First quantum network video call

Researchers in the UK have achieved a significant milestone by demonstrating a long-distance ultra-secure transfer of data over a quantum communications network, marking the UK’s first successful long-distance video call. The team, comprising experts from the Universities of Bristol and Cambridge, established the network using standard fibreoptic infrastructure spanning a distance of 410km between the two cities. This achievement is part of the UK’s Quantum Network (UKQN), which has been developed over the past decade by the dedicated researchers.

The network incorporates two distinct quantum key distribution (QKD) schemes: encryption keys concealed within particles of light, and distributed entanglement involving photons that are inherently interconnected. This groundbreaking demonstration represents the first instance of a long-distance network effectively showcasing various quantum-secure technologies such as entanglement distribution.

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The capabilities of the UKQN were showcased through a live, quantum-secure video conference link, the secure transfer of encrypted medical data, and the establishment of secure remote access to a distributed data center. The UKQN encompasses two metropolitan quantum networks centered around Bristol and Cambridge, interconnected via a ‘backbone’ consisting of four long-distance optical fibre links spanning 410 kilometers with three intermediate nodes.

This infrastructure utilizes single-mode fibre across the EPSRC National Dark Fibre Facility, along with low-loss optical switches that facilitate the reconfiguration of both classical and quantum signal traffic within the network.

Researchers worldwide have been actively engaged in the development and utilization of quantum communication networks. For instance, China recently established an extensive network covering 4,600 kilometers by linking five cities using a combination of fibreoptics and satellites. In Madrid, researchers have created a smaller network with nine connection points employing various QKD methods to securely exchange information.

In a notable achievement in 2019, researchers at Cambridge and Toshiba demonstrated a metro-scale quantum network operating at record key rates of millions of key bits per second. Subsequently, in 2020, researchers in Bristol successfully constructed a network capable of sharing entanglement among multiple users. Similar trials of quantum networks have been conducted in countries such as Singapore, Italy, and the USA.

Despite the significant progress in quantum networking, the integration of multiple quantum communication technologies, entanglement distribution, and regular data transmission within a large, long-distance network had not been realized until now. Dr. Rui Wang, Lecturer for Future Optical Networks in the Smart Internet Lab‘s High Performance Network Research Group at the University of Bristol, emphasized the importance of this achievement in paving the way for a large-scale quantum internet that connects quantum nodes and devices globally through entanglement and teleportation.

Adrian Wonfor from Cambridge’s Department of Engineering highlighted the culmination of over a decade of effort in designing and constructing the UK Quantum Network, emphasizing the utilization of multiple quantum communications technologies and secure key management systems essential for seamless end-to-end encryption. Professor Richard Penty, also from Cambridge, underscored the significance of this achievement in delivering quantum security for national-scale communications, acknowledging the collaborative efforts of the teams at Cambridge and Bristol, as well as the support from industrial partners and funders.

Gerald Buller, Director of the IQN Hub at Heriot-Watt University, commended the UK’s exceptional strengths in quantum networking technology, emphasizing the importance of the demonstration in advancing the development of a resilient, future-proof national quantum communications infrastructure. The successful demonstration of the UK Quantum Network represents a significant leap forward in establishing a secure quantum-secured future for society, underlining the potential for transformative advancements in quantum communication technologies.