089 USA Quantum Nanoelectronics Laboratory Department of Physics University of California at Berkeley Berkeley California 94720 USA Applied Math and Computational Research Division Lawrence Berkeley National Lab Berkeley California 94720 USA Department of Electrical and Computer Engineering University of Southern California Los Angeles California 90089 USA Department of Chemistry University of Southern California Los Angeles California 90089 USA

Multilevel qudit systems are increasingly being explored as alternatives to traditional qubit systems due to their denser information storage and processing potential. However, qudits are more susceptible to decoherence than qubits due to increased loss channels, noise sensitivity, and crosstalk. To address these challenges, we develop protocols for dynamical decoupling (DD) of qudit systems based on the Heisenberg-Weyl group. We implement and experimentally verify these DD protocols on a superconducting transmon processor that supports qudit operation based on qutrits (d=3) and ququarts (d=4). Specifically, we demonstrate single-qudit DD sequences to decouple qutrits and ququarts from system-bath-induced decoherence. We also introduce two-qudit DD sequences designed to suppress the detrimental cross-Kerr couplings between coupled qudits. This allows us to demonstrate a significant improvement in the fidelity of time-evolved qutrit Bell states. Our results highlight the utility of leveraging DD to enable scalable qudit-based quantum computing.

关键词： Qubits

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First-principle study of Mg adsorption on Si(111) surfaces

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Chinese physics B 2009年第1期18卷 275-281页

作者：英敏菊张平杜小龙 The Key Laboratory of Beam Technology and Material Modification of Ministry of Education Beijing Normal University College of Nuclear Science and Technology Beijing Normal University Beijing Radiation Center Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of Sciences

We have carried out first-principle calculations of Mg adsorption on Si（111） surfaces. Different adsorption sites and coverage effects have been considered. We found that the threefold hollow adsorption is energy-favoured in each coverage considered, while for the clean Si（111） surface of metallic feature, we found that 0.25 and 0.5 ML Mg adsorption leads to a semiconducting surface. The results for the electronic behaviour suggest a polarized covalent bonding between the Mg adatom and Si（111） surface.

关键词： electronic materials electronic structure

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Coulomb effects in photon-momentum partitioning during atomic ionization by intense linearly polarized light

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Physical Review A 2013年第4期87卷 041403(R)-041403(R)页

作者： J. Liu Q. Z. Xia J. F. Tao L. B. Fu National Laboratory of Science and Technology on Computational Physics Institute of Applied Physics and Computational Mathematics Beijing 100088 China HEDPS Center for Applied Physics and Technology Peking University Beijing 100084 China

Partitioning of photon momenta between the ion and electron in photoionization and the involved subcycle dynamics are investigated using an extended semiclassical model, where momentum transfer from the photon to the electron-ion system via the (magnetic) Lorentz force is taken into account. It is found that in both the tunneling and rescattering processes, Coulomb attraction between the ion and electron plays a role in the momentum partitioning. The effect is especially important for linearly polarized light since the photons that lift the electron out of the bound state do not always contribute to the forward ion momentum. The present results can have important implications in the generation of terahertz radiation and the calibration of tunnel exit by measuring final ion longitudinal momentum.

关键词： PHOTONS IONIZATION (Atomic physics) LINEAR systems OPTICAL polarization MOMENTUM transfer BOUND states (Quantum mechanics)

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ABACUS: An Electronic Structure Analysis Package for the AI Era

arXiv

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arXiv 2025年

作者： Zhou, Weiqing Zheng, Daye Liu, Qianrui Lu, Denghui Liu, Yu Lin, Peize Huang, Yike Peng, Xingliang Bao, Jie J. Cai, Chun Jin, Zuxin Wu, Jing Zhang, Haochong Jin, Gan Ji, Yuyang Shen, Zhenxiong Liu, Xiaohui Sun, Liang Cao, Yu Sun, Menglin Liu, Jianchuan Chen, Tao Liu, Renxi Li, Yuanbo Han, Haozhi Liang, Xinyuan Bao, Taoni Chen, Nuo Ren, Hongxu Zhang, Xiaoyang Liu, Zhaoqing Fu, Yiwei Liu, Maochang Li, Zhuoyuan Wen, Tongqi Tang, Zechen Xu, Yong Duan, Wenhui Wang, Xiaoyang Gu, Qiangqiang Dai, Fu-Zhi Zheng, Qijing Zhao, Jin Zhang, Yuzhi Ou, Qi Jiang, Hong Liu, Shi Xu, Ben Xu, Shenzhen Ren, Xinguo He, Lixin Zhang, Linfeng Chen, Mohan AI for Science Institute Beijing100080 China HEDPS CAPT School of Physics College of Engineering Peking University Beijing100871 China College of Engineering Peking University Beijing100871 China Institute of Artificial Intelligence Hefei Comprehensive National Science Center Hefei230026 China Key Laboratory of Quantum Information University of Science and Technology of China Hefei230026 China Supercomputing Center University of Science and Technology of China Anhui Hefei230026 China Institute of Physics Chinese Academy of Sciences Beijing100190 China School of Materials Science and Engineering Peking University Beijing100871 China School of Electrical Engineering and Electronic Information Xihua University Chengdu610039 China Academy for Advanced Interdisciplinary Studies Peking University Beijing100871 China College of Chemistry and Molecular Engineering Peking University Beijing100871 China International Research Center for Renewable Energy State Key Laboratory of Multiphase Flow Xi’an Jiaotong University Shaanxi Xi’an710049 China Suzhou Academy of Xi’an Jiaotong University Jiangsu Suzhou215123 China Center for Structural Materials Department of Mechanical Engineering The University of Hong Kong Hong Kong The University of Hong Kong Shenzhen China State Key Laboratory of Low Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China Frontier Science Center for Quantum Information Beijing China Saitama Wako351-0198 Japan Institute for Advanced Study Tsinghua University Beijing100084 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Fenghao East Road 2 Beijing100094 China School of Artificial Intelligence and Data Science University of Science and Technology of China Hefei230026 China School of Materials Science and Engineering University of Science and Technology Beijing Beijing100083 China Department of Physics University of Science and

ABACUS (Atomic-orbital Based Ab-initio Computation at USTC) is an open-source software for first-principles electronic structure calculations and molecular dynamics simulations. It mainly features density functional theory (DFT) and is compatible with both plane-wave basis sets and numerical atomic orbital basis sets. ABACUS serves as a platform that facilitates the integration of various electronic structure methods, such as Kohn-Sham DFT, stochastic DFT, orbital-free DFT, and real-time time-dependent DFT, etc. In addition, with the aid of high-performance computing, ABACUS is designed to perform efficiently and provide massive amounts of first-principles data for generating general-purpose machine learning potentials, such as DPA models. Furthermore, ABACUS serves as an electronic structure platform that interfaces with several AI-assisted algorithms and packages, such as DeePKS-kit, DeePMD, DP-GEN, DeepH, DeePTB, etc. Copyright © 2025, The Authors. All rights reserved.

关键词： Stochastic systems

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