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On the nature of localization in Ti doped Si

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arXiv 2018年

作者： Zhang, Yi Nelson, R. Tam, K.-M. Ku, W. Yu, U. Vidhyadhiraja, N.S. Terletska, H. Moreno, J. Jarrell, M. Berlijn, T. Department of Physics & Astronomy Louisiana State University Baton RougeLA70803 United States Center for Computation & Technology Louisiana State University Baton RougeLA70803 United States Institute of Inorganic Chemistry RWTH Aachen University Landoltweg 1 Aachen52056 Germany Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Department of Physics and Photon Science GIST Gwangju61005 Korea Republic of Theoretical Sciences Unit Jawaharlal Nehru Centre for Advanced Scientific Research Bangalore560064 India Department of Physics and Astronomy Middle Tennessee State University MurfreesboroTN37132 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Computer Science and Mathematics Division Oak Ridge National Laboratory Oak RidgeTN37831 United States

Intermediate band semiconductors hold the promise to significantly improve the efficiency of solar cells, but only if the intermediate impurity band is metallic. We apply a recently developed first principles method to investigate the origin of electron localization in Ti doped Si, a promising candidate for intermediate band solar cells. Although Anderson localization is often overlooked in the context of intermediate band solar cells, our results show that in Ti doped Si it plays a more important role in the metal insulator transition than Mott localization. Implications for the theory of intermediate band solar cells are discussed. Copyright © 2018, The Authors. All rights reserved.

关键词： Metal insulator transition

Noise-tolerant detection of ZNtopological orders in quantum many-body states

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arXiv 2018年

作者： Chen, Xi Ran, Shi-Ju Yang, Shuo Lewenstein, MacIej Su, Gang School of Physical Sciences University of Chinese Academy of Sciences P. O. Box 4588 Beijing100049 China Kavli Institute for Theoretical Sciences CAS Center of Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100190 China Department of Physics Capital Normal University Beijing100048 China ICFO-Institut de Ciencies Fotoniques Barcelona Institute of Science and Technology Castelldefels Barcelona08860 Spain State Key Laboratory of Low-Dimensional Quantum Physics Department of Physics Tsinghua University Beijing100084 China ICREA Passeig Lluis Companys 23 Barcelona08010 Spain

Topologically ordered states are fundamentally important in theoretical physics, which are also suggested as promising candidates to build fault-tolerant quantum devices. However, it is still elusive how topological orders can be affected or detected under noises. In this work, we find a quantity, termed as the ring degeneracy D, which is robust under pure noise to detect both trivial and intrinsic topological orders. The ring degeneracy is defined as the degeneracy of the solutions of the selfconsistent equations that encode the contraction of the corresponding tensor network(TN). For the ZNorders, we find that the ring degeneracy satisfies a simple relation D = (N +1)/2+d, with d = 0 for odd N and d = 1/2 for even N. Simulations on several non-trivial states (two-dimensional Ising model, ZNtopological states, and resonating valence bond states) show that the ring degeneracy can tolerate noises up to a strength associated to the gap of the TN boundary theory. Copyright © 2018, The Authors. All rights reserved.

关键词： Ising model

Review: Systematic quantum cluster typical medium method for the study of localization in strongly disordered electronic systems

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arXiv 2018年

作者： Terletska, Hanna Zhang, Yi Tam, Ka Ming Berlijn, Tom Chioncel, L. Vidhyadhiraja, N.S. Jarrell, Mark Department of Physics and Astronomy Middle Tennessee State University Computational Science Program MurfreesboroTN37132 United States Department of Physics and Astronomy Louisiana State University Baton RougeLA70803 United States Center for Computation and Technology Louisiana State University Baton RougeLA70803 United States Center for Nanophase Materials Sciences Oak Ridge National Laboratory Oak RidgeTN37831 United States Computer Science and Mathematics Division Oak Ridge National Laboratory Oak RidgeTN37831 United States Augsburg Center for Innovative Technologies University of Augsburg AugsburgD-86135 Germany Theoretical Physics Iii Center for Electronic Correlations and Magnetism University of Augsburg AugsburgD-86135 Germany Theoretical Sciences Unit Jawaharlal Nehru Center for Advanced Scientic Research Bengaluru560064 India

Great progress has been made in the last several years towards understanding the properties of disordered electronic systems. In part, this is made possible by recent advances in quantum effective medium methods which enable the study of disorder and electron-electronic interactions on equal footing. They include dynamical mean field theory and the coherent potential approximation, and their cluster extension, the dynamical cluster approximation. Despite their successes, these methods do not enable the first-principles study of the strongly disordered regime, including the effects of electronic localization. The main focus of this review is the recently developed typical medium dynamical cluster approximation for disordered electronic systems. This method has been constructed to capture disorder-induced localization, and is based on a mapping of a lattice onto a quantum cluster embedded in an effective typical medium, which is determined self-consistently. Unlike the average effective medium based methods mentioned above, typical medium based methods properly capture the states localized by disorder. The typical medium dynamical cluster approximation not only provides the proper order parameter for Anderson localized states but it can also incorporate the full complexity of DFT-derived potentials into the analysis, including the effect of multiple bands, non-local disorder, and electron-electron interactions. After a brief historical review of other numerical methods for disordered systems, we discuss coarse-graining as a unifying principle for the development of translationally invariant quantum cluster methods. Together, the Coherent Potential Approximation, the Dynamical Mean Field Theory and the Dynamical Cluster Approximation may be viewed as a single class of approximations with a much needed small parameter of the inverse cluster size which may be used to control the approximation. We then present an overview of various recent applications of the typical medi

关键词： Electrons

Interface induced Zeeman-protected superconductivity in ultrathin crystalline lead films

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arXiv 2018年

作者： Liu, Yi Wang, Ziqiao Zhang, Xuefeng Liu, Chaofei Liu, Yongjie Zhou, Zhimou Wang, Junfeng Wang, Qingyan Liu, Yanzhao Xi, Chuanying Tian, Mingliang Liu, Haiwen Feng, Ji Xie, X.C. Wang, Jian International Center for Quantum Materials School of Physics Peking University Beijing100871 China Collaborative Innovation Center of Quantum Matter Beijing100871 China Wuhan National High Magnetic Field Center Huazhong University of Science and Technology Wuhan430074 China Institute of Physics Chinese Academy of Sciences Beijing100190 China High Magnetic Field Laboratory Chinese Academy of Sciences Hefei Anhui230031 China Center for Advanced Quantum Studies Department of Physics Beijing Normal University Beijing100875 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100190 China

Two dimensional (2D) superconducting systems are of great importance to exploring exotic quantum physics. Recent development of fabrication techniques stimulates the studies of high quality single crystalline 2D superconductors, where intrinsic properties give rise to unprecedented physical phenomena. Here we report the observation of Zeeman-type spin-orbit interaction protected superconductivity (Zeeman-protected superconductivity) in 4 monolayer (ML) to 6 ML crystalline Pb films grown on striped incommensurate (SIC) Pb layers on Si(111) substrates by molecular beam epitaxy (MBE). Anomalous large in-plane critical field far beyond the Pauli limit is detected, which can be attributed to the Zeeman-protected superconductivity due to the in-plane inversion symmetry breaking at the interface. Our work demonstrates that in superconducting heterostructures the interface can induce Zeeman-type spin-orbit interaction (SOI) and modulate the superconductivity. Copyright © 2018, The Authors. All rights reserved.

关键词： Molecular beam epitaxy

Publisher Correction: Proton mediated spin state transition of cobalt heme analogs

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Nature communications 2019年第1期10卷 2742页

作者： Jianping Zhao Qian Peng Zijian Wang Wei Xu Hongyan Xiao Qi Wu Hao-Ling Sun Fang Ma Jiyong Zhao Cheng-Jun Sun Jianzhang Zhao Jianfeng Li College of Materials Science and Opto-electronic Technology CAS Center for Excellence in Topological Quantum Computation & Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Yanqi Lake Huairou District 101408 Beijing China. State Key Laboratory and Institute of Elemento-Organic Chemistry College of Chemistry Nankai University 300071 Tianjin China. Institute of High Energy Physics & University of Chinese Academy of Sciences Chinese Academy of Sciences 100049 Beijing China. Key Laboratory of Photochemical Conversion and Optoelectronic Materials Technical Institute of Physics and Chemistry Chinese Academy of Sciences 100190 Beijing China. Department of Chemistry and Beijing Key Laboratory of Energy Conversion and Storage Materials Beijing Normal University 100875 Beijing China. Advanced Photon Source Argonne National Laboratory Argonne IL 60439 USA. State Key Laboratory of Fine Chemicals School of Chemical Engineering Dalian University of Technology West Campus 2 Ling-Gong Road 116024 Dalian China. College of Materials Science and Opto-electronic Technology CAS Center for Excellence in Topological Quantum Computation & Center of Materials Science and Optoelectronics Engineering University of Chinese Academy of Sciences Yanqi Lake Huairou District 101408 Beijing China. jfli@***.

In the original version of this Article, the four structural depictions of orbital distributions were inadvertently omitted from Figure 5. This has now been corrected in both the HTML and PDF versions of the Article.

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Symmetry Enforced Self-Learning Monte Carlo Method Applied to the Holstein Model

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arXiv 2018年

作者： Chen, Chuang Xu, Xiao Yan Liu, Junwei Batrouni, George Scalettar, Richard Meng, Zi Yang Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing100190 China School of Physical Sciences University of Chinese Academy of Sciences Beijing100190 China Department of Physics Hong Kong University of Science and Technology Clear Water Bay Hong Kong Hong Kong Université Côte d’Azur INPHYNI CNRS Nice0600 France Beijing Computational Science Research Center Beijing100193 China MajuLab CNRS-UNS-NUS-NTU International Joint Research Unit UMI 3654 Singapore Centre for Quantum Technologies National University of Singapore 2 Science Drive 3 117542 Singapore Physics Department University of California Davis95616 United States CAS Center of Excellence in Topological Quantum Computation and School of Physical Sciences University of Chinese Academy of Sciences Beijing100190 China

Self-learning Monte Carlo method (SLMC), using a trained effective model to guide Monte Carlo sampling processes, is a powerful general-purpose numerical method recently introduced to speed up simulations in (quantum) many-body systems. In this work, we further improve the efficiency of SLMC by enforcing physical symmetries on the effective model. We demonstrate its effectiveness in the Holstein Hamiltonian, one of the most fundamental many-body descriptions of electron-phonon coupling. Simulations of the Holstein model are notoriously difficult due to the combination of the typical cubic scaling of fermionic Monte Carlo and the presence of extremely long autocorrelation times. Our method addresses both bottlenecks. This enables simulations on large lattices in the most difficult parameter regions, and evaluation of the critical point for the charge density wave transition at half-filling with high precision. We argue that our work opens a new research area of quantum Monte Carlo (QMC), providing a general procedure to deal with ergodicity in situations involving Hamiltonians with multiple, distinct low energy states. Copyright © 2018, The Authors. All rights reserved.

关键词： Monte Carlo methods

Statistical inference for community detection in signed networks

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Physical Review E 2017年第4期95卷 042313-042313页

作者： Xuehua Zhao Bo Yang Xueyan Liu Huiling Chen School of Digital Media Shenzhen Institute of Information Technology Shenzhen 518172 China Key Laboratory of Symbolic Computation and Knowledge Engineering of Ministry of Education Jilin University Changchun 130012 China College of Computer Science and Technology Jilin University Changchun 130012 China College of Physics and Electronic Information Wenzhou University Wenzhou 325035 China

The problem of community detection in networks has received wide attention and proves to be computationally challenging. In recent years, with the surge of signed networks with positive links and negative links, to find community structure in such signed networks has become a research focus in the area of network science. Although many methods have been proposed to address the problem, their performance seriously depends on the predefined optimization objectives or heuristics which are usually difficult to accurately describe the intrinsic structure of community. In this study, we present a statistical inference method for community detection in signed networks, in which a probabilistic model is proposed to model signed networks and the expectation-maximization–based parameter estimation method is deduced to find communities in signed networks. In addition, to efficiently analyze signed networks without any a priori information, a model selection criterion is also proposed to automatically determine the number of communities. In our experiments, the proposed method is tested in the synthetic and real-word signed networks and compared with current methods. The experimental results show the proposed method can more efficiently and accurately find the communities in signed networks than current methods. Notably, the proposed method is a mathematically principled method.

关键词： Clustering Community structure Stochastic inference

Joint product numerical range and geometry of reduced density matrices

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science China(physics,Mechanics & Astronomy) 2017年第2期60卷 9-17页

作者： Jianxin Chen Cheng Guo Zhengfeng Ji Yiu-Tung Poon Nengkun YU Bei Zeng Jie Zhou Joint Center for Quantum Information and Computer Science University of Maryland College Park 20740 USA Institute for Advanced Study Tsinghua University Beijing 100084 China Centre for Quantum Computation ＆ Intelligent Systems School of Software Faculty of Engineering and Information Technology University of Technology Sydney Sydney 2007 Australia State Key Laboratory of Computer Science.Institute of Software Chinese Academy of Sciences Beijing 100084 China Department of Mathematics Iowa State University Ames 50011-2140 USA Institute for Quantum Computing University of Waterloo Waterloo N2L 3G1 Canada Department of Mathematics ＆ Statistics University of Guelph Guelph N1G 2 W1 Canada Perimeter Institute for Theoretical Physics Waterloo N2L 2Y5 Canada

The reduced density matrices of a many-body quantum system form a convex set, whose three-dimensional projection is convex in R3. The boundary of may exhibit nontrivial geometry, in particular ruled surfaces. Two physical mechanisms are known for the origins of ruled surfaces： symmetry breaking and gapless. In this work, we study the emergence of ruled surfaces for systems with local Hamiltonians in infinite spatial dimension, where the reduced density matrices are known to be separable as a consequence of the quantum de Finetti＇s theorem. This allows us to identify the reduced density matrix geometry with joint product numerical range II of the Hamiltonian interaction terms. We focus on the case where the interaction terms have certain structures, such that a ruled surface emerges naturally when taking a convex hull of ∏. We show that, a ruled surface on sitting in ∏ has a gapless origin, otherwise it has a symmetry breaking origin. As an example, we demonstrate that a famous ruled surface, known as the oloid, is a possible shape of , with two boundary pieces of symmetry breaking origin separated by two gapless lines.

关键词： reduced density matrices quantum tomography numerical range quantum information oloid ruled surface

Towards the P-wave nucleon-pion scattering amplitude in the ∆(1232) channel

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arXiv 2018年

作者： Paul, Srijit Silvi, Giorgio Alexandrou, Constantia Koutsou, Giannis Krieg, Stefan Leskovec, Luka Meinel, Stefan Negele, John W. Petschlies, Marcus Pochinsky, Andrew Rendon, Gumaro Syritsyn, Sergey Computation-based Science and Technology Research Center Cyprus Institute 20 Kavafi Str. Nicosia2121 Cyprus Faculty of Mathematics und Natural Sciences University of Wuppertal Wuppertal 42119 Germany Department of Physics University of Cyprus POB 20537 Nicosia1678 Cyprus Institute for Advanced Simulation Forschungszentrum Jülich GmbH Jülich52425 Germany Theory Center Jefferson Lab Newport NewsVA23606 United States Department of Physics University of Arizona TucsonAZ85721 United States RIKEN BNL Research Center Brookhaven National Laboratory UptonNY11973 United States Center for Theoretical Physics Massachusetts Institute of Technology CambridgeMA02139 United States Helmholtz-Institut für Strahlen- und Kernphysik University of Bonn Bonn53115 Germany Department of Physics and Astronomy Stony Brook University Stony BrookNY11794 United States

We use lattice QCD and the Lüscher method to study elastic pion-nucleon scattering in the isospin I = 3/2 channel, which couples to the ∆(1232) resonance. Our Nf = 2 + 1 flavor lattice setup features a pion mass of mπ ≈ 250 MeV, such that the strong decay channel ∆ → πN is close to the threshold. We present our method for constructing the required lattice correlation functions from single- and two-hadron interpolating fields and their projection to irreducible representations of the relevant symmetry group of the lattice. We show preliminary results for the energy spectra in selected moving frames and irreducible representations, and extract the scattering phase shifts. Using a Breit-Wigner fit, we also determine the resonance mass m∆ and the g∆−πN coupling. Copyright © 2018, The Authors. All rights reserved.

关键词： Quantum theory