The first quantum satellite link in the Southern Hemisphere was established between the Chinese quantum microsatellite Jinan-1 and a South African university, a significant milestone for high-security communication in the quantum computing era.
Chinese and South African scientists have established the world’s longest intercontinental ultra-secure quantum satellite link, covering 12,900 kilometers. Laser light pulses transmitted two images, the Great Wall of China and South Africa’s Stellenbosch University (SU) campus, between Beijing and SU facilities outside of Capetown.
Quantum Security
The satellite link encrypts data by generating quantum keys in real time using Quantum Key Distribution (QKD). Chinese and South African scientists demonstrating the one-time use of pad encryption claim it’s unbreakable, providing an extremely secure link between China and South African ground stations. The team, led by Professor Juan Yin, is split between South Africa’s Stellenbosch University and the University of Science and Technology of China.
By manipulating quantum mechanics, quantum communications technologies offer new levels of security against even highly advanced adversaries. QKD encodes keys with single photons in binary superpositions that cannot be intercepted, copied, or measured without alteration, destroying the message. Their unique nature makes QKDs the best measure against fears that coming quantum computer technologies will render existing security measures useless.
Some institutions, such as banks and governments, already use QKD encryption in fiber-optic networks. Unfortunately, the cables absorb photons, limiting their effective distance. Moving to over-the-air transmission will enable messages to go virtually anywhere on the planet.
China’s Quantum Lead
Quantum physicist Prof Jian-Wei Pan is leading China’s quantum communication efforts. Presently, China boasts 2,000 kilometers of ground-based quantum connections between 32 nodes in major cities like Beijing and Shanghai. In 2017, Prof Juan Yin led China’s first successful quantum satellite project, Micius, creating a 7,600-kilometer quantum link between China and Australia.
The new satellite is a tenth of the weight and almost half the cost of Micius. By replacing dedicated functions with multipurpose instruments, such as a device that both aims the beam and controls the satellite’s orientation, the team saved tremendous room aboard Jinan-1. The receiver also improved significantly, shrinking from 13,000 kilograms to a portable 100-kilogram device.
South African Quantum Advances
Dr Yaseera Ismail led the Stellenbosch team in establishing the quantum satellite link. Another Stellenbosch researcher, Professor Francesco Petruccione, Director of the National Institute for Theoretical and Computational Sciences (NITheCS), developed one of the first fiberoptic quantum communications networks in the world. That network, located in Durban, will support Stellenbosch’s upcoming Centre for Quantum Science and Technology as South Africa invests in a leading role in the quantum field.
Stellenbosch University is ideally situated to host such a ground station. With a low humidity climate and generally clear skies, the South African station generated 1.07 million encrypted bits in a single satellite pass.
“This successful demonstration of quantum satellite technology firmly positions South Africa as a significant player in the rapidly evolving global quantum technology ecosystem. Collaborations such as this accelerate scientific breakthroughs, build local expertise, and enable translating advanced quantum research into tangible technological solutions,” explained Prof Petruccione.
Continuing Work
Jian-Wei Pan is leading the work in launching four microsatellites with commercial partner China Telecom in 2026. Next year, Canada will also launch a QKD satellite, the Quantum Encryption and Science Satellite. About a dozen QKD satellite projects are currently advancing worldwide.
sub-wavelength
“This breakthrough underscores the importance of supporting and investing in the basic sciences such as quantum computing,” concluded Prof Sibusiso Moyo, Deputy Vice-Chancellor for Research, Innovation and Postgraduate Studies at SU.
“We are proud that our researchers are pushing the frontiers of science. This work is in line with SU’s Vision 2040 to be Africa’s leading research-intensive university recognized for its excellence and advancing knowledge in service of society. Congratulations to both teams,” he added.
The paper “Microsatellite-based Real-time Quantum Key Distribution” appeared on March 19, 2025, in Nature.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted atryan@thedebrief.org, and follow him on Twitter@mdntwvlf.