BBM92 quantum key distribution over a free space dusty channel of 200 meters
This work addresses the need for secure satellite-based quantum communication by testing protocols in dusty atmospheric conditions, though it is incremental as it builds on existing entanglement-based methods.
The researchers implemented the BBM92 entanglement-based quantum key distribution protocol over a 200-meter free-space channel to study atmospheric aerosol effects on key rates, showing impacts on sift and secure key rates to validate models for satellite-based QKD.
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.