Cost-effective QKD protocol upgrading for metropolitan quantum optical networks

Abstract

Quantum key distribution (QKD) is a promising technology that can provide future-proof security. With the emergence of multiple advanced QKD protocols, the QKD protocol upgrading for a metropolitan quantum optical network (MQON) is critical for fulfilling the requirements of users for secret keys with a high security level. Conventionally, due to the lack of effective QKD protocol upgrading strategies for MQONs, massive amounts of resources have to be consumed during QKD protocol upgrading, resulting in high costs. In order to reduce the costs for practical implementation of QKD protocol upgrading, in this work, a new policy of QKD protocol upgrading is proposed, where the bypass technique is adopted to decouple multiple protocols from the linking patterns for efficient resource utilization. Moreover, we illustrate a multi-role QKD node structure for enabling the harmonious operation of multiple QKD protocols. A mixed integer linear programming (MILP) model and a novel divided-packet-based QKD protocol upgrading algorithm are designed to save costs by relying on flexible traffic management. We also propose a fixed-chain-based QKD protocol upgrading algorithm with fixed traffic management for achieving low costs. Simulation results indicate that the proposed heuristic algorithms are significantly more cost effective than the associated benchmark algorithms, while the MILP model can reduce the cost of protocol upgrading by 41% compared with the benchmark.