Entanglement concentration and teleportation of multipartite entangled states in an ion trap

We propose an effective scheme for the entanglement concentration of a four-particle state via entanglement swapping in an ion trap. Taking the maximally entangled state after concentration as a quantum channel, we can faithfully and determinatively teleport quantum entangled states from Alice to Bob without the joint Bell-state measurement. In the process of constructing the quantum channel, we adopt entanglement swapping to avoid the decrease of entanglement during the distribution of particles. Thus our scheme provides a new prospect for quantum teleportation over a longer distance. Furthermore, the success probability of our scheme is 1.0.     

Teleportation of the three-level three-particle entangled state and classical communication cost

We propose a scheme to probabilistically teleport an unknown three-level three-particle entangled state. The quantum channel is composed of a partial entangled three-level two-particle state and a partial entangled three-level three-particle state. We calculate the successful total probability and the classical communication cost required in the ideal probabilistic teleportation process, respectively. It is shown that an unknown three-level three-particle entangled state can be teleported using fewer entangled particles and lesser classical communication cost than Bennett et al.’s original protocol.     

Teleportation of Entangled States through Divorce of Entangled Pair Mediated by a Weak Coherent Field in a High-Q Cavity

We propose a scheme to partially teleport an unknown entangled atomic state. A high-Q cavity, supporting one mode of a weak coherent state, is needed to accomplish this process. By partial teleportation we mean that teleportation will occur by changing one of the partners of the entangled state to be teleported. The entangled state to be teleported is composed by one pair of particles, we called this surprising characteristic of maintaining the entanglement, even when one of the particle of the entangled pair being teleported is changed, of divorce of entangled states.     

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.     

Demonstration of Quantum Entanglement Control Using Nuclear Magnetic Resonance

With the two forms of the quantum entanglement control, the quantum entanglement swapping and preservation are demonstrated in a three-qubit nuclear magnetic resonance quantum computer. The pseudopure state is prepared to represent the quantum entangled states through macroscopic signals. Entanglement swapping is directly realized by a swap operation. By controlling the interactions between the system and its environment,we can preserve an initial entangled state for a longer time. The experimental results are in agreement with the experiment.     

Multiparty Quantum Secret Sharing of Quantum States with Quantum Registers

A quantum secret sharing scheme is proposed by making use of quantum registers. In the proposed scheme, secret message state is encoded into multipartite entangled states. Several identical multi-particle entanglement states are generated and each particle of the entanglement state is filled in different quantum registers which act as shares of the secret message. Two modes, i.e. the detecting mode and the message mode, are employed so that the eavesdropping can be detected easily and the secret message may be recovered. The security analysis shows that the proposed scheme is secure against eavesdropping of eavesdropper and cheating of participants.     

Deterministic secure quantum communication using four-particle genuine entangled state and entanglement swapping

A deterministic secure quantum communication scheme using entanglement swapping is proposed. The sender prepares four-particle genuine entangled states and sends two particles in each state to the receiver and remains the rest particles. If the quantum channel is secure, they begin to communicate. After their four-particle projective measurements, the receiver can obtain the secret information according to his measurement outcomes and classical information from the sender. Using entanglement swapping, there are no particles carrying secret information to be transmitted.     

Teleportation for atomic entangled state by entanglement swapping with separate measurements in cavity QED

Experimentally feasible scheme for teleportation of atomic entangled state via entanglement swapping is proposed in cavity quantum electrodynamics without joint Bell-state measurement. In the teleportation processes the interaction between atoms and a single-mode nonresonant cavity with the assistance of a strong classical driving field substitute the joint measurements. The discussion of the scheme indicates that it can be realized by current technologies.     

Re-examining generalized teleportation protocol

We present an explicit generalized protocol for probabilistic teleportation of an arbitrary N-qubit GHZ entangled state via only one non-maximally two-qubit entangled state. Without entanglement concentration, using standard Bell-state measurement and classical communication one cannot teleport the state with unit fidelity and unit probability. We show that by properly choosing the measurement basis it is possible to achieve unity fidelity transfer of the state. Compared with Gordon et al’s protocol [G. Gordon, G. Rigolin, Phys. Rev. A 73 (2006) 042309], this protocol has the advantage of transmitting much less qubits and classical information for teleporting an arbitrary N-qubit GHZ state.     

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.     

Probabilistic Teleportation of an Arbitrary Three-Level Two-Particle State and Classical Communication Cost

We propose a scheme to probabilistically teleport an unknown arbitrary three-level two-particle state by using two partial entangled two-particle states of three-level as the quantum channel. The classical communication cost required in the ideal probabilistic teleportation process is also calculated. This scheme can be directly generalized to teleport an unknown and arbitrary three-level K-particle state by using K partial entangled two-particle states of three-level as the quantum channel.     

Probabilistic teleportation of an M-quNit state by a single non-maximally entangled quNit-pair

In this work we devise a scheme to teleport a type of unknown M-quNit state using only a single non-maximally entangled quNit-pair as the quantum channel. The fidelity is one while the success probability is less than one and depends on N but not on M. The scheme requires M−1 ancillary quNits and 1 qubit at the receiver's and the receiver should be capable of performing some quNit-quNit/qubit operations. The classical message that the teleporter must announce consists only of 2 Nits, though the full set of his/her measurement outcome is as huge as M+1 Nits.     

Probabilistic Teleportation of an Arbitrary Three-Level Two-Particle State and Classical Communication Cost

We propose a scheme to probabilistically teleport an unknown arbitrary three-level two-particle state by using two partial entangled two-particle states of three-level as the quantum channel. The classical communication cost required in the ideal probabilistic teleportation process is also calculated. This scheme can be directly generalized to teleport an unknown and arbitrary three-level K-particle state by using K partial entangled two-particle states of three-level as the quantum channel.     

Bidirectional Quantum Teleportation by Using Five-qubit Cluster State

We propose a scheme for bidirectional quantum teleportation by using a five-qubit cluster state. In our scheme, Alice can transmit an arbitrary two-qubit entangled state to Bob and at the same time Bob can teleport an arbitrary single-qubit state to Alice.     

High energy quantum teleportation using neutral kaons

We describe a scheme of stochastic implementations of quantum teleportation and entanglement swapping in terms of neutral kaons. In this scheme, the kaon whose state is to be teleported collides with one of the two entangled kaons in an Einstein–Podolsky–Rosen state. Subsequent detection of the outgoing particles of the collision completes the two-qubit projection on Alice side. There appear novel features, which connects quantum information science with fundamental laws of particle physics.     

N粒子W纠缠态的隐形传输

提出使用纠缠交换的方法,采用N对二粒子非最大纠缠态作为量子通道来传输N粒子W纠缠态的方案。传输过程中,发送者对自己所拥有的粒子进行Bell基测量,并将测量结果通过经典通道通知接收者,接收者根据所获取的信息对她的粒子实行相应的幺正变换以恢复最初待传输的粒子态,从而,成功实现该隐形传输。文章还以三粒子的传输为例作了详细介绍。     

Teleportation of N-Particle Entangled GHZ State via Entanglement Swapping

In this scheme, N non-maximally entangled particle pairs are used as quantum channel to teleport an unknown N-particle entangled GHZ state via entanglement swapping. In order to realize this teleportation, the sender Alice operates Bell-state measurement on particles belonging to herself. Then she informs the results to the receiver Bob through classical communication. According to the results, Bob operates corresponding transformation to reconstruct the initial state. The advantage of this scheme is that it needs only one common unitary matrix for Alice＇s different results, which has a more general meaning. As a special case, teleporting an unknown three-particle entangled GHZ state is proposed.     

Scheme for Concentration of Unknown Greeberger-Horne-Zeilinger Entangled States via Cavity Decay

We present a scheme for entanglement concentration of an unknown atomic non-maximally entangled GHZ state via cavity decay. In the scheme, the atom trapped in a cavity is manipulated by laser field, so the maximally entangled GHZ state can be obtained by performing certain operation, which can be realized by illuminating the atom in a cavity. Our method is robust against spontaneous atomic decay.     

Asymmetric Bidirectional Controlled Teleportation by Using Six-qubit Cluster State

We propose a scheme for asymmetric bidirectional controlled teleportation by using a six-qubit cluster state as quantum channel. In our scheme, Alice can transmit an arbitrary two-qubit entangled state to Bob and at the same time Bob can teleport an arbitrary single-qubit state to Alice under the control of the supervisor Charlie.     

Quantum teleportation of arbitrary two-qubit state via entangled cavity fields

We propose a new protocol for quantum teleportation of an arbitrary two qubit state via continuous variables entangling channel. In our scheme two pairs of entangled light fields are employed. An outstanding characteristic of this scheme is that arbitrary state of two atoms is transmitted deterministically and directly to another pair of atoms without the help of the other atoms.