South Africa and China Establish 12,900 km Quantum Satellite Link

Scientists from South Africa and China have successfully created the world’s longest intercontinental quantum satellite communication link, spanning 12,900 kilometres between the two countries. This breakthrough, utilising China’s Jinan-1 quantum microsatellite in low Earth orbit, represents the first quantum satellite communication link established in the Southern Hemisphere. The research findings were published in Nature, documenting a significant advancement in secure global communications technology.

Technical Achievement and Methodology

The international team demonstrated real-time quantum key generation through Quantum Key Distribution (QKD) technology. This process enabled the secure encryption of images transmitted between ground stations in China and South Africa using one-time pad encryption, a method widely considered mathematically unbreakable when implemented correctly.

Stellenbosch University’s ground station achieved an exceptional key generation rate of 1.07 million secure bits during a single satellite pass, attributed to the region’s ideal environmental conditions, including clear skies and low atmospheric humidity. These conditions minimise photon scattering and absorption, which is critical for successful quantum communication.

The Jinan-1 quantum microsatellite in low Earth orbit was the intermediary for this quantum link. The satellite’s specialised quantum communication payload enables it to generate and distribute quantum keys to ground stations as it passes overhead, creating a secure connection despite the vast distance between continents.

Quantum Communication Security Principles

The security of quantum communication stems from fundamental principles of quantum mechanics. In Quantum Key Distribution, single photons encode and transmit secure cryptographic keys. According to quantum physics principles, any attempt to intercept, copy, or measure these photons would inevitably alter their quantum states, immediately alerting legitimate users to potential eavesdropping.

This inherent security feature makes quantum communication particularly resistant to computational attacks, including those potentially enabled by future quantum computers. The single-photon nature of the transmission creates a physically secure channel that remains protected even against adversaries with significant computational resources.

Research Leadership and Collaboration

The collaborative research initiative united scientists from Stellenbosch University in South Africa and the University of Science and Technology of China (USTC). The Chinese research team was led by Professor Juan Yin, who previously played a crucial role in developing China’s first quantum satellite, Micius. That satellite demonstrated a 7,600 km intercontinental quantum link between China and Austria in 2017.

On the South African side, Dr Yaseera Ismail led the research team at Stellenbosch University’s Department of Physics, serving as the lead experimentalist responsible for establishing the quantum satellite link. Professor 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, has been instrumental in developing quantum communication infrastructure in South Africa.

China’s Quantum Infrastructure Development

China currently leads the global development of quantum communication technology under the guidance of renowned quantum physicist Professor Jian-Wei Pan. The country has built an extensive quantum infrastructure with a 2,000 km terrestrial fibre-based quantum network connecting 32 trusted nodes across major cities from Beijing to Shanghai.

This existing infrastructure provided crucial technical expertise and support systems for the intercontinental quantum satellite link with South Africa. China’s continued investment in quantum technology has positioned it as a frontrunner in this emerging field, with applications spanning secure communications, computing, and sensing.

Implications for South Africa’s Quantum Research

This milestone achievement supports the upcoming launch of the Stellenbosch Centre for Quantum Science and Technology, which aims to strengthen South Africa’s position in quantum research and innovation. Professor Petruccione previously pioneered quantum communication in South Africa by developing one of the world’s first fibre-optic quantum communication networks in Durban.

The successful quantum link demonstrates South Africa’s growing capabilities in advanced quantum technologies and positions the country as a leader in quantum research within the Southern Hemisphere. This breakthrough will catalyse further investment and research in quantum technologies across Africa.

The complete research paper, “Microsatellite-based real-time quantum key distribution,” was published in Nature and is available online at: https://www.nature.com/articles/s41586-025-08739-z.