通过四个纠缠态粒子来实现未知的三个纠缠态粒子的量子几率隐形传输

提出一种分别利用四个三态粒子的最大纠缠态和非最大纠缠态作为量子通道来传输一未知的三个三态粒子纠缠态的方案.首先考察量子通道是最大纠缠态的情况,然后进一步考察量子通道是非最大纠缠态的情况,同时发现在后者情况时,通过引进一个辅助粒子,并构造一幺正变换矩阵,即可以一定的几率完成该三态粒子纠缠态的隐形传输.     

Quantum Information Splitting by Using Asymmetric Multi-particle State

We propose schemes for quantum information splitting by using asymmetric multi-particle entangled state. Explicit protocols for the quantum information splitting of a single-qubit state and a two-qubit entangled state via asymmetric three-particle entangled state are illustrated. The four-particle asymmetric entangled state are also used as quantum channel to split the unknown two-qubit entangled state. We also consider the security against certain eavesdropping attacks.     

多光子Tavis-Cummings模型中两纠缠原子的纠缠演化特性

研究了两个纠缠的二能级原子通过多光子跃迁与单模相干光场进行耦合相互作用系统中两原子纠缠的演化特性.计算分析表明,两个原子之间的纠缠呈现出周期性的演化特性,初始两原子的状态、原子间的偶极相互作用、相干光场的参数以及跃迁光子数对两个原子的纠缠有着显著的影响;并发现两原子初始处于某最大纠缠态时,两原子会永远处于该最大纠缠态,因此这一类最大纠缠态可以作为一种量子信息存储器. 关键词： 量子纠缠 部分转置矩阵负本征值 纠缠原子 相干态     

Generation of remote W-type entangled state via tripartite entanglement swapping of continuous variables

We propose a scheme for generating remote W-type entangled state via tripartite entanglement swapping of continuous variables, where two EPR pairs and a local W-type entangled state are required. Because of the co-existence of both bipartite and tripartite entanglement in a W-type entangled state, the three involved remote regions, without direct interaction, will become entangled after the prescribed entanglement swapping.     

Teleportation of Entangled States through Divorce of Entangled Pair Mediated by a Weak Coherent Field in a High-Q Cavity

We propose a scheme to partially teleport an unknown entangled atomic state. A high-Q cavity, supporting one mode of a weak coherent state, is needed to accomplish this process. By partial teleportation we mean that teleportation will occur by changing one of the partners of the entangled state to be teleported. The entangled state to be teleported is composed by one pair of particles, we called this surprising characteristic of maintaining the entanglement, even when one of the particle of the entangled pair being teleported is changed, of divorce of entangled states.     

二粒子纠缠态受控传递的最佳量子通道

本文研究了如何在二粒子纠缠态的量子受控传递中选择最佳量子通道的问题。分别利用四粒子GHZ态和四粒子特殊"反关联GHZ态"作为量子通道,本文提出了二粒子反关联纠缠态的量子受控传递的两个方案。通过对比两个方案下接受者最后采取的幺正操作的具体矩阵形式,分析了待传量子纠缠态与量子通道的关系,指出了四粒子GHZ态和四粒子特殊"反关联GHZ态"分别是二粒子正关联和反关联纠缠态各自隐形传递应该选择的最佳的量子通道。     

Teleportation of a Kind of Three-Mode Entangled States of Continuous Variables

A quantum teleportation scheme to teleport a kind of tripartite entangled states of continuous variables by using a quantum channel composed of three bipartite entangled states is proposed. The joint Bell measurement is feasible because the bipartite entangled states are complete and the squeezed state has a natural representation in the entangled state basis. The calculation is greatly simplified by using the Schmidt decomposition of the entangled states.     

二能级原子与相干态腔场相互作用过程中的纠缠交换

用量子信息学的观点，分析了发生在一个多个原子和腔场组成的系统中最大纠缠态在原子和多模类奇-偶相干态光场之间相互转移的物理过程，该系统中原子和腔场之间由依赖于强 度耦合的Jaynes-Cummings模型描述.结果发现：通过控制原子与腔场相互作用的时间，并 对原子的状态进行测量，原子的最大纠缠态可以转换为类奇-偶相干态光场的最大纠缠态，反之，纠缠的多模类奇-偶相干态光场也可以转换为原子的最大纠缠态. 关键词： 量子信息 腔量子电动力学 连续变量纠缠态 纠缠交换和传递     

Teleportation of a Kind of Three-Mode Entangled States of Continuous Variables

A quantum teleportation scheme to teleport a kind of tripartite entangled states of continuous variables by using a quantum channel composed of three bipartite entangled states is proposed. The joint Bell measurement is feasible because the bipartite entangled states are complete and the squeezed state has a natural representation in the entangled state basis. The calculation is greatly simplified by using the Schmidt decomposition of the entangled states.     

三粒子纠缠Ｗ态的隐形传态

提出利用三个二粒子纠缠态作为量子信道，实现三粒子纠缠Ｗ态的隐形传态的方案.首先考察量子信道是最大纠缠态的情形，然后进一步考察量子信道是非最大纠缠态的情形.发现在量子信道为非最大纠缠态时，通过引进一个辅助粒子，并构造一个幺正变换矩阵，即可以一定的概率完成三粒子纠缠Ｗ态的隐形传态. 关键词： 隐形传态 三粒子纠缠 纠缠Ｗ态 非最大纠缠量子信道     

Teleportation of Three-Level Multi-partite Entangled State by a Partial Three-Level Bipartite Entangled State

We present a scheme for probabilistically teleporting an unknown three-level bipartite entangled state by using a partial entangled three-level bipartite state as quantum channel This scheme can be directly generalized to probabilistically teleport an unknown three-level k-particle entangled state by a partial three-level bipartite entangled state. A11 kinds of unitary transformations are given in detail We calculate the successful total probability and the total classical communication cost required for this scheme.     

基于四波混频过程的纠缠光放大

双模纠缠态是量子信息领域一种重要的量子资源,本文基于四波混频过程从理论上提出了对双模纠缠态的单个模式(单模放大方案)和对双模纠缠态的两个模式(双模放大方案)的放大.利用光学分束器模型来模拟在光学传输过程中损耗引入的真空场噪声,利用部分转置正定判据分析了两种不同的放大方案中四波混频过程的增益对初始双模纠缠态的纠缠程度的影响.结果表明,在特定的损耗情况下,两个方案中初始双模纠缠态的纠缠度都随增益的增大而减小,直至消失,且双模放大方案中初始双模纠缠态纠缠消失得比单模放大方案中更快.本文的理论结果为实验上实现基于四波混频过程的双模纠缠态的放大奠定了理论基础.     

多模腔场与耦合原子之间量子纠缠信息的传递规律

提出了多个“耦合双原子-腔-多模光场”相互作用系统的集合模型,发现了该物理系统中量子纠缠信息的传递规律.即：处于基态的原子以特定速度通过处于纠缠态的腔场时,原子能够将光场的纠缠信息据为已有；反之,纠缠原子以特定速度通过真空场时,原子能把纠缠信息释放于腔中,这样便实现了腔-原子之间纠缠信息的交换传递.利用原子能够捡起、释放量子纠缠信息的特点,进一步实现腔-腔之间异地量子纠缠信息的传递.在不同条件下,量子纠缠信息还可以保持.     

通过cluster态实现两粒子纠缠态的量子几率隐形传态

提出通过一个四粒子cluster非最大纠缠态作为量子信道来实现一未知两粒子纠缠态的量子几率隐形传态方案。在此方案中,纠缠态可以实现一定的几率传输,此几率由cluster态中绝对值较小的两个系数决定。如果我们用cluster最大纠缠态作为量子信道,此时几率隐形传态就成了一般的隐形传态,即成功传输的几率为100%。     

Mixtures of maximally entangled pure states

We study the conditions when mixtures of maximally entangled pure states remain entangled. We found that the resulting mixed state remains entangled when the number of entangled pure states to be mixed is less than or equal to the dimension of the pure states. For the latter case of mixing a number of pure states equal to their dimension, we found that the mixed state is entangled provided that the entangled pure states to be mixed are not equally weighted. We also found that one can restrict the set of pure states that one can mix from in order to ensure that the resulting mixed state is genuinely entangled. Also, we demonstrate how these results could be applied as a way to detect entanglement in mixtures of the entangled pure states with noise.     

Entanglement and Pancharatnam Phase for Two Two-Level Atoms Interacting with a Single Mode Field

A model of two 2-level atoms interacts with a single quantized electromagnetic field is considered. We study the effect of the mean photon number and the structure of the initial states of the two atoms on the dynamics of the atomic system from the separability point of view. It is found that, if we start from a product mixed atomic state, the probability of generating long living entangled states is increased as the mean photon number increases. Starting from excited atomic system in product state, one generates a more stable entangled states with high degree of entanglement. Also, the effect of the mean photon number on atomic system prepared initially in entangled states is investigated. It is found that the entangled state generated from the initially partial entangled states are more robust than those obtained from a maximum entangled state. The Pancharatnam phase for the separable and entangled states is studied under the effect of the mean photon number and the structure of the initial state. We find that for the separable states, the collapses decrease and the amplitude of the revivals is smaller than that for the entangled state, so there are long-living entangled phases. This property give us a great chances to store safely information in entangled state.     

四粒子纠缠的一般W态的退纠缠和W态的概率隐形传态

我们推广地得到了到四粒子纠缠的一般W态,给出了一般W态的不同退纠缠的条件,得到了一个新的二粒子的一般W态,并得到对于四粒子纠缠的一般W态而言,其系数α1,α2和α3从一个直到全部为零时,这一般的|ΨW〉依次有一个粒子,二个粒子和最后全部粒子退出纠缠。还给出了一个利用四个二粒子纠缠态作为量子信道来传送四粒子纠缠W态的方案,并且进一步给出了当量子信道为非最大纠缠态时,四粒子纠缠的一般W态的隐形传态的一个方案,同时通过构造一个5×5对角投影变换矩阵,解决了使用一般纠缠量子信道并不再引入辅助态时,态畸变的恢复问题.并且这里的对角投影变换UM也与以往文献中的不同,而且比过去文献的讨论更直接.因本文的研究是一般性的,本文关于对角的投影变换矩阵UM的变换方法等可以直接推广到任意一般纠缠信道的一般纠缠态的概率隐形传态。     

Application of Bipartite and Tripartite Entangled State Representations in Quantum Teleportation of Continuous Variables

We mostly investigate two schemes. One is to teleport a multi-mode W-type entangled coherent state using a peculiar bipartite entangled state as the quantum channel different from other proposals. Based on our formalism,teleporting multi-mode coherent state or squeezed state is also possible. Another is that the tripartite entangled state is used as the quantum channel of controlled teleportation of an arbitrary and unknown continuous variable in the case of three participators.     

Classical Communication Cost and Remote Preparation of the Two-Atom Maximally Entangled State

We present a protocol for probabilistic remote preparation of the two-atom maximally entangled state using a four-atom GHZ entangled state as the quantum channel. The two-atom maximally entangled state can be successfully prepared between two distant parties with a success probability of 100%. The successful total probability and classical communication cost are calculated.     

Teleportation of the three-level three-particle entangled state and classical communication cost

We propose a scheme to probabilistically teleport an unknown three-level three-particle entangled state. The quantum channel is composed of a partial entangled three-level two-particle state and a partial entangled three-level three-particle state. We calculate the successful total probability and the classical communication cost required in the ideal probabilistic teleportation process, respectively. It is shown that an unknown three-level three-particle entangled state can be teleported using fewer entangled particles and lesser classical communication cost than Bennett et al.’s original protocol.