Quantum key distribution and 1 Gbit/s data encryption over a single fibre

TL;DR

This paper demonstrates quantum key distribution combined with 1 Gbps data encryption over a single fiber using dense wavelength division multiplexing, achieving secure communication over 50 km with minimal channel separation.

Contribution

It presents a practical implementation of QKD with classical channels in a dense wavelength division multiplexing setup, enabling secure data encryption over a single fiber.

Findings

Successful key distillation over 50 km fiber

Quantum and classical channels separated by only 200 GHz

System operates with 1 Gbps encrypted communication

Abstract

We perform quantum key distribution (QKD) in the presence of 4 classical channels in a C-band dense wavelength division multiplexing (DWDM) configuration using a commercial QKD system. The classical channels are used for key distillation and 1 Gbps encrypted communication, rendering the entire system independent from any other communication channel than a single dedicated fibre. We successfully distil secret keys over fibre spans of up to 50 km. The separation between quantum channel and nearest classical channel is only 200 GHz, while the classical channels are all separated by 100 GHz. In addition to that we discuss possible improvements and alternative configurations, for instance whether it is advantageous to choose the quantum channel at 1310 nm or to opt for a pure C-band configuration.