by Xinhua writer Bai Ge
JOHANNESBURG, March 22 (Xinhua) -- "It was a clear night, and we could see the flickering green light of the Chinese satellite as our ground station detected the signal," said Francesco Petruccione, a professor from South Africa's Stellenbosch University, describing the exciting moment of securing connection with China's quantum satellite.
China has recently established a quantum key distribution link with South Africa, extending ultra-secure quantum communication to the Southern Hemisphere for the first time.
The achievement is a milestone for South Africa, said Yaseera Ismail, the lead researcher on the South African team and a senior lecturer in the Department of Physics at Stellenbosch University.
The groundbreaking achievement, a result of collaboration between Chinese and South African scientists, was detailed in a paper published in the international journal Nature on Thursday.
Before connecting with the Southern Hemisphere, China had established optical links between the quantum micro-nano satellites and mobile ground stations in Chinese cities such as Hefei, Beijing and Shanghai, enabling real-time satellite-to-ground quantum key distribution experiments.
As one of the contributors to the paper and the experiment, Petruccione said, "This achievement is crucial as it establishes the first satellite link between the North and the South, ensuring that the South is included in future secure communication networks."
During the 10-day experiment, ground stations atop Stellenbosch University's engineering building achieved a secure key generation rate of 1.07 million bits, exceeding results previously attained in China, said Ismail.
"For several nights, we just sat around the laptop with our Chinese colleagues from the University of Science and Technology of China with eyes glued to the screen, monitoring the secure key in real-time as the satellite passes, Ismail recalled, "and when the secure key hit 1 million, we were overexcited and jumped for joy."
One of the primary challenges in quantum communication is maintaining a high key rate over increasing distances, as the key rate often decreases with greater separation between communication points.
"The results obtained in South Africa were impressive," said Ismail, attributing the success to China's latest micro-nano satellite Jinan-1, which is lighter and faster than its predecessor Micius, as well as the favorable environment at Stellenbosch University, marked with low light pollution, low humidity and clear skies.
"We are proud to collaborate with China," said Petruccione, noting that China's world-leading development in quantum communication has enabled South Africa to advance its expertise while making meaningful contributions to the field. "It's a win-win situation," he added.
Petruccione noted that quantum technology is catalyzing the rise of new industries, and the collaboration with China provides South Africa with an opportunity to ride the wave of the next industrial revolution. By working with China in this field, South Africa can enhance its expertise, foster new talents and create more job opportunities, he added.
"We learned a lot from our Chinese colleagues, and I hope they have learned something from us. We look forward to intensifying the relationship and keep doing good science together in quantum computing and other quantum aspects," said Petruccione.
Ismail noted that China is at the forefront of quantum communication development, while South Africa currently lacks the infrastructure to launch a quantum satellite. However, through international collaborations like this, the two countries are working together to establish intercontinental quantum links.
"I believe our collaboration with China is ongoing, and we are planning for the next phase of experiments. After getting such remarkable results, we want to push further and explore new breakthroughs," she said.
UNESCO has designated this year as the "International Year of Quantum Science and Technology" to mark the 100th anniversary of quantum mechanics and advance the societal integration of quantum advancements.
Ismail stressed that the development of a global quantum network requires the joint efforts of countries worldwide. "Only through international collaborations can we drive quantum technology future forward," she said.
Science is a vital tool for addressing global challenges, Petruccione said, and international scientific collaboration can foster mutual understanding.
"I hope scientific collaboration between countries will help build a peaceful and prosperous world, enabling us to tackle global challenges together," he added. ■
