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Quantum Mechanical Nature in Liquid NMR Quantum computing

Communications in Theoretical Physics 2002年第3期38卷 305-308页

作者： LONG Gui-Lu YAN Hai-Yang LI Yan-Song TU Chang-Cun ZHU Sheng-Jiang RUAN Dong SUN Yang TAO Jia-Xun CHEN Hao-Ming Department of Physics Tsinghua University Beijing 100084 China Laboratory for Quantum Computation and Quantum Measurement Beijing 100084 China Center for Atomic and Molecular Nano-Sciences Tsinghua University Beijing 100084 China Institute of Theoretical Physics the Chinese Academy of Sciences Beijing 100080 China Department of Physics Tsinghua University Beijing 100084 ChinaLaboratory for Quantum Computation and Quantum Measurement Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 ChinaLaboratory for Quantum Computation and Quantum Measurement Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 ChinaLaboratory for Quantum Computation and Quantum Measurement Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 China Laboratory for Quantum Computation and Quantum Measurement Beijing 100084 China Department of Physics and Astronomy University of Tennessee Knoxville Tennessee 37996 USA Department of Chemistry Tsinghua University Beijing 100084 China Department of Physics Tsinghua University Beijing 100084 China

The quantum nature of bulk ensemble NMR quantum computing the center of recent heated debate,is addressed. Concepts of the mixed state and entanglement are examined, and the data in a two-qubit liquid NMRquantum computation are analyzed. The main points in this paper are: i) Density matrix describes the "state" of anaverage particle in an ensemble. It does not describe the state of an individual particle in an ensemble; ii) Entanglementis a property of the wave function of a microscopic particle (such as a molecule in a liquid NMR sample), and separabilityof the density matrix cannot be used to measure the entanglement of mixed ensemble; iii) The state evolution in bulk-ensemble NMRquantum computation is quantum-mechanical; iv) The coefficient before the effective pure state densitymatrix, e, is a measure of the simultaneity of the molecules in an ensemble. It reflects the intensity of the NMR signaland has no significance in quantifying the entanglement in the bulk ensemble NMR system. The decomposition of thedensity matrix into product states is only an indication that the ensemble can be prepared by an ensemble with theparticles unentangled. We conclude that effective-pure-state NMR quantum computation is genuine, not just classicalsimulations.

关键词： quantum mechanical nature, NMR quantum computing, mixed state, entanglement

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A distributed inverse iteration method for eigenvalue analysis of interconnected power systems

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Science China(Technological Sciences) 2007年第6期50卷 774-785页

作者： SHEN Chen CHEN Ying ZHANG Xu State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China State Key Laboratory of Power Systems Department of Electrical Engineering Tsinghua University Beijing 100084 China

Since China power grids have a hierarchical architecture in operation and man- agement, centralized computation patterns are difficult to meet the demands of small-signal-stability analysis of the bulk interconnected power systems. A dis- tributed eigenvalue algorithm derived from the inverse iteration method is pro- posed. It can not only obtain eigenvalues and eigenvectors from power system state matrix but also provide participation factors of all generators. In the comput- ing process, the algorithm only requires exchanging data of boundary nodes and a small amount of other information of different regions. Therefore, it is very suitable to be deployed in a WAN (wide area network) based distributed environment. The algorithm has been tested on an IEEE39 system.

关键词： distributed computing, eigenvalue, small signal stability, inverse iteration method

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An introduction to computational crystallography:the relationship between aluminum-based spinel structures and their morphologies

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Science China(Technological Sciences) 2003年第3期46卷 259-270页

作者：施尔畏元如林陈之战郑燕青童怀水李汶军仲维卓 Shanghai Institute of Ceramics Chinese Academy of Sciences Shanghai College of Finance Donghua Institute of Technology

The computational crystallography is proposed. Its basic concept and research method are systematically introduced, with aluminum-based spinel (ABS) as an example, through (ⅰ) se-lecting basic crystal structural unit, (ⅱ) determining the mathematical expression of crystal struc-ture, (ⅲ) computing the stability energy of growth unit and finding out which is (are) favorable one(s), and (ⅳ) describing the formation process of crystal morphology. The morphology of ABS deduced from the computation is in excellent agreement with that from hydrothermal experiments.

关键词： crystallography, mathematical modeling and computing, aluminum-based spinel (ABS) crystal.

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Dephasing rate in an InAs/GaAs single-electron quantum dot qubit

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Science China Mathematics 2002年第5期45卷 666-670页

作者：潘留仙牛智川郑厚植李树深封松林刘金龙 Department of Physics Yiyang Teacher's College Yiyang 413049 China Natl. Lab. Superlattices M. Institute of Semiconductors Chinese Academy of Sciences Beijing 100083 China

We have obtained the parameter-phase diagram, which unambiguously defines the parameter region for the use of InAs/GaAs quantum dot as two-level quantum system in quantum computation in the framework of the effective-mass envelope function theory. Moreover, static electric field is found to efficiently prolong decoherence time. As a result, decoherence time may reach the order of magnitude of milli-seconds as external static electric field goes beyond 20 kV/cm if only vacuum fluctuation is taken as the main source for decoherence. Our calculated results are useful for guiding the solid-state implementation of quantum computing.

关键词： quantum dot, quantum computing, decoherence.

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Teracluster LSSC-II--Its designing principles and applications in large scale numerical simulations

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Science China Mathematics 2004年第Z1期47卷 53-68页

The teracluster LSSC-II installed at the State Key Laboratory of Scientific and Engineering computing, Chinese Academy of Sciences is one of the most powerful PC clusters in China. It has a peek performance of 2Tflops. With a Linpack performance of 1.04Tflops, it is ranked at the 43rd place in the 20th TOP500 List (November 2002), 51st place in the 21st TOP500 List (June 2003), and the 82nd place in the 22nd TOP500 List (November 2003) with a new Linpack performance of 1.3Tflops. In this paper, we present some design principles of this cluster, as well as its applications in some large-scale numerical simulations.

关键词： high performance computing, PC cluster, large scale numerical simulations.

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Managing Security in Advanced Computational Infrastructure

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Journal of Shanghai University(English Edition) 2001年第Z1期5卷 1-4页

Proposed by Education Ministry of China, Advanced Computational Infrastructure (ACI) aims at sharing geographically distributed high-performance computing and huge-capacity data resource among the universities of China. With the fast development of large-scale applications in ACI, the security requirements become more and more urgent. The special security needs in ACI is first analyzed in this paper, and security management system based on ACI is presented. Finally, the realization of security management system is discussed.

关键词： grid computing, security, Linux

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云虚拟机资源负载均衡的任务调度研究（英文）

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机床与液压 2015年第18期43卷 64-69页

作者：张勇军熊庆国李文翔武汉科技大学信息科学与工程学院武汉430081 武汉科技大学冶金自动化与检测技术教育部工程研究中心武汉430081 武汉科技大学冶金工业过程系统科学湖北省重点实验室武汉430081

针对云计算中现有任务调度模型为追求最短完成时间,而没有从物理资源的负载均衡角度考虑,提出了基于任务预先分类的调度策略(PCSS)。该策略通过综合考虑任务的最少执行时间和截止时间来设置优先级,根据优先级别将任务批量分配给合适的...

针对云计算中现有任务调度模型为追求最短完成时间,而没有从物理资源的负载均衡角度考虑,提出了基于任务预先分类的调度策略(PCSS)。该策略通过综合考虑任务的最少执行时间和截止时间来设置优先级,根据优先级别将任务批量分配给合适的物理机,实现了任务的最短完成时间和物理机的负载均衡。最后通过Cloudsim仿真实验分析和比较,该策略能很好地执行用户任务并体现出良好的负载均衡。

关键词： Cloud computing, Task scheduling, Virtual machine, Priority queue, Load balancing

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