Airborne demonstration of a quantum key distribution receiver payload

TL;DR

This paper demonstrates a ground-to-air quantum key distribution link using a satellite-compatible receiver prototype on an aircraft, showing the potential for global quantum communication via satellite.

Contribution

It presents the first successful ground-to-air QKD demonstration with a satellite-compatible receiver, paving the way for future satellite-based quantum communication.

Findings

Quantum links maintained over 3-10 km distances.

Secure keys up to 868 kb generated during flights.

Quantum bit error rates remained around 3-5%.

Abstract

Satellite-based quantum terminals are a feasible way to extend the reach of quantum communication protocols such as quantum key distribution (QKD) to the global scale. To that end, prior demonstrations have shown QKD transmissions from airborne platforms to receivers on ground, but none have shown QKD transmissions from ground to a moving aircraft, the latter scenario having simplicity and flexibility advantages for a hypothetical satellite. Here, we demonstrate QKD from a ground transmitter to a receiver prototype mounted on an airplane in flight. We have specifically designed our receiver prototype to consist of many components that are compatible with the environment and resource constraints of a satellite. Coupled with our relocatable ground station system, optical links with distances of 3-10 km were maintained and quantum signals transmitted while traversing angular rates similar to those observed of low-Earth-orbit satellites. For some passes of the aircraft over the ground station, links were established within 10 s of position data transmission, and with link times of a few minutes and received quantum bit error rates typically 3-5%, we generated secure keys up to 868 kb in length. By successfully generating secure keys over several different pass configurations, we demonstrate the viability of technology that constitutes a quantum receiver satellite payload and provide a blueprint for future satellite missions to build upon.