Integration of Quantum Key Distribution Networks and Classical Networks: An Evolution Perspective

As a promising quantum application, Quantum Key Distribution (QKD) technology has been rapidly developed from point-to-point communication to a large-scale commercial network. However, considering the cost of QKD components and network infrastructure, building a QKD network is challenged by its expensive capital expenditure, which significantly hinders its future popularization. In this article, we envision an evolution roadmap consisting of three stages for the future development of QKD networks, aiming at achieving a fully integrated network architecture that combines QKD and telecommunications networks. Powered by several critical technologies, such as link multiplexing, miniaturized QKD, and transmission optimization, QKD is foreseen to be integrated into telecommunications networks as an add-on module that can be flexibly deployed. After that, we introduce the integrated network architecture design in detail, and respectively provide four QKD-related function implementations. At last, key technologies that should be concerned and further investigated are also discussed with performance evaluation, which can provide theoretical guidance for both industries and academia. Based on the proposed roadmap and integrated architecture, we believe a scalable, easy-to-use, and affordable QKD service can be brought to current telecommunication networks, and extensively applied by ordinary people while using daily applications.