Twin-field quantum key distribution with passive-decoy state

TL;DR

This paper introduces a passive-decoy state method for Twin-Field quantum key distribution, enhancing security by avoiding active modulation and achieving comparable key rates with fewer detectors.

Contribution

It proposes a passive-decoy scheme for TF-QKD that improves source security and maintains high key rates, simplifying practical implementation.

Findings

Passive-decoy TF-QKD performs as well as active-decoy schemes.

The scheme requires only a few photon detectors.

Simulation results confirm practical feasibility.

Abstract

Twin-Field quantum key distribution (TF-QKD) and its variants, e.g. Phase-Matching QKD, Sending-or-not-sending QKD, and No Phase Post-Selection TFQKD promise high key rates at long distance to beat the rate distance limit without a repeater. The security proof of these protocols are based on decoy-state method, which is usually performed by actively modulating a variable optical attenuator together with a random number generator in practical experiments, however, active-decoy schemes like this may lead to side channel and could open a security loophole. To enhance the source security of TF-QKD, in this paper, we propose passive-decoy based TF-QKD, in which we combine TF-QKD with the passive-decoy method. And we present a simulation comparing the key generation rate with that in active-decoy, the result shows our scheme performs as good as active decoy TF-QKD, and our scheme could reach satisfactory secret key rates with just a few photon detectors. This shows our work is meaningful in practice.