The generation of entangled photon pairs by parametric down--conversion from solid state CW lasers with small coherence time is theoretically and experimentally analyzed. We consider a compact and low-cost setup based on a two-crystal scheme with Type-I phase matching. We study the effect of the pump coherence time over the entangled state visibility and over the violation of Bell's inequality, as a function of the crystals length. The full density matrix is reconstructed by quantum tomography. The proposed theoretical model is verified using a purification protocol based on a compensation crystal.
@article{arxiv.0802.3131,
title = {Properties of entangled photon pairs generated by a CW laser with small coherence time: theory and experiment},
author = {Simone Cialdi and Fabrizio Castelli and Matteo G. A. Paris},
journal= {arXiv preprint arXiv:0802.3131},
year = {2009}
}