Cambridge quantum network

TLDR

Future‑proofing current fibre networks with quantum key distribution is an attractive approach to combat growing data‑theft breaches, yet existing quantum networks either require dark fibres or provide insufficient bit rates for many users. The goal is to deliver broadband quantum keys, efficient key delivery, and seamless user interaction within existing fibre networks, as demonstrated by the Cambridge quantum network operating on high‑bandwidth traffic‑laden fibres. The network uses a robust key‑delivery layer that supports 100 Gbps data encryption with rapidly refreshed quantum keys, while high link rates and redundancy provide resilience against link disruption. The network can support tens of thousands of users at over 1 kbps per user, demonstrating a clear path to implementing quantum security in metropolitan fibre networks.

Abstract

Abstract Future-proofing current fibre networks with quantum key distribution (QKD) is an attractive approach to combat the ever growing breaches of data theft. To succeed, this approach must offer broadband transport of quantum keys, efficient quantum key delivery and seamless user interaction, all within the existing fibre network. However, quantum networks to date either require dark fibres and/or offer bit rates inadequate for serving a large number of users. Here we report a city wide high-speed metropolitan QKD network—the Cambridge quantum network—operating on fibres already populated with high-bandwidth data traffic. We implement a robust key delivery layer to demonstrate essential network operation, as well as enabling encryption of 100 Gigabit per second (Gbps) simultaneous data traffic with rapidly refreshed quantum keys. Network resilience against link disruption is supported by high-QKD link rates and network link redundancy. We reveal that such a metropolitan network can support tens of thousands of users with key rates in excess of 1 kilobit per second (kbps) per user. Our result hence demonstrates a clear path for implementing quantum security in metropolitan fibre networks.