Satellites will soon beam quantum encryption keys across continents, bypassing the 150-kilometre range limit of fibre-based quantum key distribution (QKD). Current fibre networks require vulnerable “trusted nodes” for longer distances, creating security weak points that satellite QKD avoids. This project tackles the practical barriers to making satellite QKD work for government customers who need formal accreditation. The team will build sector-specific demonstrators before the first satellite launches, develop cheaper, higher-performance optical ground receivers, test the system against real-world side-channel attacks, and create portable test equipment for interoperability standards. If successful, this work could accelerate the adoption of unhackable encryption for global communications—securing everything from financial transactions to national security data. The research is applied, not fundamental: it directly addresses the engineering and accreditation hurdles standing between a working satellite constellation and its use by governments.
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Quantum Key Distribution (QKD) facilitates the secure sharing of encryption keys using quantum technology. These keys can encrypt data for transmission over conventional fibre links across any distance, but QKD itself is limited over fibre to around 150km with current technology. Beyond this, 'trusted nodes' are required, but at major risk of creating security vulnerabilities. A number of dark fibre QKD networks are being built, including in the UK, but all are subject to this constraint. QKD through free space is less sensitive to distance. Thus, satellites provide the means for distributing keys across very large distances between end users spread across countries or continents - they are a facilitator of global QKD networks. Satellite components in QKD networks are being planned or researched in a number of countries. A consortium led by Arqit aims to establish the world's first commercial QKD satellite constellation. The first satellite is being built under contract with the European Space Agency, with further satellite already being developed. This project aims to overcome important barriers to the adoption of QKD based infrastructure and services by government customers that will need accreditation. We will establish sector specific demonstrators of the service prior to satellite launch to support live end to end demonstrations, enabling customer integration to accelerate adoption; develop QKD optimised detectors to enhance performance of optical ground receivers whilst reducing cost; address operational security by performing practical side channel attacks on key elements of the system; and develop satellite specific QKD standards, supported by generating portable test equipment to support interoperability testing with other satellite QKD systems.
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