Generation of unconventional geometric phase gates in ion trap-optical cavity system by squeezed operators

Based on squeezed operators this paper has implemented an ideal unconventional geometric quantum gate (GQG) in ion trap-optical cavity system by radiating the trapped ions with the cavity field of frequency w_c and an external laser field of frequency w_L. It can ensure that the gate time is shorter than the coherence time for qubits and the decay time of the optical cavity by appropriately tuning the ionic transition frequency w₀, the frequencies of the cavity mode w_c and the vibrational mode ν. It has also realized the unconventional GQG under the influence of the cavity decay based on the squeezed-like operators and found that the present scheme works well for the smaller cavity decay by investigating the corresponding fidelity and success probability.     

基于腔QED技术的量子信息的多方秘密共享

提出了一个基于腔QED技术的量子信息的多方秘密共享方案.该方案不受腔的衰减和热场的影响,并考虑了几种可能偷听下的安全性.     

有互感和电源的介观耦合电路的量子涨落

通过正则变换和幺正变换的方法研究了有互感和电源存在的情况下的介观电容耦合电路的量子涨落.结果表明电荷和电流的量子涨落与电源无关;互感的有无对涨落的影响很大;适当选取回路中电器件的参数,可以控制耦合系数K对涨落的影响.并且,每个回路中电荷和电流的量子涨落是相互制约的.     

依赖于时间的光场与四能级原子的相互作用

研究了依赖于时间的单模光场与N 型四能级原子的相互作用系统,分析了原子布居的时间演化特性.结果表明,由于受到时间脉冲的调制,原子粒子数布居最后会处于一个稳定的状态.     

Quantum logic operations on two distant atoms trapped in two optical-fibre-connected cavities

Based on the coupling of two distant three-level atoms in two separate optical cavities connected with two optical fibres, schemes on the generation of several two-qubit logic gates are discussed under the conditions of Δ = δ - 2ν cos πk/2 >> g/2 and ν ~ g. Discussion and analysis of the fidelity, gate time and experimental setups show that our schemes are feasible with current optical cavity, atomic trap and optical fibre techniques. Moreover, the atom-cavity- fibre coupling can be used to generate an N-qubit nonlocal entanglement and transfer quantum information among N distant atoms by arranging N atom-cavity assemblages in a line and connecting each two adjacent cavities with two optical fibres.     

Creating unconventional geometric phase gate using squeeze-like operator assisted by strong driving field

Based on the idea that a squeezing process can be thought of as a total cumulative effect of a large number of tiny squeezing processes, we define a squeeze-like operator with a time-dependent squeeze parameter. Applying this operator to and combining with a system which includes a two-photon interaction between two atoms and an initial vacuum cavity field, and resorting to a resonant strong driving classical field, we obtain an unconventional geometric phase gate with a shorter gating time.     

Generation of multi-atom cluster states via an unconventional geometric phase shift in cavity QED

This paper proposes two schemes to generate the multi-atom cluster states. The first scheme is based on the interaction of atoms with a highly detuned cavity mode and a classical field, the second scheme is based on the interaction of atoms with a cavity mode, strongly driven by a resonant classical field.     

辫子Hopf代数的积分(英)

本文引进了无限维辫子Hopf代数$H$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$H^{d {\rm rat} }$ 与积分的关系, 即: $H^{d {\rm rat}}\cong \int ^l_{H^d} \otimes H$.给出了在Yetter-Drinfeld范畴$(^B_B{\cal YD},C)$中的辫子Hopf代数的积分的存在性和唯一性.