Quantum key distribution for nanosatellite-to-ground application

Sheng‐Kai Liao, Wenqi Cai, Wei-Yue Liu +31 more

Thomas D. Jennewein, C. Cordell Grant, E. Choi +6 more

The NanoQEY (Nano Quantum Encryption) Satellite is a proposed nanosatellite mission concept developed by the Institute for Quantum Computing (IQC) at the University of Waterloo and the Space Flight Laboratory (SFL) at the University of Toronto Institute for Aerospace Studies (UTIAS) that would demonstrate long-distance quantum key distribution (QKD) between two distant ground stations on Earth using an optical uplink. SFL’s existing and proven NEMO (Nanosatellite for Earth Monitoring and Observation) bus forms the baseline spacecraft for NanoQEY, with a QKD receiver payload designed by IQC. The primary objective of the NanoQEY mission would be to successfully distribute at least 10 kbit of secure key between two optical ground stations, where the satellite acts as a trusted node. The secondary mission objective would be to perform Bell tests for entangled photons between ground and space. We designed a compact QKD receiver payload that would be compatible with the mass, volume, power and performance constraints of a low-cost nanosatellite platform. The low-cost rapid schedule “microspace” approach of UTIAS/SFL would allow for the proposed NanoQEY mission to be developed in 2.5 years from project kick-off to launch of the spacecraft, followed by a one-year on-orbit mission.

Yang Li, Wen-Qi Cai, Ji-Gang Ren +40 more

Denis P. Naughton, Robert Bedington, Simon Barraclough +12 more

Quantum key distribution (QKD) is a method for establishing secure cryptographic keys between two parties who share an optical, “quantum” channel and an authenticated classical channel. To share such keys across the globe, space-based links are required and in the near term these will take the form of trusted node, key management satellites. We consider such channels between two nanosatellite spacecraft for polarization entanglement-based QKD, and the optical channel is described in detail. Quantum channels between satellites are useful for balancing keys within constellations of trusted node QKD satellites and, in the future, may have applications in long-distance qubit exchange between quantum computers and in fundamental physics experiments. The nanosatellite mission proposed uses an optical link with 80-mm diameter optical terminals. If such a link could be maintained with 10-μrad pointing accuracy, then this would allow QKD to be performed for satellite separations up to around 400 km. A potential pointing and tracking system is also described although currently this design would likely limit the satellite separation to 100 to 150 km.

Junyong Wang, Hongyu Chen, Zhencai Zhu

Robert Bedington, Xueliang Bai, Edward Truong-Cao +6 more

We present a programme for establishing the space worthiness of highly-miniaturised, polarisation-entangled, photon pair sources using CubeSat nanosatellites. Once demonstrated, the photon pair sources can be deployed on more advanced satellites that are equipped with optical links to establish a global space-based quantum key distribution network. In doing so, this work will also bring experimental tests of the overlap between quantum and relativistic regimes closer to realisation.