Quantum state sharing of an arbitrary qudit state by using nonmaximally generalized GHZ state

We present a scheme for quantum state sharing of an arbitrary qudit state by using nonmaximally entangled generalized Greenberger-Horne-Zeilinger （GHZ） states as the quantum channel and generalized Bell-basis states as the joint measurement basis. We show that the probability of successful sharing an unknown qudit state depends on the joint measurements chosen by Alice. We also give an expression for the maximally probability of this scheme.     

Deterministic remote state preparation of arbitrary three-qubit state through noisy cluster-GHZ channel

We propose a novel scheme for remote state preparation of an arbitrary three-qubit state with unit success probability, utilizing a nine-qubit cluster-GHZ state without introducing auxiliary qubits. Furthermore, we proceed to investigate the effects of different quantum noises (e.g., amplitude-damping, phase-damping, bit-flip and phase-flip noises) on the systems. The fidelity results of three-qubit target state are presented, which are usually used to illustrate how close the output state is to the target state. To compare the different effects between the four common types of quantum noises, the fidelities under one specific identical target state are also calculated and discussed. It is found that the fidelity of the phase-flip noisy channel drops the fastest through the four types of noisy channels, while the fidelity is found to always maintain at 1 in bit-flip noisy channel.     

Joint remote state preparation of arbitrary two-qubit state with six-qubit state

We present a novelty scheme for joint remote preparation of an arbitrary two-qubit state in a probabilistic manner from a spatially separated multi-sender to one receiver. The probability of success regarding this preparation scheme is calculated in both general and some particular cases. Our results show that in general such remote state preparation can be realized with a probability of 1/4. But in several special cases, the probability of success can be improved to 1/2 or even 1.     

真空场注入非对称五态叠加多模泛函叠加态的高次振幅压缩

构造了由多模真空态、多模泛函相干态、多模泛函相干态的相反态、多模复共轭泛函相干态和多模复共轭泛函相干态的相反态这五个宏观上完全可分辩的量子态线性叠加所构成的强度不等的非对称五态叠加多模泛函叠加态光场|Ψ(5)vas〉q.利用多模压缩态理论,首次研究了态|Ψ(5)vas〉q的广义非线性等幂奇数次高次振幅压缩特性.结果发现:在一定的条件下,态|Ψ(5)vas〉q可呈现任意次的广义非线性等幂次高次振幅压缩效应,其压缩程度、压缩深度和压缩幅度与压缩次数、腔模总数、态间叠加几率幅、各模光场的经典强度以及经典初始相位的空间分布函数等强烈地非线性相关联;特别是,在特定条件下,真空场的注入可以提高压缩程度.     

利用一个三粒子W态隐形传送N粒子GHZ态

杨洪钦等提出一个用两个三粒子W态作为量子信道将N粒子GHZ态从发送者传送给两个接收者中任意一个的量子隐形传送方案. 给出其理论分析,并提出了一个仅用一个三粒子W态作为量子信道将N粒子GHZ态传送给两个接收者之一的量子隐形传送的方案. 关键词： 隐形传态 GHZ态 W态量子信道     

相干态的小波变换

根据小波变换的量子力学机理, 通过选取不同的系数, 构造出两组新的母小波函数. 在此基础上, 利用正规乘积内积分技术, 推导出相干态和粒子数态的小波变换, 并数值模拟出它们的小波变换图谱.     

Quantum interference between a single-photon Fock state and a coherent state

We derive analytical expressions for the single mode quantum field state at the individual output ports of a beam splitter when a single-photon Fock state and a coherent state are incident on the input ports. The output states turn out to be a statistical mixture between a displaced Fock state and a coherent state. Consequently we are able to find an analytical expression for the corresponding Wigner function. Because of the generality of our calculations the obtained results are valid for all passive and lossless optical four port devices. We show further how the results can be adapted to the case of the Mach-Zehnder interferometer. In addition we consider the case for which the single-photon Fock state is replaced with a general input state: a coherent input state displaces each general quantum state at the output port of a beam splitter with the displacement parameter being the amplitude of the coherent state.     

Remote preparation of a two-particle state using a four-qubit cluster state

We present a scheme of remote preparation of two-particle states using a particular four-qubit cluster state as the quantum channel. The probability of success regarding this preparation scheme is calculated in both general and some particular cases. Our results show that in general such remote state preparation can be realized with a probability of 1/4. But in several special cases, the probability of success can be improved to 1/2 or even 1.     

基于非最大纠缠的五粒子Cluster态的高效量子态共享方案

本文提出了一个新的未知量子态共享方案,使用一个非最大纠缠的五粒子Cluster态作为量子通道来实现任意两粒子未知量子态的共享. 即就是发送方（Alice）,接收方（Bob）和控制方（Charlie）共享一个非最大纠缠的五粒子Cluster态. 与以前传统方案不同,在本方案中发送方引入一个辅助粒子,并对其手中的粒子进行正交完备基测量,而接收方不需要引入辅助粒子,只需要执行适当的幺正操作,即可以方便的完成信息的顺利接收. 控制方通过对自己手中的粒子做单粒子投影测量来控制和协助通信双方,使得任意两粒子的未知量子态共享方案得以成功实现. 关键词： 量子态共享 五粒子Cluster态 正交完备基测量 单粒子投影测量     

利用cluster态隐形传送任意三原子W态

提出一个隐形传送任意三原子纠缠W态的方案,在此方案中,选用由四个全同的二能级原子组成的cluster态作为量子信道.研究表明,接收者基于发送者的经典信息,借助于一个附加原子,实行联合幺正变换以及单原子幺正变换,可实现三原子W态的隐形传送.该方案不受外界热场和腔场耗散的影响,不需要贝尔态测量,成功实现传送的几率为1.     

Quantum interference between heralded single photon state and coherent state

Balanced homodyne detection has been introduced as a reliable technique of reconstructing the quantum state of a single photon Fock state, which is based on coupling the single photon state and a strong coherent local oscillator in a beam splitter and detecting the field quadrature at the output ports separately. The main challenge associated with a tomographic characterization of the single photon state is mode matching between the single photon state and the local oscillator. Utilizing the heralded single photon generated by the spontaneous parametric process, the multi-mode theoretical model of quantum interference between the single photon state and the coherent state in the fiber beam splitter is established.Moreover, the analytical expressions of the temporal-mode matching coefficient and interference visibility and relationship between the two parameters are shown. In the experimental scheme, the interference visibility under various temporalmode matching coefficients is demonstrated, which is almost accordant with the theoretical value. Our work explores the principle of temporal-mode matching between the single photon state and the coherent photon state, originated from a local oscillator, and could provide guidance for designing the high-performance balanced homodyne detection system.     

Joint remote state preparation of a W-type state via W-type states

An all W-type state task is put forward: joint remote state preparation of a W-type state via W-type states. We propose two probabilistic yet faithful schemes for the task. The first scheme uses two arbitrary W-type states as the shared quantum resource and the second scheme exploits three such states. We show that, while the first scheme requires some additional quantum resource and technical operations from the receiver, the second scheme allows any completely unequipped party to play the role of receiver. In both schemes the classical communication cost is one bit per preparer.     

玻色-爱因斯坦凝聚原子与Schrodinger猫态相互作用系统中的保真度

利用全量子理论及量子信息保真度理论,研究了薛定谔猫态光场与玻色爱因斯坦凝聚原子相互作用系统中,量子态保真度随时间的演化特性.讨论了光场强度和玻色爱因斯坦凝聚原子间的耦合强度对量子态保真度的影响.结果表明：光场强度可调制量子态的保真效果,而原子间的耦合常数主要影响量子态保真度的振荡频率.     

An optical scheme for conditional generation of W state and photon-added coherent state

We propose a simple scheme to generate an arbitrary photon-added coherent state of a travelling optical field by combining an array of degenerate parametric amplifiers and corresponding single-photon detectors. Particularly, when the single-photon-added coherent state is observed by developing the novel technique of Zavatta et al （2004 Science 306 660）, we can simultar/eously obtain the generalized N-qubit W state.     

玻色-爱因斯坦凝聚原子与Schrodinger猫态相互作用系统中的保真度

利用全量子理论及量子信息保真度理论,研究了薛定谔猫态光场与玻色爱因斯坦凝聚原子相互作用系统中,量子态保真度随时间的演化特性.讨论了光场强度和玻色爱因斯坦凝聚原子间的耦合强度对量子态保真度的影响.结果表明:光场强度可调制量子态的保真效果,而原子间的耦合常数主要影响量子态保真度的振荡频率.     

Remote preparation of a Greenberger--Horne--Zeilinger state via a two-particle entangled state

We present two schemes for realizing the remote preparation of a Greenberger--Horne--Zeilinger (GHZ) state. The first scheme is to remotely prepare a general N-particle GHZ state with two steps. One is to prepare a qubit state by using finite classical bits from sender to receiver via a two-particle entangled state, and the other is that the receiver introduces N - 1 additional particles and performs N - 1 controlled-not (C-Not) operations. The second scheme is to remotely prepare an N-atom GHZ state via a two-atom entangled state in cavity quantum electrodynamics (QED). The two schemes require only a two-particle entangled state used as a quantum channel, so we reduce the requirement for entanglement.     

Generation of a new bipartite coherent-entangled state and its applications

A new bipartite coherent-entangled state is introduced in the two-mode Fock space, which exhibits the properties of both a coherent state and an entangled state. The set of coherent-entangled states makes up a complete and partly nonorthogonal representation. A simple experimental scheme to produce the coherent-entangled state using an asymmetric beamsplitter is proposed. Some applications of the coherent-entangled state in quantum optics are also presented.     

Generation of a new bipartite coherent-entangled state and its applications

A new bipartite coherent-entangled state is introduced in the two-mode Fock space,which exhibits the properties of both a coherent state and an entangled state.The set of coherent-entangled states makes up a complete and partly nonorthogonal representation.A simple experimental scheme to produce the coherent-entangled state using an asymmetric beamsplitter is proposed.Some applications of the coherent-entangled state in quantum optics are also presented.     

利用三粒子部分纠缠GHZ 态和二粒子纠缠态概率隐形传送任意二粒子态

我们提出了利用三粒子非最大纠缠GHZ态和二粒子非最大纠缠态从一个发送者概率隐形传送任意未知二粒子态至两个接收者中的一个的方案。发送者进行两次Bell-state 测量，接收者以另一个可能的接收者进行的Hadamard操作和投影测量的结果为条件引入两个适当的幺正变换就可以概率隐形传送任意未知二粒子态。     

Probabilistic remote state preparation by W states

In this paper we consider a scheme for probabilistic remote state preparation of a general qubit by using W states. The scheme consists of the sender, Alice, and two remote receivers Bob and Carol. Alice performs a projective measurement on her qubit in the basis spanned by the state she wants to prepare and its orthocomplement. This allows either Bob or Carol to reconstruct the state with finite success probability. It is shown that for some special ensembles of qubits, the remote state preparation scheme requires only two classical bits, unlike the case in the scheme of quantum teleportation where three classical bits are needed.