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     

利用Bell态实现量子隐形传态

量子隐形传态利用了量子的纠缠特性,在物理层实现了不可破译的量子密码通信.文章从信息论的角度描述了量子纠缠态的特性,给出了实现量子纠缠态的物理门线路;利用该量子纠缠态的量子线路,分析隐形传态的通信模型,给出了利用Bell态实现隐形传态的简单结构的量子线路,证明该量子线路是可行的,为进一步研究量子密码通信提供参考.     

多个量子节点确定性纠缠的建立

量子纠缠是一种重要的量子资源,在多个空间分离的量子存储器间建立确定性的量子纠缠,然后在用户控制的时刻将所存储的量子纠缠转移到量子信道中进行信息的分发和传送,这对于实现量子信息网络是至关重要的.本文介绍了用光学参量放大器制备与铷原子D1吸收线对应的非经典光场,而且在三个空间分离的原子系综中确定性量子纠缠的产生、存储和转移.利用电磁感应透明光和原子相互作用的原理,将制备的多组分光场纠缠态模式映射到三个远距离的原子系综以建立原子自旋波之间的纠缠.然后,存储在原子系综中的纠缠态通过三个量子通道,纠缠态的量子噪声被转移到三束空间分离的正交纠缠光场.三束释放的光场间纠缠的存在验证了该系统具有保持多组分纠缠的能力.这个方案实现了三个量子节点间的纠缠,并且可以直接扩展到具有更多节点的量子网络,为未来实现大型量子网络通信奠定了基础.     

由任意多个独立的观察者共享Werner态的纠缠

量子关联共享问题是量子信息理论研究中一个有趣的课题.最近, Srivastava等在[Phys. Rev. A 2022105 062413]中证明了存在一类T态,其纠缠可以被任意多个独立观察者共享.通过选择合适的纠缠见证算子和Bob的非锐化测量,本文证明了存在两量子比特纠缠的初始共享Werner态,其纠缠可以被任意多个观察者Bobs和单个观察者Alice共享.     

两个海森堡热纠缠信道中纠缠态的隐形传送

利用两个海森堡热纠缠信道,实现了一对量子纠缠态的隐形传送,求得输出的密度矩阵,进而算出隐形传送的保真度.分析外界环境（温度T和磁场B）对热纠缠及量子隐形传送的影响.发现在磁场较弱,温度很低的时候,以海森堡热纠缠混合态作为量子信道进行隐形传送优于经典信道.     

纠缠相干态的量子隐形传态

提出利用双模纠缠相干态作为量子信道，实现纠缠相干态量子隐形传态的方案. 分别在非正交的相干态表象和另一个由相干态构成的正交态表象对双模纠缠相干态的隐形传态进行具体分析. 发现在相干态表象，虽然只要线性光学元件就可以完成隐形传态，但成功的概率小于1/2，而在正交态表象，只要能分辨4个由相干态构成的Bell态，成功的概率就是1. 关键词： 隐形传态 纠缠相干态 纠缠相干态量子信道     

耦合系数对Tavis-Cummings模型中三体纠缠态纠缠量的影响

研究了两个全同二能级原子与单模场相互作用的Tavis-Cummings模型中的量子纠缠.在两原子初始时处于基态,光场处于单光子状态下,得出体系状态演化为近似W纠缠态.结果表明:两原子耦合量越大,三体纠缠态中两两纠缠量和三体纠缠量越小,其中两原子间纠缠量和三体纠缠量减小的程度更大,并且三体纠缠态中两两纠缠量和三体纠缠量的振荡周期也相应减小.     

陆地量子移动通信最优纠缠多址中继方案

为了解决EPR纠缠通过大气空间在通信终端之间的分发问题,使量子移动用户之间及时建立纠缠,提出了一种新的陆地量子移动通信网络的量子纠缠多址中继方案和分区服务模型.分析比较了基于量子受控非门和极化分束器的两种纠缠纯化方法.结果表明:即使在量子移动终端之间没有共享EPR纠缠对的情况下,通过纠缠纯化和量子多址中继,仍然可以完成...     

基于双模压缩信道的双模高斯态量子隐形传态

研究了双模高斯态的两个模经由两个双模压缩量子信道的隐形传态.结果表明，当输入态有纠缠时，若要输出态的纠缠不为零，量子信道的纠缠必须大于一确定值，其大小在输入态为纯态时依赖于输入态的纠缠度；在输入态为混合态时不仅与输入态的纠缠有关，还依赖于输入态的整体纯度. 关键词： 量子隐形传态 量子纠缠 双模高斯态     

海森堡模型中量子隐形传递的研究

通过对海森堡模型中量子热纠缠的研究,进而研究以海森堡热纠缠混合态为信道的量子隐形传递,计算出纠缠度和保真度,分析外界环境(温度、磁场等)对热纠缠及隐形传递的影响.     

Two-mode excited entangled coherent states and their entanglement properties

This paper introduces two types of two-mode excited entangled coherent states (TMEECSs) |Ψ_±(α,m,n)>, studies their entanglement characteristics, and investigates the influence of photon excitations on quantum entanglement. It shows that for the state |Ψ₊(α,m,m)> the two-mode photon excitations affect seriously entanglement character while the state |Ψ_-(α,m,m)> is always a maximally entangled state, and shows how such states can be produced by using cavity quantum electrodynamics and quantum measurements. It finds that the entanglement amount of the TMEECSs is larger than that of the single-mode excited entangled coherent states with the same photon excitation number.     

Calculation of Entanglement Entropy for Continuous-Variable Entangled State Based on General Two-Mode Boson Exponential Quadratic Operator in Fock Space

We obtain an explicit formula to calculate the entanglement entropy of bipartite entangled state of general two-mode boson exponential quadratic operator with continuous variables in Fock space. The simplicity and generality of our formula are shown by some examples.     

Quantum communication for satellite-to-ground networks with partially entangled states

To realize practical wide-area quantum communication,a satellite-to-ground network with partially entangled states is developed in this paper.For efficiency and security reasons,the existing method of quantum communication in distributed wireless quantum networks with partially entangled states cannot be applied directly to the proposed quantum network.Based on this point,an efficient and secure quantum communication scheme with partially entangled states is presented.In our scheme,the source node performs teleportation only after an end-to-end entangled state has been established by entanglement swapping with partially entangled states.Thus,the security of quantum communication is guaranteed.The destination node recovers the transmitted quantum bit with the help of an auxiliary quantum bit and specially defined unitary matrices.Detailed calculations and simulation analyses show that the probability of successfully transferring a quantum bit in the presented scheme is high.In addition,the auxiliary quantum bit provides a heralded mechanism for successful communication.Based on the critical components that are presented in this article an efficient,secure,and practical wide-area quantum communication can be achieved.     

利用两能级原子与腔场的相互作用转移纠缠

分析了大失谐情况下一个两能级原子和相干态腔场相互作用的特点;讨论了利用两能级原子和相干态腔场相互作用制备纠缠相干态的方法;提出了一个关于纠缠相干态的纠缠转移的方案。在这个纠缠转移的方案里,通讯伙伴之间使用的量子信道是由两个振幅相同位相相反的相干态构成的纠缠态。通过使用两能级原子和腔肠相干态的相互作用和两模正交态测量并在经典信息的帮助下完成了三个通讯伙伴之间的纠缠转移。随着近来腔量子电动力学技术的发展,这个方案是能够被实行的。     

Deformed photon-added entangled squeezed vacuum and one-photon states: Entanglement,polarization, and nonclassical properties

In this paper, after a brief review on the entangled squeezed states, we produce a new class of the continuous-variabletype entangled states, namely, deformed photon-added entangled squeezed states. These states are obtained via the iterated action of the f-deformed creation operator A = f(n)aon the entangled squeezed states. In the continuation, by studying the criteria such as the degree of entanglement, quantum polarization as well as sub-Poissonian photon statistics, the twomode correlation function, one-mode and two-mode squeezing, we investigate the nonclassical behaviors of the introduced states in detail by choosing a particular f-deformation function. It is revealed that the above-mentioned physical properties can be affected and so may be tuned by justifying the excitation number, after choosing a nonlinearity function. Finally, to generate the introduced states, we propose a theoretical scheme using the nonlinear Jaynes–Cummings model.     

Detection of Tripartite Genuine Entanglement by Two Bipartite Entangled States

There are practical motivations to construct genuine tripartite entangled states based on the collective use of two bipartite entangled states. Here, the case that the states are two‐qubit Werner states is considered. The intervals of parameters of two‐qubit Werner states are revealed such that the tripartite state is genuinely entangled. Furthermore, we also investigate the lower bound of genuine multipartite entanglement concurrence for tripartite qudit states. Several examples are given to show the effectiveness of the lower bound.     

Quantum cobwebs: Universal entangling of quantum states

Entangling an unknown qubit with one type of reference state is generally impossible. However, entangling an unknown qubit with two types of reference states is possible. To achieve this, we introduce a new class of states called zero sum amplitude (ZSA) multipartite, pure entangled states for qubits and study their salient features. Using shared-ZSA states, local operations and classical communication, we give a protocol for creating multipartite entangled states of an unknown quantum state with two types of reference states at remote places. This provides a way of encoding an unknown pure qubit state into a multiqubit entangled state.     

连续变量量子纠缠态的非对称量子克隆

该文讨论了连续变量量子纠缠态非对称克隆过程,从理论上讨论了在Local e-cloner方案中,入射和出射分束器的反射率可变情况下的纠缠态克隆,并利用纠缠不可分判据分析了所获得的非对称克隆纠缠态的纠缠特性.结果指出,克隆得到的两组纠缠态的纠缠特性不相同.     

利用V-型三能级原子与双模腔场双光子大失谐相互作用制备W纠缠态

本文提出利用V-型三能级原子与双模腔场的双光子大失谐相互作用制备W纠缠态,该方案要求三个三能级原子和一个双模腔场,第一个与腔场作用的原子最初处于激发态,第二个和第三个原子均处于基态,腔场最初处于真空态,合适地选择原子与腔场之间的相互作用时间即可获得三原子W纠缠态.并且此方案可以推广至多原子W纠缠态和多腔场W纠缠态的制备;通过计算共生纠缠度研究系统中态的纠缠演化以及热纠缠现象.