Simultaneous classical communication and quantum key distribution using continuous variable

TL;DR

This paper introduces a novel scheme enabling simultaneous classical communication and quantum key distribution over the same optical infrastructure, using a coherent communication approach with shared encoding and decoding.

Contribution

It presents a unified scheme for concurrent classical and quantum communication on the same hardware, reducing complexity and cost.

Findings

Achieves classical communication with a bit error rate of 10^{-9}

Enables secure key distribution over tens of kilometers

Uses practical system parameters for simulation

Abstract

Presently, classical optical communication systems employing strong laser pulses and quantum key distribution (QKD) systems working at single-photon levels are very different communication modalities. Dedicated devices are commonly required to implement QKD. In this paper, we propose a scheme which allows classical communication and QKD to be implemented simultaneously using the same communication infrastructure. More specially, we propose a coherent communication scheme where both the bits for classical communication and the Gaussian distributed random numbers for QKD are encoded on the same weak coherent pulse, and decoded by the same coherent receiver. Simulation results based on practical system parameters show that both deterministic classical communication with a bit error rate of 10^{-9} and secure key distribution could be achieved over tens of kilometers single mode fibers. It is conceivable that in the future coherent optical communication network, QKD is operated in the background of classical communication at a minimal cost.