Quantum key distribution over 25 km with an all-fiber continuous-variable system

TL;DR

This paper demonstrates a practical continuous-variable quantum key distribution system over 25 km of fiber, achieving high secret key rates suitable for real-world secure communication.

Contribution

It introduces a complete all-fiber CV-QKD system with real-time reverse reconciliation and time multiplexing, advancing field deployment capabilities.

Findings

Secret keys generated at over 2 kb/s over 25 km fiber

Use of time multiplexing for signal and phase reference transmission

Implementation of real-time reverse reconciliation with LDPC codes

Abstract

We report on the implementation of a reverse-reconciliated coherent-state continuous-variable quantum key distribution system, with which we generated secret keys at a rate of more than 2 kb/s over 25 km of optical fiber. Time multiplexing is used to transmit both the signal and phase reference in the same optical fiber. Our system includes all experimental aspects required for a field implementation of a quantum key distribution setup. Real-time reverse reconciliation is achieved by using fast and efficient LDPC error correcting codes.