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Peta-electron volt gamma-ray emission from the Crab Nebula

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arXiv 2021年

作者： Cao, Zhen Aharonian, F. An, Q. Axikegu Bai, L.X. Bai, Y.X. Bao, Y.W. Bastieri, D. Bi, X.J. Bi, Y.J. Cai, H. Cai, J.T. Cao, Zhe Chang, J. Chang, J.F. Chen, B.M. Chen, E.S. Chen, J. Chen, Liang Chen, Liang Chen, Long Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Cheng, N. Cheng, Y.D. Cui, S.W. Cui, X.H. Cui, Y.D. Piazzoli, B. D'Ettorre Dai, B.Z. Dai, H.L. Dai, Z.G. Danzengluobu Volpe, D. della Dong, X.J. Duan, K.K. Fan, J.H. Fan, Y.Z. Fan, Z.X. Fang, J. Fang, K. Feng, C.F. Feng, L. Feng, S.H. Feng, Y.L. Gao, B. Gao, C.D. Gao, L.Q. Gao, Q. Gao, W. Ge, M.M. Geng, L.S. Gong, G.H. Gou, Q.B. Gu, M.H. Guo, F.L. Guo, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Han, Y.A. He, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. Heller, M. Hor, Y.K. Hou, C. Hou, X. Hu, H.B. Hu, S. Hu, S.C. Hu, X.J. Huang, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, X.Y. Huang, Z.C. Ji, F. Ji, X.L. Jia, H.Y. Jiang, K. Jiang, Z.J. Jin, C. Ke, T. Kuleshov, D. Levochkin, K. Li, B.B. Li, Cheng Li, Cong Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, Jie Li, Jian Li, K. Li, W.L. Li, X.R. Li, Xin Li, Xin Li, Y. Li, Y.Z. Li, Zhe Li, Zhuo Liang, E.W. Liang, Y.F. Lin, S.J. Liu, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, Ruoyu Y. Liu, S.M. Liu, W. Liu, Y. Liu, Y.N. Liu, Z.X. Long, W.J. Lu, R. Lv, H.K. Ma, B.Q. Ma, L.L. Ma, X.H. Mao, J.R. Masood, A. Min, Z. Mitthumsiri, W. Montaruli, T. Nan, Y.C. Pang, B.Y. Pattarakijwanich, P. Pei, Z.Y. Qi, M.Y. Qi, Y.Q. Qiao, B.Q. Qin, J.J. Ruffolo, D. Rulev, V. Sáiz, A. Shao, L. Shchegolev, O. Sheng, X.D. Shi, J.Y. Song, H.C. Stenkin, Yu.V. Stepanov, V. Su, Y. Sun, Q.N. Sun, X.N. Sun, Z.B. Tam, P.H.T. Tang, Z.B. Tian, W.W. Wang, B.D. Key Laboratory of Particle Astrophyics & Experimental Physics Division & Computing Center Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China University of Chinese Academy of Sciences Beijing100049 China Tianfu Cosmic Ray Research Center Sichuan Chengdu China Dublin Institute for Advanced Studies 31 Fitzwilliam Place 2 Dublin Ireland Max-Planck-Institut for Nuclear Physics P.O. Box 103980 Heidelberg69029 Germany State Key Laboratory of Particle Detection and Electronics China University of Science and Technology of China Anhui Hefei230026 China School of Physical Science and Technology School of Information Science and Technology Southwest Jiao-tong University Sichuan Chengdu610031 China College of Physics Sichuan University Sichuan Chengdu610065 China School of Astronomy and Space Science Nanjing University Jiangsu Nanjing210023 China Center for Astrophysics Guangzhou University Guangdong Guangzhou510006 China School of Physics and Technology Wuhan University Hubei Wuhan430072 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Jiangsu Nanjing210023 China Hebei Normal University Hebei Shijiazhuang050024 China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai200030 China Ministry of Education Tibet Lhasa850000 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Sun Yat-sen University Guangdong Zhuhai519000 China Dipartimento di Fisica dell’Università di Napoli "Federico II" Complesso Universitario di Monte Sant’Angelo via Cinthia Napoli80126 Italy School of Physics and Astronomy Yunnan University Yunnan Kunming650091 China D’epartement de Physique Nucl’eaire et Corpusculaire Facult’e de Sciences Universit’e de Genève 24 Quai Ernest Ansermet Geneva1211 Switzerland Institute of Frontier and Interdisciplinary Science Shan

The Crab pulsar and the surrounding nebula powered by the pulsar’s rotational energy through the formation and termination of a relativistic electron-positron wind is a bright source of gamma-rays carrying crucial information about this complex conglomerate. We report the detection of γ-rays with a spectrum showing gradual steepening over three energy decades, from 5 × 10−4 to 1.1 petaelectronvolt (PeV). The ultra-high-energy photons exhibit the presence of a PeV electron accelerator (a pevatron) with an acceleration rate exceeding 15 % of the absolute theoretical limit. Assuming that unpulsed γ-rays are produced at the termination of the pulsar’s wind, we constrain the pevatron’s size, between 0.025 and 0.1 pc, and the magnetic field, ≈ 110µG. The production rate of PeV electrons, 2.5×1036erg s−1, constitutes 0.5% of the pulsar’s spin-down luminosity, although we do not exclude a non-negligible contribution of PeV protons to the production of the highest energy γ-rays. Copyright © 2021, The Authors. All rights reserved.

关键词： Pulsars

Generation and detection of coherent longitudinal acoustic waves in ultrathin 1T'-MoTe2

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arXiv 2019年

作者： Rivas, Nicolas Zhong, Shazhou Dekker, Tina Cheng, Meixin Gicala, Patrick Chen, Fangchu Luo, Xuan Sun, Yuping Petruk, Ariel A. Pichugin, Kostyantyn Tsen, Adam W. Sciaini, Germán Ultrafast Electron Imaging Lab Department of Chemistry Waterloo Institute for Nanotechnology University of Waterloo WaterlooONN2L3G1 Canada Institute for Quantum Computing Department of Physics and Astronomy Department of Electrical and Computer Engineering Department of Chemistry University of Waterloo WaterlooONN2L3G1 Canada 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 Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China

Layered transition metal dichalcogenides have attracted substantial attention owing to their versatile functionalities and compatibility with current nanofabrication technologies. Thus, noninvasive means to determine the mechanical properties of nanometer (nm) thick specimens are of increasing importance. Here, we report on the detection of coherent longitudinal acoustic phonon modes generated by impulsive femtosecond (fs) optical excitation. Broadband fs-transient absorption experiments in 1T-f-MoTe2 flakes as a function of thickness (7 nm . 30 nm) yield a longitudinal sound speed of vl = (2990± 90) m s-1. In addition, temperature dependent measurements unveil a linear decrease of the normalized Young-fs modulus El/El,295Kwith a slope of δ(***,%' ))/δT = (.2.0± 0.1) 10-3K-1and no noticeable change caused by the Td-1T-f structural phase transition or variations in film thickness. Copyright © 2019, The Authors. All rights reserved.

关键词： Elastic moduli

Performance of LHAASO-WCDA and Observation of Crab Nebula as a Standard Candle

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arXiv 2021年

作者： Aharonian, F. An, Q. Axikegu Bai, L.X. Bai, Y.X. Bao, Y.W. Bastieri, D. Bi, X.J. Bi, Y.J. Cai, H. Cai, J.T. Cao, Z. Cao, Z. Chang, J. Chang, J.F. Chang, X.C. Chen, B.M. Chen, J. Chen, L. Chen, L. Chen, L. Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Cheng, N. Cheng, Y.D. Cui, S.W. Cui, X.H. Cui, Y.D. Dai, B.Z. Dai, H.L. Dai, Z.G. Danzengluobu Volpe, D. della Piazzoli, B. D'Ettorre Dong, X.J. Fan, J.H. Fan, Y.Z. Fan, Z.X. Fang, J. Fang, K. Feng, C.F. Feng, L. Feng, S.H. Feng, Y.L. Gao, B. Gao, C.D. Gao, Q. Gao, W. Ge, M.M. Geng, L.S. Gong, G.H. Gou, Q.B. Gu, M.H. Guo, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Han, Y.A. He, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. Heller, M. Hor, Y.K. Hou, C. Hou, X. Hu, H.B. Hu, S. Hu, S.C. Hu, X.J. Huang, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, Z.C. Ji, F. Ji, X.L. Jia, H.Y. Jiang, K. Jiang, Z.J. Jin, C. Kuleshov, D. Levochkin, K. Li, B.B. Li, C. Li, C. Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, J. Li, K. Li, W.L. Li, X. Li, X. Li, X.R. Li, Y. Li, Y.Z. Li, Z. Li, Z. Liang, E.W. Liang, Y.F. Lin, S.J. Liu, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y.N. Liu, Z.X. Long, W.J. Lu, R. Lv, H.K. Ma, B.Q. Ma, L.L. Ma, X.H. Mao, J.R. Masood, A. Mitthumsiri, W. Montaruli, T. Nan, Y.C. Pang, B.Y. Pattarakijwanich, P. Pei, Z.Y. Qi, M.Y. Ruffolo, D. Rulev, V. Sáiz, A. Shao, L. Shchegolev, O. Sheng, X.D. Shi, J.R. Song, H.C. Stenkin, Yu V. Stepanov, V. Sun, Q.N. Sun, X.N. Sun, Z.B. Tam, P.H.T. Tang, Z.B. Tian, W.W. Wang, B.D. Wang, C. Wang, H. Wang, H.G. Wang, J.C. Wang, J.S. Wang, L.P. Wang, L.Y. Wang, R.N. Wang, W. Wang, W. Wang, X.G. Wang, X.J. Wang, X.Y. Key Laboratory of Particle Astrophyics & Experimental Physics Division & Computing Center Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China University of Chinese Academy of Sciences Beijing100049 China TIANFU Cosmic Ray Research Center ChengduSichuan China State Key Laboratory of Particle Detection and Electronics China University of Science and Technology of China Hefei Anhui230026 China Department of Engineering Physics Tsinghua University Beijing100084 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China National Space Science Center Chinese Academy of Sciences Beijing100190 China School of Physics Peking University Beijing100871 China Center for Astrophysics Guangzhou University GuangzhouGuangdong510006 China Sun Yat-sen University ZhuhaiGuangdong519082 China School of Physical Science and Technology Guangxi University Nanning Guangxi530004 China Hebei Normal University Shijiazhuang Hebei050024 China School of Physics and Microelectronics Zhengzhou University ZhengzhouHenan450001 China School of Astronomy and Space Science Nanjing University NanjingJiangsu210023 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences NanjingJiangsu210023 China Institute of Frontier and Interdisciplinary Science Shandong University QingdaoShandong266237 China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai200030 China Tsung-Dao Lee Institute & School of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China School of Physical Science and Technology School of Information Science and Technology Southwest Jiaotong University ChengduSichuan610031 China College of Physics Sichuan University ChengduSichuan610065 China Ministry of Education Lhasa Tibet850000 China School of Physics and Technology Wuhan University Wuhan

The first Water Cherenkov detector of the LHAASO experiment (WCDA-1) has been operating since April, 2019. The first 10 months of data have been analyzed to test its performance by observing the Crab Nebula as a standard candle. The WCDA-1 achieves the sensitivity of 65 mCU per year with a statistical threshold of 5 σ. In order to do so, 97.7% cosmic ray background rejection rate around 1 TeV and 99.8% around 6 TeV with an approximately photon acceptance about 50% by using the compactness of the shower footprints to be greater than 10 as the discriminator between gamma induced showers and the cosmic ray backgrounds. The angular resolution is measured using the Crab Nebula as a point source about 0.45◦ at 1 TeV and better than 0.2◦ above 6 TeV with the pointing accuracy better than 0.05◦. They are all matching the design specifications. The energy resolution is found 33% for gamma rays around 6 TeV. The spectral energy distribution of the Crab Nebula in the range from 500 GeV and 15.8 TeV is measured and in agreement with results of other TeV gamma ray observatories. © 2021, CC BY.

关键词： Spectroscopy

γ-ray spectroscopy of low-lying yrast and non-yrast states in neutron-rich Kr94,95,96

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Physical Review C 2022年第2期105卷 024302-024302页

作者： R.-B. Gerst A. Blazhev K. Moschner P. Doornenbal A. Obertelli K. Nomura J.-P. Ebran S. Hilaire J. Libert G. Authelet H. Baba D. Calvet F. Château S. Chen A. Corsi A. Delbart J.-M. Gheller A. Giganon A. Gillibert V. Lapoux T. Motobayashi M. Niikura N. Paul J.-Y. Roussé H. Sakurai C. Santamaria D. Steppenbeck R. Taniuchi T. Uesaka T. Ando T. Arici F. Browne A. M. Bruce R. Caroll L. X. Chung M. L. Cortés M. Dewald B. Ding F. Flavigny S. Franchoo M. Górska A. Gottardo J. Jolie A. Jungclaus J. Lee M. Lettmann B. D. Linh J. Liu Z. Liu C. Lizarazo S. Momiyama S. Nagamine N. Nakatsuka C. R. Nita C. Nobs L. Olivier R. Orlandi Z. Patel Zs. Podolyák M. Rudigier T. Saito C. Shand P.-A. Söderström I. Stefan V. Vaquero V. Werner K. Wimmer Z. Xu Institut für Kernphysik Universität zu Köln 50937 Köln Germany RIKEN Nishina Center Wako Saitama 351-0198 Japan IRFU CEA Université Paris-Saclay 91191 Gif-sur-Yvette France Department of Physics Faculty of Science University of Zagreb HR-10000 Zagreb Croatia CEA DAM DIF F-91297 Arpajon France Laboratoire Matière en Conditions Extrêmes CEA Université Paris-Saclay 91680 Bruyères-le-Châtel France School of Physics and State Key Laboratory of Nuclear Physics and Technology Peking University Beijing 100871 China Department of Physics University of Tokyo 7-3-1 Hongo Bunkyo Tokyo 113-0033 Japan Laboratoire Kastler Brossel Sorbonne Université CNRS ENS-PSL Research University Collège de France Case 74 4 Place Jussieu F-75005 Paris France GSI Helmholtzzentrum für Schwerionenforschung GmbH 64291 Darmstadt Germany School of Computing Engineering and Mathematics University of Brighton Brighton BN2 4GJ United Kingdom Department of Physics University of Surrey Guildford GU2 7XH United Kingdom Institute for Nuclear Science and Technique VINATOM 179 Hoang Quoc Viet Road Cau Giay Hanoi Vietnam Institut für Kernphysik Technische Universität Darmstadt 64289 Darmstadt Germany Institute of Modern Physics Chinese Academy of Sciences Lanzhou 730000 China Institut de Physique Nucléaire CNRS-IN2P3 Université Paris-Saclay 91406 Orsay Cedex France LPC Caen CNRS/IN2P3 Normandie Université ENSICAEN UNICAEN 14000 Caen France Instituto de Estructura de la Materia CSIC 28006 Madrid Spain Department of Physics The University of Hong Kong Pokfulam 999077 Hong Kong China School of Nuclear Science and Technology University of Chinese Academy of Sciences Beijing 100049 China Department of Physics Faculty of Science Kyoto University Kyoto 606-8502 Japan Horia Hulubei National Institute of Physics and Nuclear Engineering (IFIN-HH) R-077125 Bucharest Romania Advanced Science Research Center Japan Atomic Energy Agency Tokai Ibaraki 319-1195 Japan

We report on γ-ray spectroscopy of low-lying excited states in the neutron-rich Kr94,95,96 isotopes measured as part of the “Shell Evolution And Search for Two-plus energies At RIBF” (SEASTAR) campaign at the RIKEN Radioactive Isotope Beam Factory. Excited yrast and non-yrast states were observed, and half-lives extracted via geant4 simulations. In Kr94,96 candidates for the 31− state were identified. For Kr95, the prompt SEASTAR data were combined with delayed spectroscopic data measured with the EURICA array to observe transitions on top of the known (7/2)+ isomer at a level energy of 195.5(3) keV. The comparison of the new experimental results with five-dimensional collective Hamiltonian (5DCH) and mapped interacting boson model (IBM) calculations, both using the Gogny D1M interaction, could suggest oblate-prolate shape coexistence already in Kr96.

关键词： Electromagnetic transitions Isomer decays Nuclear structure & decays 90 ≤ A ≤ 149

Exploring Lorentz invariance violation from ultra-high-energy gamma rays observed by LHAASO

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arXiv 2021年

作者： Cao, Zhen Aharonian, F. An, Q. Axikegu Bai, L.X. Bai, Y.X. Bao, Y.W. Bastieri, D. Bi, X.J. Bi, Y.J. Cai, H. Cai, J.T. Cao, Zhe Chang, J. Chang, J.F. Chen, B.M. Chen, E.S. Chen, J. Chen, Liang Chen, Liang Chen, Long Chen, M.J. Chen, M.L. Chen, Q.H. Chen, S.H. Chen, S.Z. Chen, T.L. Chen, X.L. Chen, Y. Cheng, N. Cheng, Y.D. Cui, S.W. Cui, X.H. Cui, Y.D. D'Ettorre Piazzoli, B. Dai, B.Z. Dai, H.L. Dai, Z.G. Danzengluobu Della Volpe, D. Dong, X.J. Duan, K.K. Fan, J.H. Fan, Y.Z. Fan, Z.X. Fang, J. Fang, K. Feng, C.F. Feng, L. Feng, S.H. Feng, Y.L. Gao, B. Gao, C.D. Gao, L.Q. Gao, Q. Gao, W. Ge, M.M. Geng, L.S. Gong, G.H. Gou, Q.B. Gu, M.H. Guo, F.L. Guo, J.G. Guo, X.L. Guo, Y.Q. Guo, Y.Y. Han, Y.A. He, H.H. He, H.N. He, J.C. He, S.L. He, X.B. He, Y. Heller, M. Hor, Y.K. Hou, C. Hou, X. Hu, H.B. Hu, S. Hu, S.C. Hu, X.J. Huang, D.H. Huang, Q.L. Huang, W.H. Huang, X.T. Huang, X.Y. Huang, Z.C. Ji, F. Ji, X.L. Jia, H.Y. Jiang, K. Jiang, Z.J. Jin, C. Ke, T. Kuleshov, D. Levochkin, K. Li, B.B. Li, Cheng Li, Cong Li, F. Li, H.B. Li, H.C. Li, H.Y. Li, Jian Li, Jie Li, K. Li, W.L. Li, X.R. Li, Xin Li, Xin Li, Y. Li, Y.Z. Li, Zhe Li, Zhuo Liang, E.W. Liang, Y.F. Lin, S.J. Liu, B. Liu, C. Liu, D. Liu, H. Liu, H.D. Liu, J. Liu, J.L. Liu, J.S. Liu, J.Y. Liu, M.Y. Liu, R.Y. Liu, S.M. Liu, W. Liu, Y. Liu, Y.N. Liu, Z.X. Long, W.J. Lu, R. Lv, H.K. Ma, B.Q. Ma, L.L. Ma, X.H. Mao, J.R. Masood, A. Min, Z. Mitthumsiri, W. Montaruli, T. Nan, Y.C. Pang, B.Y. Pattarakijwanich, P. Pei, Z.Y. Qi, M.Y. Qi, Y.Q. Qiao, B.Q. Qin, J.J. Ruffolo, D. Rulev, V. Sáiz, A. Shao, L. Shchegolev, O. Sheng, X.D. Shi, J.R. Song, H.C. Stenkin, Y.V. Stepanov, V. Su, Y. Sun, Q.N. Sun, X.N. Sun, Z.B. Tam, P.H.T. Tang, Z.B. Tian, W.W. Wang, B.D. Wang, C. Wang, H. Key Laboratory of Particle Astrophyics and Experimental Physics Division and Computing Center Institute of High Energy Physics Chinese Academy of Sciences Beijing100049 China University of Chinese Academy of Sciences Beijing100049 China Tianfu Cosmic Ray Research Center Sichuan Chengdu China Dublin Institute for Advanced Studies 31 Fitzwilliam Place Dublin Ireland Max-Planck-Institut for Nuclear Physics P.O. Box 103980 Heidelberg69029 Germany State Key Laboratory of Particle Detection and Electronics China University of Science and Technology of China Anhui Hefei230026 China School of Physical Science and Technology School of Information Science and Technology Southwest Jiaotong University Sichuan Chengdu610031 China College of Physics Sichuan University Sichuan Chengdu610065 China School of Astronomy and Space Science Nanjing University Jiangsu Nanjing210023 China Center for Astrophysics Guangzhou University Guangdong Guangzhou510006 China School of Physics and Technology Wuhan University Hubei Wuhan430072 China Key Laboratory of Dark Matter and Space Astronomy Purple Mountain Observatory Chinese Academy of Sciences Jiangsu Nanjing210023 China Hebei Normal University Hebei Shijiazhuang050024 China Key Laboratory for Research in Galaxies and Cosmology Shanghai Astronomical Observatory Chinese Academy of Sciences Shanghai200030 China Ministry of Education Tibet Lhasa850000 China National Astronomical Observatories Chinese Academy of Sciences Beijing100101 China Sun Yat-sen University Guangdong Zhuhai519000 China Dipartimento di Fisica Dell'Università di Napoli Federico Ii Complesso Universitario di Monte Sant'Angelo via Cinthia Napoli80126 Italy School of Physics and Astronomy Yunnan University Yunnan Kunming650091 China D'epartement de Physique Nucl'eaire et Corpusculaire Facult'e de Sciences Universit'e de Genève 24 Quai Ernest Ansermet Geneva1211 Switzerland Institute of Frontier and Interdisciplinary Science Shando

Recently the LHAASO Collaboration published the detection of 12 ultra-high-energy gamma-ray sources above 100 TeV, with the highest energy photon reaching 1.4 PeV. The first detection of PeV gamma rays from astrophysical sources may provide a very sensitive probe of the effect of the Lorentz invariance violation (LIV), which results in decay of high-energy gamma rays in the superluminal scenario and hence a sharp cutoff of the energy spectrum. Two highest energy sources are studied in this work. No signature of the existence of LIV is found in their energy spectra, and the lower limits on the LIV energy scale are derived. Our results show that the first-order LIV energy scale should be higher than about 105times the Planck scale Mpland that the second-order LIV scale is > 10-3Mpl. Both limits improve by at least one order of magnitude the previous results. © 2021, CC BY-NC-ND.

关键词： Gamma rays

Joint power allocation and splitting (JoPAS) for SWIPT in doubly selective vehicular channels

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Joint power allocation and splitting (JoPAS) for SWIPT in do...

作者： Wang, Dexin Zhang, Rongqing Cheng, Xiang Quan, Zhi Yang, Liuqing Department of Electrical and Computer Engineering Colorado State University Fort CollinsCO80523 United States State Key Laboratory of Advanced Optical Communication Systems and Networks School of Electronics Engineering and Computing Sciences Peking University Beijing100871 China College of Information Engineering Shenzhen University Shenzhen518060 China

In recent years, the capacity and charging speed of batteries have become the bottleneck of mobile communications systems. With the development of wireless power transfer technologies, simultaneous wireless information and power transfer (SWIPT) emerges as a potential solution for green communications. Due to hardware limitations, the energy harvesting circuit cannot decode the signal directly. Power splitting is a popular and effective solution to this problem. Consequently, the problem of optimal power splitting at the receiver arises in addition to the conventional problem of power allocation in communications systems. SWIPT in vehicular networks is a promising technology that helps extend the lifetime of sensors installed on vehicles and roadside units. However, existing SWIPT schemes fail to consider the doubly selective characteristics of vehicular channels. In this paper, joint power allocation and splitting for SWIPT over such channels is proposed with the objective of maximizing the achievable data rate with constraints on the delivered energy. Simulations show significantly improved performance compared with the existing dynamic power splitting scheme. A suboptimal algorithm, named decoupled power allocation and splitting, is also proposed with significantly reduced computational complexity and simulations demonstrate its near-optimum performance. © 2017 IEEE.

关键词： Energy harvesting

Efficient Verification of Pure Quantum states in the Adversarial Scenario

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arXiv 2019年

作者： Zhu, Huangjun Hayashi, Masahito Department of Physics Center for Field Theory and Particle Physics Fudan University Shanghai200433 China State Key Laboratory of Surface Physics Fudan University Shanghai200433 China Institute for Nanoelectronic Devices and Quantum Computing Fudan University Shanghai200433 China Collaborative Innovation Center of Advanced Microstructures Nanjing210093 China Graduate School of Mathematics Nagoya University Nagoya464-8602 Japan Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology Shenzhen518055 China Centre for Quantum Technologies National University of Singapore 3 Science Drive 2 117542 Singapore

Efficient verification of pure quantum states in the adversarial scenario is crucial to many applications in quantum information processing, such as blind measurement-based quantum computation and quantum networks. However, little is known about this subject so far. Here we establish a general framework for verifying pure quantum states in the adversarial scenario and clarify the resource cost. Moreover, we propose a simple and general recipe to constructing efficient verification protocols for the adversarial scenario from protocols for the nonadversarial scenario. With this recipe, arbitrary pure states can be verified in the adversarial scenario with almost the same efficiency as in the nonadversarial scenario. Many important quantum states in quantum information processing can be verified in the adversarial scenario with unprecedented high efficiencies. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum optics

Optimal verification and fidelity estimation of maximally entangled states

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arXiv 2019年

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. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum entanglement

General framework for verifying pure quantum states in the adversarial scenario

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arXiv 2019年

Bipartite and multipartite entangled states are of central interest in quantum information processing and foundational studies. Efficient verification of these states, especially in the adversarial scenario, is a key to various applications, including quantum computation, quantum simulation, and quantum networks. However, little is know about this topic in the adversarial scenario. Here we initiate a systematic study of pure-state verification in the adversarial scenario. In particular, we introduce a general method for determining the minimal number of tests required by a given strategy to achieve a given precision. In the case of homogeneous strategies, we can even derive an analytical formula. Furthermore, we propose a general recipe to verifying pure quantum states in the adversarial scenario by virtue of protocols for the nonadversarial scenario. Thanks to this recipe, the resource cost for verifying an arbitrary pure state in the adversarial scenario is comparable to the counterpart for the nonadversarial scenario, and the overhead is at most three times for high-precision verification. Our recipe can readily be applied to efficiently verify bipartite pure states, stabilizer states, hypergraph states, weighted graph states, and Dicke states in the adversarial scenario. This paper is an extended version of the companion paper [1]. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum chemistry