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Nonabelian magnonics in antiferromagnets

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arXiv 2018年

作者： Daniels, Matthew W. Cheng, Ran Yu, Weichao Xiao, Jiang Xiao, Di Department of Physics Carnegie Mellon University PittsburghPA15213 United States Department of Electrical and Computer Engineering Carnegie Mellon University PittsburghPA15213 United States Department of Physics and State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China Institute for Nanoelectronics Devices and Quantum Computing Fudan University Shanghai200433 China

We present a semiclassical formalism for antiferromagnetic (AFM) magnonics which promotes the central ingredient of spin wave chirality, encoded in a quantity called magnonic isospin, to a first-class citizen of the theory. We use this formalism to unify results of interest from the field under a single chirality-centric formulation. Our main result is that the isospin is governed by unitary time evolution, through a Hamiltonian projected down from the full spin wave dynamics. Because isospin is SU(2)-valued, its dynamics on the Bloch sphere are precisely rotations-which, in general, do not commute. Consequently, the induced group of operations on AFM spin waves is nonabelian. This is a paradigmatic departure from ferromagnetic magnonics, which operates purely within the abelian group generated by spin wave phase and amplitude. Our investigation of this nonabelian magnonics in AFM insulators focuses on studying several simple gate operations, and offering in broad strokes a program of study for interesting new logic families in antiferromagnetic spin wave systems. Copyright © 2018, The Authors. All rights reserved.

关键词： Spin waves

Entanglement entropy of topological orders with boundaries

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arXiv 2018年

作者： Chen, Chaoyi Hung, Ling-Yan Li, Yingcheng Wan, Yidun State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China Institute for Nanoelectronic devices and Quantum computing Fudan University Shanghai200433 China Department of Physics Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China

In this paper we explore how non trivial boundary conditions could inuence the entanglement entropy in a topological order in 2+1 dimensions. Specifically we consider the special class of topological orders describable by the quantum double. We will find very interesting dependence of the entanglement entropy on the boundary conditions particularly when the system is non-Abelian. Along the way, we demonstrate a streamlined procedure to compute the entanglement entropy, which is particularly effcient when dealing with systems with boundaries. We also show how this method effciently reproduces all the known results in the presence of anyonic excitations. Copyright © 2018, The Authors. All rights reserved.

关键词： Boundary conditions

Anyonic exclusions statistics on surfaces with gapped boundaries

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arXiv 2018年

作者： Li, Yingcheng Wang, Hongyu Hu, Yuting Wan, Yidun State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China Institute for Nanoelectronic devices and Quantum computing Fudan University Shanghai200433 China Department of Physics Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China

An anyonic exclusion statistics, which generalizes the Bose-Einstein and Fermi-Dirac statistics of bosons and fermions, was proposed by Haldane[1]. When fusion of anyons is involved, certain 'pseudo-species' anyons appear in the exotic statistical weights of non-Abelian anyon systems;however, the meaning and significance of pseudospecies remains an open problem. The relevant past studies had considered only anyon systems without any physical boundary but boundaries often appear in real-life materials. In this paper, we propose an extended anyonic exclusion statistics on surfaces with gapped boundaries, introducing mutual exclusion statistics between anyons as well as the boundary components. Motivated by Refs. [2, 3], we present a formula for the statistical weight of many-anyon states obeying the proposed statistics. Taking the (doubled) Fibonacci topological order as an example, we develop a systematic basis construction for non-Abelian anyons on any Riemann surfaces with gapped boundaries. The basis construction offers a standard way to read off a canonical set of statistics parameters and hence write down the extended statistical weight of the anyon system being studied. The basis construction reveals the meaning of pseudo-species. A pseudo-species has different 'excitation' modes, each corresponding to an anyon species. The 'excitation' modes of pseudo-species corresponds to good quantum numbers of subsystems of a non-Abelian anyon system. This is important because often (e.g., in topological quantum computing) we may be concerned about only the entanglement between such subsystems. Copyright © 2018, The Authors. All rights reserved.

关键词： Statistics

Spin-valley-controlled photonic topological insulator

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arXiv 2018年

作者： Xue, Haoran Gao, Fei Yu, Yang Chong, Yidong Shvets, Gennady Zhang, Baile State Key Laboratory of Modern Optical Instrumentation College of Information Science and Electronic Engineering Zhejiang University Hangzhou310027 China Division of Physics and Applied Physics School of Physical and Mathematical Sciences Nanyang Technological University Singapore637371 Singapore School of Applied and Engineering Physics Cornell University IthacaNY14853 United States Centre for Disruptive Photonic Technologies Nanyang Technological University Singapore637371 Singapore Key Lab. of Advanced Micro/Nano Electronic Devices and Smart Systems of Zhejiang Electromagnetics Academy Zhejiang University Zhejiang University Hangzhou310027 China

The discovery of photonic topological insulators (PTIs)1-3 has opened the door to fundamentally new topological states of light. Current time-reversal-invariant PTIs emulate either the quantum spin Hall (QSH) effect4-11 or the quantum valley Hall (QVH) effect12-17 in condensed-matter systems, in order to achieve topological transport of photons whose propagation is predetermined by either 'photonic pseudospin' (abbreviated as 'spin') or valley. Here we demonstrate a new class of PTIs, whose topological phase is not determined solely by spin or valley, but is controlled by the competition between their induced gauge fields. Such a competition is enabled by tuning the strengths of spin-orbit coupling (SOC) and inversion-symmetry breaking in a single PTI18,19. An unprecedented topological transition between QSH and QVH phases that is hard to achieve in condensed-matter systems is demonstrated. Our study merges the emerging fields of spintronics and valleytronics in the same photonic platform, and offers novel PTIs with reconfigurable topological phases. Copyright © 2018, The Authors. All rights reserved.

关键词： Electric insulators

Random asynchronous iterations in distributed coordination algorithms

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arXiv 2018年

作者： Chen, Yao Xia, Weiguo Cao, Ming Lü, Jinhu Department of Computer Science Southwestern University of Finance and Economics Chengdu611130 China School of Control Science and Engineering Dalian University of Technology Dalian116024 China Faculty of Science and Engineering ENTEG University of Groningen Groningen9747 AG Netherlands School of Automation Science and Electrical Engineering State Key Laboratory of Software Development Environment Beijing Advanced Innovation Center for Big Data and Brain Computing Beihang University Beijing100191 China Academy of Mathematics and Systems Science Chinese Academy of Sciences Beijing100190 China

Distributed coordination algorithms (DCA) carry out information processing processes among a group of networked agents without centralized information fusion. Though it is well known that DCA characterized by an SIA (stochastic, indecomposable, aperiodic) matrix generate consensus asymptotically via synchronous iterations, the dynamics of DCA with asynchronous iterations have not been studied extensively, especially when viewed as stochastic processes. This paper aims to show that for any given irreducible stochastic matrix, even non-SIA, the corresponding DCA lead to consensus successfully via random asynchronous iterations under a wide range of conditions on the transition probability. Particularly, the transition probability is neither required to be independent and identically distributed, nor characterized by a Markov chain. Copyright © 2018, The Authors. All rights reserved.

关键词： Stochastic systems

Rapid detection of stego images based on identifiable features 18

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Rapid detection of stego images based on identifiable featur...

18th International Conference on advanced Communications Technology, ICACT 2016

作者： Pang, Weiwei Luo, Xiangyang Ren, Jie Yang, Chunfang Liu, Fenlin State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou450001 China Zhengzhou Science and Technology Institute Zhengzhou450001 China Science and Technology on Information Assurance Laboratory Beijing100072 China

ISBN: (纸本)9788996865063

An increasing number of images in the Internet brings forward a higher requirement on the speed of steganalysis. For the problem of real-time detection of stego images, a rapid images steganalysis method based on identifiable features is proposed, where the identifiable features are specific character sequences left in stego images by steganography tools. The stego and cover images are distinguished according to whether the identifiable features are found in the detected images. Meanwhile, for the case of that multiple identifiable features appeared on the same location of an image, the AC (Aho-Corasick) multi-features matching algorithm is applied to improve the detection speed. In experiments, the detection method is used to detect eight steganography tools such as Invisible Secrets, E-Show, BMP Secrets and so on. The results show that the proposed steganalysis method can achieve a nearly perfect detection precision, and the detection speed can be improved significantly comparing with traditional methods (matching bytes one by one). © 2016 Global IT Research Institute (GiRI).

关键词： Steganography

A framework for test data generation of object-oriented programs based on complete testing chain

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A framework for test data generation of object-oriented prog...

ACIS International Conference on Software engineering, Artificial Intelligence, Networking, and Parallel/Distributed computing (SNPD)

作者： Gang Li Lei Yu Huihui Sun State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou China

Test data generation is always a hot topic in software testing since efficient test data generation method can significantly increase the efficiency of software testing and decrease the cost. Method call relation and parameter list are seldom considered in existing test data generation methods for object-oriented programs. In this paper, we present the concept of complete testing chain which stipulates the order of methods to be followed when generating test data for object-oriented programs to guarantee the correctness of test data generation. Basing on this, a framework for test data generation of object-oriented programs is proposed. We discuss encoding paradigm of test data, updating of test data and design of fitness function. For updating of test data, particle swarm optimization is introduced to realize the update of parameter list with genetic algorithm used for method sequence updating. Last but not least, a method to improve the initial population by using generated test data is presented for programs whose branch statements consist of method calls. The results show that the proposed methods can greatly increase the success rate and efficiency of test data generation for object-oriented programs.

关键词： Testing Sociology Statistics Sun

A method of metamorphic relations constructing for object-oriented software testing

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A method of metamorphic relations constructing for object-or...

ACIS International Conference on Software engineering, Artificial Intelligence, Networking, and Parallel/Distributed computing (SNPD)

作者： Xinglong Zhang Lei Yu Xuemei Hou State Key Laboratory of Mathematical Engineering and Advanced Computing Zhengzhou China

To solve the Oracle problem of methods sequence in object-oriented software testing, a method of metamorphic relations constructing for object-oriented software testing based on algebraic specification was proposed. Firstly, metamorphic relations constructing criteria for object-oriented testing was defined based on the characteristics of object-oriented software program. Then metamorphic relations were constructed based on GFT algorithm (Generating a Finite Number of Test Case). Finally the metamorphic relations were improved according to these criteria. The improved method was verified through constructing IntStrack class and SavAcc class metamorphic relations. The experiment results show that the metamorphic relations redundancy is decreased significantly. So the new method has a low metamorphic relations redundancy and improves the efficiency of software testing.

关键词： Testing Observers

Eavesdropper’s ability to attack a free-space quantum-key-distribution receiver in atmospheric turbulence

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arXiv 2019年

作者： Chaiwongkhot, Poompong Kuntz, Katanya B. Zhang, Yanbao Huang, Anqi Bourgoin, Jean-Philippe Sajeed, Shihan Lütkenhaus, Norbert Jennewein, Thomas Makarov, Vadim Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada NTT Basic Research Laboratories NTT Corporation AtsugiKanagawa Japan NTT Research Center for Theoretical Quantum Physics NTT Corporation AtsugiKanagawa Japan Institute for Quantum Information & State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China Department of Electrical and Computer Engineering University of Waterloo WaterlooONN2L 3G1 Canada Aegis Quantum WaterlooON Canada Department of Electrical and Computer Engineering University of Toronto M5S 3G4 Canada Quantum Information Science Program Canadian Institute for Advanced Research TorontoONM5G 1Z8 Canada Russian Quantum Center Skolkovo Moscow143025 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 Shanghai201315 China NTI Center for Quantum Communications National University of Science and Technology MISiS Moscow119049 Russia

The ability of an eavesdropper (Eve) to perform an intercept-resend attack on a free-space quantum key distribution (QKD) receiver by precisely controlling the incidence angle of an attack laser has been previously demonstrated. However, such an attack could be ineffective in the presence of atmospheric turbulence due to beam wander and spatial mode aberrations induced by the air’s varying index of refraction. We experimentally investigate the impact turbulence has on Eve’s attack on a free-space polarization-encoding QKD receiver by emulating atmospheric turbulence with a spatial light modulator. Our results identify how well Eve would need to compensate for turbulence to perform a successful attack by either reducing her distance to the receiver, or using beam wavefront correction via adaptive optics. Furthermore, we use an entanglement-breaking scheme to find a theoretical limit on the turbulence strength that hinders Eve’s attack. Copyright © 2019, The Authors. All rights reserved.

关键词： Atmospheric turbulence