Continuous-variable quantum key distribution based on high-rate phase reference

Abstract

We propose a high-rate phase reference scheme for continuous-variable quantum key distribution (CV-QKD). In this scheme, a transmission mode has been employed in which several quantum signal pulses are accompanied by a pair of reference pulses, calibrating the measurement bases of the communicating parties. Within a certain range, and with the ratio between quantum signal pulses and reference pulses increased, the secret key rate approaches that of the traditional CV-QKD scheme (which is a scheme without phase noise). Compared with general CV-QKD schemes, which adopt the transmission mode of a quantum signal pulse plus a pair of reference pulses, this scheme has a higher spectral efficiency, enabling high-rate CV-QKD. In addition, we reduce the interference of strong reference pulses with weak quantum signal pulses by using a pair of polarization beam splitters with a dynamic polarization controller. Simulation results demonstrate that we achieve a higher secret key rate than the self-coherent phase reference scheme. This provides a pathway towards large-scale quantum communication networks.