Generalized tripartite scheme for sharing arbitrary 2n-qudit state

Utilizing three non-maximally entangled qutrit pairs as quantum channels, we first propose a generalized tripartite scheme for sharing an arbitrary two-qutrit state with generalized Bell-state measurements. In the scheme if and only if the two recipients collaborate together, they can recover the split qutrit state with the probability determined uniquely by the smallest coefficients of the non-maximally entangled pairs. Afterwards, we further extend the scheme for sharing an arbitrary 2n-qudit state by taking 3n non-maximally entangled qudit pairs as quantum channels. Moreover, the scheme success probability relative to the inherent entanglement in quantum channels and its structure is simply discussed.     

Sharing a Qudit State by Using Bell States Channel

We propose a tripartite scheme for sharing a ququart pure state by using three Bell states as the quantum channel. The scheme is then generalized to qudit state case. We also show that this scheme is applicable to sharing any multi-qudit entangled states.     

Quantum state sharing of an arbitrary multiqubit state using nonmaximally entangled GHZ states

We explicitly present a scheme for quantum state sharing of an arbitrary multiqubit state using nonmaximally entangled GHZ states as the quantum channel and generalized Bell states as the measurement basis. The scheme succeeds only probabilistically with its total success probability depending on the degree of entanglement matching between the quantum channel and the generalized Bell states. Security of the scheme is guaranteed by the fact that attacks of an outside eavesdropper or/and an inside dishonest party will inevitably introduce detectable errors.     

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     

Several teleportation schemes of an arbitrary unknown multi-particle state via different quantum channels

We first provide four new schemes for two-party quantum teleportation of an arbitrary unknown multi-particle state by using three-, four-, and five-particle states as the quantum channel, respectively. The successful probability and fidelity of the four schemes reach 1. In the first two schemes, the receiver can only apply one of the unitary transformations to reconstruct the original state, making it easier for these two schemes to be directly realized. In the third and fourth schemes, the sender can preform Bell-state measurements instead of multipartite entanglement measurements of the existing similar schemes, which makes real experiments more suitable. It is found that the last three schemes may become tripartite controlled teleportation schemes of teleporting an arbitrary multi-particle state after a simple modification. Finally, we present a new scheme for three-party sharing an arbitrary unknown multi-particle state. In this scheme, the sender first shares three three-particle GHZ states with two agents. After setting up the secure quantum channel, an arbitrary unknown multi-particle state can be perfectly teleported if the sender performs three Bell-state measurements, and either of two receivers operates an appropriate unitary transformation to obtain the original state with the help of other receiver's three single-particle measurements. The successful probability and fidelity of this scheme also reach 1. It is demonstrated that this scheme can be generalized easily to the case of sharing an arbitrary unknown multi-particle state among several agents.     

Splitting a qudit state via Greenberger-Horne-Zeilinger states of qubits

We present a tripartite quantum information splitting scheme which splits a qutrit state via two GHZ states. The scheme is then generalized to splitting a qudit state among any number of receivers. We show that this scheme is also applicable to splitting any multi-qudit entangled states.     

利用广义Bell态信道联合远程制备一个任意三量子比特态

研究了一个联合远程制备任意三量子比特态的方案。该方案利用广义的Bell态作为量子信道,两个发送者分别选择合适的测量基进行测量,然后利用经典信道把测量结果传送出去,接收者根据测量结果对自己手中的粒子采取适当的幺正操作,然后引入辅助粒子并进行选择性测量,就能概率性的得到想要制备的量子态。研究结果表明:利用不同形式的广义Bell态信道成功实现联合远程制备一个任意三量子比特态的概率是一样的,当量子信道处于最大纠缠态时,可以得到最大的成功概率。     

A generalized tripartite scheme for splitting an arbitrary 2-qubit state with three 2-qubit partially entangled states and the Kraus measurement

We put forward a generalized tripartite scheme for splitting an arbitrary 2-qubit pure state with three 2-qubit non-maximally en-tangled states as quantum channels.The scheme for the first time incorporates the Kraus measurement into quantum information splitting scheme.In contrast to the similar scheme using the same quantum channels and the ancilla-entangled measurement,our scheme is superior in terms of operation and complexity,success probability,resource consumption and effciency.     

Quantum state sharing with a genuinely entangled five-qubit state and Bell-state measurements

We construct several distinct schemes for tripartite Quantum state sharing (QSTS) of arbitrary single- and two-qubit states. Our schemes use genuinely entangled five-qubit state that has recently been introduced by Brown et al. [J. Phys. A 38 1119 (2005)] as the quantum channel. The Bell-state measurements and the single-qubit measurement are needed in our schemes. In comparison with the QSTS scheme using the same quantum channel [Phys. Rev. A 77 (2008) 032321], not joint measurement, which makes this scheme simpler than the latter.     

Controlled teleportation of high-dimension quantum-states with generalized Bell-state measurement

In this paper a scheme for controlled teleportation of arbitrary high-dimensional unknown quantum states is proposed by using the generalized Bell-basis measurement and the generalized Hadamard transformation. As two special cases, two schemes of controlled teleportation of an unknown single-qutrit state and an unknown two-qutrit state are investigated in detail. In the first scheme, a maximally entangled three-qutrit state is used as the quantum channel, while in the second scheme, an entangled two-qutrit state and an entangled three-qutrit state are employed as the quantum channels. In these schemes, an unknown qutrit state can be teleported to either one of two receivers, but only one of them can reconstruct the qutrit state with the help of the other. Based on the case of qutrits, a scheme of controlled teleportation of an unknown qudit state is presented.     

Teleportations of Mixed States and Multipartite Quantum States

In this paper, we propose a protocol to deterministically teleport an unknown mixed state of qubit by utilizing a maximally bipartite entangled state of qubits as quantum channel. Ira non-maximally entangled bipartite pure state is employed as quantum channel, the unknown mixed quantum state of qubit can be teleported with 1 -√ 1- C^2 probability, where C is the concurrence of the quantum channel. The protocol can also be generalized to teleport a mixed state of qudit or a multipartite mixed state. More important purpose is that, on the basis of the protocol, the teleportation of an arbitrary multipartite （pure or mixed） quantum state can be decomposed into the teleportation of each subsystem by employing separate entangled states as quantum channels. In the case of deterministic teleportation, Bob only needs to perform unitary transformations on his single particles in order to recover the initial teleported multipartite quantum state.     

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.     

Efficient and economic five-party quantum state sharing of an arbitrary m-qubit state

We present an efficient and economic scheme for five-party quantum state sharing of an arbitrary m-qubit state with 2m three-particle Greenberger-Horne-Zeilinger (GHZ) states and three-particle GHZ-state measurements. It is more convenient than other schemes as it only resorts to three-particle GHZ states and three-particle joint measurement, not five-particle entanglements and five-particle joint measurements. Moreover, this symmetric scheme is in principle secure even though the number of the dishonest agents is more than one. Its total efficiency approaches the maximal value.     

Probabilistic joint remote preparation of a high-dimensional equatorial quantum state

<正>This paper proposes a scheme for probabilistic joint remote preparation of an arbitrary high-dimensional equatorial quantum state by using high-dimensional single-particle orthogonal projective measurement and appropriate unitary operation.As a special case,a scheme of joint remote preparation of a single-qutrit equatorial state is presented in detail.The scheme is also generalized to the multi-party high-dimensional case.It shows that,only if when all the senders collaborate with each other,the receiver can reconstruct the original state with a certain probability.     

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.     

Teleportation of an arbitrary three—particle state

We propose two schemes for teleporting an arbitrary three-particle state.In the first scheme,a two-particle state and a three-particle entangled state (both non-maximally entangled states)are used as quantum channels,while in the second scheme,three non-mnaximally entangled particle pairs are employed as quantum channels.We show that teleportation can be successfully realized with certain probability if a receiver adopts some appropriate unitary transformations.Their success probabilities and the classical communication costs are different.     

Teleportation of a multiqubit state by an entangled qudit channel

We investigate the problem of teleportation of an M-qubit state by using an entangled qudit pair as a quantum channel and show that the teleportation of a multiparticle state can correspond to the teleportation of a multi-dimensional state. We also introduce a quantum-state converter composed of beamsplitter arrays, on/off-detectors and cross-Kerr couplers and demonstrate that the state conversion from an M-qubit to an N-dimensional qudit and vice versa can be implemented with this converter, where N=2^M. Based on this, an experimentally feasible scheme for the teleportation of an M-qubit via an entangled N-level qudit pair channel is proposed.     

Quantum state sharing of an arbitrary three-qubit state by using four sets of W-class states

A new application of the W-class state is investigated for quantum state sharing (QSTS) of an arbitrary three-qubit state. We demonstrate that four sets of W-class states can be used to realize the deterministic QSTS of an arbitrary three-qubit state based on the three-qubit von Neumann measurements and the local unitary operations. Our scheme considered here is secure against certain eavesdropping attacks.     

Tripartite Arbitrary Two-Qutrit Quantum State Sharing

A tripartite scheme for securely sharing an arbitrary unknown two-qutrit state is proposed, where two generalized Greenberger-Horne-Zeilinger （GHZ） states serve as the quantum channel linking the three legitimate parties. The quantum information （i.e., the arbitrary unknown two-qutrit state） from the sender can be split in such a way that it can be reconstructed deterministically by any agent via a proper unitary operation provided that both agents collaborates together. Moreover, the generalization of the tripartite scheme to more-party case is also outlined.     

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