Strathclyde researchers advance space quantum technology on two fronts

22/06/2023

THE use of quantum technology in space is being advanced by University of Strathclyde researchers in two new projects funded by the UK Space Agency (UKSA) under the Enabling Technology Programme.

Strathclyde leads one of the projects in partnership with the University of Bristol, which will use recent developments in the fabrication and device integration of ultraviolet micro-LEDs (light emitting diodes) to enable compact, low-power, robust sources for satellite QKD (quantum key distribution), which offers future-proof security based on fundamental laws of physics.

The University is also a partner in a parallel project, led by Swansea University, in which nanoparticles will be used as special sensors, both on Earth and in space, for purposes such as measuring gravity and the density of the thermosphere, in the upper region of Earth’s atmosphere.

The Strathclyde and Bristol-led project, with Strathclyde’s Department of Physics and Institute of Photonics, will explore the use of micro-LEDs to overcome difficulties with laser diodes in satellite QKD sources, such as fluctuations in intensity and the need for thermal control.

It will take two interlinked directions of development will be pursued: the optimisation of photonic sources of secure quantum signals that are both robust and designed for easy integration into small satellite platforms, along with the use of shorter wavelengths for intersatellite QKD.

The innovative aspect of the project is the exploitation of the latest developments in UV micro-LEDs, capable of being integrated with its driving and control circuitry and consequent miniaturisation. These have already shown promise for conventional terrestrial free-space optical communication (FSOC) but so far not for satellite QKD. The use of short wavelengths for intersatellite QKD, where the lack of atmosphere allows for the use of UV, has the advantage of enabling narrower beam widths for a given aperture.

Dr Daniel Oi, a Reader in Strathclyde’s Department of Physics, is leading the project. He said: “Satellite QKD is a promising solution to global-scale secure communications that are proof against advances in cryptanalysis and accelerating developments in quantum computers that threaten existing public key infrastructure.

“Space-based quantum communication overcomes the exponential losses inherent in fibre transmission and allows mobile connectivity to remote areas, aircraft and other satellites. Satellite QKD is also expected to provide the underlying basis for global quantum communication networks, large scale distribution of quantum entanglement, and, eventually, the establishment of the quantum internet.”

Dr Siddarth Joshi a lecturer at the University of Bristol’s Quantum Engineering Technology Labs said: “We are excited to explore the advantages that micro-LEDs and novel wavelengths bring towards creating a network of interconnected satellites for quantum communication at a global scale.”

Dr Susan Spesyvtseva and Dr Johannes Herrnsdorf, of Strathclyde’s Institute of Photonics, and John Rarity, Professor of Optical Communications Systems at the University of Bristol, are also working on the project.

Dr Oi is also a partner in the Swansea-led project, in which a UK-wide consortium is developing technologies to use nanoparticles as state-of-the-art sensors on small, shoebox-sized satellites known as CubeSats.

Recent advances in the field of levitated optomechanics – the motion of tiny particles held and measured in free space by laser light – have shown that nanoparticles can exhibit behaviours that are governed by the laws of quantum mechanics, a fundamental theory which describes how atoms and subatomic particles interact.

This has led to nanoparticles, which are a thousand times larger than an atom and a thousand times smaller than a single grain of sand, being investigated as new sensors in laboratory conditions. But scientists are yet to apply this to the real world – and beyond.

Researchers are pushing the limits of quantum technology so that nanoparticles can be used as sensors in space. LOTIS (Levitated Optomechanical Technologies in Space) is an 18-month project to develop technologies to enable future space-borne devices using nanoparticles.

LOTIS will develop techniques which are small, lightweight, and rather than car-sized satellites, can fit on to the more compact CubeSats. This approach dramatically lowers development and launch costs.

Dr Oi said: “We are developing highly sensitive sensors for satellites which are greatly reduced in size and able to perform measurements of the space environment.

“This is part of a wider, international quantum technology programme which will extend its applications from Earth and space bound applications.”

Dr James Bateman of Swansea University, Principal Investigator in the project, said: “I am thrilled to lead this UKSA project, which will create the necessary technologies to establish a functioning sensing platform for both space and terrestrial applications. Our team is comprised of experts in nanosatellites, quantum sensing, and experimental optomechanics, and this project will help to make levitated optomechanical sensors a reality.”

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