Routing subcarrier wave quantum key distribution through a metropolitan optical transport network

Subject of study. This study investigates a method of finding a sequence of nodes in a metropolitan optical transport network to connect a sender and receiver through a quantum channel propagating in the same optical fiber as the information channels to maximize the secret key generation rate. Aim of the work. The purpose of this work is to route the subcarrier wave quantum key distribution in a metropolitan optical transport network to maximize the secret key generation rate. Method. A metropolitan optical transport network is represented as a graph, where the vertices are the network nodes and the edges are the fiber optic lines connecting them. The weight of an edge corresponds to the secret key generation rate on the respective segment of the fiber optic line. The final key generation rate is limited by the slowest section of the path. The desired optimal route can be found by solving the graph bottle-neck problem. A brute force algorithm is used. Main results. The optimal paths connecting two given nodes via a quantum channel for different network topologies are found. The results demonstrate the need for a more efficient algorithm when considering a larger number of nodes. Practical significance. The findings of this study could be used in the integration of quantum communications in existing metropolitan optical transport networks. (c) 2023 Optica Publishing Group