In Great Britain, scientists from the Universities of Bristol and Cambridge conducted the country’s first long-distance video call protected by quantum technology. They also managed to create a network based on conventional fiber-optic infrastructure that uses a number of quantum effects to ensure secure data transmission. About this informs AZoQuantum.
The constructed network uses two forms of quantum key distribution (QKD): encrypted keys embedded in light particles, and distributed quantum entanglement, a phenomenon in which particles remain connected regardless of distance.
The quantum-secure network has successfully enabled the transmission of encrypted medical data over a distance of 410 km between Bristol and Cambridge, enabled secure video conferencing and provided remote access to a data centre. This practical example demonstrates the potential of quantum networks to counter future cyber threats, including threats from quantum computers.
The network was built using single-mode fiber provided by the EPSRC National Dark Fiber Facility infrastructure and low-loss optical switches that allow simultaneous operation of classical and quantum signals. Similar developments were also carried out in China – there they created a 4,600 km long quantum network connecting cities using optical fiber and satellites, as well as a nine-point network in Madrid using various QKD technologies.
In addition, Cambridge and Toshiba successfully demonstrated high-speed transmission of quantum keys over short distances, and Bristol implemented a network capable of distributing quantum entanglement among many users. Similar experiments also took place in Singapore, Italy and the USA.
However, until now, no one has been able to develop a large-scale long-distance quantum network capable of simultaneously supporting two types of QKD, distributed entanglement and conventional data transmission.
This experiment proved the flexibility of quantum networks, which are able to simultaneously support a variety of secure communication methods and work on existing infrastructure. Thanks to funding from the EPSRC Integrated Quantum Networks Hub project, the team of researchers will continue to develop such systems.
Within the framework of the initiative, it is planned to create quantum networks of various scales — from intercontinental ones using satellites in low Earth orbit to national networks for secure communication, distributed computing and precise sensing.
