UK’s first long-distance ultra-secure communication over a quantum network

Quantum communications provide unmatched security against future threats like quantum computers, which could break current cryptographic methods.

Researchers have developed quantum networks worldwide. China built a 4,600-kilometer network linking cities via fiber optics and satellites. In Madrid, a smaller nine-node network securely shares data using various Quantum Key Distribution (QKD) types. Cambridge and Toshiba achieved record key rates in 2019, while Bristol created a network enabling entanglement sharing in 2020. Similar trials have occurred in Singapore, Italy, and the USA.

However, no one has created a large, long-distance network combining QKD, entanglement, and regular data transmission until now.

A team from the Universities of Bristol and Cambridge has successfully demonstrated the UK’s first long-distance quantum-secured video call and ultra-secure data transfer over a quantum communications network. This network, spanning over 410 kilometers of fibreoptic infrastructure between Bristol and Cambridge, utilizes two quantum key distribution (QKD) schemes: encryption keys embedded in light particles and distributed entanglement, where quantum particles remain intrinsically linked.

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The demonstration showcased the network’s capabilities through a quantum-secure video call, encrypted medical data transfer, and remote access to a distributed data center. This marks the first successful integration of long-distance quantum-secure technologies like entanglement distribution and regular data transmission.

The experiment highlights:

1. The potential of quantum networks to integrate various quantum-secure approaches alongside traditional communication infrastructure.
2. It utilized the UK’s Quantum Network (UKQN), which has been developed over the past decade with support from the Engineering and Physical Sciences Research Council (EPSRC) and the Quantum Communications Hub project.
3. The use of multiple quantum communication technologies, including secure key management systems for seamless encryption.
4. This is a significant advancement in delivering quantum security at a national scale, laying the groundwork for a future quantum internet, connecting nodes and devices through entanglement and teleportation.
5. Exemplifies the UK’s strengths in quantum networking technology and sets the stage for developing resilient, future communication systems.

The team plans to continue their work through a new EPSRC-funded project, the Integrated Quantum Networks Hub. The project aims to develop quantum networks at all scales, from connecting local quantum processors to creating national and intercontinental networks using low-earth orbit satellites for secure communication, computing, and sensing.

Journal Reference:

1. R. Yang et al. A UK nationwide heterogeneous quantum network. Presented at the 2025 Optical Fiber Communications Conference and Exhibition (OFC)