基于预报单光子源,提出了一种相位匹配被动诱骗态量子密钥分配方案。在此方案中,通信双方仅需各产生单个强度的信号。根据通信双方本地探测器的响应情况,第三方的探测结果被分为四个集合,既起到信号态和诱骗态的作用,又共同参与参数估计和密钥生成,降低了系统实现的难度并改善了方案性能。仿真结果表明:相位匹配被动诱骗态方案的最大安全传输距离可达到552 km,性能趋近于现有的相位匹配主动诱骗态方案,且无需主动产生诱骗态;在一定程度上克服了相位匹配主动诱骗态方案严重依赖探测器探测效率的缺陷,性能更为稳定;随着数据长度的下降,方案的传输性能有所下降,但数据长度即使下降至10 7,方案的最大安全传输距离依然可以达到507 km。

A scheme for phase-matched passive-decoy-state quantum key distribution is proposed based on the heralded single photon source. In the scheme, both communication parties only need to generate one-intensity signals. The detection results of the third party are divided into four sets according to the response of the local detectors of both communication parties. These four sets not only serve as the signal state and the decoy state, but also jointly participate in parameter estimation and key generation. Thus, the difficulty of system implementation is reduced and the performance of the scheme is improved. The simulation results show that the maximum safe transmission distance of the phase-matched passive-decoy-state scheme can reach 552 km, and the performance is close to those of the existing phase-matched active-decoy-state schemes. Moreover, there is no need to generate decoy states actively. To some extent, this scheme overcomes the drawback that the phase-matched active-decoy-state scheme relies on the detection efficiency heavily and makes the performance more stable. As the data length decreases, the transmission performance of the scheme is declined. Even if the data length drops to 10 ⁷, the maximum safe transmission distance of the scheme can still reach 507 km.