Teleportation of Two-Particle Entangled State via Cluster State

In this paper,two schemes for teleporting an unknown two-particle entangled state from the sender (Alice)to the receiver (Bob) via a four-particle entangled cluster state are proposed.In these two schemes,the unknown twoparticle entangled state can be teleported perfectly.The successful probabilities and fidelities of the schemes can reach unity.     

Probabilistic Teleportation of a Four-Particle Entangled W State

In this paper, two schemes for teleporting an unknown four-particle entangled W state is proposed. In the first scheme, two partial entangled four-particle states are used as quantum channels, while in the second scheme, four non-maximally entangled particle pairs are considered as quantum channels. It is shown that the teleportation can be successfully realized with certain probability, for both schemes, if a receiver adopts some appropriate unitary transformations. It is also shown that the successful probabilities of these two schemes are different.     

Trojan Horse Attack Free Fault-Tolerant Quantum Key Distribution Protocols Using GHZ States

Recently, Yang and Hwang (Quantum Inf. Process. 13(3): 781–794, 19) proposed two fault-tolerant QKD protocols based on their proposed coding functions for resisting the collective noise, and their QKD protocols are free from Trojan horse attack without employing any specific detecting devices (e.g., photon number splitter (PNS) and wavelength filter). By using four-particle Greenberger-Horne-Zeilinger (GHZ) state and four-particle GHZ-like state in their proposed coding functions, Yang and Hwang’s QKD protocols can resist each kind of the collective noise–collective-dephasing noise, collective-rotation noise. However, their proposed coding function can be improved by the utilization of three-particle GHZ state (three-particle GHZ-like state) instead of four-particle GHZ state (four-particle GHZ-like state) that will eventually reduce the consumption of the qubits. As a result, this study proposed the improved version of Yang and Hwang’s coding functions to enhance the qubit efficiency of their schemes from 20 % to 22 %.     

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.     

Quantum Tasks with Non-maximally Quantum Channels via Positive Operator-Valued Measurement

By using a proper positive operator-valued measure (POVM), we present two new schemes for probabilistic transmission with non-maximally four-particle cluster states. In the first scheme, we demonstrate that two non-maximally four-particle cluster states can be used to realize probabilistically sharing an unknown three-particle GHZ-type state within either distant agent’s place. In the second protocol, we demonstrate that a non-maximally four-particle cluster state can be used to teleport an arbitrary unknown multi-particle state in a probabilistic manner with appropriate unitary operations and POVM. Moreover the total success probability of these two schemes are also worked out.     

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。     

Scheme for Cloning an Unknown Entangled State with Assistance via Non-maximally Entangled Cluster States

We propose a scheme for cloning unknown two-particle entangled state and its orthogonal complement state with assistance from a state preparer. Two stages were included in this scheme. The first stage requires usual teleportation by using a one-dimensional non-maximally four-particle cluster state as quantum channel, after Alice’s (the state sender) Bell measurement, Bob (the state receiver) can get the original state with certain probability. In the second stage, after having received Victor’s (the state preparer) classical message, the perfect copies and complement copies of an unknown state can be produced in Alice’s place, the probability of Alice to get the original state or its orthogonal complement state are calculated. Assisted cloning of an arbitrary unknown two-particle entangled state is discussed in the latter scheme.     

量子比特的普适远程翻转和克隆

提出一种把量子隐形传态、最佳普适量子比特翻转和最佳普适量子克隆三者结合起来的量子比特普适远程翻转和克隆方案.当发送者和处于不同地点的三个接收者共享一个特定的四粒子纠缠态作为量子信道时,通过发送者的Bell基测量、经典通信和各个接收者的局域幺正变换,一个接收者能够以2/3的最佳保真度得到一份原未知量子比特的正交补态,另外两个接收者能够分别以5/6的最佳保真度得到原未知量子比特的一份拷贝.此方案用较少的量子纠缠资源同时完成了未知量子比特的普适远程翻转和克隆,且其保真度分别达到了最佳.实现此方案的关键在于构造出发送者和接收者共享的特定四粒子纠缠态作为量子信道,分析了此特殊四粒子态内在的纠缠结构.     

Teleportation of Three-Particle W State

We present two schemes for teleporting a three-particle W state by using four-particle state. We consider that the quantum channel is a maximally entangled state (four-particle cluster state) or a non-maximally entangled state. In our schemes, it is necessary to introduce additional particle and construct unitary transformation for realize perfect or probabilistic teleportation of the three-particle W state. In order to transmit target state successfully, Alice firstly performs two controlled-NOT on the initial state. The success probabilities of our two schemes are 1 and 4α ², respectively. Compared with other schemes proposed before, our scheme has higher efficiency.     

Scheme for Teleportation of Unknown Entangled Atomic States via Cavity Decay

We present a physical scheme to teleport an unknown atomic entangled state via cavity decay. In the teleportation process, four-particle Greenberger-Horne-Zeilinger (GHZ) state is used as quantum channel, and two unknown entangled atoms and two of four atoms in the four-particle GHZ state are trapped in four leaky cavities,respectively. Based on the joint detection of the photons leak out from the four cavities, we can teleport an unknown entangled state to two other remote atoms with certain probability and high fidelity.     

Deterministic Joint Assisted Cloning of Unknown Two-Qubit Entangled States

We present two schemes for perfect cloning unknown two-qubit and general two-qubit entangled states with assistance from two state preparers, respectively. In the schemes, the sender wish to teleport an unknown two-qubit (or general two-qubit) entangled state which from two state preparers to a remote receiver, and then create a perfect copy of the unknown state at her place. The schemes include two stages. The first stage of the schemes requires usual teleportation. In the second stage, to help the sender realize the quantum cloning, two state preparers perform two-qubit projective measurements on their own qubits which from the sender, then the sender can acquire a perfect copy of the unknown state. To complete the assisted cloning schemes, several novel sets of mutually orthogonal basis vectors are introduced. It is shown that, only if two state preparers collaborate with each other, and perform projective measurements under suitable measuring basis on their own qubit respectively, the sender can create a copy of the unknown state by means of some appropriate unitary operations. The advantage of the present schemes is that the total success probability for assisted cloning a perfect copy of the unknown state can reach 1.     

Scheme for Teleportation of Unknown Entangled Atomic States via Cavity Decay

We present a physical scheme to teleport an unknown atomic entangled state via cavity decay. In the teleportation process, four-particle Greenberger-Horne-Zeilinger （GHZ） state is used as quantum channel, and two unknown entangled atoms and two of four atoms in the four-particle GHZ state are trapped in four leaky cavities, respectively. Based on the joint detection of the photons leak out from the four cavities, we can teleport an unknown entangled state to two other remote atoms with certain probability and high fidelity.     

Quantum Sharing an Unknown Multi-Particle State via POVM

Our purpose in this paper is to present a new tripartite quantum state sharing using partially quantum resources. The first scheme is to probabilistically split an unknown n-particle state using pre-shared a partially entangled four-particle cluster state as quantum resource by constructing some proper POVM. This scheme is further extended to share an unknown multi-particle cluster state using different states as quantum resources. Our schemes with general quantum channels are useful for various quantum information processing and quantum network tasks.     

Two schemes of teleportation one-particle state by a three-particle GHZ state

In accordance with transformation operator, we give two schemes for teleporting an unknown one-particle state via a general GHZ state, Two Von Neumann type measurements are given for teleporting an unknown one-particle state. The first Von Neumann type measurement use four orthogonal states and the second Von Neumann type measurement is eight orthogonal states. For maximally entangled GHZ state, the successful probability and fidelity of two schemes both reach 1.     

Controlled Dense Coding with a Four-Particle Non-maximally Entangled State

Two schemes for controlled dense coding with a four-particle entangled state are investigated, one with entanglement concentration and the other with generalized measurement. In these protocols, the supervisor (Cliff) can control the average amount of information transmitted from the sender (Alice and David) to the receiver (Bob) only by adjusting his local measurement angle θ. It is shown that the results for the average amounts of information are unique from the different two schemes.     

量子纠缠态的普适远程克隆

提出一种任意两粒子纠缠态1→2普适远程克隆方案. 此方案仅需一个特殊的四粒子纠缠态作为量子信道, 就可使处于空间不同位置的两个接收者分别以5/6的保真度得到任意输入态的近似拷贝, 该保真度远高于已有方案中的保真度. 将方案推广到任意两粒子纠缠态1→N(N>2)普适远程克隆的情况, 可使处于不同地点的N个接收者分别以(2N+1)/(3N)的保真度得到输入态的近似拷贝. 另外, 提出一种以上述单个特殊四粒子纠缠态作为量子信道, 在多目标量子比特受控非门和 关键词： 量子纠缠态 普适远程克隆 保真度     

Probabilistic Teleportation of Two-Particle State of General Formation

A scheme for probabilistic teleporting an unknown two-particle state of general formation by partly pure entangled four-particle state is proposed. It is shown that after performing two Bell state measurements, proper unitary transformation and the measurement on an auxiliary qubit, the unknown two-particle state of general formation, which was destroyed at one place, can be reconstructed at another place with certain probability.     

Deterministic joint remote state preparation of arbitrary single- and two-qubit states

In this paper, two novel schemes for deterministic joint remote state preparation(JRSP) of arbitrary single- and twoqubit states are proposed. A set of ingenious four-particle partially entangled states are constructed to serve as the quantum channels. In our schemes, two senders and one receiver are involved. Participants collaborate with each other and perform projective measurements on their own particles under an elaborate measurement basis. Based on their measurement results,the receiver can reestablish the target state by means of appropriate local unitary operations deterministically. Unit success probability can be achieved independent of the channel's entanglement degree.     

Teleportation of N-particle entangled W state via entanglement swapping

A scheme for teleporting an unknown N-particle entangled W state is proposed via entanglement swapping. In this scheme, N maximally entangled particle pairs are used as quantum channel. As a special case, the teleportation of an unknown four-particle entangled W state is studied.     

Secure four-site distribution and quantum communication of χ−type entangled states

The research of multi-particle entanglement is a hot topic because of its important applications and far-reaching effects on vast aspects of quantum information. The article is devoted to the χ − type entangled state, a peculiar four-particle entangled state, which is different from a four-particle GHZ or W state under stochastic local operations and classical communication (SLOCC). Secure four-site distribution using decoy particles is proposed. Moreover, applying it, several communication protocols are presented, including four-party hierarchical quantum secret sharing, supervisory three-party asymmetric deterministic secure quantum communication, etc. The security of the four-site distribution and the communication protocols are also analyzed.