Measurement-device-independent quantum key distribution protocol with phase post-selection

Measurement-device-independent quantum key distribution (MDI-QKD) protocol can remove all the loopholes of the detection devices and, thus, has attracted much attention. Based on the technique of single-photon interference, we propose a modified MDI-QKD protocol with phase post-selection. We prove the security of the announcement of the private phases in the X basis and show how to apply the phase post-selection method to the double-scanning four-intensity MDI-QKD protocol. The numerical results show that the phase postselection method can significantly improve the key rates at all distances. In the double-scanning method, two parameters need to be scanned in the calculation of the final key rate, and the global parameter optimization is pretty time-consuming. We propose an accelerated method that can greatly reduce the running time of the global parameter optimization program. This makes the method practically useful in an unstable channel. (C) 2022 Chinese Laser Press.

Automated summary

This study proposes a modified MDI-QKD protocol with phase post-selection, which eliminates the loopholes of detection devices using single-photon interference. The security of private phase announcement in the X basis is proven, and the phase post-selection method is applied to the double-scanning four-intensity MDI-QKD protocol. Numerical results demonstrate that the phase post-selection method significantly improves key rates at all distances. An accelerated method is also introduced to reduce the running time of global parameter optimization, making it practically useful in unstable channels.