基于低品质腔的多光子纠缠纯化方案

基于低品质腔,我们提出了一个光子系统的多体纠缠纯化方案(multipartite entanglement purification protocol,简称MEPP).在这个方案中,通过执行比特反转纠错和相位反转纠错这两个步骤,多光子缠态就能够被纯化.而且可以重复这两步,来得到一个高保真度的纠缠光子态.通过光子在低品质腔中的输入输出过程,光子极化态的宇称能被非破坏性的探测.不同于其他的MEPP,这个方案在目前的实验条件下是非破坏性的而且是可行的.     

Dissipative preparation of a steady three-dimensional entangled state via quantum-jump-based feedback

A robust and scalable scheme to generate a steady three-dimensional entangled state for a V-type atom and a A- type atom trapped in a strongly dissipative bimodal cavity is proposed by direct feedback control based on quantum-jump detection. The robustness of this scheme reflects in the insensitivity to detection inefficiencies and the strong ability against the parameter fluctuations in the feedback, driving, and coupling strengths. The influence of atomic spontaneous emission can be suppressed by using the local feedback control. The scalability is ensured that N-dimensional entangled states of two atoms can be deterministically generated.     

Entanglement dynamics of two distant atoms in two detuning cavities

We investigate the entanglement dynamics via the concurrence of two distant atoms interacting off-resonantly with two cavity fields in Fock states,respectively.We find that the evolution of entanglement has sudden death and sudden birth phenomena,that with the increase of photon numbers in the two cavities,the alternate frequency of sudden death and sudden birth turns fast,and that the amplitude of concurrence oscillates regularly with oscillation frequency becoming slow when the cavity fields have the same photon numbers.While,the maximum of concurrence declines and the amplitude of concurrence oscillates irregularly when the two cavity fields have different photon numbers.In addition,we find the length of death time is dependent on the initial entanglement.     

Generation of an N-qubit phase gate via atom--cavity nonidentical coupling

A scheme for approximate generation of an N-qubit phase gate is proposed in cavity QED based on nonidentical coupling between the atoms and the cavity. The atoms interact with a highly detuned cavity-field mode, but quantum information does not transfer between the atoms and cavity field, and thus the cavity decay is negligible. The gate time does not rise with an increase in the number of qubits. With the choice of a smaller odd number l （related to atom-cavity coupling constants）, the phase gate can be generated with a higher fidelity and a higher success probability in a shorter time （the gate time is much shorter than the atomic radiative lifetime and photon lifetime）. When the number of qubits N exceeds certain small values, the fidelity and success probability rise slowly with an increase in the number of qubits N. When N→∞, the fidelity and success probability infinitely approach 1, but never exceed 1.     

对称群的分歧数据系统分类

含特征标的分歧数据系统能被用来分类PM箭图Hopf代数.本文给出了对称群Sn(n≠6)上含特征标的分歧数据系统的同构类个数的计算公式.     

辫子Hopf代数的因子分解

我们获得了辫子双代数和辫子Hopf代数的双重分解, 给出了辫子Hopf代数的积分和半单性与它的因子的积分和半单性之间的关系.     

色李代数中的李定理

作者证明了无挠群上的色李代数的李定理, 同时, 也给出例子说明 无挠性是必要的     

有源RLC介观电路量子化过程中幺正算符的选择

采用正则变换和正变换方法对有源RLC介观电路实现了量子化，通过构造几种不同形式的幺正算，对介观电路实施量子化的计算过程的比较分析，得到了构造幺正算符的最佳方案，该方案能够使正则变换与幺正变换的结果完全吻合。     

Zero—Point Energy in a Mesoscopic Nonlinear Inductance—Capacitance Circuit

The zero-point energy of a mesoscopic nonlinear inductance-capacitance (L-C) circuit is obtained by making use of the variation method.This is somewhat less than that of simple harmonic oscillator.     

利用非局域控制非门操作纯化三粒子纠缠态

提出了两套三粒子纠缠态的纯化方案.第一个方案选择部分纠缠GHZ态作为量子通道,利用具有一个控制位和一个靶位的非局域控制非门操作和采用集体么正操作及适当地制备三粒子A,B和C的初始态,可以以最佳几率2|β|2获得最大三粒子纠缠态.第二个方案选择EPR对作为量子通道,通过利用具有一个控制位和两个靶位的非局域控制非门操作和采用集体么正操作及适当地制备三粒子A,B和C的初始态,可以以与第一个方案相同的几率获得最大三粒子纠缠态.两个方案都可以推广到N粒子纠缠态的纯化.