Nonlocal quantum cloning via quantum dots trapped in distant cavities

A scheme for implementing nonlocal quantum cloning via quantum dots trapped in cavities is proposed.By modulating the parameters of the system,the optimal 1 → 2 universal quantum cloning machine,1 → 2 phase-covariant cloning machine,and 1 → 3 economical phase-covariant cloning machine are constructed.The present scheme,which is attainable with current technology,saves two qubits compared with previous cloning machines.     

Secure quantum dialogue based on single-photon

In this paper a quantum dialogue scheme is proposed by using N batches of single photons. The same secret message is encoded on each batch of single photons by the sender with two different unitary operations, and then the N batches of single photons are sent to the receiver. After eavesdropping check, the message is encoded on the one remaining batch by the receiver. It is shown that the intercept-and-resend attack and coupling auxiliary modes attack can be resisted more efficiently, because the photons are sent only once in our quantum dialogue scheme.     

Complete hyperentangled state analysis and generation of multi-particle entanglement based on charge detection

We propose the schemes for implementing hyperentangled state analysis and generating four-electron high entan-gled states （including cluster state, ｜X） state, and symmetric Dicke state） based on the charge detection of free electrons. These schemes are deterministic and rely only on charge detection and single-spin rotations. This method, which uses noninteracting electrons, is not only efficient but also saves on quantum resources.     

Generation of the nonlocal quantum entanglement of three three-level particles by local operations

We propose a scheme to realize the nonlocal quantum entanglement of three three-level particles by using a three-particle entangled state of three levels as a quantum channel with the aid of some local unitary transformations. This scheme can be directly generalized to the nonlocal quantum entanglement of N three-level particles.     

辫子Hopf代数的积分

本文引进了无限维辫子Hopf代数日的忠实拟对偶H~d和严格拟对偶H~(d′)．证明了每个严格拟对偶H~(d′)是一个H-Hopf模．发现了H~d的极大有理H~d-子模H~(drat)与积分的关系,即：H~(drat)≌∫_(H~d)~l■H．给出了在Yetter-Drinfeld范畴(_B~ByD,C)中的辫子Hopf代数的积分的存在性和唯—性．     

Secure Quantum Secret Sharing Based on Reusable GHZ States as Secure Carriers

We show that a potential eavesdropper can eavesdrop whole secret information when the legitimate users use secure carrier to encode and decode classical information repeatedly in the protocol proposed by Bagherinezhad S and Karimipour V [Phys. Rev. A 67（2003）044302]. Then we present a revised quantum secret sharing protocol by using the Greenberger-Horne-Zeilinger state as secure carrier. Our protocol can resist Eve＇s attack.     

Probabilistic remote preparation of a two-atom entangled state

A scheme for remotely preparing a two-atom entangled state via entanglement swapping in cavity quantum electronic dynamics （QED） with the help of separate measurements is proposed. And the effect of cavity decay is eliminated in our scheme.     

不同激光脉冲对J-C模型中的反聚束效应的影响

选取三种不同的激光脉冲形式,研究了依赖于时间的J-C模型中的反聚束效应.并对三种不同脉冲形式下所得的结果进行比较.     

原子运动对与V型三能级原子作用的双模光场压缩效应的影响

应用全量子理论和数值分析的方法研究了在双模光场与运动的V型三能级原子相互作用过程中，原子运动对双模场压缩的影响。结果表明，当初始光场处于非关联双模相干态时，只有光场的第一正交分量被压缩，压缩程度随着原子运动与场模结构参数的增大而增大。另一方面，当初始光场处于双模压缩真空态时，主要是光场的第二正交分量被压缩，并且通过适当选择原子运动与场模结构参数，能够获得稳定的压缩光。     

Implementation of unambiguous comparison for unknown pure quantum states with cavity-assisted interaction

We propose two effective schemes for local and remote unknown atomic state comparisons with a cavity-assisted single photon input-output process without any initial entanglement or auxiliary resource. The unambiguous state discrimination is considered using the state comparison process as the basic module. All the implementation schemes here just involve common quantum logic gates and the single qubit measurement. The analysis shows that our schemes are feasible under the current experimental conditions.