Field Experiment on a Robust Hierarchical Metropolitan Quantum Cryptography Network

TL;DR

This paper reports a practical hierarchical metropolitan quantum cryptography network using telecom fiber cables, demonstrating secure communication among government departments with high security and expandability.

Contribution

It introduces a scalable, hierarchical quantum cryptography network with integrated quantum routers, optical switches, and trusted relays for practical secure communications.

Findings

Successful implementation of a 7-user quantum cryptography network

Secure key distribution enabling encrypted multimedia communication

Demonstration of network expandability and practical application

Abstract

A hierarchical metropolitan quantum cryptography network upon the inner-city commercial telecom fiber cables is reported in this paper. The seven-user network contains a four-node backbone net with one node acting as the subnet gateway, a two-user subnet and a single-fiber access link, which is realized by the Faraday-Michelson Interferometer set-ups. The techniques of the quantum router, optical switch and trusted relay are assembled here to guarantee the feasibility and expandability of the quantum cryptography network. Five nodes of the network are located in the government departments and the secure keys generated by the quantum key distribution network are utilized to encrypt the instant video, sound, text messages and confidential files transmitting between these bureaus. The whole implementation including the hierarchical quantum cryptographic communication network links and corresponding application software shows a big step toward the practical user-oriented network with high security level.