integrated photonic quantum chips Photo: Beijing University

Chinese scientists have built the world's first large-scale quantum key distribution (QKD) network based on integrated photonic quantum chips, which provides a feasible solution for building large-scale quantum communication chip networks and applications. The international journal Nature published the results online on Thursday.

This quantum network allows parallel communication among 20 users equipped with these quantum chips. It can span distances of up to 3,700 kilometers, placing it at the global leading level in terms of both the number of users and overall network reach, according to reports from Xinhua News Agency.

The new achievement overcomes the long-standing barrier through the development of high-performance, fully integrated photonic quantum chips by a research team led by Professor Wang Jianwei from Peking University and Academician Gong Qihuang.

QKD uses the principles of quantum mechanics to securely share encryption keys. By transmitting keys through quantum states, it ensures that any eavesdropping attempt would be detectable, providing security for communication. Twin-field quantum key distribution (TF-QKD) is an advanced form of QKD. It excels at long-distance transmission and allows multiple users to share expensive detection equipment, making it more efficient and practical for extended networks.

However, TF-QKD demands extremely high-performance light sources and modulation devices. Integrating these components into compact, chip-level hardware has been a major technical hurdle. As a result, the technology has mostly been limited to simple point-to-point connections so far, the Xinhua report said.

Wang stated that this is the first demonstration in over 20 years internationally of a quantum key distribution network based on photonic quantum chips. 

Experiments show that the photonic quantum chips developed by the team exhibit high uniformity in wafer-level fabrication, holding promise for low-cost mass production and laying a technical foundation for building longer-distance, larger-scale user quantum key distribution networks, per Xinhua. 

"The QKD chip network represents one of the important paths toward system miniaturization and practical device deployment," Wang said. High-performance, low-cost photonic quantum chips hold tremendous potential in promoting the large-scale application of quantum networks.

Gong believed this development serves as an exemplary case of integrated photonic quantum technology driving the development of quantum communication.  

The achievement provides a feasible solution for building large-scale quantum communication chip networks and holds important significance for promoting the miniaturization, practicality, and scalability of quantum communication systems, the Xinhua report said.


Global Times