Quantum key distribution and 1 Gbps data encryption over a single fibre

Abstract

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