Experimental quantum key distribution with an untrusted source

TL;DR

This paper presents a practical method to monitor photon statistics in quantum key distribution systems with an untrusted source, enhancing security analysis and demonstrating real-world implementation with a modest impact on key rate.

Contribution

It introduces a simple, practical monitoring technique for photon statistics in QKD systems with untrusted sources, validated through a Plug&Play setup.

Findings

Secure key rate of 52 bit/s with the monitoring method

Comparison shows a decrease from 78 bit/s when source is trusted

Method is highly practical for real-world QKD implementations

Abstract

The photon statistics of a quantum key distribution (QKD) source is crucial for security analysis. In this paper, we propose a practical method, with only a beam splitter and photodetector involved, to monitor the photon statistics of a QKD source. By implementing in a Plug&Play QKD system, we show that the method is highly practical. The final secure key rate is 52 bit/s, comparing to 78 bit/s when the source is treated as a trusted source.