Ultra-compact payload for a LEO-orbit based entanglement QKD mission using cubesats

Within the publicly funded project CubEnik an ultra-compact payload for an entanglement Quantum Key Distribution (QKD) mission, using a double downlink scenario from a LEO orbit around 700 km, was developed until the Preliminary Design Review (PDR) status of a typical space mission phase B. The optical payload part, consisting of a double telescope with 80 mm apertures, risley-prism based coarse pointing mechanisms to address Alice and Bob recipients on ground at a distance >300 km, and a high-performant, GHz capable entangled photon source, fits into a 8..12U format of a CubeSat, enabling for a 12..16U CubeSat, or mini-sat Entanglement QKD mission. Link simulations reveal a potential key rate >100 bit per contact (satellite flyover), a first engineering model of the coarse pointing mechanism indicated achievable pointing rates that are suitable for the desired link budget. The consortium now is looking to move forward to phase C and the critical design review (CDR), in collaboration with satellite platform, launch, and mission control partners.