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Emergence of power laws in noncritical neuronal systems

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Physical Review E 2019年第1期100卷 010401(R)-010401(R)页

作者： Ali Faqeeh Saeed Osat Filippo Radicchi James P. Gleeson Mathematics Consortium for Science and Industry Department of Mathematics and Statistics University of Limerick Limerick V94 T9PX Ireland Center for Complex Networks and Systems Research School of Informatics Computing and Engineering Indiana University Bloomington Indiana 47408 USA Deep Quantum Labs Skolkovo Institute of Science and Technology Moscow 143026 Russia

Experimental and computational studies provide compelling evidence that neuronal systems are characterized by power-law distributions of neuronal avalanche sizes. This fact is interpreted as an indication that these systems are operating near criticality, and, in turn, typical properties of critical dynamical processes, such as optimal information transmission and stability, are attributed to neuronal systems. The purpose of this Rapid Communication is to show that the presence of power-law distributions for the size of neuronal avalanches is not a sufficient condition for the system to operate near criticality. Specifically, we consider a simplistic model of neuronal dynamics on networks and show that the degree distribution of the underlying neuronal network may trigger power-law distributions for neuronal avalanches even when the system is not in its critical regime. To certify and explain our findings we develop an analytical approach based on percolation theory and branching processes techniques.

关键词： Continuous percolation transition Degree distributions Network diffusion Network structure Neuronal dynamics Neuronal network activity Spreading Brain network Directed networks Neuronal avalanches Neuronal networks Scale free & inhomogeneous networks Spiking neurons Collective behavior models Integrate-and-fire model Networks Analysis Tools Percolation theory Spreading models

Corrections to “Secure Network Code for Adaptive and Active Attacks With No-Randomness in Intermediate Nodes” [Mar 20 1428-1448]

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IEEE Transactions on Information Theory 2020年第6期66卷 3954-3954页

作者： Ning Cai Masahito Hayashi School of Information Science and Technology ShanghaiTech University Shanghai China Graduate School of Mathematics Nagoya University Nagoya Japan Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen China Centre for Quantum Technologies National University of Singapore Singapore Center for Quantum Computing Peng Cheng Laboratory Shenzhen China

In the proof of Theorem 5, we stated that Eq. (47) follows from Eq. (59) of Lemma 4 . However, the derivation of Eq. (59) is incorrect, and the inequality used in the derivation of Eq. (47) is not Eq. (59) . Eq.... 详细信息

关键词： Network coding Adaptive systems Communication system security Multicast communication

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

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Physical Review A 2019年第6期99卷 062315-062315页

作者： Poompong Chaiwongkhot Katanya B. Kuntz Yanbao Zhang Anqi Huang Jean-Philippe Bourgoin Shihan Sajeed Norbert Lütkenhaus Thomas Jennewein Vadim Makarov Institute for Quantum Computing University of Waterloo Waterloo ON Canada N2L 3G1 Department of Physics and Astronomy University of Waterloo Waterloo ON Canada N2L 3G1 NTT Basic Research Laboratories NTT Corporation Atsugi Kanagawa 243-0198 Japan NTT Research Center for Theoretical Quantum Physics NTT Corporation Atsugi Kanagawa 243-0198 Japan Institute for Quantum Information and State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha 410073 People's Republic of China Department of Electrical and Computer Engineering University of Waterloo Waterloo ON Canada N2L 3G1 Aegis Quantum Waterloo ON Canada Department of Electrical and Computer Engineering University of Toronto Toronto Canada M5S 3G4 Quantum Information Science Program Canadian Institute for Advanced Research Toronto ON Canada M5G 1Z8 Russian Quantum Center Skolkovo Moscow 143025 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

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.

关键词： quantum cryptography

Optimal verification and fidelity estimation of maximally entangled states

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Physical Review A 2019年第5期99卷 052346-052346页

作者： Huangjun Zhu Masahito Hayashi Department of Physics and Center for Field Theory and Particle Physics Fudan University Shanghai 200433 China State Key Laboratory of Surface Physics Fudan University Shanghai 200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai 200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing 210093 China Graduate School of Mathematics Nagoya University Nagoya 464-8602 Japan Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 China Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 117542 Singapore

We study the verification of maximally entangled states by virtue of the simplest measurement settings: local projective measurements without adaption. We show that optimal protocols are in one-to-one correspondence with complex projective 2-designs constructed from orthonormal bases. Optimal protocols with minimal measurement settings are in one-to-one correspondence with complete sets of mutually unbiased bases. Based on this observation, optimal protocols are constructed explicitly for any local dimension, which can also be applied to estimating the fidelity with the target state and to detecting entanglement. In addition, we show that incomplete sets of mutually unbiased bases are optimal for verifying maximally entangled states when the number of measurement settings is restricted. Moreover, we construct optimal protocols for the adversarial scenario in which state preparation is not trusted. The number of tests has the same scaling behavior as the counterpart for the nonadversarial scenario; the overhead is no more than three times. We also show that the entanglement of the maximally entangled state can be certified with any given significance level using only one test as long as the local dimension is large enough.

关键词： quantum entanglement quantum tomography

quantum state estimation with nuisance parameters

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arXiv 2019年

作者： Suzuki, Jun Yang, Yuxiang Hayashi, Masahito Graduate School of Informatics and Engineering University of Electro-Communications Tokyo182-8585 Japan Institute for Theoretical Physics ETH Zürich Zürich8093 Switzerland Graduate School of Mathematics Nagoya University Nagoya464-8602 Japan Center for Quantum Computing Peng Cheng Laboratory Shenzhen518000 China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Centre for Quantum Technologies National University of Singapore Singapore117542 Singapore

In parameter estimation, nuisance parameters refer to parameters that are not of interest but nevertheless affect the precision of estimating other parameters of interest. For instance, the strength of noises in a probe can be regarded as a nuisance parameter. Despite its long history in classical statistics, the nuisance parameter problem in quantum estimation remains largely unexplored. The goal of this article is to provide a systematic review of quantum estimation in the presence of nuisance parameters, and to supply those who work in quantum tomography and quantum metrology with tools to tackle relevant problems. After an introduction to the nuisance parameter and quantum estimation theory, we explicitly formulate the problem of quantum state estimation with nuisance parameters. We extend quantum Cramér-Rao bounds to the nuisance parameter case and provide a parameter orthogonalization tool to separate the nuisance parameters from the parameters of interest. In particular, we put more focus on the case of one-parameter estimation in the presence of nuisance parameters, as it is most frequently encountered in practice. Copyright © 2019, The Authors. All rights reserved.

关键词： State estimation

Symmetry-Protected Ideal Type-II Weyl Phonons in CdTe

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Physical Review Letters 2019年第6期123卷 065501-065501页

作者： B. W. Xia R. Wang Z. J. Chen Y. J. Zhao H. Xu Department of Physics and Shenzhen Key Laboratory of Quantum Science and Engineering Southern University of Science and Technology Shenzhen 518055 People’s Republic of China Department of Physics The Hong Kong University of Science and Technology Clear Water Bay Hong Kong People’s Republic of China Institute for Structure and Function and Department of Physics Chongqing University Chongqing 400044 People’s Republic of China Department of Physics South China University of Technology Guangzhou 510640 People’s Republic of China Center for Quantum Computing Peng Cheng Laboratory Shenzhen 518055 People’s Republic of China

Nontrivial low-energy excitations of crystalline solids have insightfully strengthened understanding of elementary particles in quantum field theory. Usually, topological quasiparticles are mainly focused on fermions in topological semimetals. We alternatively show by first-principles calculations and symmetry analysis that ideal type-II Weyl phonons are present in zinc-blende cadmium telluride, a well-known II-VI semiconductor. Importantly, these type-II Weyl phonons originate from the inversion between the longitudinal acoustic and transverse optical branches. Symmetry guarantees that the type-II Weyl points lie along the high-symmetry lines at the boundaries of the Brillouin zone even with a breaking of inversion symmetry, exhibiting the robustness of protected phonon features. The nontrivial phonon surface states and surface arcs projected on the semifinite (001) and (111) surfaces are investigated. The phonon surface arcs connecting the Weyl points with opposite chirality, guaranteed to be very long, are clearly visible. We not only offer a promising candidate for studying type-II Weyl phonons but also provide a route to realize symmetry-protected nontrivial phonons and related applications in realistic materials.

关键词： Acoustic phonons Optical phonons Phonons Symmetry protected topological states Topological phases of matter Topological materials Weyl semimetal k dot p method

Photocurrent imaging of multi-memristive charge density wave switching in two-dimensional 1T-TaS2

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arXiv 2020年

作者： Patel, Tarun Okamoto, Junichi Dekker, Tina Yang, Bowen Gao, Jingjing Luo, Xuan Lu, Wenjian Sun, Yuping Tsen, Adam W. Institute for Quantum Computing Department of Physics and Astronomy Department of Electrical and Computer Engineering Department of Chemistry University of Waterloo WaterlooONN2L 3G1 Canada Institute of Physics University of Freiburg FreiburgD-79104 Germany Key Laboratory of Materials Physics Institute of Solid State Physics Chinese Academy of Sciences Hefei230031 China University of Science and Technology of China Hefei230026 China High Magnetic Field Laboratory Chinese Academy of Sciences Hefei230031 China Collaborative Innovation Centre of Advanced Microstructures Nanjing University Nanjing210093 China

Transport studies of atomically thin 1T-TaS2 have demonstrated the presence of intermediate resistance states across the nearly commensurate (NC) to commensurate (C) charge density wave (CDW) transition, which can be further switched electrically. While this presents exciting opportunities for the material in memristor applications, the switching mechanism has remained elusive and could be potentially attributed to the formation of inhomogeneous C and NC domains across the 1T-TaS2 flake. Here, we present simultaneous electrical driving and scanning photocurrent imaging of CDWs in ultrathin 1T-TaS2 using a vertical heterostructure geometry. While micron-sized CDW domains form upon changing temperature, electrically driven transitions result in largely uniform changes, indicating that states of intermediate resistance for the latter likely correspond to true metastable CDW states in between the NC and C phases, which we then explain by a free energy analysis. Additionally, we are able to perform repeatable and bidirectional switching across the multiple CDW states without changing sample temperature, demonstrating that atomically thin 1T-TaS2 can be further used as a robust and reversible multi-memristor material. Copyright © 2020, The Authors. All rights reserved.

关键词： Memristors

quantum advantages in hypercube game

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arXiv 2018年

作者： He, Xiaoyu Fang, Kun Sun, Xiaoming Duan, Runyao Institute of Computing Technology Chinese Academy of Sciences Institute for Quantum Computing Baidu Inc. Beijing100193 China Centre for Quantum Software and Information Faculty of Engineering and Information Technology University of Technology SydneyNSW2007 Australia

We introduce a novel generalization of the Clauser-Horne-Shimony-Holt (CHSH) game to a multiplayer setting, i.e., Hypercube game, where all m players are required to assign values to vertices on corresponding facets of an m-dimensional hypercube. The players win if and only if their answers satisfy both parity and consistency conditions. We completely characterize the maximum winning probabilities (game value) under classical, quantum and no-signalling strategies, respectively. In contrast to the original CHSH game designed to demonstrate the superiority of quantumness, we find that the quantum advantages in the Hypercube game significantly decrease as the number of players increase. Notably, the quantum value decays exponentially fast to the classical value as m increases, while the no-signalling value always remains to be one. Copyright © 2018, The Authors. All rights reserved.

关键词： Geometry

Induced percolation on networked systems

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arXiv 2020年

作者： Xie, Jiarong Wang, Xiangrong Feng, Ling Zhao, Jin-Hua Moreno, Yamir Hu, Yanqing School of Information Science and Technology Sun Yat-sen University Guangzhou510006 China Institute of Future Networks Southern University of Science and Technology Shenzhen China Research Center of Networks and Communications Peng Cheng Laboratory Shenzhen China Institute of High Performance Computing A*STAR 138632 Singapore Department of Physics National University of Singapore 117551 Singapore Guangdong Provincial Key Laboratory of Nuclear Science Institute of Quantum Matter South China Normal University Guangzhou510006 China Institute for Biocomputation and Physics of Complex Systems University of Zaragoza Zaragoza50018 Spain Department of Theoretical Physics University of Zaragoza Zaragoza50018 Spain ISI Foundation Torino10126 Italy Southern Marine Science and Engineering Guangdong Laboratory Zhuhai519082 China

Percolation theory has been widely used to study phase transitions in complex networked systems. It has also successfully explained several macroscopic phenomena across different fields. Yet, the existent theoretical framework for percolation places the focus on the direct interactions among the system’s components, while recent empirical observations have shown that indirect interactions are common in many systems like ecological and social networks, among others. Here, we propose a new percolation framework that accounts for indirect interactions, which allows to generalize the current theoretical body and understand the role of the underlying indirect influence of the components of a networked system on its macroscopic behavior. We report a rich phenomenology in which first-order, second-order or hybrid phase transitions are possible depending on whether the links of the substrate network are directed, undirected or a mix, respectively. We also present an analytical framework to characterize the proposed induced percolation, paving the way to further understand network dynamics with indirect interactions. Copyright © 2020, The Authors. All rights reserved.

关键词： Solvents