Implementing a 46-node quantum metropolitan area network

Quantum key distribution (QKD) is a method used for secure or secret key exchanges between two remote users. Using secure communication, cyberscientists ultimately aim to establish a global quantum network. Existing field tests suggest that such quantum networks are feasible. To achieve a practical quantum network, several challenges must be overcome including the realization of varied topologies at large scales, simple network maintenance and robustness to node failures. In a new report now published on Science Advances, Teng-Yun Chen and a research team in quantum physics, quantum information and interdisciplinary information sciences in China, presented a field operation of a quantum metropolitan area network with 46 nodes. They realized diverse topological structures and ran the network for 31 months via standard equipment. They then realized QKD pairing and key management for secure communications including real-time voice telephone, text messaging and file transmission with one-time pad encryption to support 11 pairs of users to make simultaneous audio calls. The technique can be combined with an intercity quantum backbone and via ground-satellite links to form a global quantum network.