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arXiv 2017年

作者： Xin, Tao Hao, Liang Hou, Shi-Yao Feng, Guan-Ru Long, Gui-Lu State Key Laboratory of Low-dimensional Quantum Physics and Department of Physics Tsinghua University Beijing100084 China Tsinghua National Laboratory of Information Science and Technology Beijing100084 China Institute of Applied Physics and Computational Mathematics Beijing100094 China Microsystem and Terahertz Research Center China Academy of Engineering Physics Chengdu610200 China Institute of Electronic Engineering China Academy of Engineering Physics Mianyang621999 China Institute for Quantum Computing WaterlooONN2L 3G1 Canada Department of Physics and Astronomy University of Waterloo WaterlooONN2L 3G1 Canada Innovative Center of Quantum Matter Beijing100084 China

Quantum state preparation plays an equally important role with quantum operations and measurements in quantum information processing. The previous methods of preparing initial state for bulk quantum computation all have inevitable disadvantages, such as, requiring multiple experiments, causing loss of signals, or requiring molecules with restrictive structure. In this work, three kinds of quantum circuits are introduced to prepare the pseudo-pure states of (n − 1) qubits in the Hilbert space of n coupled spins which merely need the assist of one ancilla spin and two experiments independent of n. Being without gradient fields effectively avoids the reduction of the signals. Our methods have no special requirements on the structure of the used molecules. To test these methods more comprehensively, we experimentally demonstrate the preparation of the labeled pseudo-pure states using heteronuclear 2-qubit and homonuclear 4-qubit nuclear magnetic resonance quantum information processor. Copyright © 2017, The Authors. All rights reserved.

关键词： Molecules

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Guidance law recognition of target pursuing vehicle

Guidance law recognition of target pursuing vehicle

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IEEE Metrology for Aerospace

作者： Runle Du Jiaqi Liu Zhifeng Li Zhenhong Niu National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics Beijing China

Research on guidance law has begun to incorporate behavior information from non-cooperative target, and thus emphasized the importance and necessity of guidance law recognition. Recognition of guidance law on non-cooperative vehicle is highly supportive for pursued vehicle to conduct guidance law optimization, guidance law evaluation, and trajectory prediction. Huge variety of design and implementation of guidance law made recognition a hard problem. In this paper, a generic implicit guidance function is proposed to establish unified description of all known guidance laws. A practical model with time-varying guidance parameter is formulated to approximate generic implicit guidance function, and a Kalman Filter based observation data processing algorithm is proposed to build real-time guidance recognition. Simulation results show that, whether the vehicle under pursuit maneuvers or not, the guidance parameters of pursuing vehicle change or not, recognition algorithm can provide reasonable results.

关键词： Vehicles Kalman filters Trajectory Target recognition Target tracking Optimization Chapters

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X-band narrowband high-temperature super-conducting filter with high selectivity

X-band narrowband high-temperature super-conducting filter w...

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IET International Radar Conference 2015

作者： Gao, L. Jiang, Z.Y. Liu, J.Q. Liu, H.Y. Bai, J.L. Xu, F. Li, H. Chen, S.Y. Sun, L. Bian, Y.B. Wang, J. He, Y.S. National Key Laboratory of Science and Technology on Test Physics and Numerical Mathematics P.O. Box 9200 Beijing100076 China Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences P.O. Box 603 Beijing100190 China

ISBN: (纸本)9781785610387

This paper presents a development of a narrowband hightemperature superconducting filter with high selectivity. The center frequency of this filter is 8.625 GHz and the 3 dB bandwidth is 156 MHz (a fractional bandwidth of 1.81 %). In order to achieve high band edge steepness, we introduce a 10-resonator quasi-elliptic function response with two pairs of transmission zeros in the cascaded quadruplet coupling structure. The filter was manufactured on a 2-in-diameter 0.5-mm-thick MgO wafer with double-sided YBCO films. The measured results show a midband insertion loss of 0.58 dB and a return loss better than 16 dB. Band edge steepness reaches over 3.82 dB/MHz at both the high and low frequency edges. The 60 dB rectangle ratio is less than 1.19. The out-of-band rejection is over 60 dB at 17.8 MHz from the 3 dB band edge.

关键词： Magnesia

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The Study on Porous Media Phase Change Coupling Heat transfer model in Enclosed Metal Cavity

The Study on Porous Media Phase Change Coupling Heat transfe...

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The 2nd International Conference on Materials science and Engineering technology (MSET 2015)

作者： WU Run-hui LIU Jia-qi LIU Xin REN Ai-min ZHANG Sheng-jun MENG Gang National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical

This thesis is aimed to the external instantaneous high energy heat source,according to enclosed metal cavity,porous medium in the cavity,porous media can by phase change heat transfer characteristic of variegated medium coupling state target's special requirements in the field of aerospace,it is innovatively to put forward a kind of applicable to simulate sealed coupling target,under the condition of instant high energy heat source excitation,By heat source-metal cavityporous medium—porous medium's phase-changeable phase change process heat-transfer characteristic numerical calculation model-creation approach,in use of the metal cavity,in the porous medium incompressible flow phase transition of working medium's heat energy conservation,momentum conservation and mass conservation principle,it is to establish analysis model of coupled heat transfer characteristics of multiple parts,in order to acquire the full target area of airtight coupling state targets,temperature field,pressure field,velocity field and phase change of phase transition of working medium characteristics change with time and space change numerical value to analog *** study results points out:when the incentive heat source keep constant,the change rule of full target area temperature,pressure flow rate and phase change characteristic parameters is in conformity with theory of heat transfer *** heat transfer model can be popularized and applied to the optimization design of incentive heat source,and comprehensive performance optimization of enclosed coupling state objects.

关键词： Enclosed metal cavity,Porous foam materials,Phase transition working medium,Heat transfer model,numerical modeling

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Higher order shift operater FDTD scheme for scattering of cloaking structure

Higher order shift operater FDTD scheme for scattering of cl...

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IET International Radar Conference 2015

作者： Xia Ai Shengjun Zhang Mingliang Wang Weidong Wang Jiaqi Liu Chengguo Liu Xuemei Liu National Key Laboratory of Science and Technology on Test physics & Numerical Mathematical China

ISBN: (纸本)9781510822023

In this paper, a higher-order shift operater (SO) FDTD scheme with second-order accuracy in time and fourth-order in space has been proposed to accurately model scattering of perfect electronic conductor coated with cloaking structures. Several different electromagnetic parameters of the cloaks are taken into account using SO-FDTD method. numerical results indicate that the proposed method is more accuracy than the traditional method maintaining the same grid size. Scattering of different kinds of simplified cylindrical cloaks including thickness and loss are presented and could be served as further study on this subject.

关键词： Finite difference time domain method Higher-order algorithm Scattering of cloaks

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Dispersive FDTD scheme with conformal technology for analyzing electromagnetic scattering of inhomogeneous plasma array

Dispersive FDTD scheme with conformal technology for analyzi...

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IET International Radar Conference 2015

作者： Xia Ai Shendong Liu Shengjun Zhang Mingliang Wang Jiaqi Liu Gang Meng Hongchao Zhou National Key Laboratory of Science and Technology on Test physics & Numerical Mathematical China

ISBN: (纸本)9781510822023

In this paper, a dispersive conformal FDTD method have been proposed to accurate model the interface between two adjacent dispersive mediums. The method is based on the technology of area average between two adjacent dispersive interfaces, which is different from existing dispersive conformal FDTD schemes which involve with the interface between free space and dispersive medium. numerical results show the proposed method would enhance the accurate level compared to the staircasing FDTD scheme involved in the inhomogeneous plasma.

关键词： Conformal method FDTD electromagnetic scattering

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RCS analysis of disk target covered with non-uniform plasma

RCS analysis of disk target covered with non-uniform plasma

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IET International Radar Conference 2015

作者： Runhui Wu Jiaqi Liu Xin Liu Gang Meng Aimin Ren Zhaohui Qi National Key Laboratory of Science and Technology on Test Physics & Numerical Mathematical Beijing 100076

ISBN: (纸本)9781510822023

This paper presents a model of RCS characteristic of non-uniform plasma sheltering disk target, by considering the absorption and refraction of electromagnetic wave, and combining graphic electromagnetic and ray tracking methods. The results show that: (1) RCS is reduced more than 10dB at wide-band frequency of electromagnetic wave, when the incident direction of electromagnetic wave is near the vertical surface. (2)For optimization of RCS reduction scheme, it is effective to optimize the relation between the plasma parameters (including electronic density, collision frequency, over-dense target scale) and incident wavelength. When the area of over-dense surface was larger than the target scale, the larger the collision frequency could lead to greater RCS reduction. When the area of over-dense scale was smaller than target, the RCS reduction has to be achieved by increasing electronic density and collision frequency.

关键词： Disk Target Electromagnetic Wave Non-uniform Plasma Radar Cross Section(RCS)

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The seasonal variations in the significant wave height and sea surface wind speed of the China's seas

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Acta Oceanologica Sinica 2015年第9期34卷 58-64页

作者： ZHENG Chongwei PAN Jing TAN Yanke GAO Zhansheng RUI Zhenfeng CHEN Chaohui College of Meteorology and Oceanography People’s Liberation Army University of Science and Technology National Key Laboratory of Numerical Modeling for Atmospheric Sciences and Geophysical Fluid Dynamics(LASG) Institute of Atmospheric PhysicsChinese Academy of Sciences Dalian Naval Academy

Long-term variations in a sea surface wind speed （WS） and a significant wave height （SWH） are associated with the global climate change, the prevention and mitigation of natural disasters, and an ocean resource exploitation, and other activities. The seasonal characteristics of the long-term trends in China＇s seas WS and SWH are determined based on 24 a （1988-2011） cross-calibrated, multi-platform （CCMP） wind data and 24 a hindcast wave data obtained with the WAVEWATCH-III （WW3） wave model forced by CCMP wind data. The results show the following. （1） For the past 24 a, the China＇s WS and SWH exhibit a significant increasing trend as a whole, of 3.38 cm/（s.a） in the WS, 1.3 cm/a in the SWH. （2） As a whole, the increasing trend of the China＇s seas WS and SWH is strongest in March-April-May （MAM） and December-January-February （DJF）, followed by June-July-August （JJA）, and smallest in September-October-November （SON）. （3） The areal extent of significant increases in the WS was largest in MAM, while the area decreased in JJA and DJF; the smallest area was apparent in SON. In contrast to the WS, almost all of China＇s seas exhibited a significant increase in SWH in MAM and DJF; the range was slightly smaller in JJA and SON. The WS and SWH in the Bohai Sea, the Yellow Sea, East China Sea, the Tsushima Strait, the Taiwan Strait, the northern South China Sea, the Beibu Gull and the Gulf of Thailand exhibited a significant increase in all seasons. （4） The variations in China＇s seas SWH and WS depended on the season. The areas with a strong increase usually appeared in DJF.

关键词： sea surface wind speed significant wave height long-term variation seasonal difference

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Cooling a mechanical resonator to the quantum regime by heating it

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Physical Review A 2016年第5期94卷 053836-053836页

作者： Yue Ma Zhang-qi Yin Pu Huang W. L. Yang Jiangfeng Du Center for Quantum Information Institute for Interdisciplinary Information Sciences Tsinghua University Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 China Hefei National Laboratory for Physics Sciences at Microscale and Department of Modern Physics University of Science and Technology of China Hefei 230026 China State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics Wuhan Institute of Physics and Mathematics Chinese Academy of Sciences Wuhan 430071 China

We consider a mechanical resonator made of diamond, which contains a nitrogen-vacancy center (NV center) locating at the end of the oscillator. A second-order magnetic gradient is applied and induces coupling between mechanical modes and the NV center. By applying a proper external magnetic field, the energy difference between NV center electron spin levels can be tuned to match the energy difference between two mechanical modes a and b. A laser is used for continuously initializing the NV center electron spin. The mode a with lower frequency is driven by a thermal bath. We find that the temperature of the mode b is significantly cooled when the heating bath temperature is increased. We discuss the conditions that quantum regime cooling requires and confirm the results by numerical simulation. Finally we give the intuitive physical explanation of this unusual effect.

关键词： Cavity quantum electrodynamics Cooling & trapping Hybrid quantum systems Optomechanics Micromechanical & nanomechanical oscillators Nitrogen vacancy centers in diamond

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L2 Gain-Based Guidance Law with Acceleration Saturation

L2 Gain-Based Guidance Law with Acceleration Saturation

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The Society of Instrument and Control Engineers Annual Conference 2015

作者： Kezi Meng Di Zhou Runle Du Department of Control Science and Engineering Harbin Institute of Technology National Key Laboratory of Science and Technology on Test Physics&Numerical Mathematics

This paper focuses on the problem of designing a 2L, gain-scheduling state-feedback guidance law with acceleration saturation based on linear matrix inequality(LMI) approach. The planar target-missile engagement is described in a polar coordinate system and the target acceleration is viewed as unpredictable disturbance. Saturated state-feedback is placed into the convex hull of a group of linear feedbacks. Furthermore,2L gain guidance problem is formulated and solved as an optimization problem with parameter-dependent LMI constraints which are then converted into a finite number of LMIs to facilitate the computation. Finally, simulation results demonstrate that the proposed guidance law copes with acceleration saturation effectively and obtains excellent guidance performance in terms of miss distance.

关键词： L2 gain guidance law acceleration saturation LPV system linear matrix inequality(LMI)

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