Unbreakable Quantum Link Beams Across Nearly 13,000 km From China to South Africa

A major scientific leap has been made with the creation of the longest ultra-secure quantum satellite link between China and South Africa, spanning nearly 13,000 km.

This unprecedented achievement, marking the first quantum satellite link in the Southern Hemisphere, relied on real-time quantum key distribution to transmit encrypted images between continents.

World’s Longest Quantum Satellite Link Established

Scientists from South Africa and China have successfully created the world’s longest intercontinental quantum satellite link, spanning 12,900 kilometers (~8,000 miles). This ultra-secure connection was made possible using China’s Jinan-1 quantum microsatellite, which orbits in low Earth orbit. The achievement also marks a historic first: the establishment of a quantum satellite communication link in the Southern Hemisphere.

In the demonstration, researchers used Quantum Key Distribution (QKD) to generate encryption keys in real time. These keys were then used to securely transmit images between ground stations in China and South Africa using one-time pad encryption—a method considered theoretically unbreakable. The breakthrough is the result of a collaboration between Stellenbosch University in South Africa and the University of Science and Technology of China, and the findings were published on March 19 in Nature.

Stellenbosch’s favorable weather conditions, particularly its clear skies and low humidity, enabled the ground station to achieve a remarkable key generation rate of 1.07 million secure bits during a single satellite pass.

How Quantum Communication Ensures Unbreakable Security

Quantum communication leverages fundamental principles of quantum mechanics, guaranteeing highly secure information transfer. Quantum Key Distribution, a critical component, employs single photons to encode and transmit secure keys. Because single photons cannot be intercepted, copied, or measured without altering their quantum states, this technology provides unparalleled security, even against powerful adversaries.

China is currently at the forefront of quantum communication technology, guided by renowned quantum physicist Prof Jian-Wei Pan. The country’s extensive quantum infrastructure includes a 2,000 km terrestrial fibre-based quantum network connecting 32 trusted nodes across major cities, from Beijing to Shanghai. Prof Juan Yin was instrumental in developing China’s first quantum satellite, Micius, previously demonstrated groundbreaking satellite-based quantum links, including a notable 7,600 km intercontinental link between China and Austria in 2017. For this South Africa-China collaboration, Prof Juan Yin again led the Chinese research team.

The South African research team at Stellenbosch University’s Department of Physics was led by Dr Yaseera Ismail, the lead experimentalist responsible for successfully establishing the quantum satellite link. Prof Francesco Petruccione, Professor of Quantum Computing in the School of Data Science and Computational Thinking and Director of the National Institute for Theoretical and Computational Sciences (NITheCS) at Stellenbosch University, pioneered quantum communication in South Africa, notably developing one of the world’s first fiber-optic quantum communication networks in Durban. This landmark achievement also supports the forthcoming launch of the Stellenbosch Centre for Quantum Science and Technology, which aims to strengthen South Africa’s leading role in quantum research and innovation.

The Power of Global Collaboration in Science

Reflecting on this achievement, Dr. Yaseera Ismail emphasized the importance of collaboration: “International and national collaborations are essential to drive cutting-edge research and push scientific boundaries. Implementing the first quantum satellite link in the Southern Hemisphere is an outstanding achievement for South Africa, demonstrating the significant potential to develop a thriving quantum ecosystem.”

Prof Francesco Petruccione added: “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.”

Vision for the Future: Africa’s Quantum Potential

Prof Sibusiso Moyo, Deputy Vice-Chancellor for Research, Innovation and Postgraduate Studies at SU, said: “This breakthrough underscores the importance of supporting and investing in the basic sciences such as quantum computing. 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.”

Reference: “Microsatellite-based real-time quantum key distribution” by Yang Li, Wen-Qi Cai, Ji-Gang Ren, Chao-Ze Wang, Meng Yang, Liang Zhang, Hui-Ying Wu, Liang Chang, Jin-Cai Wu, Biao Jin, Hua-Jian Xue, Xue-Jiao Li, Hui Liu, Guang-Wen Yu, Xue-Ying Tao, Ting Chen, Chong-Fei Liu, Wen-Bin Luo, Jie Zhou, Hai-Lin Yong, Yu-Huai Li, Feng-Zhi Li, Cong Jiang, Hao-Ze Chen, Chao Wu, Xin-Hai Tong, Si-Jiang Xie, Fei Zhou, Wei-Yue Liu, Yaseera Ismail, Francesco Petruccione, Nai-Le Liu, Li Li, Feihu Xu, Yuan Cao, Juan Yin, Rong Shu, Xiang-Bin Wang, Qiang Zhang, Jian-Yu Wang, Sheng-Kai Liao, Cheng-Zhi Peng and Jian-Wei Pan, 19 March 2025, Nature.
DOI: 10.1038/s41586-025-08739-z