A quantum secure direct communication protocol with cluster states is proposed.Compared with the deterministic secure quantum communication protocol with the cluster state proposed by Yuan and Song(Int.J.Quant.Inform.,2009,7:689),this protocol can achieve higher intrinsic efficiency by using two-step transmission.The implementation of this protocol is also discussed.
Two simple quantum broadcast communication schemes are proposed. A central party can broadcast his secret message to all the legitimate receivers simultaneously. Compared with the three schemes proposed recently （Wang et al. 2007 Chin. Phys. 16 1868）, the proposed schemes have the advantages of consuming fewer quantum and classical resources, lessening the difficulty and intensity of necessary operations, and having higher efficiency.
Based on x-type entangled states and the two-step protocol [Deng F G, Long G L and Liu X S 2003 Phys. Rev. A 68 042317], a quantum secret sharing protocol of secure direct communication based on x-type entangled states ｜X00〉3214 is proposed. Using some interesting entanglement properties of this state, the agent entirety can directly obtain the secret message from the message sender only if they collaborate together. The security of the scheme is also discussed.
We present a quantum secret sharing protocol against collective-amplitude-damping noise. Each logical qubit is encoded in two qubit noiseless states. So it can function over such a noisy channel. The two agents encode their messages on each logical qubit only by performing a permutation operation on two physical qubits. Although each logical qubit received by each agent only carries a bit of information, the boss Alice can read out her agents' information by discriminating two orthogonal states by performing single-qubit measurements assisted by local operation and classical communication (LOCC).
YANG YuGuangCHAI HaiPingWANG YuanTENG YiWeiWEN QiaoYan
