On the 16th, it was learned from the University of Science and Technology of China that Pan Jianwei, Bao Xiaohui, Zhang Qiang and others recently built the world's first entanglement-based metropolitan three-node quantum network, which increased the distance of realistic quantum entanglement networks from the previous tens of meters to tens of kilometers, an increase of three orders of magnitude.

　　The related research results were published online on May 15 in the international academic journal Nature. This research has laid a scientific and technological foundation for subsequent quantum network applications such as blind quantum computing, distributed quantum computing, and quantum-enhanced long-baseline interferometry.

　　Building quantum networks through the remote transmission of quantum states is a fundamental element of large-scale quantum information processing. Based on quantum networks, wide-area quantum key distribution as well as distributed quantum computing and quantum sensing can be realized, forming the technological foundation of the future "quantum internet." At present, quantum key networks based on single-photon transmission have matured, while further quantum network applications such as distributed quantum computing require connecting various quantum information processing nodes through wide-area quantum teleportation.

　　In recent years, the team of Pan Jianwei at the University of Science and Technology of China has made many important advances in the quantum field. For example, in the direction of quantum memory networks, in 2020 the team successfully realized two-node quantum entanglement in the laboratory between two quantum memories connected by 50-kilometer-long optical fibers.

　　To establish entanglement between independent quantum memories separated by long distances, the main challenge lies in how to control the phase of single photons. Based on previous research advantages in entanglement rate and other aspects, the research team designed and developed a very sophisticated phase control scheme, successfully achieving entanglement between quantum memories more than ten kilometers apart, and on this basis built the world's first metropolitan three-node quantum entanglement network.

　　Nature also published in the same issue the related experimental progress of the Lukin team at Harvard University in the United States, which for the first time achieved long-distance two-node entanglement in a SiV color center system. Compared with the two, the results of the University of Science and Technology of China have a clear advantage in entanglement efficiency.