Continuous-variable QKD over 50km commercial fiber

TL;DR

This paper demonstrates successful continuous-variable quantum key distribution over nearly 50 km of commercial fiber, achieving high secure key rates suitable for metropolitan networks through advanced control and reconciliation techniques.

Contribution

It reports the first field tests of continuous-variable QKD over nearly 50 km of commercial fiber with significantly improved secure key rates using automatic control and rate-adaptive reconciliation.

Findings

Secure key rates two orders-of-magnitude higher than previous field tests

Successful deployment over 30 km and nearly 50 km commercial fibers

Development of a fully automatic control system for stable excess noise

Abstract

The continuous-variable version of quantum key distribution (QKD) offers the advantages (over discrete-variable systems) of higher secret key rates in metropolitan areas as well as the use of standard telecom components that can operate at room temperature. An important step in the real-world adoption of continuous-variable QKD is the deployment of field tests over commercial fibers. Here we report two different field tests of a continuous-variable QKD system through commercial fiber networks in Xi'an and Guangzhou over distances of 30.02 km (12.48 dB) and 49.85 km (11.62 dB), respectively. We achieve secure key rates two orders-of-magnitude higher than previous field test demonstrations. This is achieved by developing a fully automatic control system to create stable excess noise and by applying a rate-adaptive reconciliation protocol to achieve a high reconciliation efficiency with high success probability. Our results pave the way to achieving continuous-variable QKD in a metropolitan setting.