Improving the Performance of Continuous-Variable Measurement-Device-Independent Quantum Key Distribution via a Noiseless Linear Amplifier

Abstract

In the continuous variable measurement-device-independent quantum key distribution (CV-MDI-QKD) protocol, both Alice and Bob send quantum states to an untrusted third party, Charlie, for detection through the quantum channel. In this paper, we mainly study the performance of the CV-MDI-QKD system using the noiseless linear amplifier (NLA). The NLA is added to the output of the detector at Charlie’s side. The research results show that NLA can increase the communication distance and secret key rate of the CV-MDI-QKD protocol. Moreover, we find that the more powerful the improvement of the performance with the longer gain of NLA and the optimum gain is given under different conditions.

Improvement of a continuous-variable measurement-device-independent quantum key distribution system via quantum scissors

“…[35][36][37] Among the mentioned methods, photon subtraction and quantum catalysis can improve the system performance by enhancing the success probability of non-Gaussion operations, while optical amplifier improves the system performance by amplifying the amplitude of the coherent state. Among various amplifiers, the heralded noiseless linear amplifier (NLA) [38][39][40][41] outperforms the other linear amplifiers, since it will maintain the initial noise level while amplifying the amplitude of the coherent state. However, the implementation of NLA should be under strict assumption that the amplifier is ideally noiseless, and it is of challenge to apply it to a practical CV-MDI-QKD system.…”