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Building a world first commercial quantum-secured metro network

17 May 20223 min read
Guest Insights
Building a world first commercial quantum-secured metro network

We are on the cusp on a quantum revolution. In the years ahead, further advances in quantum driven technologies, solutions, products and services are expected to bring profound changes to the technology sector. These changes are expected to be transformational in areas as diverse as pharma, finance, telecommunications, construction and civil engineering, as well as for national priorities such as climate change. 

However, with the quantum revolution comes a threat to data security from quantum computing. Quantum computers have the potential to revolutionise businesses by making certain types of classically intractable problems solvable. Some estimates suggest that quantum computer enabled security attacks are possible within five years, and likely to occur within 10. But this is not just a problem for the future. Securing encrypted traffic is a pressing problem today because data that requires long-term security could be at risk of ‘store today, crack later’ attacks, in which the key-exchange and encrypted traffic are stored now and broken when a sufficiently powerful quantum computer is available. With communication services being more critical than ever, this presents a significant threat to the way business is done.  

A world first

This April, BT and Toshiba, in association with EY, were proud to announce the launch of a world first commercial quantum secured metro network. Connecting sites in the City, West End and M4 Corridor, the infrastructure will be able to link numerous customers across London, helping them to secure the transmission of valuable data and information between physical locations over standard fibre optic links using quantum key distribution (QKD). QKD provides an additional layer of security that complements existing and post-quantum cryptography. The network’s first commercial customer, EY, will use the network to connect two of its sites in London, one in Canary Wharf and one near London Bridge, and will demonstrate how data secured using QKD can move between sites and will showcase the possibilities this network brings to its own customers. 

The new network, operated by BT, will provide a range of quantum-secured services including dedicated high bandwidth end-to-end encrypted links, delivered over Openreach’s Optical Spectrum Access Filter Connect solution for private fibre networks. The QKD links will be provided using a quantum network that includes both core and access components and will be integrated into BT’s existing national network management operations. Toshiba will provide QKD hardware and key management software. Optical transmission equipment and encryption cards from ADVA complete the technical solution. 

The network extends the point-to-point solution built by BT and Toshiba for the National Composites Centre and Centre for Modelling and Simulation. While other QKD systems and research networks are being built around the world, this is the first commercially ready QKD network to include fully integrated, encrypted data, a complete network monitoring and management system and a network-wide key management system. The network is also capable of deploying commercial services to multiple customers on the same infrastructure. In addition, Toshiba’s innovative multiplexing compatibility allows the data and the quantum keys to be transmitted on the same fibre, eliminating the need for costly dedicated infrastructure for key distribution.  

This trial is a tangible commercial outcome of the National Quantum Technologies Programme and provides the first step to a UK quantum communications infrastructure. In particular, it represents a key milestone in achieving the UK government’s ambition to become a quantum-enabled economy. 


Jonathan Legh-Smith is Principal, Scientific Affairs for BT. He leads engagement with national research & innovation priorities and is based at BT’s global R&D Headquarters at Adastral Park, Suffolk. He is a member of the EPSRC Science, Engineering & Technology Board and NPL’s Quantum Metrology Institute Advisory Board. Jonathan is also a founding member of UKQuantum, the voice of the UK’s quantum industry. Jonathan directed BT’s Strategic Research programme for over 10 years along with BT’s academic and industrial research partnerships. He was also BT’s Head of Standards, responsible for engagement in national and international standards organisations such as ETSI, ITU and ISO. He is based at BT’s R&D Headquarters at Adastral Park, Suffolk.  

Jonathan Legh-Smith - Principal, Scientific Affairs - BT | LinkedIn  


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