BBM92 quantum key distribution over a free space dusty channel of 200 meters

TL;DR

This paper demonstrates the implementation of the entanglement-based BBM92 quantum key distribution protocol over a 200-meter free space dusty channel, highlighting atmospheric effects on secure key rates for satellite-like quantum communication.

Contribution

It reports the first implementation of BBM92 over a dusty free space channel in India, analyzing atmospheric effects on key rates for satellite-based QKD.

Findings

Atmospheric aerosols reduce sift key rate.

Secure key rate is affected by dust and aerosols.

Experimental validation of atmospheric impact models.

Abstract

Free space quantum communication assumes importance as it is a precursor for satellite-based quantum communication needed for secure key distribution over longer distances. Prepare and measure protocols like BB84 consider the satellite as a trusted device, which is fraught with security threat looking at the current trend for satellite-based optical communication. Therefore, entanglement-based protocols must be preferred, so that one can consider the satellite as an untrusted device too. The current work reports the implementation of BBM92 protocol, an entanglement-based QKD protocol over 200 m distance using an indigenous facility developed at Physical Research Laboratory (PRL), Ahmedabad, India. Our results show the effect of atmospheric aerosols on sift key rate, and eventually, secure key rate. Such experiments are important to validate the models to account for the atmospheric effects on the key rates achieved through satellite-based QKD.