利用四粒子纠缠态实现单粒子信息分裂

我们提出了一个在三者之间利用四粒子纠缠态作为量子通道实现对任意单粒子态的信息分裂的方案.在我们的方案中,两个接收方之间有且只有在对方提供合作的情况下才能全部获得这个原始信息,而且接收方彼此之间都有同等权限去获得该原始信息,他们获得原始信息的概率是一样的,均为1.     

Quantum Secure Direct Communication with Four-Particle Genuine Entangled State and Dense Coding

A quantum secure direct communication scheme using dense coding is proposed. At first, the sender (Alice) prepares four-particle genuine entangled states and shares them with the receiver (Bob) by sending two particles in each entangled state to him. Secondly, Alice encodes secret information by performing the unitarytransformations on her particles and transmits them to Bob. Finally, Bob performs the joint measurements on his particles to decode the secret information. The two-step security test guarantees the security of communication.     

Quantum Secure Direct Communication with Four-Particle Genuine Entangled State and Dense Coding

A quantum secure direct communication scheme using dense coding is proposed. At first, the sender （Alice） prepares four-particle genuine entangled states and shares them with the receiver （Bob） by sending two particles in each entangled state to him. Secondly, Alice encodes secret information by performing the unitary transformations on her particles and transmits them to Bob. Finally, Bob performs the joint measurements on his particles to decode the secret information. The two-step security test guarantees the security of communication.     

Probabilistic Hierarchical Quantum Information Splitting of Arbitrary Multi-Qubit States

By utilizing the non-maximally entangled four-qubit cluster states as the quantum channel, we first propose a hierarchical quantum information splitting scheme of arbitrary three-qubit states among three agents with a certain probability. Then we generalize the scheme to arbitrary multi-qubit states. Hierarchy is reflected on the different abilities of agents to restore the target state. The high-grade agent only needs the help of one low-grade agent, while the low-grade agent requires all the other agents’ assistance. The designated receiver performs positive operator-valued measurement (POVM) which is elaborately constructed with the aid of Hadamard matrix. It is worth mentioning that a general expression of recovery operation is derived to disclose the relationship with measurement outcomes. Moreover, the scheme is extended to multiple agents by means of the symmetry of cluster states.     

A Protocol for Bidirectional Quantum Secure Communication Based on Genuine Four-Particle Entangled States

By swapping the entanglement of genuine four-particle entangled states, we propose a bidirectional quantum secure communication protocol. The biggest merit of this protocol is that the information leakage does not exist. In addition, the ideas of the ＂two-step＂ transmission and the block transmission are employed in this protocol. In order to analyze the security of the second sequence transmission, decoy states are used.     

A Protocol for Bidirectional Quantum Secure Communication Based on Genuine Four-Particle Entangled States

By swapping the entanglement of genuine four-particle entangled states, we propose a bidirectional quantum secure communication protocol. The biggest merit of this protocol is that the information leakage does not exist. In addition, the ideas of the ``two-step" transmission and the block transmission are employed in this protocol. In order to analyze the security of the second sequence transmission, decoy states are used.     

Quantum Private Comparison of Equal Information Based on Highly Entangled Six-Qubit Genuine State

Using the highly entangled six-qubit genuine state we present a quantum private comparison (QPC) protocol, which enables two users to compare the equality of two bits of their secrets in every round comparison with the assistance of a semi-honest third party (TP). The proposed protocol needs neither unitary operations nor quantum entanglement swapping technology, both of which may consume expensive quantum devices. Single particle measurements and Bell-basis measurements, which are easy to implement with current technologies, are employed by two users and TP in the proposed protocol, respectively. The proposed protocol can withstand all kinds of outside attacks and participant attacks. Moreover, none of information about the two users’ private secrets and the comparison result is leaked out to TP.     

Generation of a Genuine Six-Atom Entangled State in Cavity QED

We propose a potential scheme to generate a genuine six-atom entangled state [J. Phys. A 42 (2009) 415301] by using atoms in cavity QED system, where the atoms interact simultaneously with the highly detuned single-mode cavity and the strong classical driving field. Thus our approach is insensitive to both the cavity decay and thermal field.     

基于六粒子纠缠态和Bell态测量的量子信息分离

通过介绍六粒子纠缠态的新应用研究,提出了一个二粒子任意态的信息分离方案.在这个方案中,发送者Alice、控制者Charlie和接受者Bob共享一个六粒子纠缠态,发送者先执行两次Bell基测量|然后控制者执行一次Bell基测量|最后接受者根据发送者和控制者的测量结果,对自己拥有的粒子做适当的幺正变换,从而能够重建要发送的二粒子任意态.这个信息分离方案是决定性的,即成功概率为100%.与使用相同的量子信道进行二粒子任意态的信息分离方案相比,本文提出的方案只需要进行Bell基测量而不需要执行多粒子的联合测量,从而使得这个方案更简单、更容易,并且在目前的实验室技术条件下是能够实现的.     

Probabilistic Teleportation of a Four-Particle Entangled State

A Scheme for teleporting an unknown four-particle entangled state is proposed via entangled swapping. In this scheme, four pairs of entangled particles are used as quantum channel. It is shown that, if the four pairs of particles are nonmaximally entangled, the teleportation can be successfully realized with certain probability if a receiver adopts some appropriate unitary transformations.     

Generation of a Genuine Six-Atom Entangled State in Cavity QED

We propose a potential scheme to generate a genuine six-atom entangled state [J. Phys. A 42 (2009) 415301] by using atoms in cavity QED system, where the atoms interact simultaneously with the highly detuned single-mode cavity and the strong classical driving field. Thus our approach is insensitive to both the cavity decay and thermal field.     

Quantum Information Splitting of an Arbitrary Three-Qubit State by Using Cluster States and Bell States

A new application of cluster states is investigated for quantum information splitting (QIS) of an arbitrary three-qubit state. In our scheme, a four-qubit cluster state and a Bell state are shared by a sender (Alice), a controller (Charlie), and areceiver (Bob). Both the sender and controller only need to perform Bell-state measurements (BSMs), the receiver can reconstruct the arbitrary three-qubit state by performing some appropriately unitary transformations on his qubits after he knows the measured results of both the sender and the controller. This QIS scheme is deterministic.     

Generalized Quantum Two-Qutrit-State Splitting

A three-party scheme for splitting an arbitrary unknown two-qutrit state is proposed, where two nonmaximally-entangled three-qutrit states are taken as the quantum channel among three parties. With the sender＇s help, if and only if both receivers collaborate together, they can securely share the quantum state in a probabilistic way by introducing an ancilla qutrit and performing appropriate unitary operations. The relation between the success probability and coefficients characterizing the quantum channel is revealed. The security of the present scheme is analyzed and confirmed. Moreover, the generalization of the three-party scheme to more-party case is also sketched.     

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.     

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.     

Generalized Quantum Two-Qutrit-State Splitting

A three-party scheme for splitting an arbitrary unknown two-qutrit state is proposed, where two non-maximally-entangled three-qutrit states are taken as the quantum channel among three parties. With the sender's help, if and only if both receivers collaborate together, they can securely share the quantum state in a probabilistic way by introducing an ancilla qutrit and performing appropriate unitary operations. The relation between the success probability and coefficients characterizing the quantum channel is revealed. The security of the present scheme is analyzed and confirmed. Moreover, the generalization of the three-party scheme to more-party case is also sketched.     

Tripartite Splitting Arbitrary 2-Qubit Quantum Information by Using Two Asymmetric W States

In this paper we propose a tripartite scheme for splitting an arbitrary 2-qubit quantum information by using two asymmetric W states as the quantum channel. In the schemem if the two recipients collaborate together, they can deterministically recover the quantum information by performing first a 4-qubit collective unitary operation and then two single-qubit unitary operations. In addition, since the asymmetric W states are employed as the quantum channel, the scheme is robust against decoherence.     

Quantum Fisher Information of Entangled Coherent States in a Lossy Mach–Zehnder Interferometer

We give an analytical result for the quantum Fisher information of entangled coherent states in a lossy Mach-Zehnder interferometer recently proposed by Joo et al., [Phys. Rev. Lett. 107 （2011） 083601]. For small loss of photons, we find that the entangled coherent state can surpass the Heisenberg limit. Phrthermore, the formalism developed here is applicable to the study of phase sensitivity of multipartite entangled coherent states.     

Detection of Tripartite Genuine Entanglement by Two Bipartite Entangled States

There are practical motivations to construct genuine tripartite entangled states based on the collective use of two bipartite entangled states. Here, the case that the states are two‐qubit Werner states is considered. The intervals of parameters of two‐qubit Werner states are revealed such that the tripartite state is genuinely entangled. Furthermore, we also investigate the lower bound of genuine multipartite entanglement concurrence for tripartite qudit states. Several examples are given to show the effectiveness of the lower bound.     

Multiparty Quantum Secret Sharing via Introducing Auxiliary Particles Using a Pure Entangled State

We propose a new multiparty quantum secret sharing protocol via introducing auxiliary particles using a non-maximally entangled （pure） two-particle state without a Bell measurement. The communication parties utilize decoy particles tO check eavesdropping. After ensuring the security of the quantum channel, the sender encodes the secret message and transmits it to the receiver by using controlled-NOT operation and von Neumann measurement. If and only if all the agents agree to collaborate, they can read out the secret message.