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

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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, tsinghua university, beijing 100084. china Key Laboratory for Atomic and Molecular NanoSciences, tsinghua university, beijing 100084. china) Key Laboratory for quantum information and Measurements Department of Physics Tsinghua University Bejjing 100084 China Key Laboratory for Atomic and Molecular NanoSciences Tsinghua University Bejing 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.

Multiparty quantum secret sharing of classical and quantum messages

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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, 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) Key Laboratory for quantum information and Measurements Department of Physics Tsinghua University Beijing 100084 China Key Laboratory of Beam Technology and Material Modification Beijing Normal University Beijing 100875 China Institute of Low Energy Nuclear Physics 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 information but also the quantum informati... 详细信息

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

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

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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 Beijing China Department of Computer Science and Technology Tsinghua University Beijing China Network Research center Tsinghua University Beijing China

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

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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,tsinghua university,beijing100084.china~2 Key Laboratory for Atomic and Molecular Nanosciences,tsinghua 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 Beijing 100084 China Key Laboratory for Atomic and Molecular Nanosciences Tsinghua University Beijing 100084 China National Laboratory for information Science and Technology Hsinghua University Beijing 100084 China

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

Experimental realization of quantum cryptography communication in free space

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Science china(Physics,Mechanics & Astronomy) 2005年第2期48卷 237-246页

作者： WANG Chuan1, ZHANG Jingfu1, WANG Pingxiao1, DENG Fuguo1, AI Qing1 & LONG Guilu1,2 1. Department of Physics, Key Laboratory for quantum information and Measurements, tsinghua Univer- sity, beijing 100084. china 2. center for Atomic and Molecular NanoSciences, tsinghua university, beijing 100084. china Department of Physics Key Laboratory for Quantum Information and Measurements Tsinghua University Beijing China Atomic and Molecular NanoSciences Tsinghua University Beijing China

Utilizing linear optical devices, the principle of B92 quantum key distribution (QKD) protocol is demonstrated in free space with a distance of transmission of 2.2 meters. The faint laser pulses with 650 nm wavelength are used as the single photon sources. The experimental results show that the eavesdropping behavior in the signal transmission can be detected. We also discuss the problems and solutions in using the quantum cryptography communication practically. It is pointed out that one of the approaches to increasing the distance of the quantum communication is to overcome the attenuation of the single photon in transmission. This could not be solved by the use of single photon source, and new quantum communication protocols are needed to solve these problems.

关键词： quantum key distribution, free space, linear optics, faint pulses.

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

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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, tsinghua university, beijing 100084. china 2. Key Laboratory for Atomic and Molecular NanoSciences, tsinghua university, beijing 100084. china) Key Laboratory for quantum information and Measurements Department of Physics Tsinghua University Beijing 100084 China Key Laboratory for Atomic and Molecular NanoSciences 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

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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. china 2. center of quantum information Science and Technology, tsinghua National Laboratory for information Science and Technology, beijing 100084. china 3. Institute of Physics, School of Sciences, beijing university of Posts and Telecommunications, beijing 100876, china) Key Laboratory for Atomic and Molecular NanoSciences Department of Physics Tsinghua University Beijing 100084 China center of quantum information Science and Technology Tsinghua National Laboratory for Information Science and Technology Beijing 100084 China Institute of Physics School of Sciences Beijing University of Posts and Telecommunications Beijing 100876 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.

Theoretical research progress in new-generation Internet architecture

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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 100084.china 2 Network Research center,tsinghua university,beijing 100084.china 3 tsinghua National Laboratory for information Science and Technology(TNList) ,beijing 100084.china Department of Computer Science Tsinghua University Beijing China Network Research center Tsinghua University Beijing China tsinghua National Laboratory for information Science and Technology (TNList) Beijing China

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

A formal method to real-time protocol interoperability testing

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Science in china(Series F) 2008年第11期51卷 1723-1744页

作者： WANG ZhiLiang1,3,YIN Xia2,3 & JING ChuanMing2,3 1 Network Research center,tsinghua university,beijing 100084.china 2 Department of Computer Science and Technology,tsinghua university,beijing 100084.china 3 tsinghua National Laboratory for information Science and Technology(TNList) ,beijing 100084.china Network Research center Tsinghua University Beijing China tsinghua National Laboratory for information Science and Technology (TNList) Beijing China Department of Computer Science and Technology Tsinghua University Beijing China

Interoperability testing is an important technique to ensure the quality of implementations of network communication protocol. In the next generation Internet protocol, real-time applications should be supported effectively. However, time constraints were not considered in the related studies of protocol interoperability testing, so existing interoperability testing methods are difficult to be applied in real-time protocol interoperability testing. In this paper, a formal method to real-time protocol interoperability testing is proposed. Firstly, a formal model CMpTIOA （communicating multi-port timed input output automata） is defined to specify the system under test （SUT） in real-time protocol interoperability testing; based on this model, timed interoperability relation is then defined. In order to check this relation, a test generation method is presented to generate a parameterized test behavior tree from SUT model; a mechanism of executability pre-determination is also integrated in the test generation method to alleviate state space explosion problem to some extent. The proposed theory and method are then applied in interoperability testing of IPv6 neighbor discovery protocol to show the feasibility of this method.

关键词： protocol testing interoperability testing real-time testing test generation timed input output automata(TIOA)