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Many-body localization in a non-Hermitian quasiperiodic system

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Physical Review B 2020年第6期102卷 064206-064206页

作者： Liang-Jun Zhai Shuai Yin Guang-Yao Huang The School of Mathematics and Physics Jiangsu University of Technology Changzhou 213001 China School of Physics Sun Yat-Sen University Guangzhou 510275 China Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha 410073 China

In the present study, the interplay among interaction, topology, quasiperiodicity, and non-Hermiticity is studied. The hard-core bosons model on a one-dimensional lattice with asymmetry hoppings and quasiperiodic onsite potentials is selected. This model, which preserves time-reversal symmetry (TRS), will exhibit three types of phase transition: Real-complex transition of eigenenergies, topological phase transition, and many-body localization (MBL) phase transition. For the real-complex transition, it is found that the imaginary parts of the eigenenergies are always suppressed by the MBL. Moreover, by calculating the winding number, a topological phase transition can be revealed with the increase of potential amplitude, and we find that the behavior is quite different from the single-particle systems. Based on our numerical results, we conjecture that these three types of phase transition occur at the same point in the thermodynamic limit, and the MBL transition of quasiperiodic system and disordered system should belong to different universality classes. Finally, we demonstrate that these phase transitions can profoundly affect the dynamics of the non-Hermitian many-body system.

关键词： Phase transitions Quantum phase transitions Topological phase transition Topological phases of matter

Precise learning of source code contextual semantics via hierarchical dependence structure and graph attention networks

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arXiv 2021年

作者： Zhao, Zhehao Yang, Bo Li, Ge Liu, Huai Jin, Zhi Key Laboratory of High Confidence Software Technologies Peking University Beijing100871 China School of Information Science and Technology Beijing Forestry University Beijing100083 China Department of Computing Technologies Swinburne University of Technology HawthornVIC3122 Australia

Deep learning is being used extensively in a variety of software engineering tasks, e.g., program classification and defect prediction. Although the technique eliminates the required process of feature engineering, the construction of source code model significantly affects the performance on those tasks. Most recent works was mainly focused on complementing AST-based source code models by introducing contextual dependencies extracted from CFG. However, all of them pay little attention to the representation of basic blocks, which are the basis of contextual dependencies. In this paper, we integrated AST and CFG and proposed a novel source code model embedded with hierarchical dependencies. Based on that, we also designed a neural network that depends on the graph attention mechanism. Specifically, we introduced the syntactic structural of the basic block, i.e., its corresponding AST, in source code model to provide sufficient information and fill the gap. We have evaluated this model on three practical software engineering tasks and compared it with other state-of-the-art methods. The results show that our model can significantly improve the performance. For example, compared to the best performing baseline, our model reduces the scale of parameters by 50% and achieves 4% improvement on accuracy on program classification task. © 2021, CC BY.

关键词： Semantics

Genetic algorithm based hyper-parameters optimization for transfer convolutional neural network

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arXiv 2021年

作者： Li, Chen Jiang, JinZhe Zhao, YaQian Li, RenGang Wang, EnDong Zhang, Xin Zhao, Kun State Key Laboratory of High-end Server & Storage Technology Beijing100085 China Inspur Group Co. Ltd Beijing100085 China Shandong Hailiang Information Technology Institutes Jinan250014 China State Key Laboratory of High-End Server & Storage Technology Jinan250014 China Inspur Electronic Information Industry Co. Ltd Jinan250014 China Guangdong Inspur Intelligent Computing Technology Co. Ltd Guangzhou510000 China

Hyperparameter optimization is a challenging problem in developing deep neural networks. Decision of transfer layers and trainable layers is a major task for design of the transfer convolutional neural networks (CNN). Conventional transfer CNN models are usually manually designed based on intuition. In this paper, a genetic algorithm is applied to select trainable layers of the transfer model. The filter criterion is constructed by accuracy and the counts of the trainable layers. The results show that the method is competent in this task. The system will converge with a precision of 97% in the classification of Cats and Dogs datasets, in no more than 15 generations. Moreover, backward inference according the results of the genetic algorithm shows that our method can capture the gradient features in network layers, which plays a part on understanding of the transfer AI models. Copyright © 2021, The Authors. All rights reserved.

关键词： Genetic algorithms

Giant domain wall anomalous Hall effect in an antiferromagnet

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arXiv 2023年

作者： Xia, Wei Bai, Bo Chen, Xuejiao Yang, Yichen Zhang, Yang Yuan, Jian Li, Qiang Yang, Kunya Liu, Xiangqi Shi, Yang Ma, Haiyang Yang, Huali He, Mingquan Li, Lei Xi, Chuanying Pi, Li Lv, Xiaodong Wang, Xia Liu, Xuerong Li, Shiyan Zhou, Xiaodong Liu, Jianpeng Chen, Yulin Shen, Jian Shen, Dawei Zhong, Zhicheng Wang, Wenbo Guo, Yanfeng School of Physical Science and Technology ShanghaiTech University Shanghai201210 China CAS Key Laboratory of Magnetic Materials Devices Zhejiang Province Key Laboratory of Magnetic Materials and Application Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Sciences Ningbo315201 China State Key Laboratory of Functional Materials for Informatics Shanghai Institute of Microsystem and Information Technology Chinese Academy of Sciences Shanghai200050 China State Key Laboratory of Surface Physics Department of Physics Fudan University Shanghai200433 China Low Temperature Physics Lab College of Physics Center of Quantum Materials and Devices Chongqing University Chongqing401331 China Xi’an Institute of Biomedical Materials & Engineering Northwestern Polytechnical University Xi’an710072 China Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory of the Chinese Academy of Sciences Anhui Hefei230031 China ShanghaiTech Laboratory for Topological Physics ShanghaiTech University Shanghai201210 China College of Physics and Electronic Information Inner Mongolia Normal University 81 Zhaowuda Road Inner Mongolia Hohhot010022 China Analytical Instrumentation Center School of Physical Science and Technology ShanghaiTech University Shanghai201210 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Clarendon Laboratory Department of Physics University of Oxford OxfordOX1 3PU United Kingdom National Synchrotron Radiation Laboratory University of Science and Technology of China 42 South Hezuohua Road Anhui Hefei230029 China

Generally, the dissipationless Hall effect in solids requires time-reversal symmetry breaking (TRSB), where TRSB induced by external magnetic field results in ordinary Hall effect, while TRSB caused by spontaneous magnetization gives rise to anomalous Hall effect (AHE) which scales with the net magnetization. The AHE is therefore not expected in antiferromagnets with vanishing small magnetization. However, large AHE was recently observed in certain antiferromagnets with noncolinear spin structure and nonvanishing Berry curvature. Here, we report another origin of AHE in a layered antiferromagnet EuAl2Si2, namely the domain wall (DW) skew scattering with Weyl points near the Fermi level, in experiments for the first time. Interestingly, the DWs form a unique periodic stripe structure with controllable periodicity by external magnetic field, which decreases nearly monotonically from 975 nm at 0 T to 232 nm at 4 T. Electrons incident on DW with topological bound states experience strong asymmetric scattering, leading to a giant AHE, with the DW Hall conductivity (DWHC) at 2 K and 1.2 T reaching a record value of ∼1.51×104 S cm-1 among bulk systems and being two orders of magnitude larger than the intrinsic anomalous Hall conductivity. The observation not only sets a new paradigm for exploration of large anomalous Hall effect, but also provides potential applications in spintronic devices. © 2023, CC BY.

关键词： Hall effect

Quingo: A programming framework for heterogeneous quantum-classical computing with NISQ features

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arXiv 2020年

作者： Fu, Xiang Yu, Jintao Su, Xing Jiang, Hanru Wu, Hua Cheng, Fucheng Deng, Xi Zhang, Jinrong Jin, Lei Yang, Yihang Xu, Le Hu, Chunchao Huang, Anqi Huang, Guangyao Qiang, Xiaogang Deng, Mingtang Xu, Ping Xu, Weixia Liu, Wanwei Zhang, Yu Deng, Yuxin Wu, Junjie Feng, Yuan Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou450001 China College of Computer National University of Defense Technology Changsha410073 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518055 China Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai200062 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518055 China School of Information Engineering Zhengzhou University Zhengzhou450001 China Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China Department of Computing Science College of Computer National University of Defense Technology Changsha410073 China School of Computer Science and Technology University of Science and Technology of China Hefei230027 China Shanghai Key Laboratory of Trustworthy Computing East China Normal University Shanghai200062 China Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China Centre for Quantum Software and Information University of Technology Sydney Sydney2007 Australia

Completely polarized eg orbitals realized in d7−Ni3+ based heterointerface

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Physical Review Materials 2020年第12期4卷 124804-124804页

作者： Ce Ji Gang Wu Shuowang Yang Xiaoping Yang Anhui Province Key Laboratory of Condensed Matter Physics at Extreme Conditions High Magnetic Field Laboratory Chinese Academy of Sciences Hefei 230031 China Science Island Branch of Graduate School University of Science and Technology of China Hefei 230026 China Institute of High Performance Computing 1 Fusionopolis Way 16-16 Connexis Singapore 138632 Singapore

Using parameter-free density functional approximation and maximally localized Wannier functions analysis, we demonstrate how the Ni3+-based heterointerface can present a complete orbital polarization of the Ni-eg orbitals without introducing additional electronic correlation, which is very inspiring for superconductivity research in two-dimensional confined nickelate layers. The polarized internal electric field from the insulating DyScO3 layer, spontaneous oxygen octahedral distortion, and in-plane tensile strain can fine-tune means for the generation of single occupied Ni-dx2−y2 band structures and cuperate-like Fermi surfaces. Furthermore, by including electronic correlation through on-site Hubbard U, we also find a stronger antiferromagnetic correlation than that in the recent synthetic infinite-layer NdNiO2 with hole-doped Ni1+ superconductivity. The low-energy electronic and spin excitations in the nickelate layer resemble those of high-temperature cuprate superconductors. Our study sheds light on promising directions for the preparation of nickelate superconductors.

关键词： Electronic structure Superconductivity Heterostructures Transition metal oxides Band structure methods First-principles calculations

Fast Linear Prediction Hyperspectral Image Visualization Algorithm

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IOP Conference Series: Earth and Environmental Science 2021年第1期693卷

作者： Yunpeng Xu Yuanxi Peng Jian Long State Key Laboratory of High-Performance Computing College of Computer National University of Defense Technology Changsha 410073 China

How to generate a color image with as much information as possible from hyperspectral images on a trichromatic display is a subject of great concern. In a sense, effective bands containing important information can be extracted from hyperspectral data for image visualization through the method of band selection. In this paper, two improved methods are proposed for the linear prediction (LP) band selection algorithm. According to the information entropy, the band with the greatest difference in information domain is selected as initial ***, the max pooling method is used to select the pixel which can better reflect the image features. Finally, the band similarity is used to select the most distinctive band for hyperspectral image visualization. The experimental results are measured by the metrics such as feature separability, standard deviation, operation efficiency and image displaying *** final experimental results show that fast linear prediction (LP) algorithm is an effective method for hyperspectral image visualization.

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highly Stable Zinc Anodes Enabled by a Dual-Function Additive of In-Situ Film Formation and Electrostatic Shielding

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SSRN

SSRN 2024年

作者： Ji, Rui-Han Fu, Hao Wen, Qing Li, Pei-Yao Yang, Pei Chen, Yu-Jing Chen, He-Zhang Zhang, Jia-Feng Li, Ling-Jun Wang, Jie-Xi Wu, Qing Zhang, Xia-Hui Zheng, Jun-Chao Washington State University United States School of Metallurgy and Environment Central South University Hunan Changsha410083 China Engineering Research Center of the Ministry of Education for Advanced Battery Materials Central South University Hunan Changsha410083 China National Energy Metal Resources and New Materials Key Laboratory Central South University Hunan Changsha410083 China School of Chemistry and Chemical Engineering Hunan University of Science and Technology Hunan Xiangtan411201 China School of Materials Science and Engineering Changsha University of Science and Technology Changsha410114 China National Engineering Research Centre of Advanced Energy Storage Materials Changsha410205 China School of Information and Network Center Central South University Hunan Changsha410083 China Center for High-Performance Computing United States

The practical application of aqueous Zn-ion batteries (AZIBs) is significantly hindered by the short lifespan and low utilization of zinc metal anodes caused by the notorious hydrogen evolution reaction (HER), corrosion, and dendritic growth. The in-situ formation of a dense Zn-ion conducting solid electrolyte interphase (SEI) is an ideal approach to handle these problems. Herein, we present a twofold-protective strategy involving the dense in-situ SEI layer and the electrostatic shielding layer by incorporating 0.01 M yttrium nitrate (YN) additive into 2 M zinc sulfate electrolyte. The robust oxidizing characteristic of the nitrate induces rapid passivation on the surface of Zn anodes, by which these inevitable passivation byproducts are utilized for in-situ fabricating a dense SEI protection layer with excellent wettability. Besides, the infusion of high-valence rare-earth Y3+ forms a durable, dynamic electrostatic shielding layer around the growth tip of the protuberances. This can regulate Zn2+ deposition and aid in rectifying the irregular and sharp surface on zinc anodes. Benefiting from the synergistic effect of the static film protection and the dynamic electrostatic rectification, zinc anodes exhibit outstanding stability, as evidenced by remarkable cycling lifespan of exceeding 2000 h at 1 mAh cm-2 and 600 h at 10 mAh cm-2 in Zn symmetric cells and the preeminent CE of 99.83% with stably cycling over 2200 times in half-cells at 4 mA cm-2. This study reveals a straightforward yet pragmatic avenue of synergistic dual-protection effect to achieve anti-corrosion and dendrite-free Zn anodes. © 2024, The Authors. All rights reserved.

关键词： Passivation

Characterization of State-Preparation Uncertainty in Quantum key Distribution

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Physical Review Applied 2023年第1期19卷 014048-014048页

作者： Anqi Huang Akihiro Mizutani Hoi-Kwong Lo Vadim Makarov Kiyoshi Tamaki Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer Science and Technology National University of Defense Technology Changsha 410073 People’s Republic of China Graduate School of Engineering Science Osaka University Toyonaka Osaka 560-8531 Japan Department of Electrical & Computer Engineering and Department of Physics Centre for Quantum Information and Quantum Control (CQIQC) University of Toronto Toronto Ontario M5S 3G4 Canada Department of Physics University of Hong Kong Pokfulam Hong Kong Quantum Bridge Technologies Inc. 100 College Street Toronto Ontario M5G 1L5 Canada Russian Quantum Center Skolkovo Moscow 121205 Russia Shanghai Branch National Laboratory for Physical Sciences at Microscale and CAS Center for Excellence in Quantum Information University of Science and Technology of China Shanghai 201315 People’s Republic of China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow 119049 Russia Faculty of Engineering University of Toyama Gofuku 3190 Toyama 930-8555 Japan

To achieve secure quantum key distribution, all imperfections in the source unit must be incorporated in a security proof and measured in the lab. Here we perform a proof-of-principle demonstration of the experimental techniques for characterizing the source phase and intensity fluctuation in commercial quantum key distribution systems. When we apply the measured phase-fluctuation intervals to the security proof that takes into account fluctuations in the state preparation, it predicts a key distribution distance of over 100km of fiber. The measured intensity fluctuation intervals are, however, so large that the proof predicts zero key, indicating a source improvement may be needed. Our characterization methods pave the way for a future certification standard.

关键词： Fluctuations & noise Optical quantum information processing Quantum cryptography Quantum engineering Quantum state engineering