User-independent optical path length compensation scheme with sub-ns timing resolution for 1xN quantum key distribution network system

TL;DR

This paper presents a practical 1xN quantum key distribution network with sub-nanosecond optical path length compensation, enabling stable, multi-user secure communication with simplified hardware and software.

Contribution

Developed a plug-and-play 1xN QKD network with FPGA-based timing control, achieving long-term stability and multi-user key sharing without complex algorithms.

Findings

Successfully operated a 1x64 QKD network system.

Demonstrated a 1x4 QKD network over metropolitan fiber.

Achieved stable, long-term multi-user key sharing.

Abstract

Quantum key distribution (QKD) networks constitute promising solutions for secure communication. Beyond conventional point-to-point QKD, we developed 1xN QKD network systems with a sub-ns resolution optical path length compensation scheme. With a practical plug-and-play QKD architecture and compact timing control modules based on a field programmable gate array (FPGA), we achieved long term stable operation of a 1x64 QKD network system. Using this architecture, 64 users can simultaneously share secret keys with one server, without using complex software algorithms and expensive hardware. We demonstrated the working of a 1x4 QKD network system using the fiber network of a metropolitan area.