Mayuko Koezuka

We considered research and development aimed at improving the operability and scalability of large-scale QKD net-works (QKDNs) by introducing hierarchical control architecture. This paper focus on a distributed-control QKDN within such a hierarchical large scale QKDN and presents the design and implementation of a QKDN controller (QKDN-C) that selects appropriate key relay routes in response to control instructions from an orchestrator (QKDN-O). In particular, it describes a method for distributed key relay and routing table management, in which the routing tables of individual key managers (KMs) are dynamically updated on instructions from the QKDN-O. It also shows that, in a hierarchically structured QKDN, coordinated operation between the QKDN-O and distributed QKDNs enable key re-laying to be realized over optimal routes.

In this paper, we describe a key routing method for large-scale quantum key distribution (QKD) networks. The proactive and dynamic key routing method decides the amount of key for distribution which is based on the key usage history of each application and stored key status of each link. Furthermore, we also propose a key routing method which applies multiple routing protocols according to the network domain of destination. The method provides key usage efficiently and promotes scalability for large-scale QKD networks.

To construct a large-scale quantum key distribution network (QKDN) as future secure infrastructure, it is necessary interwork many QKDNs. Here, we demonstrate an interoperable key relay between two different types of QKDNs: a centralized QKDN and a distributed QKDN. In the demonstration, we build an experimental environment for interworking by using physical QKDNs and implement three fundamental functions (key relay, delivery confirmation, and status information collection) for performing key relay between heterogeneous QKDNs.