检索结果-南通市图书馆

Dense coding scheme using superpositions of Bell-states and its NMR implementation

在线全文

学校读者我要写书评

暂无评论

Science china(Physics,Mechanics & Astronomy) 2005年第1期48卷 57-67页

作者： ZHANG Jingfu, XIE Jingyi, DENG Zhiwei & LU Zhiheng Key Laboratory for quantum information and Measurements, Department of Physics,{2., Beijing 100084, china center for quantum information,{2., Beijing 100084, china Department of Materials Science and Engineering, Beijing Normal university, Beijing 100875, china Testing and Analytical center, Beijing Normal university, Beijing 100875, china Department of Physics, Beijing Normal university, Beijing 100875, china Key Laboratory for quantum information and Measurements Department of Physics Tsinghua University Beijing 100084 China center for quantum information Tsinghua University Beijing 100084 China Department of Materials Science and Engineering Beijing 100875 China Testing and Analytical center Beijing Normal University Beijing 100875 China Department of Physics Beijing Normal University Beijing 100875 China

Dense coding using superpositions of Bell-states is proposed. The generalized Grover's algorithm is used to prepare the initial entangled states, and the reverse process of the quantum algorithm is used to determine the entangled state in the decoding measurement. Compared with the previous schemes, the superpositions of two Bell-states are exploited. Our scheme is demonstrated using a nuclear magnetic resonance (NMR)quantum computer. The corresponding manipulations are obtained. Experimental results show a good agreement between theory and experiment. We also generalize the scheme to transmit eight messages by introducing an additional two-state system.

关键词： dense coding, superpositions of Bell-states, generalized Grover's algorithm, nuclear magnetic res-onance, quantum computer.

A scheme to implement the Deutsch-Josza algorithm on a superconducting charge-qubit quantum computer

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第6期16卷 594-599页

作者： HUO Wenyi and LONG Guilu (Key Laboratory for quantum information and Measurements, and Department of Physics,{2., Beijing 100084, china Key Laboratory for Atomic and Molecular NanoSciences,{2., Beijing 100084, china) Key Laboratory for quantum information and Measurements and Department of Physics Tsinghua University Beijing 100084 China Key Laboratory for Atomic and Molecular NanoSciences Tsinghua University Beijing 100084 China

We have studied the implementation of the Deutsch-Josza quantum algorithm in a superconducting charge-qubit quantum computer. Different from previous studies, we have used the inductance coupled system of You et al. The detailed pulse sequences have been designed for the four possible functions in a 2.qubit system. The result is generalized to an arbitrary n-qubit system. This scheme will be useful for practical implementation of the algorithm.

关键词： superconducting quantum computer Deutsch-Josza algorithm.

Measuring-basis-encrypted six-state quantum key distribution scheme

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第1期16卷 84-89页

作者： CHEN Pan1, DENG Fuguo1, WANG Pingxiao1 and LONG Guilu1,2.(Key Laboratory for quantum information and Measurements and Department of Physics,{2., Beijing 100084, china 2. Key Laboratory for Atomic and Molecular NanoSciences,{2., Beijing 100084, china) Key Laboratory for quantum information and Measurements and Department of Physics Tsinghua University Beijing 100084 China

A six-state quantum key distribution scheme with measuring-basis encryption technique, which is based on the six-state protocol and the MBE protocol, is proposed. In this modified six-state quantum key distribution protocol, Alice and Bob use a control key to synchronize the use of their measuring-basis so that they always use the same measuring-basis. This modified six-state quantum key distribution protocol retains the advantage of higher security and at the same time has a higher efficiency.

关键词： quantum key distribution measuring-basis encrypted six-state security.

Influence of magnetic current on the ground state entanglement in an isotropic transverse XY chain

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第10期17卷 1147-1151页

作者： Liu Dan1,2., Zhang Yong3 and Long Guilu1,2.1. Key Laboratory for Atomic and Molecular NanoSciences, and Department of Physics, tsinghua university, Beijing 100084,{2. 2. center of quantum information Science and Technology, tsinghua National Laboratory for information Science and Technology, Beijing 100084,{2. 3. Institute of Physics, School of Sciences, Beijing university of Posts and Telecommunications, Beijing 100876,{2.) Key Laboratory for Atomic and Molecular NanoSciences and Department of Physics Tsinghua University Beijing 100084 China

We study the ground state entanglement in a three-qubit XY chain under the influence of a magnetization current. It is found that the ground state changes from a W state to a disentangled state as the magnetic field varies. When the Lagrange multiplier λ>3, namely under a strong magnetic current, the ground state holds onto a W state for a large range of the magnetic field strength. A phase transition to the magnetization-current phase occurs under a certain condition.

关键词： Heisenberg-XY chain magnetic-current phase transition.

Electric-stimulus rate encoding algorithm of Mandarin tonal information in cochlear implant

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2006年第12期16卷 1315-1321页

作者： GUAN Tian~1, GONG Qin~1 and YE Datian~2.*(1. Department of Biomedical Engineering, tsinghua university, Beijing 100084,{2. 2. Research center of Biomedical Engineering, Graduate School at Shenzhen, tsinghua university, Shenzhen 518055,{2.) Department of Biomedical Engineering Tsinghua University Beijing 100084 China. Research center of Biomedical Engineering Graduate School Shenzhen Tsinghua University Shenzhen 518055 China

The modern multi-channel cochlear implants usually extract and encode the temporal envelope cues. This kind of algorithms can hardly satisfy the users who speak tonal languages, such as Mandarin. Many studies have tried to enhance the recognition ability of Mandarin through encoding tonal information and made suggestions to frequency-modulate the fixed pulse-rate carrier with the extracted tonal information based on the rate-pitch theory in electric hearing. However, how to encode and deliver the tonal information such as F_0by changing electric-stimulus rate has not got further study in clinical electric-stimulus mode. The present paper focuses on this matter by piecewise calculating the appreciable electric-stimulus rates. Then an electric-stimulus encoding algorithm of Mandarin tone is brought forward and testified through acoustic simulations. Such conclusion can be drawn that this algorithm of electric-stimulus rate could convey tonal information well and help to enhance the Mandarin speech recognition ability.

关键词： cochlear implant tone fundamental frequency electric-stimulus rate.

RRM:An incentive reputation model for promoting good behaviors in distributed systems

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science in china(Series F) 2008年第11期51卷 1871-1882页

作者： ZHANG Hong1,2.DUAN HaiXin1,3 & LIU Wu1,3 1 tsinghua National Laboratory for information Science and Technology,tsinghua university,Beijing 100084,china 2.Department of Computer Science and Technology,tsinghua university,Beijing 100084,china 3 Network Research center,tsinghua university,Beijing 100084,china tsinghua National Laboratory for information Science and Technology Tsinghua University Department of Computer Science and Technology Tsinghua University Network Research center Tsinghua University

Reputation systems represent soft security mechanisms that complement traditional information security mechanisms. They are now widely used in online e-commerce markets and communities in order to stimulate good behaviors as well as to restrain adverse behaviors. This paper analyzes the limitations of the conversational reputation models and proposes an incentive reputation model called the resilient reputation model （RRM） for the distributed reputation systems. The objective of this reputation model is not only to encourage the users to provide good services and, therefore, to maximize the probability of good transaction outcomes, but also to punish those adverse users who are trying to manipulate the application systems. The simulation results indicate that the proposed reputation model （RRM） could effectively resist against the common adverse behaviors, while protecting the profits of sincere users from being blemished by those adversaries.

关键词： reputation model distributed system trust soft security

Absence of State Collapse and Revival in a Superconducting Charge Qubit

在线全文

学校读者我要写书评

暂无评论

Communications in Theoretical Physics 2007年第12期48卷 1029-1032页

作者： HUO Wen-Yi~1 and LONG Gui-Lu~(1,2.3)~1 Department of Physics amd Key Laboratory for quantum information and Measurements,{2. university,Beijing100084,china~2.Key Laboratory for Atomic and Molecular Nanosciences,{2. university,Beijing 100084,china~3 National Laboratory for information Science and Technology,Hsinghua university,Beijing 100084,china Department of Physics amd Key Laboratory for quantum information and Measurements Tsinghua University Key Laboratory for Atomic and Molecular Nanosciences Tsinghua University National Laboratory for information Science and Technology Hsinghua Univers

The Hamiltonian of a superconducting charge qubit with a configuration of dc SQUID contains an interac-tion between the LC oscillator part and charge *** interaction may leads to quantum state collapse and revivalwhich degrades the charge qubits and leads to serious *** analysis shows that the existing charge qubitparameters do not lead to this phenomenon,which is very good for the superconducting charge

关键词： quantum computer superconducting charge qubit absence and revival

Multiparty quantum secret sharing of classical and quantum messages

在线全文

学校读者我要写书评

暂无评论

Progress in Natural Science:Materials International 2007年第1期17卷 26-31页

作者： CHEN Pan, DENG Fuguo and LONG Guilu ( Key Laboratory for quantum information and Measurements, and Department of Physics,{2., Beijing 100084, china Key Laboratory of Beam Technology and Material Modification, MOE, Institute of Low Energy Nuclear Physics, and Department of Material Science and Engineering, Beijing Normal university, Beijing 100875, china Beijing Radiation center, Beijing 100875, china Key Laboratory for Atomic and Molecular Nano-Sciences,{2., Beijing 100084, china) Key Laboratory for quantum information and Measurements and Department of Physics Tsinghua University Beijing 100084 China Key Laboratory of Beam Technology and Material Modification MOE Institute of Low Energy Nuclear Physics and Department of Material Science and Engineering Beijing Normal University Beijing 100875 China Beijing Radiation center Beijing 100875 China Key Laboratory for Atomic and Molecular Nano-Sciences Tsinghua University Beijing 100084 China

A scheme for multiparty quantum secret sharing of classical and quantum messages is proposed by using entanglement swapping. This scheme can distribute not only the classical {2. but also the quantum informati... 详细信息

关键词： quantum secret sharing classical message quantum message EPR pair.

Theoretical research progress in new-generation Internet architecture

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science in china(Series F) 2008年第11期51卷 1634-1660页

作者： WU JianPing1,2.3,LIU Ying2.3 & WU Qian2.3 1 Department of Computer Science,tsinghua university,Beijing {2.,china 2.Network Research center,tsinghua university,Beijing {2.,china 3 tsinghua National Laboratory for information Science and Technology(TNList) ,Beijing {2.,china Department of Computer Science Tsinghua University Network Research center Tsinghua University tsinghua National Laboratory for information Science and Technology (TNList)

Internet has become the most important information infrastructure supporting modern socio-economic development, social progress and technological Innovation. Invented 30 years ago, today Internet is facing increasingly severe technical challenges. This paper introduces the progress of the major international newgeneration Internet research plans; analyzes its basic characteristics and the principal contradictions during the development; detsiledly introduces the research carried out by 973 Project ＂Research of Future Internet Architecture＂ on the key scientific issues of new-generation Internet architecture and its latest research results; and looks to the future of the research-focus faced with the new situations of the basic research of new-generation Internet architecture as well as the new demands of innovative applications on Internet architecture.

关键词： new-generation Internet network architecture multi-dimension scalability