An international team of researchers is developing technology to enable long-range quantum networks.
The University of Strathclyde is leading AL FreSQO (Atom-Light Free-Space Quantum Optics networking), a three-year, €2 million project funded by the European Union which will develop quantum ‘memories’ - systems to store quantum information – for communication networks based on cold atoms.
Quantum memories can be used in repeater devices that buffer data over long distance links, helping to mitigate signal loss through the distribution of entanglement.
Quantum entanglement, which allows secure communications and enables more efficient sensing and computation, is a fundamental resource for quantum information technologies.
AL FreSQO will explore how quantum communications can operate using several technologies, including free-space optical links, as an alternative to fibre networks, and systems which inter-convert the wavelength of light between those used in telecommunications and those that can more easily ‘talk’ to quantum systems.
These approaches could reduce the need for bulky, energy-intensive cryogenic systems, which are frequently used for alternative quantum memory platforms.
Transport applications
AL FreSQO technology could have applications in space, as well as aviation, shipping, rail and haulage, where optical fibre links are not practical.
Strathclyde is working on the project with the Universities of Southampton and Padova, Humboldt University of Berlin, Sabancı University in Istanbul Province and University of Padova spinout ThinkQuantum.
Professor Daniel Oi, of Strathclyde’s Department of Physics, the lead coordinator of AL FreSQO, said:
Quantum signals are fragile and easily lost over long distances. Because they can’t be copied or amplified, we need new ways to extend their range. Our approach uses repeater devices and quantum memories to break long links into shorter ones and reconnect them through entanglement swapping, allowing information to travel much further.
The project brings together expertise in quantum optics, atomic and solid-state physics, and systems engineering.
Professor Oi added: “Free-space links are important where fibre networks are not practical, such as for satellite communications.
“Frequency conversion allows us to connect free-space and fibre networks by matching different wavelengths, giving greater flexibility in how quantum networks are built.”
As part of the project, Dr Aidan Arnold, a Reader in Physics at Strathclyde, will carry out experiments in quantum non-demolition, detecting a photon without destroying it.
The research could support secure communications, clock synchronisation, sensing networks and, ultimately, the quantum internet. It could also help to train the next generation of quantum physicists.
AL FreSQO is aligned with the Integrated Quantum Networks Quantum Technology Research Hub, one of four UK-wide quantum hubs in which Strathclyde is a partner, and follows the EPSRC International Network in Space Quantum Technologies, that was led by Strathclyde with Professor Oi as Principal Investigator. The project also supports the UK National Quantum Strategy, which aims to deliver advanced quantum networks at scale by 2035.
AL FreSQO is funded under QuantERA, a transnational quantum technologies programme supported by the European Commission.