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Optics InfoBase Conference Papers

Field demonstration of quantum key distribution in the Tokyo QKD Network

Mikio Fujiwara, Hirokazu Ishizuka, Shigehito Miki, Taro Yamashita, Z. Wang, Akihiro Tanaka, K. Yoshino, Y. Nambu, Satoshi Takahashi, A. Tajima, Akihisa Tomita, T. Hasegawa, Toyohiro Tsurumaru, M. Matsui, Toshimori Honjo, Kiyoshi Tamaki, Y. Tokura, Masahide Sasaki

Published Aug 1, 2011• 6 citations
Publisher

Abstract

A secure communication network with novel quantum key distribution systems in a metropolitan area (very center of Tokyo) is reported. Different QKD schemes are integrated to demonstrate key relay for secure TV conferencing over a distance 45 km, stable long-term operation.
DOI
10.1109/iqec-cleo.2011.6193793

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A secure communication network with quantum key distribution in a metropolitan area is reported. Six different QKD systems are integrated into a mesh-type network. GHz-clocked QKD links enable us to demonstrate the world-first secure TV conferencing over a distance of 45km. The network includes a commercial QKD product for long-term stable operation, and application interface to secure mobile phones. Detection of an eavesdropper, rerouting into a secure path, and key relay via trusted nodes are demonstrated in this network.
The advent of cryptographically relevant quantum computers poses an existential threat to classical public-key infrastructure. Quantum Key Distribution (QKD) addresses this challenge by providing information-theoretic security for key establishment, independently of any computational hardness assumption. In this work, the deployment and experimental validation of a metropolitan-scale quantum-secure network between data centers in Milan is reported. The network operates over installed fiber infrastructure and implements a layered architecture integrating QKD hardware, standards-compliant Key Management (KM), and centralized Software-Defined Networking (SDN) orchestration. Dynamic path reconfiguration via active optical switching and trusted-node routing allow automated fail-over solutions. Application-layer validation across diverse protocols and workloads confirms the seamless interoperability of all system components. These results establish the technical and operational readiness of metropolitan QKD networks for production deployment, and offer a replicable blueprint for building quantum-secure communication infrastructure at metropolitan scale.
Securing information in communication networks is an important challenge in today's world. Quantum Key Distribution (QKD) can provide unique capabilities towards achieving this security, allowing intrusions to be detected and information leakage avoided. We report here a record high bit rate prototype QKD system providing a total of 878 Gbit of secure key data over a 34 day period corresponding to a sustained key rate of around 300 kbit/s. The system was deployed over a standard 45 km link of an installed metropolitan telecommunication fibre network in central Tokyo. The prototype QKD system is compact, robust and automatically stabilised, enabling key distribution during diverse weather conditions. The security analysis includes an efficient protocol, finite key size effects and decoy states, with a quantified key failure probability of ε = 10⁻¹⁰.
Secure communication and information protection become more and more important in the modern society. Quantum key distribution (QKD) enables two remote legitimate users to share unconditionally secure keys. Different from the former ones, the security of these keys is based on the principles of quantum physics and could be proved. Combined with one-time pad encryption, QKD can provide us an effective way for secure communication and information protection[1, 2]. Since Bennett and Brassard proposed the famous BB84 protocol[3], QKD or quantum cryptography has become one of the most dynamic research fields. After about twenty years of development, experimental QKD has achieved significant improvements, such as the transmission distance increased from 32 cm[4]to 260 km[5], the speed increased from 200 Hz[4]to 10 GHz[6].