Scientists have set a new record in quantum communication by establishing the world’s longest quantum link, spanning 12,900 km between China and South Africa. The project was realized using the Jinan-1 microsatellite and quantum key distribution (QKD) technology, which enables ultra-secure data transmission. The connection was established between the University of Science and Technology of China and Stellenbosch University.
While the transmitted information—images of the Great Wall of China and Stellenbosch—was classical, its encryption was carried out using quantum methods. The satellite encoded keys into individual photons and sent them to both stations. The key advantage of QKD is its resistance to hacking: any attempt to intercept the data alters the quantum state of the photons, making tampering immediately detectable.
During the experiment, Jinan-1 transmitted over 250 million quantum photons per second, generating more than a million secure keys per pass over the station. This achievement surpasses the previous record of 7,600 km, set between China and Austria using the Micius satellite.
The new generation of microsatellites—just 23 kg in weight—and compact ground stations (100 kg instead of the previous 13-ton setups) pave the way for a future global quantum internet. The study, published in Nature, highlights the promising potential of this technology for next-generation secure communications.
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