Utilizing a three-particle W state, we come up with a protocol for the teleportation of an unknown two-particle entangled state. It is shown that the teleportation can be deterministically and exactly realized. Moreover, two-particle entanglement teleportation is generalized to a system consisting of many particles via a three-particle W state and a multi-particle W state, respectively. All unitary transformations performed by the receiver are given in a concise formula.
A new protocol for the anonymous communication of quantum information is proposed. The anonymity of the receiver and the privacy of the quantum information are perfectly protected except with exponentially small probability in this protocol. Furthermore, this protocol uses single photons to construct anonymous entanglement instead of multipartite entangled states, and therefore it reduces quantum resources compared with the pioneering work.
The discrimination of quantum operations plays a key role in quantum information and computation. Unlike discriminating quantum states, it has some special properties which can be carried out in practice. In this paper, we provide a general description of discriminating quantum operations. Concretely speaking, we describe the distinguisha- bility between quantum operations using a measure called operator fidelity. It is shown that, employing the theory of operator fidelity, we can not only verify some previous results to discriminate unitary operations, but also exhibit a more general discrimination condition. We further apply our results to analysing the security of some quantum cryptographic protocols and discuss the realization of our method using well-developed quantum algorithms.
We present a new fair blind signature scheme based on the fundamental properties of quantum mechanics.In addition,we analyse the security of this scheme,and show that it is not possible to forge valid blind signatures.Moreover,comparisons between this scheme and public key blind signature schemes are also discussed.
An efficient quantum secure direct communication protocol is presented over the amplitude damping channel.The protocol encodes logical bits in two-qubit noiseless states,and so it can function over a quantum channel subjected to collective amplitude damping.The feature of this protocol is that the sender encodes the secret directly on the quantum states,the receiver decodes the secret by performing determinate measurements,and there is no basis mismatch.The transmission's safety is ensured by the nonorthogonality of the noiseless states traveling forward and backward on the quantum channel.Moreover,we construct the efficient quantum circuits to implement channel encoding and information encoding by means of primitive operations in quantum computation.
We propose a new scheme for controlled quantum teleportation with Bell states in which classical keys for controllers' portion are used. We also discuss the security of the proposed scheme and show that it can satisfy the requirements for controlled quantum teleportation. The comparison between this scheme and the previous ones shows that it is more economical and efficient.
We show a scheme to distribute the entanglement by using three-mode separable Gaussian state prepared with imperfect equipments.The scheme achieves the aim that the entanglement is distributed between two distant parties with only Gaussian operations and linear optics elements.Moreover,we analyse the logarithmic negativity of the entanglement shared between the two parties when the systems are imperfect and arrive at the conclusion that the logarithmic negativity is asymptotically stable with fluctuations within a certain space range.
