Daylight operation of a free space, entanglement-based quantum key distribution system

TL;DR

This paper demonstrates a free space, entanglement-based quantum key distribution system capable of continuous operation during daytime by employing advanced filtering techniques to mitigate background light, thus overcoming previous night-only limitations.

Contribution

The authors introduce a novel QKD system that operates continuously in daylight conditions using spectral, spatial, and temporal filtering, expanding practical deployment options.

Findings

Secure key established over several days during day and night

Effective filtering techniques mitigate background light interference

Continuous operation under varying weather conditions

Abstract

Many quantum key distribution (QKD) implementations using a free space transmission path are restricted to operation at night time in order to distinguish the signal photons used for a secure key establishment from background light. Here, we present a lean entanglement-based QKD system overcoming that imitation. By implementing spectral, spatial and temporal filtering techniques, we were able to establish a secure key continuously over several days under varying light and weather conditions.