Research Confirms Feasibility of Quantum Communications via Satellites

Canadian researchers have reached a significant milestone in facilitating secure quantum communication through moving satellites, aligning with the Canadian Government’s announcement in April 2017. Their findings, featured in the newly introduced Quantum Science and Technology journal, showcase the first-ever quantum key distribution transmissions from a ground transmitter to a quantum payload onboard a mobile aircraft.

To ensure the tests served as a meaningful proof of concept for the anticipated satellite mission, the team from the Institute for Quantum Computing (IQC) and the Department of Physics and Astronomy at the University of Waterloo, Ontario, designed a prototype receiver with components suitable for the size and operational conditions of a micro satellite. Christopher Pugh, the lead author, highlighted the significance of quantum key distribution (QKD) in establishing cryptographically unbreakable cryptographic keys between two distant parties.

While ground-based QKD systems are limited to a few hundred kilometers due to absorption losses in optical fiber links, the researchers aimed to extend the range to a global scale using satellite-based systems. The team utilized the National Research Council’s Twin Otter aircraft to conduct 14 passes over their ground transmitting station at varying distances, successfully establishing a quantum signal link for seven passes and extracting a secret key for six of the seven successful passes. Principal Investigator Professor Thomas Jennewein emphasized the importance of this achievement after nearly eight years of preparation, stating that it demonstrates the viability of their technology.

The optical links achieved angular rates similar to low-Earth-orbit satellites, and quantum bit error rates remained between three and five percent, generating secure keys up to 868 kilobits in length. These results provide a blueprint for future satellite missions, coinciding with the Canadian Government’s announcement of a quantum satellite mission.

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