The collaboration between Stellenbosch University in South Africa and the University of Science and Technology of China enabled the real-time generation of quantum keys through Quantum Key Distribution (QKD). These keys facilitated the transmission of encrypted images between ground stations in both countries using one-time pad encryption, a method regarded as virtually unbreakable. The outcomes of this pioneering project were published in *Nature*.

Stellenbosch's advantageous environmental conditions, including clear skies and low humidity, contributed to the successful generation of 1.07 million secure bits during a single satellite pass. This notable performance was made possible by QKD, which uses single photons to encode encryption keys. The quantum nature of these photons prevents any form of interception or duplication without disrupting their state, ensuring exceptionally secure communication.

China continues to lead in the field of quantum communication, under the guidance of distinguished physicist Prof Jian-Wei Pan. The nation boasts a vast quantum infrastructure, including a 2,000 km terrestrial quantum network linking 32 trusted nodes from Beijing to Shanghai. Prof Juan Yin, who played a pivotal role in developing China's first quantum satellite, Micius, previously established a 7,600 km quantum satellite link between China and Austria in 2017. For this South Africa-China initiative, Prof Juan Yin once again led the Chinese research team.

On the South African side, Dr Yaseera Ismail from Stellenbosch University's Department of Physics led the effort to establish the satellite link. Prof Francesco Petruccione, a prominent figure in quantum computing and director of the National Institute for Theoretical and Computational Sciences (NITheCS), was instrumental in pioneering quantum communication in the country, including the creation of an early fibre-optic quantum network in Durban. This recent accomplishment also supports the planned launch of the Stellenbosch Centre for Quantum Science and Technology, aimed at positioning South Africa as a leader in quantum research.

Dr Yaseera Ismail emphasized the significance of international cooperation: "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."

Prof Sibusiso Moyo, Deputy Vice-Chancellor for Research, Innovation and Postgraduate Studies at SU, noted: "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 recognised for its excellence and advancing knowledge in service of society. Congratulations to both teams."

Research Report:Microsatellite-based real-time quantum key distribution

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