量子信道中不可避免存在的噪声将扭曲被传输的信息,对通信造成危害。目前克服量子信道噪声的较好方案是量子避错码(QEAC)。将量子避错码思想用于量子密钥分发,能有效克服信道中的噪声,且无需复杂的系统。用六光子构造了量子避错码,提出了一种基于六光子避错码的量子密钥分发(QDK)方案。以提高量子密钥分发的量子比特效率和安全性为前提,对六光子避错码的所有可能态进行组合,得到一种六光子避错码的最优组合方法,可将两比特信息编码在一个态中,根据测量结果和分组信息进行解码,得到正确信息的平均概率为7/16。与最近的基于四光子避错码的克服量子信道噪声的量子密钥分发方案相比,该方案的量子比特效率提高了16.67%,密钥分发安全性是它的3.5倍。

Noise that unavoidably exists in the quantum channel will distort transmitted information and destroy the communication. The superior scheme to overcome the noise at present is quantum error-avoiding code (QEAC). The quantum key distribution (QKD) using the QEAC will be robust in the quantum noisy channel without complex system. Six-photon error-avoiding code (SPEAC) is constituted and a robust QKD scheme based on it is proposed. In order to improve the qubit efficiency and the security of QKD, all the possible quantum states in the SPEAC are assembled, and as a result,an optimal scheme is developed,by which two key bits can be encoded in each state and Bob can decode the information successfully with an average probability of 7/16. Compared with the recent QKD scheme based on four-photon QEAC, the qubit efficiency of the authors' scheme increases by 16.67%, and the security is 3.5 times of it.