Reconfigurable multi-user entanglement distribution over metropolitan fiber

Overview

The University of Bristol has developed a metropolitan-scale quantum communication network that enables dynamic, multi-user, and multi-protocol entanglement distribution. At the heart of this system is a quantum reconfigurable optical add-drop multiplexer (q-ROADM), which allows for the flexible and programmable allocation of entanglement resources across a network. This architecture supports various network topologies, including full-mesh, partial-mesh, and sliced sub-networks, enabling the system to adapt to changing user demands, link conditions, and specific service requirements over existing telecommunications fibre-optic infrastructure.

Technical specifications

The system utilizes a q-ROADM that integrates wavelength multiplexing, optical switching, and polarization control to distribute polarization-entangled photon pairs from a broadband source. Key features include:

• Programmable network configurations: Supports full-mesh, partial-mesh, and sliced sub-network topologies.
• Multi-protocol support: Capable of running diverse quantum protocols, such as Quantum Key Distribution (QKD) and Secure Inaugural Authentication-Transfer (SIAT).
• Scalability: Designed for metropolitan-scale deployment, allowing for the efficient onboarding of new users through multi-path authentication and flooding protocols.
• Stability: Demonstrated stable operation over extended periods (e.g., over 150 hours in a six-user configuration) using deployed campus and metropolitan fibre links.

Technology readiness level

The technology is at TRL 4, representing lab and field-environment validation. The University of Bristol has successfully demonstrated this architecture in a metropolitan-scale testbed, including stable multi-user operation over deployed fibre infrastructure and the execution of complex quantum protocols. It remains a research-based demonstration of a novel quantum networking architecture.