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arXiv 2019年

作者： Wang, Kunpeng He, Xiaodong Gao, Xiang Guo, Ruijun Xu, Peng Zhuang, Jun Li, Runbing Liu, Min Wang, Jin Li, Jiaming Zhan, Mingsheng State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan National Laboratory for Optoelectronics Wuhan430071 China Center for Cold Atom Physics Chinese Academy of Sciences Wuhan430071 China School of Physics University of Chinese Academy of Sciences Beijing100049 China Institute for Theoretical Physics Vienna University of Technology ViennaA-1040 Austria Beijing Computational Science Research Center Beijing100193 China Department of Physics Center for Atomic and Molecular Nanosciences Tsinghua University Beijing100084 China Department of Physics and Astronomy Shanghai Jiao Tong University Shanghai200240 China Collaborative Innovation Center of Quantum Matter Beijing100084 China

As a physically motivated and computationally simple model for cold atomic and molecular collisions, the multichannel quantum defect theory (MQDT) with frame transformation (FT) formalism provides an analytical treatment of scattering resonances in an arbitrary partial wave between alkali-metal atoms, leading to the experimental observation of p− and d−wave resonances. However, the inconsistency of quantum defects for describing scattering resonances shows up when compared with experiments. Here, with two heteronuclear atoms in the ground state of an optical tweezer, the energy dependence of quantum defects is obviously revealed by comparing the measured s-wave scattering length with the prediction of MQDT-FT. By dividing the quantum defects into energy sensitive and insensitive categories, the inconsistency is ultimately removed while retaining the analytic structure of MQDT-FT. This study represents a significant improvement in the analytical MQDT-FT and demonstrates that a clean two-particle system is valuable to the test of collisional physics. Copyright © 2019, The Authors. All rights reserved.

关键词： Atoms

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Optimal verification and fidelity estimation of maximally entangled states

arXiv

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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 Singapore117542 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. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum entanglement

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Dual-band checkerboard plasma electromagnetic surface for radar cross section reduction

Dual-band checkerboard plasma electromagnetic surface for ra...

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IEEE Asia-Pacific Conference on Antennas and Propagation (APCAP)

作者： Qiang Xu Zhifeng Li Jinjun Mo National University of Defense Technology Changsha China National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing China

ISBN: (纸本)9781538616093

Radar cross section (RCS) can be reduced along the principal planes by applying electromagnetic band gap (EBG) structures. Checkerboard plasma electromagnetic surface (PES), combining with EBG and plasma layer, can realize a narrow band near 3 GHz and a wide band 10-dB radar cross section reduction (RCSR) covered X-band, by redirecting the scattered fields towards four quadrants. Bistatic RCS of the checkerboard PES is simulated and the results compared to the corresponding perfect electric conductor (PEC) surface show that the maxima of the bistatic RCS pattern are reduced by 5.4 dB at fixed frequency 10 GHz.

关键词： Plasmas Periodic structures Metamaterials Electromagnetics Radar cross-sections Electromagnetic scattering

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Spin-triplet excitonic insulator: The case of graphone

arXiv

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arXiv 2019年

作者： Jiang, Zeyu Lou, Wenkai Liu, Yu Li, Yuanchang Song, Haifeng Chang, Kai Duan, Wenhui Zhang, Shengbai State Key Laboratory of Low-Dimensional Quantum Physics Collaborative Innovation Center of Quantum Matter Department of Physics Tsinghua University Beijing100084 China SKLSM Institute of Semiconductors Chinese Academy of Sciences P.O. Box 912 Beijing100083 China Laboratory of Computational Physics Institute of Applied Physics and Computational Mathematics Beijing100088 China Advanced Research Institute of Multidisciplinary Science Beijing Institute of Technology Beijing100081 China CAEP Software Center for High Performance Numerical Simulation Beijing100088 China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of Sciences Beijing100190 China Institute for Advanced Study Tsinghua University Beijing100084 China Department of Physics Applied Physics and Astronomy Rensselaer Polytechnic Institute TroyNY12180 United States

While various excitonic insulators have been studied in the literature, due to the perceived too-small spin splitting, spin-triplet excitonic insulator is rare. In two-dimensional systems such as a graphone, however, it is possible, as revealed by first-principles calculations coupled with Bethe-Salpeter equation. The critical temperature, given by an effective Hamiltonian, is 11.5 K. While detecting excitonic insulators is still a daunting challenge, the condensation of triplet excitons will result in spin superfluidity, which can be directly measured by a transport experiment. Nonlocal dielectric screening also leads to an unexpected phenomenon, namely, an indirect-to-direct transition crossover between single-particle band and exciton dispersion in graphone, which offers yet another test by experiment. Copyright © 2019, The Authors. All rights reserved.

关键词： Calculations

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Optimal selection of regularization parameter for 1-based image restoration based on SURE

Optimal selection of regularization parameter for 1-based im...

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International Symposium on Infrared technology and Application and the International Symposiums on Robot Sensing and Advanced Control

作者： Xue, Feng Liu, Xin Liu, Hongyan Liu, Jiaqi National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781510607729

To exploit the sparsity in transform domain (e.g. wavelets), the image deconvolution can be typically formulated as a 1-penalized minimization problem, which, however, generally requires proper selection of regularization parameter for desired reconstruction quality. The key contribution of this paper is to develop a novel data-driven scheme to optimize regularization parameter, such that the resultant restored image achieves minimum prediction error (p-error). First, we develop Stein's unbiased risk estimate (SURE), an unbiased estimate of p-error, for image degradation model. Then, we propose a recursive evaluation of SURE for the basic iterative shrinkage/thresholding (IST), which enables us to find the optimal value of regularization parameter by exhaustive search. The numerical experiments show that the proposed SURE-based optimization leads to nearly optimal deconvolution performance in terms of peak signal-to-noise ratio (PSNR). © 2016 SPIE.

关键词： Image reconstruction

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Frequency divided adaptive Kalman filter in guidance law recognition 24

Frequency divided adaptive Kalman filter in guidance law rec...

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24th European Navigation Conference, ENC 2016

作者： Run-Le, Du Jia-Qi, Liu Zhi-Feng, Li Zhen-Hong, Niu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing100076 China

ISBN: (纸本)9781479989157

Recognition of guidance law on non-cooperative vehicle is drawing research interest among the literature, while insufficient accuracy of modeling and measurement makes it a hard problem. In this paper, a Frequency Divided Adaptive Kalman Filter is proposed to implement guidance law recognition. In FD-AKF, a Low Pass Filter is applied to extract the noise directly from state vector and measurement vector, and estimate the co-variance matrices of observation noise and prediction noise online. Without intertwined iterating equation of prediction noise and observation noise, FD-AKF decouples the estimation on prediction noise and observation noise, and thus avoids the risk of bias and divergence. Simulation results show that, FD-AKF improves robustness of guidance recognition significantly over Kalman Filter and Sage-Husa. © 2016 IEEE.

关键词： Forecasting

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Constraints on Cosmic Strings Using Data from the Third Advanced LIGO–Virgo Observing Run

引用

Physical Review Letters 2021年第24期126卷 241102-241102页

作者： R. Abbott T. D. Abbott S. Abraham F. Acernese K. Ackley A. Adams C. Adams R. X. Adhikari V. B. Adya C. Affeldt D. Agarwal M. Agathos K. Agatsuma N. Aggarwal O. D. Aguiar L. Aiello A. Ain P. Ajith T. Akutsu K. M. Aleman G. Allen A. Allocca P. A. Altin A. Amato S. Anand A. Ananyeva S. B. Anderson W. G. Anderson M. Ando S. V. Angelova S. Ansoldi J. M. Antelis S. Antier S. Appert Koya Arai Koji Arai Y. Arai S. Araki A. Araya M. C. Araya J. S. Areeda M. Arène N. Aritomi N. Arnaud S. M. Aronson H. Asada Y. Asali G. Ashton Y. Aso S. M. Aston P. Astone F. Aubin P. Auclair P. Aufmuth K. AultONeal C. Austin S. Babak F. Badaracco M. K. M. Bader S. Bae Y. Bae A. M. Baer S. Bagnasco Y. Bai L. Baiotti J. Baird R. Bajpai M. Ball G. Ballardin S. W. Ballmer M. Bals A. Balsamo G. Baltus S. Banagiri D. Bankar R. S. Bankar J. C. Barayoga C. Barbieri B. C. Barish D. Barker P. Barneo S. Barnum F. Barone B. Barr L. Barsotti M. Barsuglia D. Barta J. Bartlett M. A. Barton I. Bartos R. Bassiri A. Basti M. Bawaj J. C. Bayley A. C. Baylor M. Bazzan B. Bécsy V. M. Bedakihale M. Bejger I. Belahcene V. Benedetto D. Beniwal M. G. Benjamin T. F. Bennett J. D. Bentley M. BenYaala F. Bergamin B. K. Berger S. Bernuzzi D. Bersanetti A. Bertolini J. Betzwieser R. Bhandare A. V. Bhandari D. Bhattacharjee S. Bhaumik J. Bidler I. A. Bilenko G. Billingsley R. Birney O. Birnholtz S. Biscans M. Bischi S. Biscoveanu A. Bisht B. Biswas M. Bitossi M.-A. Bizouard J. K. Blackburn J. Blackman C. D. Blair D. G. Blair R. M. Blair F. Bobba N. Bode M. Boer G. Bogaert M. Boldrini F. Bondu E. Bonilla R. Bonnand P. Booker B. A. Boom R. Bork V. Boschi N. Bose S. Bose V. Bossilkov V. Boudart Y. Bouffanais A. Bozzi C. Bradaschia P. R. Brady A. Bramley A. Branch M. Branchesi M. Breschi T. Briant J. H. Briggs A. Brillet M. Brinkmann P. Brockill A. F. Brooks J. Brooks D. D. Brown S. Brunett G. Bruno R. Bruntz J. Bryant A. Buikema T. Bulik H. J. Bulten A. Buonanno R. Buscicchio D. Buskulic L. Cadonati M. Caesar G. Cagnoli C. Cahillane H. W. Cain, III J. Calderón Bustillo J. D LIGO Laboratory California Institute of Technology Pasadena California 91125 USA Louisiana State University Baton Rouge Louisiana 70803 USA Inter-University Centre for Astronomy and Astrophysics Pune 411007 India Dipartimento di Farmacia Università di Salerno I-84084 Fisciano Salerno Italy INFN Sezione di Napoli Complesso Universitario di Monte S.Angelo I-80126 Napoli Italy OzGrav School of Physics and Astronomy Monash University Clayton 3800 Victoria Australia Christopher Newport University Newport News Virginia 23606 USA LIGO Livingston Observatory Livingston Louisiana 70754 USA OzGrav Australian National University Canberra Australian Capital Territory 0200 Australia Max Planck Institute for Gravitational Physics (Albert Einstein Institute) D-30167 Hannover Germany Leibniz Universität Hannover D-30167 Hannover Germany University of Cambridge Cambridge CB2 1TN United Kingdom Theoretisch-Physikalisches Institut Friedrich-Schiller-Universität Jena D-07743 Jena Germany University of Birmingham Birmingham B15 2TT United Kingdom Center for Interdisciplinary Exploration and Research in Astrophysics (CIERA) Northwestern University Evanston Illinois 60208 USA Instituto Nacional de Pesquisas Espaciais 12227-010 São José dos Campos São Paulo Brazil Gravity Exploration Institute Cardiff University Cardiff CF24 3AA United Kingdom Gran Sasso Science Institute (GSSI) I-67100 L’Aquila Italy INFN Laboratori Nazionali del Gran Sasso I-67100 Assergi Italy INFN Sezione di Pisa I-56127 Pisa Italy Università di Pisa I-56127 Pisa Italy International Centre for Theoretical Sciences Tata Institute of Fundamental Research Bengaluru 560089 India Gravitational Wave Science Project National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan Advanced Technology Center National Astronomical Observatory of Japan (NAOJ) Mitaka City Tokyo 181-8588 Japan California State University Fullerton Fullerton California 92831 USA NCSA University of Illi

We search for gravitational-wave signals produced by cosmic strings in the Advanced LIGO and Virgo full O3 dataset. Search results are presented for gravitational waves produced by cosmic string loop features such as cusps, kinks, and, for the first time, kink-kink collisions. A template-based search for short-duration transient signals does not yield a detection. We also use the stochastic gravitational-wave background energy density upper limits derived from the O3 data to constrain the cosmic string tension Gμ as a function of the number of kinks, or the number of cusps, for two cosmic string loop distribution models. Additionally, we develop and test a third model that interpolates between these two models. Our results improve upon the previous LIGO–Virgo constraints on Gμ by 1 to 2 orders of magnitude depending on the model that is tested. In particular, for the one-loop distribution model, we set the most competitive constraints to date: Gμ≲4×10−15. In the case of cosmic strings formed at the end of inflation in the context of grand unified theories, these results challenge simple inflationary models.

关键词： Cosmic strings & domain walls Gravitational waves

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A high-resolution land model with groundwater lateral flow,water use and soil freeze-thaw front dynamics and its applications in an endorheic basin

A high-resolution land model with groundwater lateral flow,w...

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第35届中国气象学会年会

作者： Zhenghui Xie Shuang Liu Yujin Zeng Junqiang Gao Peihua Qin Binghao Jia Jinbo Xie Bin Liu Ruichao Li Yan Wang Longhuan Wang State Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics Institute of Atmospheric Physics Chinese Academy of Sciences College of Earth Science University of Chinese Academy of Sciences Program in Atmospheric and Oceanic Sciences Princeton University School of Mathematics and Statistics Nanjing University of Information Science and Technology

Human water regulation(HWR), groundwater lateral flow(GLF) and the movement of frost and thaw fronts(FTFs) affect soil water and thermal processes, as well as energy and water exchanges between the land surface and atmosphere. Reasonable representation of these processes in land surface models is very important to improving the understanding of land-atmosphere interactions. In this study,mathematical descriptions of GLF, HWR and FTFs were synchronously incorporated into a high-resolution community land model named the Land Surface Model for Chinese Academy of sciences(CAS-LSM). With a series of atmospheric forcings and high-resolution land surface data from the Heihe Watershed Allied Telemetry Experimental Research(Hi WATER) program, numerical simulations of the period1981–2013 using CAS-LSM with 1-km resolution were conducted for an endorheic basin, the Heihe River Basin in China. Compared with observations, CAS-LSM reproduced the distributions of groundwater, evapotranspiration and permafrost reasonably, and well matched the temporal changes in ground temperature, heat fluxes and FTFs. Results illuminate the temporal and spatial characteristics of frozen soil and the changes in the land-atmosphere exchange of carbon, water and energy. The permafrost and seasonally frozen soil were distinguished. In the seasonally frozen areas, the maximum soil frost depth increased by 0.65 mm/year within natural areas and decreased by 2.12 mm/year in human-dominated areas. The active layer thickness increased 8.63 mm/year for permafrost. In the permafrost zone evapotranspiration and latent heat flux increased, and the sensible heat flux declined. In the human-dominated areas water use raised the latent heat flux and reduced the sensible heat flux, net ecosystem exchange and streamflow recharging to the eco-fragile region in the lower reaches. Results suggested that the land surface model CAS-LSM is a potential tool for studying land surface processes, especially in cold and arid r

关键词： A high-resolution land model with groundwater lateral flow,water use and soil freeze-thaw front dynamics and its applications in an endorheic basin CAS

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Suppressing the Effects of Ionospheric Scintillation on Geosynchronous SAR by Optimised Orbit Design

Suppressing the Effects of Ionospheric Scintillation on Geos...

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International Conference on Radar Systems

作者： YuanHao Li XiangRong Liu Cheng Hu XiChao Dong Beijing Institute of Technology Beijing Beijing CN National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics 100076 China Beijing Key Laboratory of Embedded Real-time information Processing Technology 100081 China

ISBN: (纸本)9781785616723

An L band geosynchronous synthetic aperture radar (GEO SAR) will be sensitive to ionosphere scintillation because of its low carrier frequency. Meanwhile, because of the high orbit, GEO SAR has a higher probability to meet ionospheric scintillation. In this paper, we propose an orbit strategy for eliminating the impacts of ionospheric scintillation. It is realized by selecting a proper orbit element (time past perigee) to avoid imaging for the sensitive region of ionospheric scintillation during the eruption time interval of ionospheric scintillation with the highest probability. Finally, the simulation based on systems tool kit (STK) software was conducted to verify the effectiveness of the method.

关键词： Geosynchronous SAR Ionospheric scinitllation Orbit design SAR imaging

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Observing geometry of quantum states in a three-level system

arXiv

引用

arXiv 2019年

作者： Xie, Jie Zhang, Aonan Cao, Ningping Xu, Huichao Zheng, Kaimin Poon, Yiu-Tung Sze, Nung-Sing Xu, Ping Zeng, Bei Zhang, Lijian National Laboratory of Solid State Microstructures College of Engineering and Applied Sciences School of Physics Nanjing University Nanjing210093 China Collaborative Innovation Center of Advanced Microstructures Nanjing University Nanjing210093 China Center for Quantum Computing Peng Cheng Laboratory Shenzhen518055 China Department of Mathematics & Statistics University of Guelph GuelphONN1G 2W1 Canada Institute for Quantum Computing University of Waterloo WaterlooONN2L 3G1 Canada Department of Mathematics Iowa State University AmesIA50011 United States Department of Applied Mathematics Hong Kong Polytechnic University Hong Kong Institute for Quantum Information State Key Laboratory of High Performance Computing College of Computer National University of Defense Technology Changsha410073 China Department of Physics Hong Kong University of Science and Technology Clear Water Bay Kowloon Hong Kong

Geometric characters of physical objects greatly facilitate our understanding of the world. Along with the founding of quantum mechanics, of particular interest is the geometry of quantum systems from which many non-classical behaviors arise and exotic properties of the system can be inferred. However, there is always the difficulty to illustrate geometry of quantum systems beyond the simplest quantum bit model. One approach is to project the state space of quantum systems to the familiar Euclidean space via measurements of observables on the system. Here we report the first experiment measuring the geometry of such projections beyond one quantum bit. Specifically, we observe the joint numerical ranges of a triple of observables in a three-level photonic system, providing complete classification of the geometric objects. We further show that the geometry of different classes reveals ground-state degeneracies of corresponding Hamiltonians, which is related to quantum phases in the thermodynamic limit. Our results offer a versatile geometric approach for exploring and utilizing the higher dimensional quantum systems. Copyright © 2019, The Authors. All rights reserved.

关键词： Quantum optics

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