Implementing a 46-node quantum metropolitan area network

To achieve a practical quantum network, we need to overcome several challenges including realizing versatile topologies for large scales, simple network maintenance, extendable configuration, and robustness to node failures. To this end, an international team of researchers (China, Germany) developed a field operation of a quantum metropolitan-area network with 46 nodes and showed that all these challenges can be overcome with cutting-edge quantum technologies. They used different topological structures and continuously ran the network for 31 months, by employing standard equipment for network maintenance with an extendable configuration. QKD pairing and key management was done with a sophisticated key control centre. The final keys were used for secure communication such as real-time voice telephone, text messaging and file transmission with one-time pad encryption, which can support 11 pairs of users to make audio calls simultaneously. Combined with intercity quantum backbone and ground–satellite links, the metropolitan implementation paves the way toward a global quantum network…read more. TECHNICAL ARTICLE   Open Access 1  ,  2