A breakthrough in quantum repeater technology has enabled secure quantum communication over 100 kilometers.
Researchers led by Jianwei Pan, Qiang Zhang, and Xiaohui Bao at the University of Science and Technology of China (USTC), part of the Chinese Academy of Sciences (CAS), have achieved a major milestone in quantum communication. For the first time, they demonstrated a key component required for scalable quantum repeaters, which later allowed them to carry out device-independent quantum key distribution (DI-QKD) across 100 kilometers.
The results, published in Nature and in Science, represent important progress toward building a functional quantum internet. The work also reinforces China’s position at the forefront of quantum research and technology.
At the heart of quantum information science is the effort to create networks that are both highly secure and highly efficient. These quantum networks would combine quantum precision metrology, quantum communication, and distributed quantum computing. Together, these capabilities could enable extremely sensitive measurements, secure data transmission, and dramatically faster information processing.
Overcoming Distance Limits in Quantum Communication
A major technical challenge has been reliably distributing quantum entanglement over long distances. Entanglement is essential for large-scale quantum networks, but photons traveling through optical fibers are gradually lost, which sharply restricts how far entanglement can be directly transmitted.
This same problem has limited quantum key distribution, a cornerstone of secure quantum communication. While DI-QKD ensures security even if the devices involved cannot be fully trusted, previous experiments were restricted to distances of only a few hundred meters.
To push beyond this boundary, the team developed a quantum repeater system capable of creating memory–memory entanglement between two separate nodes. By linking these nodes through entanglement swapping, the researchers successfully extended entanglement across much greater distances.
A Breakthrough in Quantum Repeater Technology
This was the first time in the world that long-lived quantum entanglement suitable for scalable quantum repeater architectures was achieved. By maintaining entanglement significantly longer than the time required to establish inter-segment connections, this achievement paves the way for practical long-distance quantum networks.
Based on these achievements in quantum repeater technology, the researchers extended the distance of DI-QKD beyond 100 km for the first time—marking a critical leap toward scalable quantum repeaters by simultaneously realizing long-distance, high-fidelity atom–atom entanglement.
Jiawei Pan, a leader of the research team and a CAS member and executive vice president of USTC, noted the importance of quantum repeaters, calling them the “building blocks” that will enable the linkage of universal quantum computers to be developed over the next 10–15 years.
“Therefore, the quantum internet will be realized, connecting precise information sensing and supercomputing, securely and efficiently,” said Pan.
Source: scitechdaily.com
