World’s first quantum microsatellite demonstrates secure communication with multiple ground stations

A research team has developed the world’s first quantum microsatellite and demonstrated real-time quantum key distribution (QKD) between the satellite and multiple compact, mobile ground stations.

The research, led by Pan Jianwei, Peng Chengzhi, and Liao Shengkai from USTC, jointly with the Jinan Institute of Quantum Technology, Shanghai Institute of Technical Physics, the Innovation Academy for Microsatellites of the Chinese Academy of Sciences, and Stellenbosch University of South Africa, is published in Nature.

Quantum secure communication is fundamental to national information security and socioeconomic development. QKD, a communication method with proven unconditional security, significantly enhances data transmission security. While fiber-based QKD networks have achieved regional implementation, their practical application over long distances remains constrained by signal loss and limited coverage. Satellite-based systems present a viable solution through free-space communication, potentially enabling QKD on a global scale.

USTC has pioneered groundbreaking research in satellite-based QKD. The launch of the Micius quantum satellite has achieved the world’s first successful demonstration of space-to-ground QKD, which was subsequently integrated with the fiber-based Beijing-Shanghai backbone to create the space-ground quantum secure communication network.

Towards practical applications, however, compact payload and portable ground station are essential for widespread deployment and swift implementation. In particular, the small-size payload can be assembled on satellites of various sizes to compose a quantum satellite internet constellation for global services.

To achieve this, the team developed several key technologies, including miniaturized decoy-state QKD light sources for quantum state preparation, real-time key distillation and encrypted communication based on laser communication, and high-precision tracking based on satellite attitude control to maintain stable optical links.

Building on these advances, the team successfully launched Jinan-1, the world’s first quantum microsatellite, on July 27, 2022. Additionally, the team developed compact optical ground stations, reducing the weight by two orders of magnitude to less than 100 kg. This lightweight design allows for rapid deployment in different locations, significantly increasing the flexibility and practicality.

During the experiments, Jinan-1 established optical links with multiple optical ground stations in Jinan, Hefei, Nanshan, Wuhan, Beijing, Shanghai, in China, and Stellenbosch in South Africa. The satellite transmitted approximately 250 million quantum photons per second. For each satellite pass, the system generated up to 1 Mbits of secure keys. Using the satellite as a trusted relay, the team demonstrated successful secure key sharing and encrypted communication between Beijing and Stellenbosch—two cities separated by 12,900 km.

The team’s work lays a solid foundation for the deployment of a constellation of quantum microsatellites, providing crucial technical support for large-scale quantum communication networks and holding immense promise for the global deployment of the quantum internet.