Vector—towards quantum key distribution with small satellites

EPJ QUANTUM TECHNOLOGY. 2023. Vol. 10. No. 1. P. 52–72.

Miller A., Pismeniuk L., Дуплинский А. В., Merzlinkin V., Plukchi A., Tikhonova K., Nesterov I., Севрюков Д. О., Левашов С. Д., Fetisov V., Krasnopejev S., Бахшалиев Р. М.

A satellite-constellation based global quantum network could allow secure quantum
communication between remote users worldwide. Such a constellation could be
formed of micro- or even nanosatellites, which have the advantage of being more
cost-effective than larger expensive spacecrafts. At the same time, the features of
quantum communication impose a number of technical requirements that are more
difficult to meet when using small satellites. Full-fledged quantum communication
has been demonstrated with neither a micro- nor a nanosatellite so far. The authors
took up this challenge and have developed a 6U CubeSat weighting 9.5 kg. The
satellite is to be launched in 2023 and has already successfully passed all the pre-flight
tests. The mission is not yet intended for fully quantum communication. Nevertheless,
the authors are testing such key functional elements as polarization reference-frame
synchronization and acquisition, pointing and tracking system on it. Besides that, the
payload accommodates a full-duplex telecommunication system operating at a bit
rate of 50 Mbit/s: an up- and a downlink at wavelengths of 808 and 850 nm. After the
satellite is launched, the main goal to be achieved is to demonstrate stable
connection between it and an optical ground station and carry out multiple
communication sessions. In quantum communication, generating secret keys from
raw measurement data implies two-way exchange of significant amount of
information and therefore availability of a classical communication channel with a
high bandwidth is one of the crucial things. In the following mission, which envisages
an overall quantum key distribution system, we plan to use the free-space optical link
for such an exchange of data, whereas the RF link will only be used for telemetry and
telecommand.

Keywords: Quantum Cryptography, Quantum key distribution, Free-space optical communication, Satellite laser communication, Satellite quantum communication