Figure 1

Artist’s impression of the communications system. We consider ten locations throughout the UK to represent potential nodes in a national quantum-secured communications network. Conventional communication between these nodes is encrypted with symmetric key pairs distributed via a satellite placed in a Sun-Synchronous Orbit. The satellite has a single quantum transmitter that can send single-photon level signals to optical ground stations. The dashed arc is the ground track the spacecraft follows. The satellite passes over the UK mainland territory South to North around local midnight