Light Source Monitoring in Quantum Key Distribution with Single Photon Detector at Room Temperature

TL;DR

This paper demonstrates a practical photon number resolving monitoring scheme for QKD systems using a room-temperature detector, showing that dark count rate is irrelevant, thus simplifying detector requirements for real-world applications.

Contribution

The study introduces a room-temperature detector for photon number resolving monitoring in QKD, relaxing the need for low-temperature detectors and analyzing parameter stability at room temperature.

Findings

Dark count rate is irrelevant to monitoring performance.

The scheme is effective with room-temperature detectors.

Validation in a real QKD system confirms practicality.

Abstract

Photon number resolving monitoring is a practical light source monitoring scheme in QKD systems, which reduces the impacts from untrusted sources effectively. This scheme requires a single photon detector, normally working at low temperature to suppress its dark count rate. In this paper, we use a room-temperature detector and show that the dark count rate is irrelevant to the monitoring performance in our scheme, which can sufficiently relax requirements on the detector's working conditions as well as integration complexity, and this would be highly demanded for practical systems. Furthermore, influences of parameter drifts at room temperature are analyzed, and the monitoring scheme is testified in a real QKD system.