Impact of non-orthogonal measurement in Bell detection on continuous-variable measurement-device-independent quantum key distribution

Continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD), whose core is Bell detection, can effectively resist attacks on the detection system. However, in CV-MDIQKD, Charlie is untrusted; the external environment will cause non-ideal Bell detection that will open security loopholes. We give a complete security analysis under non-ideal Bell detection caused by on-orthogonal measurement. The simulation results indicate that compared with no angle error, only 1 degrees angle error will cause the transmission distance to drop by 7 km. Therefore, our research further improves and perfects the security of CV-MDI QKD.

Automated summary

Continuous-variable measurement-device-independent quantum key distribution (CV-MDI QKD), with Bell detection as its core, can effectively defend against attacks on the detection system. However, in CV-MDI QKD, the untrustworthiness of Charlie and non-ideal Bell detection caused by the external environment create security vulnerabilities. We conducted a comprehensive security analysis of non-ideal Bell detection caused by non-orthogonal measurement. Simulation results show that even a 1-degree angle error can lead to a decrease in transmission distance by 7 km. Therefore, our research further enhances and improves the security of CV-MDI QKD.