Quantum key distribution over25kmwith an all-fiber continuous-variable system

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 $2\mathrm{kb}∕\mathrm{s}$ over $25\mathrm{km}$ 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 low-density parity check error correcting codes.