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Experimental Demonstration of Largeness in Bipartite Entanglement Sudden Death

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Chinese Physics Letters 2011年第7期28卷 43-46页

作者： peng Liang HUANG yun-feng LI Li LIU Bi-Heng LI Chuan-feng GUO Guang-Can Key Lab of Quantum Information University of Science and Technology of ChinaHefei 230026

Quantum coherence is the most distinct feature of quantum ***,inevitable decoherence processes will finally destroy it and make the"Schrödinger's cat"invisible in our classical *** this"quantum-to-classical transition",the so-called"largeness"plays a critical *** experimentally study the largeness phenomena in the bipartite entanglement decay process through a depolarizing channel with two-photon entangled states generated from a spontaneous parametric down-conversion *** experiment demonstrates how the speed of entanglement decay and the time when"entanglement sudden death"happens depend on the size of the system exposed to the environment noise.

关键词： decay quantum bipartite

Spontaneous T-symmetry breaking and exceptional points in cavity quantum electrodynamics systems

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Science Bulletin 2018年第17期63卷 1096-1100页

作者： Yu-Kun Lu Pai peng Qi-Tao Cao Da Xu Jan wiersig Qihuang Gong yun-feng Xiao State Key Laboratory for Mesoscopic Physics and Collaborative Innovation Center of Quantum Matter School of Physics Peking University Beijing 100871 China Collaborative Innovation Center of Extreme Optics Shanxi University Taiyuan 030006 China Department of Electrical Engineering and Computer Science Massachusetts Institute of Technology Cambridge MA 02139 USA Institut für Physik Otto-von-Guericke-Universitat Magdeburg Postfach 4120 D-39016 Magdeburg Germany

Spontaneous symmetry breaking has revolutionized the understanding in numerous fields of modern physics. Here, we theoretically demonstrate the spontaneous time-reversal symmetry breaking in a cavity quantum electrodynamics system in which an atomic ensemble interacts coherently with a single resonant cavity mode. The interacting system can be effectively described by two coupled oscillators with positive and negative mass, when the two-level atoms are prepared in their excited states. The occurrence of symmetry breaking is controlled by the atomic detuning and the coupling to the cavity mode,which naturally divides the parameter space into the symmetry broken and symmetry unbroken *** two phases are separated by a spectral singularity, a so-called exceptional point, where the eigenstates of the Hamiltonian coalesce. When encircling the singularity in the parameter space, the quasiadiabatic dynamics shows chiral mode switching which enables topological manipulation of quantum states.

关键词： Exceptional point Spontaneous symmetry breaking Topological singularity Cavity QED

Influence of Protective Coating at High Temperature on Surface Quality of Stainless Steel

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Journal of Iron and Steel Research International 2014年第2期21卷 202-207页

作者： Xiao-meng ZHANG Lian-qi WEI peng LIU Sen WANG Shu-feng YE yun-fa CHEN State Key Laboratory of Multi-phase Complex Systems Institute of Process EngineeringChinese Academy of Sciences School of Engineering Technology China University of Geosciences

A ceramic matrix coating for minimizing steel loss of stainless steel at high temperatures was prepared by handled air-spraying technique, and the influence of coating on surface quality of stainless steel was mainly investiga ted in laboratory. Experimental results showed that the protective coating reduced the oxidation of stainless steel by more than 91% and minimized high temperature scaling and also enhanced steel surface quality. The scales of coated specimen were removed completely and the scales of uncoated specimen were partly residual on the surface after cool ing process. Mn-rich and Fe-rich zones were found in the oxides. The Cr2 O3 found in scales came from the underlying stainless steel and formed a Cr rich layer along the spalled surface.

关键词： protective coating oxidation loss surface quality stainless steel

Stepwise approach for view synthesis

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2007年第8期8卷 1218-1226页

作者： CHAI Deng-feng peng Qun-sheng State Key Lab of CAD and CG Zhejiang University Hangzhou 310027 China Institute of Spatial Information Technique Zhejiang University Hangzhou 310027 China

This paper presents some techniques for synthesizing novel view for a virtual viewpoint from two given views cap-tured at different viewpoints to achieve both high quality and high efficiency. The whole process consists of three passes. The first pass recovers depth map. We formulate it as pixel labelling and propose a bisection approach to solve it. It is accomplished in log2n(n is the number of depth levels) steps,each of which involves a single graph cut computation. The second pass detects occluded pixels and reasons about their depth. It fits a foreground depth curve and a background depth curve using depth of nearby fore-ground and background pixels,and then distinguishes foreground and background pixels by minimizing a global energy,which involves only one graph cut computation. The third pass finds for each pixel in the novel view the corresponding pixels in the input views and computes its color. The whole process involves only a small number of graph cut computations,therefore it is efficient. And,visual artifacts in the synthesized view can be removed successfully by correcting depth of the occluded pixels. Experimental results demonstrate that both high quality and high efficiency are achieved by the proposed techniques.

关键词： View synthesis Occlusion Graph cut

One-dimensional dynamic equations of a piezoelectric semiconductor beam with a rectangular cross section and their application in static and dynamic characteristic analysis

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Applied Mathematics and Mechanics(English Edition) 2018年第5期39卷 685-702页

作者： peng LI feng JIN Jianxun MA School of Human Settlements and Civil Engineering Xi'an Jiaotong University State Key Laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University

Within the framework of continuum mechanics, the double power series ex- pansion technique is proposed, and a series of reduced one-dimensional （1D） equations for a piezoelectric semiconductor beam are obtained. These derived equations are universal, in which extension, flexure, and shear deformations are all included, and can be degen- erated to a number of special cases, e.g., extensional motion, coupled extensional and flexural motion with shear deformations, and elementary flexural motion without shear deformations. As a typical application, the extensional motion of a ZnO beam is analyzed sequentially. It is revealed that semi-conduction has a great effect on the performance of the piezoelectric semiconductor beam, including static deformations and dynamic be- haviors. A larger initial carrier density will evidently lead to a lower resonant frequency and a smaller displacement response, which is a little similar to the dissipative effect. Both the derived approximate equations and the corresponding qualitative analysis are general and widely applicable, which can clearly interpret the inner physical mechanism of the semiconductor in the piezoelectrics and provide theoretical guidance for further experimental design.

关键词： piezoelectric semiconductor beam reduced one-dimensional (1D) equation,double power series expansion technique stress relaxation initial carrier density

Special Issue on the 60^(th)anniversary of the first laser-Series I:Microcavity Photonics-from fundamentals to applications

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Light(Science & Applications) 2021年第8期10卷 1395-1397页

作者： yun-feng Xiao Frank Vollmer State Key Laboratory for Mesoscopic Physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking UniversityBeijingChina Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuanChina Department of Physics and Astronomy Living Systems InstituteUniversity of ExeterExeterUK

Optical microcavities confine light to small volumes by resonant *** of their ultrahigh quality factors(Q)and small mode volumes(Vm),optical microcavities have attracted strong research interests for their unique property of significantly enhancing light-matter interaction.1 In recent decades,optical microcavities have become cornerstones for a wide range of studies and applications。

关键词： interaction. corners resonant

The Gift from Nature： Bio-Inspired Strategy for Developing Innovative Bridges

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Journal of Bionic Engineering 2013年第4期10卷 405-414页

作者： Nan Hu peng feng Gonglian Dai Department of Civil and Environmental Engineering Michigan State University East Lansing MI 48824 USA Department of Civil Engineering Tsinghua University Beijing 100084 P. R. China Department of Bridge Engineering Central South University Changsha 410075 P. R. China

Biology has been a brilliant teacher and a precious textbook to man-made construction for thousands of years, because it allows one to learn and be inspired by nature＇s remarkable and efficient structural systems. However, the emerging biomimetic studies have been of increasing interest for civil engineering design only in the past two decades. Bridge design is one of aspects on structural engineering of biomimeties that offers an enormous potential for inspiration in various aspects, such as the ge- ometry, structure, mechanism, energy use and the intelligence. Recently built bridges and design proposals in which biological systems have produced a range of inspiration are reviewed in this paper. Multidisciplinary cooperation is discussed for the implementation of bio-inspired methods in future design. A case study about using bio-inspired strategy is trying to present a problem-solving approach, yet further cooperation is still needed to utilize biomimetie studies for design inspiration. This paper aims to call a close multidisciplinary collaboration that promotes engineers to build more sustainable and smart structural systems for bridges in the 21 st century.

关键词： bionics bridges bio-inspired method conceptual design form-finding sustainability

Improved H-infinity channel estimator based on EM for MIMO-OFDM systems

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Journal of Systems Engineering and Electronics 2011年第4期22卷 572-578页

作者： peng xu Jinkuan Wang feng Qi Engineering Optimization and Smart Antenna Institute Northeastern University Shenyang 110004 R R. China Electrical Engineering Department (ESAT)-Telecommunications Microwaves (TELEMIC) Katholieke Universiteit Leuven (K. U. Leuven) Leuven 3001 Belgium

H-infinity estimator is generally implemented in timevariant state-space models, but it leads to high complexity when the model is used for multiple input multiple output with orthogo- hal frequency division multiplexing （MIMO-OFDM） systems. Thus, an H-infinity estimator over time-invariant system models is pro- posed, which modifies the Krein space accordingly. In order to avoid the large matrix inversion and multiplication required in each OFDM symbol from different transmit antennas, expectation maximization （EM） is developed to reduce the high computational load. Joint estimation over multiple OFDM symbols is used to resist the high pilot overhead generated by the increasing number of transmit antennas. Finally, the performance of the proposed estimator is enhanced via an angle-domain process. Through performance analysis and simulation experiments, it is indicated that the pro- posed algorithm has a better mean square error （MSE） and bit error rate （BER） performance than the optimal least square （LS） estimator. Joint estimation over multiple OFDM symbols can not only reduce the pilot overhead but also promote the channel performance. What is more, an obvious improvement can be obtained by using the angle-domain filter.

关键词： multiple input multiple output (MIMO) orthogonalfrequency division multiplexing (OFDM) channel estimation H-infinity expectation maximization (EM) angle domain.

Stability Control Method for Hybrid AC-DC Transmission Systems Considering Cross-region Multi-energy Coordination

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CSEE Journal of Power and Energy Systems 2021年第4期7卷 753-760页

作者： peng Sun yun Teng Ouyang Leng Zhe Chen Shenyang University of Technology Shenyang 110870China State Grid East Inner Mongolia Economic Research Institute Huhhot 010020China Department of Energy Technology Aalborg UniversityAalborgDenmark

China has built the largest hybrid AC-DC power systems with the highest voltage levels in the *** to effectively guarantee the stable operation of the hybrid AC-DC power systems is a critical undertaking and technical *** view of the stability problems of hybrid AC-DC transmission systems with a high percentage of wind power,a hybrid AC・DC transmission system's stability control method that considers cross-region multi-energy coordination is established in this *** at the uncertainty of a high percentage of wind power,the dynamic inversion method is used as the inner loop for robust control,and the battery energy storage and regenerative electric boiler are used as multiple energy sources to coordinate,and the outer loop robust control is used for uncertainty *** hybrid AC-DC weak-sending terminal system with wind power is analyzed and designed by//-synthesis based on the Hg control,and a stability control method for hybrid AC-DC transmission systems,considering cross-region multi-energy coordination,is *** results show that the model proposed in this paper can guarantee the robustness of the dynamic inversion method and improves the control performance of AC-DC transmission systems.

关键词： AC-DC transmission system multi-energy coordination robust control uncertainty