High speed coherent one-way quantum key distribution prototype

TL;DR

This paper presents a high-speed, real-world implementation of a coherent one-way quantum key distribution system capable of operating over long distances and integrating with existing fiber networks, demonstrating practical quantum communication.

Contribution

It introduces a scalable, high-speed QKD prototype using the COW protocol with both laboratory and field validation over significant fiber distances.

Findings

Achieved 2.5 bps key rate over 150 km in field conditions.

Demonstrated system operation over a 43dB-loss fiber line.

Validated the protocol's suitability for real-world quantum networks.

Abstract

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).