为提高昌燕等提出的量子安全直接通信的通信效率和安全性,设计了基于d维Bell纠缠态的量子安全直接通信方案。 通信前发送方(Alice)对d维Bell态粒子进行幺正变换来编码秘密信息,将变换后的d维Bell态粒子二序列发送给接收方(Bob),利用通信双方各自的POVM测量结果和 Bell态粒子的纠缠特性,结合部分经典信息实现秘密消息的传输。采用熵理论、概率论分析协议的安全性,结果表明提出方案是安全的,且比昌燕等提出方案的传输效率高, 窃听探测率也提高了11%。

In order to improve the communication efficiency and security of quantum secure direct communication proposed by Chang Yan etal, a quantum secure direct communication scheme based on d-dimensional Bell entangled state is designed. Before communication, the unitary transformation is carried out on d-dimensional Bell-state particles by the sender Alice to encode the secret information. Then the transformed d-dimensional Bell-state two-order sequence is transmitted to the receiver Bob. Combining with some classical information, the transmission of secret message is achieved by using the results of respective POVM measurement and the entanglement characteristics of Bell state particles. By using entropy theory and probability theory, the protocol security is analyzed. Results show that the proposed scheme is secure, and it has a higher transmission efficiency and a rise of 11% in the eavesdropping detection rate than that of the scheme proposed by Chang Yan et al.