Record-breaking 12,900 km ultra-secure quantum satellite link

In this demonstration, quantum keys were generated in real-time through Quantum Key Distribution (QKD), enabling the secure encryption of images transmitted between ground stations in China and South Africa via one-time pad encryption -- considered unbreakable. The results from this pioneering experiment from a collaborative research initiative between scientists from Stellenbosch University (South Africa) and the University of Science and Technology of China were published in Nature today

Stellenbosch's ideal environmental conditions -- clear skies and low humidity -- allowed the local ground station to achieve an exceptional key generation rate of 1.07 million secure bits during a single satellite pass.

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 has impressive accomplishments in quantum communication technology, guided by 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 fibre-optic quantum communication networks in Durban.