VQKD: A Novel Model for Quantum Key Distribution Network

Similar to the Internet, Quantum Key Distribution (QKD) networks typically have diverse participants, such as users, operators, and infrastructure builders. In order to achieve loose functional coupling, a multi-layer structure is frequently indispensable. Nevertheless, once the architecture of the QKD network is designed, further expansion and modification prove to be extremely challenging. To address this issue, a QKD network architecture based on virtual Quantum Key Distribution (VQKD) is proposed. In this architecture, all devices at both ends that are capable of providing consistent quantum keys are regarded as a pair of quantum key distribution devices. The bottom layer is real QKD, while all other layers are virtual QKD. All real and virtual QKDs provide quantum keys to the upper layers. This network structure is an iterative one, and theoretically, the number of layers in a quantum key distribution network can be infinitely increased based on actual needs. In this paper, we present a practical application case. This case addresses the actual needs of network operators, network service providers, and those involved in user network construction. We have designed a three-layer quantum secure communication network exchange structure that is suitable for network infrastructure developers, network operators, and those involved in user network construction. Network infrastructure developers, network operators, and users can carry out network construction, network operation, and user network construction at different network layers, realizing a loosely coupled hierarchical design of quantum secure communication networks. This model can dynamically increase or decrease the number of quantum network exchange layers based on actual needs, without affecting the network exchange of quantum secure communication networks, demonstrating strong versatility and adaptability.