Discrete modulation can make up for the shortage of transmission distance in measurement-device-independent continuous-variable quantum key distribution (MDI-CVQKD), providing a unique advantage against all side-channel attacks but also creating a challenge for further performance improvement. Here we suggest a quantum catalysis (QC) approach for enhancing the performance of the discrete-modulated (DM) MDI-CVQKD in terms of the achievable secret key rate and lengthening the maximal transmission distance. The numerical simulation results show that the QC-based MDI-CVQKD with discrete modulation, involving a zero-photon catalysis (ZPC) operation, can not only obtain a higher secret key rate than the original DM protocol, but also contribute to a reasonable increase of the corresponding optimal variance. As for the extreme asymmetric and symmetric cases, the secret key rate and maximal transmission distance of the ZPC-involved DM MDI-CVQKD system can be further improved under the same parameters. This approach enables the system to tolerate lower reconciliation efficiency, which may provide excellent potential for practical implementations with state-of-art technology.

离散调制可以弥补与测量设备无关的连续变量量子密钥分配（MDI-CVQKD）中传输距离的不足，为抵御所有侧信道攻击提供了独特的优势，但也给进一步提高性能提出了挑战。在这里，我们提出了一种量子催化（QC）方法，以实现可实现的秘密密钥速率并延长最大传输距离的方式来增强离散调制（DM）MDI-CVQKD的性能。数值仿真结果表明，具有零调制的基于QC的MDI-CVQKD涉及零光子催化（ZPC）操作，不仅可以获得比原始DM协议更高的秘密密钥率，而且还有助于合理增加相应的最佳方差。对于极端非对称和对称情况，在相同参数下可以进一步提高涉及ZPC的DM MDI-CVQKD系统的秘密密钥率和最大传输距离。这种方法使系统能够容忍较低的对帐效率，这可以为使用最新技术的实际实施提供极好的潜力。