Remote Preparation of Three-Particle GHZ Class States

We propose a remote state preparation （RSP） scheme of three-particle Greenberger Horne-Zeilinger （GHZ） class states, where quantum channels are composed of two maximally entangled states. With the aid of forward classical bits, the preparation of the original state can be successfully realized with the probability 1/2, the necessary classical communication cost is 0.5 bit on average. If the state to be prepared belongs to some special states, the success probability of preparation can achieve 1 after consuming one extra bit on average. We then generalize this scheme to the case that the quantum channels consist of two non-maximally entangled states.     

Probabilistic Remote Preparation of a Tripartite High-Dimensional Equatorial Entangled State

We present a scheme for probabilistic remote preparation of a tripartite qutrit entangled state with a partial tripartite qutrit entangled state and a partial bipartite qutrit entangled state as the quantum channel. It is found that a bipartite qutrit orthogonal projective measurement, an auxiliary qutrit particle, and the corresponding unitary transformation are required. A scheme for probabilistic remote preparation of a tripartite qudit equatorial entangled state by using a partial tripartite qudit entangled state and a partial bipartite qudit entangled state as the quantum channel is also proposed. We calculate the successful total probability and the total classical communication cost required in the RSP process, respectively.     

Deterministic Secure Quantum Communication with Cluster State and Bell-Basis Measurements

We present a novel protocol for deterministic secure quantum communication by using the lour-qubit cluster state as quantum channel. It is shown that two legitimate users can directly transmit the secret messages based on Bellbasis measurements and classical communication. The present protocol makes use of the ideas of block transmission and decoy particle checking technique. It has a high capacity as each cluster state can carry two 5its of information, and has a high intrinsic efficieney 5ecause almost all the instances except the decoy checking particles （its numSer is negligible） are useful. Furthermore, this protocol is feasible with present-day technique.     

Quantum Communication Scheme Using Non-symmetric Quantum Channel

A theoretical quantum communication scheme based on entanglement swapping and superdense coding is proposed with a 3-dimensional Bell state and 2-dimensional Bell state function as quantum channel, quantum key distribution and quantum secure direct communication can be simultaneously accomplished in the scheme. The scheme is secure and has high source capacity. At last, we generalize the quantum communication scheme to d-dimensional quantum channel     

Quantum Secure Direct Communication and Quantum Sealed-Bid Auction with EPR Pairs

I present a new protocol for three-party quantum secure direct communication （QSDC） with a set of ordered M Einstein-Podolsky-Rosen （EPR） pairs. In the scheme, by performing two unitary operations and Bell state measurements, it is shown that the three legitimate parties can exchange their respective secret message simultaneously. Then I modify it for an experimentally feasible and secure quantum sealed-bid auction （QSBD） protocol. Furthermore, I also analyze th~ecurity of the protocol, and the scheme is proven to be secure against the intercept-and-resend attack, the disturbancb attack and the entangled-and-measure attack.     

Classical Communication Cost and Remote Preparation of Multi-qubit with Three-Party

We present a scheme for probabilistic remote preparation of multi-qubit with three-party from a sender to either of two receivers. The quantum channel is composed of a partial entangled tripartite GHZ state. We obtain the successful totM probability of the scheme in the general case and special case, respectively. We also calculate total classical communication cost required in the RSP process with three-party in the general case and special case, respectively.     

Quantum Hadamard Operators and Their Decomposition Derived by Virtue of IWOP Technique

We introduce the quantum Hadamard operator in continuum state vector space and find that it can be decomposed into a single-mode squeezing operator and a position-momentum mutual transform operator. The two-mode Hadamard operator in bipartite entangled state representation is also introduced, which involves the two-mode squeezing operator and [η〉 ←→｜ξ〉 mutual transformation operator, where [η〉 and ｜ξ〉 are mutual conjugate entangled states. All the discussions are proceeded by virtue of the IWOP technique.     

Classical Communication Cost and Probabilistic Remote Preparation of Four-Particle Entangled W State

We present a scheme for probabilistic remote preparation of the four-particle entangled W state by using four partial entangled two-particle states as the quantum channel. In this scheme, if Alice （sender） performs four-particle projective measurements and Bob （receiver） adopts some appropriate unitary operation, the remote state preparation can be successfully realized with certain probability. The classical communication cost is also calculated. However, the success probability of preparation can be increased to 1 for four kinds of special states.     

Efficient Quantum Dialogue by Using the Two-Qutrit Entangled States Without Information Leakage

A quantum dialogue protocol, based on the two-qutrit entangled states is proposed in this paper. In this protocol, the security of communication is ensured by the secret transmitting order of qutrits. Two legitimate users can directly transmit their secret messages by generalized Bell-basis measurement and classical communication. The efficiency of our scheme is high, which can reach to 100 %. Besides, the protocol is not only feasible in practice but also can discard the drawback “information leakage” or “classical correlation”.     

Teleportation of an Arbitrary Two-Particle State via a Single Cluster-Class State

Teleportation of an arbitrary two-qubit state with a single partially entangled state, a four-qubit linear cluster-class state, is studied. The case is more practical than previous ones using maximally entangled states as the quantum channel. In order to realize teleportation, we first construct a cluster-basis of 16 orthonormal cluster states. We show that quantum teleportation can be successfully implemented with a certain probability if the receiver can adopt appropriate unitary transformations after receiving the sender＇s cluster-basis measurement information. In addition, an important conclusion can be obtained that a four-qubit maximally entangled state （cluster state） can be extracted from a single copy of the cluster-class state with the same probability as the teleportation in principle.     

Three-Party Quantum State Sharing of an Arbitrary Unknown Two-Qubit State Based on Entanglement Swapping and Bell-State Measurements

We propose a scheme for sharing an arbitrary unknown two-qubit state among three parties by using a four-qubit cluster-class state and a Bell state as a quantum channel. With a quantum controlled phase gate （QCPG） operation and a local unitary operation, any one of the two agents has the access to reconstruct the original state if he/she collaborates with the other one, whilst individual agent obtains no information. As all quantum resource can be used to carry the useful information, the intrinsic efficiency of qubits approaches the maximal value. Moreover, the present scheme is more feasible with present-day technique.     

Efficient Atomic One-Qubit Phase Gate Realized by a Cavity QED and Identical Atoms System

We present a scheme to implement a one-qubit phase gate with a two-level atom crossing an optical cavity in which some identical atoms are trapped. One can conveniently acquire an arbitrary phase shift of the gate by properly choosing the number of atoms trapped in the cavity and the velocity of the atom crossing the cavity. The present scheme provides a very simple and efficient way for implementing one-qubit phase gate.     

Quantum Systems Connected by a Time-Dependent Canonical Transformation

We study both classical and quantum relation between two Hamiltonian systems which are mutually connected by time-dependent canonical transformation. One is ordinary conservative system and the other is timedependent Hamiltonian system. The quantum unitary operator relevant to classical canonical transformation between the two systems are obtained through rigorous evaluation. With the aid of the unitary operator, we have derived quantum states of the time-dependent Hamiltonian system through transforming the quantum states of the conservative system. The invariant operators of the two systems are presented and the relation between them are addressed. We showed that there exist numerous Hamiltonians, which gives the same classical equation of motion. Though it is impossible to distinguish the systems described by these Hamiltonians within the realm of classical mechanics, they can be distinguishable quantum mechanically.     

Controlled quantum secure direct communication using a non-symmetric quantum channel with quantum superdense coding

We present a controlled quantum secure direct communication protocol that uses a 2-dimensional Greenberger–Horne–Zeilinger (GHZ) entangled state and a 3-dimensional Bell-basis state and employs the high-dimensional quantum superdense coding, local collective unitary operations and entanglement swapping. The proposed protocol is secure and of high source capacity. It can effectively protect the communication against a destroying-travel-qubit-type attack. With this protocol, the information transmission is greatly increased. This protocol can also be modified, so that it can be used in a multi-party control system.     

Phase State as a Limiting Case of SU（1,1） Coherent State

We show that the Susskind-Glogower phase state is a limiting case of a kind of SU（1,1） coherent states. By analogy, based on the bipartite entangled state representation （ESR） we demonstrate that an appropriate SU（1,1） coherent state composed of the two-mode unitary phase operator e^i also leads to a new phase state in two-mode Fock space, e^i is diagonalized in the ESR.     

Teleportation of Atomic States in a Vacuum-Induced Environment

We present a scheme for teleporting atomic state through a dissipative quantum channel induced by spontaneous emission and investigate the destructive effect of the atomic decay on the success probability and the fidelity of teleportation associated to different channels. It is found that there exists an optimal channel to realize faithful teleportation.     

利用三粒子W态隐形传送三粒子GHZ态

提出一个三粒子GHZ(Greenberger-Horne-Zeilinger)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。此方案用两个三粒子W态作为量子信道。若发送者进行两次贝尔态测量和阿达码门操作,想得到所需传送的三粒子GHZ态的接收者引进一个辅助粒子,进行控制-非操作,同时根据另一个接收者的测量结果实施一个适当的幺正变换操作,可以一定的概率成功地隐形传送三粒子GHZ态。同时,此方案可推广至隐形传送n粒子GHZ态,这时也只需用两个三粒子W态作为量子信道,但这时想得到所需传送的n粒子GHZ态的接收者需引进(n-2)个辅助粒子,进行(n-2)次控制非操作,同时根据另一个接收者的测量结果实施一个适当的幺正变换操作,可以一定的概率成功地隐形传送n粒子GHZ态。     

任意 n 粒子纠缠态的概率传送及其量子逻辑线路

采用n对两粒子非最大纠缠态作为量子通道,使用纠缠交换的方法实现了n粒子任意纠缠态的概率隐形传送。在传输过程中,发送者Alice对自己所拥有的粒子进行贝尔基测量,并将测量结果通过经典通道通知远方的接收者Bob,Bob根据所获取的信息对他的粒子实行相应的幺正变换以恢复原始的粒子信息态,从而成功实现隐形传送。该方案将所有参与传送的粒子划分为n个单元,将对n 1个粒子在2n 1维基下的复杂联合幺正操作分解为n次类似的重复操作,每次重复都是对两个粒子在四维基下的简单操作,大大降低了实验实现的难度。设计了n粒子量子态概率传送的量子逻辑线路,并对每组重复操作的单元线路做了提取。传送成功的总概率为2n∏ni=1ci2。     

Quantum Secure Direct Communication with W State

A new theoretical scheme for quantum secure direct communication is proposed, where four-qubit symmetric W state functions as quantum channel. It is shown that two legitimate users can directly transmit the secret messages by using Bell-basis measurements and classical communication. The scheme is completely secure if the quantum channel is perfect. Even if the quantum channel is unsecured, it is still possible for two users to perform their secure communication. One bit secret message can be transmitted by sending a bit classical information.     

An Efficient Protocol for the Secure Multi-party Quantum Summation

In this paper, a new and efficient quantum protocol which allows a group of mutually distrustful players to perform the summation computation is proposed. Different from previous protocols, we utilize the multi-particle entangled states as the information carriers. A third party, i.e. TP, is assumed semi-honest in the two-party quantum summation protocol. All various kinds of outside attacks and participant attacks are discussed in detail. In addition, we code all players’ Bell-basis measurement outcomes into one classical bit (cbit). Not only the cost of classical information in the public communication network is decreased, but also the security of the protocol is improved. The protocol is also generalized into multi-party quantum summation. It is secure for the collusive attack performed by at most n−2 players.