QUARC: Quantum Research Cubesat - a constellation for quantum communication

Quantum key distribution (QKD) offers future proof security based on fundamental laws of physics. Long distance QKD spanning regions such as the United Kingdom (UK) may employ a constellation of satellites. Small satellites, CubeSats in particular, in low earth orbit (LEO) are a relatively low cost alternative to traditional, large platforms. They allow the deployment of a large number of spacecraft ensuring greater coverage and mitigating some of the risk associated with availability due to cloud cover. We present our mission analysis showing how a constellation of low cost 6U CubeSats can be used to form a secure communication backbone for ground based and metropolitan networks across the UK. We have estimated the monthly key rates at 43 sites across the UK incorporating local meteorological data, atmospheric channel modelling and orbital parameters. We have optimized the constellation topology for rapid revisit and thus low latency key distribution.