振幅阻尼信道量子隐形传态保真度恢复机理

Fidelity recovery scheme for quantum teleportation in amplitude damping channel

在振幅阻尼信道上进行量子隐形传态的过程中,量子Bell纠缠态将发生退相干,导致隐形传态质量下降甚至通信失败.为克服该影响,本文提出了一种Bell纠缠态补偿方法.在估计振幅阻尼信道参数的基础上,将对纠缠态的补偿分为纠缠退相干发生之前的预补偿以及经历量子振幅阻尼信道之后的匹配补偿两部分.前者在纠缠源处进行,后者在两个量子通信用户处进行,预补偿及匹配补偿参数与信道特性参数相关.纠缠补偿完成后,再进行隐形传态.理论推导与性能分析结果表明,相比于不进行纠缠补偿及仅在发生退相干之后进行的纠缠补偿,本方法能够获得更高的隐形传态保真度,适当调整补偿参数,可使保真度接近于1,对克服纠缠退相干带来的隐形传态质量下降问题具有一定的意义.

During the course of quantum teleportation in amplitude damping channel, the quantum Bell entanglement state will suffer a de-coherence, which will lead to the quality decrease of quantum teleportation, or even communication failure. To overcome this influence, we propose a method to compensate for the de-coherence of Bell entanglement state. Based on the parameter estimation of the amplitude damping channel, the compensation is divided into two steps. The first step （called pre-compensation） is carried out before the occurrence of de-coherence; the second step （called match- compensation） is carried out after the quantum entanglement state has experienced the de-coherence in the amplitude damping channel. The former is done at the EPR source device, while the latter is done at the quantum user device. The parameters of pre-compensation and match-compensation are determined by the amplitude damping coefficient. The quantum teleportation is carried out after the entanglement compensation. We will give the theoretical derivation and performance analysis of this method. Compared with the method that has no compensation and the method that the compensation is only done after de-coherence, the method given in this paper has a higher quantum teleportation fidelity which is close to 1, when the compensation parameter is adjusted accurately. Our method shows an effectiveinfluence on the teleportation quality decrease due to the entanglement de-coherence.