Quantum-correlated photon sources provide a means of suppressing multiple photon emission and thus improving the security and efficiency of quasi single-photon quantum key distribution systems. We present illustrative photon-counting statistics for a Poissonian source conditioned by photon number measurements on a fully correlated twin beam with a non-ideal photon counter. We show that high photon counting efficiency is needed to obtain significant improvement in channel efficiency (bits per symbol) and/or security (in the form of reduced Shannon entropy leakage) over a single beam source.
@article{arxiv.quant-ph/0008013,
title = {A Note on Quantum Key Channel Efficiency and Security using Correlated Photon Beam Transmitters},
author = {PJ Edwards and W N Cheung and H van Pham and G Ganesharajah and P Lynam and L Barbopoulos},
journal= {arXiv preprint arXiv:quant-ph/0008013},
year = {2007}
}