Field and long-term demonstration of a wide area quantum key distribution network

TL;DR

This paper reports the deployment and long-term operation of a large-scale quantum key distribution network across multiple cities in China, demonstrating practical stability and integration of QKD technologies in real-world communication infrastructure.

Contribution

It presents the first large-scale, long-term field demonstration of a wide area QKD network with complex topology and stability measures, integrating point-to-point and networked QKD systems.

Findings

Network operated for over 5000 hours with stable performance.

Successfully integrated point-to-point QKD with network schemes.

Demonstrated practical deployment in real-world communication infrastructure.

Abstract

A wide area quantum key distribution (QKD) network deployed on communication infrastructures provided by China Mobile Ltd. is demonstrated. Three cities and two metropolitan area QKD networks were linked up to form the Hefei-Chaohu-Wuhu wide area QKD network with over 150 kilometers coverage area, in which Hefei metropolitan area QKD network was a typical full-mesh core network to offer all-to-all interconnections, and Wuhu metropolitan area QKD network was a representative quantum access network with point-to-multipoint configuration. The whole wide area QKD network ran for more than 5000 hours, from 21 December 2011 to 19 July 2012, and part of the network stopped until last December. To adapt to the complex and volatile field environment, the Faraday-Michelson QKD system with several stability measures was adopted when we designed QKD devices. Through standardized design of QKD devices, resolution of symmetry problem of QKD devices, and seamless switching in dynamic QKD network, we realized the effective integration between point-to-point QKD techniques and networking schemes.