Continuous high speed coherent one-way quantum key distribution

We report the first real world implementation of a Quantum Key Distribution (QKD) system over a 43dB-loss transmission line in the Swisscom fibre optic network.The QKD system is capable of continuous and autonomous operation and uses the coherent one-way (COW) protocol.This system brings together three key concepts for future QKD systems: a simple high-speed protocol; high performance detection; and integration, both at the component level as well for connectivity with standard fibre networks.Here, we show laboratory and field trial results for this system.The full prototype version uses InGaAs/InP avalanche photodiodes (APDs) and was laboratory tested up to 150km, with a 10-hour exchange averaging around 2kbps of real-time distilled secret bits over 100km.In the field trials, we obtained average distribution rates, during 3 hours, of 2.5bps over a 43dB-loss line of 150km, when using superconducting single photon detectors (SSPDs).