George Kanellos

We demonstrated for the first time a coexistence between a quantum QKD channel and 4×100 Gbps pm-qpsk carrier-grade classical optical channels in a 2 km Nested Antiresonant Nodeless Hollow Core fibre. Our results show a drop of less than 10% in the Secret Key Rate (SKR) when using a HCF compared to a significant drop of 97% in the SKR when quantum and classical signals coexist on a single core of a Multicore fibre (MCF) with equal losses, indicating that NANF type HCF significantly outperforms single-mode fibres (SMF) performance for quantum/classical coexistence. This significant difference in the SKR drop is due to the ultra-low nonlinear effects in HCF comparing to glass core fibres such as SMF and MCF.

Two QKD systems employing different encoding schemes are evaluated over a mixed 29.5km fiber infrastructure, including 16km of aerial fiber segments. The work examines the systems’ performance and compares it to corresponding in-lab fiber setups.