Koji Kanazawa

As the volume of data and connections exchanged across telecom/datacom networks continues to increase, there is a growing need for technologies that deploy quantum key distribution (QKD) on a large scale in a practical and sustainable manner. To realize high-speed, real-time communication of large-volume data using one-time pad cryptography with QKD modules, it will be important to multiplex QKD modules in the future. Furthermore, it is necessary to consider the physical size of the device for the practical application of multiplexed QKD modules. In this study, we focused on miniaturizing the key distillation process required at the back end of the QKD chip. To reduce the size of the device, it is necessary to estimate as accurately as possible the minimum computing power required to run the key distillation process for the target secret key rate (SKR). However, the performance of the key distillation process requires computing power and involves the exchange of messages via classical channels. Therefore, we evaluate the performance by a network simulator before performing evaluations on the actual equipment. In this paper, we focus on the behavior of classical communication paths in the multiplexed QKD system, which is a problem in studying the key distillation process, and we evaluate it with the simulator. Specifically, we clarify the relationship between the required performance of the key distillation process (i.e., throughput) and the target SKR, which is necessary to realize a part of the key distillation process in hardware.