Microsatellite-based real-time quantum key distribution

TL;DR

This paper reports the development of a lightweight quantum microsatellite and portable ground stations enabling real-time satellite-based quantum key distribution, significantly reducing size and weight compared to previous systems and demonstrating practical secure communication.

Contribution

The authors developed a compact quantum microsatellite and portable ground stations for real-time space-to-ground QKD, enabling scalable satellite constellations for global quantum networks.

Findings

Successfully demonstrated satellite-based QKD with multiple ground stations.

Shared up to 0.59 million secure bits in a single satellite pass.

Achieved significant size and weight reductions over previous satellite systems.

Abstract

A quantum network provides an infrastructure connecting quantum devices with revolutionary computing, sensing, and communication capabilities. As the best-known application of a quantum network, quantum key distribution (QKD) shares secure keys guaranteed by the laws of quantum mechanics. A quantum satellite constellation offers a solution to facilitate the quantum network on a global scale. The Micius satellite has verified the feasibility of satellite quantum communications, however, scaling up quantum satellite constellations is challenging, requiring small lightweight satellites, portable ground stations and real-time secure key exchange. Here we tackle these challenges and report the development of a quantum microsatellite capable of performing space-to-ground QKD using portable ground stations. The quantum microsatellite features a payload weighing approximately 23 kg, while the portable ground station weighs about 100 kg. These weights represent reductions by more than an order and two orders of magnitude, respectively, compared to the Micius satellite. Additionally, we multiplex bidirectional satellite-ground optical communication with quantum communication, enabling key distillation and secure communication in real-time. Using the microsatellite and the portable ground stations, we demonstrate satellite-based QKD with multiple ground stations and achieve the sharing of up to 0.59 million bits of secure keys during a single satellite pass. The compact quantum payload can be readily assembled on existing space stations or small satellites, paving the way for a satellite-constellation-based quantum and classical network for widespread real-life applications.