Security of Continuous-Variable Quantum Key Distribution with Imperfect Phase Compensation

Abstract

Phase compensation is a necessary procedure in practical application of continuous-variable quantum key distribution (CVQKD) for the reason of unavoidable phase drifts of quantum signals in quantum channel. However, the phase compensation may become imperfect in practical applications. The security of CVQKD scheme with imperfect phase compensation is investigated under realistic conditions of quantum channel and detector. In particular, a tight security bound to the phase noise of the imperfect phase compensation are derived for reverse reconciliation and realistic homodyne detection. Moreover, the phase noise is analyzed experimentally and a practical phase compensation procedure is applied to simulate the imperct processing. The simulation results show its coincidence to the security bound, and reveal the sensitivity of the security of the reverse reconciliation CVQKD protocol to the noise arising from imperfect phase compensation.