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     

Teleportation of a bipartite entangled coherent state via cavity QED

Based on the atom--cavity--field interaction, this paper proposes a scheme for the teleportation of a bipartite entangled coherent state (ECS) with high fidelity as long as $\left| \alpha \right|$ is not too small. In this proposal, only four cavities and a three-level cascade atom are needed. The fidelity of the ECS is calculated and analysed in detail.     

用非最大纠缠信道对任意二粒子纠缠态的量子秘密分享

提出一个对任意二粒子纠缠态在N者之间的量子秘密分享方案,该方案利用非最大纠缠Einstein-Podolsky-Rosen(EPR)对作为量子信道,利用广义的贝尔基进行测量.接收者通过引入辅助粒子,并对其做选择性测量,就会概率性地得到最初的量子态. 关键词： 非最大纠缠的Einstein-Podolsky-Rosen(EPR)对 广义的贝尔测量     

Transfer of entangled state, entanglement swapping and quantum information processing via the Rydberg blockade

We provide a scheme with which the transfer of the entangled state and the entanglement swapping can be realized in a system of neutral atoms via the Rydberg blockade. Our idea can be extended to teleport an unknown atomic state. According to the latest theoretical research of the Rydberg excitation and experimental reports of the Rydberg blockade effect in quantum information processing, we discuss the experimental feasibility of our scheme.     

Cluster-type entangled coherent states

We present the cluster-type entangled coherent states (CTECS) and discuss their properties. A cavity QED generation scheme using suitable choices of atom-cavity interactions, obtained via detunings adjustments and the application of classical external fields, is also presented. After the realization of simple atomic measurements, CTECS representing nonlocal electromagnetic fields in separate cavities can be generated.     

Generation of multipartite entangled coherent states via a superconducting charge qubit

In this paper, we propose a method to generate multipartite entangled coherent states (MECS) using a multi-mode superconducting cavity containing an SQUID-based charge qubit. After the projective measurement of simple charge states, MECS representing nonlocal electromagnetic fields of cavity modes have been generated. Furthermore, we investigate the nonlocal properties of the generated MECS by constructing the new concurrence-like entanglement based on the Bell–Klyshko argument.     

Scheme for sharing classical information via tripartite entangled states

We investigate schemes for quantum secret sharing and quantum dense coding via tripartite entangled states. We present a scheme for sharing classical information via entanglement swapping using two tripartite entangled GHZ states. In order to throw light upon the security affairs of the quantum dense coding protocol, we also suggest a secure quantum dense coding scheme via W state by analogy with the theory of sharing information among involved users.     

Implementation of non-local multiple qubits controlled-not operation via partially entangled channels

We propose two different schemes for probabilistic implementing a non-local multiple qubits controlled-not operation via partially entangled quantum channels. The overall physical resources required for accomplishing these schemes are different, and the successful implementation probabilities are also different.     

Preparing arbitrary mode superconducting LC entangled coherent state via a superconducting charge qubit

We design a pure solid-device comprised by LC circuits, which are coupled to superconducting charge qubit to entangle superconducting LC coherent modes. The operation time of the state of the system does not increase with the increase of the number of LC modes. Based on the measurement of charge states, an arbitrary mode of the state can be easily generated. A brief discussion about the experimental feasibility of the scheme is also shown.     

远程控制纠缠原子的偶极压缩

考虑初始处于EPR态的两个二能级原子A、B,将B原子注入处于真空态和单光子态的叠加态的腔中,演化一段时间后,对B原子进行选择性测量,通过选择合适的腔场初始叠加状态和演化时间,可控制原子A的偶极矩压缩效应.     

Teleportation of tripartite entangled coherent states

This paper proposes a feasible scheme for the quantum teleportation of tripartite entangled coherent states by using linear optical devices such as beam splitters, phase shifters and photo detectors. The scheme is based on the bipartite maximally entangled coherent state and the tripartite entangled coherent state with bipartite maximal entanglement as quantum channels. It shows that when the mean number of photons is equal to 2, the total minimum of the average fidelity for an arbitrary tripartite entangled state is 1-0.67×10 ^-3.     

Quantum metrology with entangled coherent states

We present an improved phase estimation scheme employing entangled coherent states and demonstrate that these states give the smallest variance in the phase parameter in comparison to NOON, "bat," and "optimal" states under perfect and lossy conditions. As these advantages emerge for very modest particle numbers, the optical version of entangled coherent state metrology is achievable with current technology.     

Scheme for remotely preparing a four-particle entangled cluster-type state

A protocol for remotely preparing a four-particle entangled cluster-type state by a set of new four-particle orthogonal basis projective measurement. It is secure that the entangled four-particle cluster-type state can be successfully realized at Bob place. Moreover we have also investigated that quantum channel shared by Alice and Bob is composed of four non-maximally entangled states. It is shown that Bob can also reestablish the original state (to be prepared remotely) with certain probability by means of appropriate unitary transformation.     

增加光子纠缠相干态的统计性质

引入了增加光子纠缠相干态.研究了在纠缠相干态的某个模上加入光子对光场统计性质的影响.由于两个场模间的纠缠,在a模上加入光子不但可以使a模的平均光子数增加,也可以使b模的平均光子数发生变化(增加或减少).加入光子后,光场的亚泊松分布和压缩特征得到明显增强. 关键词： 纠缠 增加光子态 统计性质     

Measurement-based entanglement purification for entangled coherent states

The entangled coherent states (ECSs) have been widely used to realize quantum information processing tasks. However, the ECSs may suffer from photon loss and decoherence due to the inherent noise in quantum channel, which may degrade the fidelity of ECSs. To overcome these obstacles, we present a measurement-based entanglement purification protocol (MBEPP) for ECSs to distill some highquality ECSs from a large number of low-quality copies. We first show the principle of this MBEPP without considering the photon loss. After that, we prove that this MBEPP is feasible to correct the error resulted from the photon loss. Additionally, this MBEPP only requires to operate the Bell state measurement without performing local two-qubit gates on the noisy pairs and the purified high-quality ECSs can be preserved for other applications. This MBEPP may have application potential in the implementation of long-distance quantum communication.     

可控三模纠缠相干态的产生

采用量子理论,考虑边界振动的微腔与腔内的三模辐射场构成的系统,给出了系统的时间演化算符及其变换,得到了系统的态函数随时间的演化关系.结果表明,当振动边界回到初态时,三模腔场处于纠缠相干态,并且可以调控不同纠缠相干态的产生.给出了九个不同的三模纠缠相干态,这些态中含有不同的相位因子,这些相位因子充分体现了场和振动边界的相互作用和相互影响.这些结果为可控纠缠相干态的实验制备提供了重要的理论依据.     

Entanglement concentration for W-type entangled coherent states

An entangled coherent state(ECS) is one type of entanglement, which is widely discussed in the application of quantum information processing(QIP). In this paper, we propose an entanglement concentration protocol(ECP) to distill the maximally entangled W-type ECS from the partially entangled W-type ECS. In the ECP, we adopt the balanced beam splitter(BS) to make the parity check measurement. Our ECP is quite different from the conventional ECPs. After performing the ECP, not only can we obtain the maximally entangled ECS with some success probability, but also we can increase the amplitude of the coherent state. Therefore, it is especially useful in long-distance quantum communication, if the photon loss is considered.     

Joint remote preparation of an arbitrary five-qubit Brown state via non-maximally entangled channels

We firstly present a novel scheme for deterministic joint remote state preparation of an arbitrary five-qubit Brown state using four Greenberg–Horme–Zeilinger(GHZ)entangled states as the quantum channel.The success probability of this scheme is up to 1,which is superior to the existing ones.Moreover,the scheme is extended to the generalized case where three-qubit and four-qubit non-maximally entangled states are taken as the quantum channel.We simultaneously employ two common methods to reconstruct the desired state.By comparing these two methods,we draw a conclusion that the first is superior to the second-optimal positive operator-valued measure only taking into account the number of auxiliary particles and the success probability.     

Proposal for teleporting an entangled coherent state via the dispersive atom–cavity-field interaction

A proposal is presented for teleporting an entangled coherent state. The process of the teleportation is achieved through the dispersive atom–cavity-field interaction. In our proposal, only measurement on the cavity field and on the singlet atomic state are used.     

Scheme for probabilistic remotely preparing a multi-particle entangled GHZ state

This paper presents a scheme for probabilistic remote preparation of a three-particle entangled Greenberger-Horne-Zeilinger （GHZ） state via three-particle orthonormal basis projective measurement, and then directly generalize the scheme to multi-particle case. It is shown that by using N pairs of bipartite non-maximally entangled states as the quantum channel and N-particle orthonormal basis projective measurement, the multi-particle remote preparation can be successfully realized with a certain probability.