Quantum-tomography of entangled photon pairs by quantum-dot cascade decay

Abstract

We compute the concurrence of the polarization-entangled photon pairs generated by the biexciton cascade decay of a semiconductor quantum dot. We show how a cavity-induced increase of the photon rate emission reduces the detrimental effect of the dot dephasing and of the excitonic fine structure. However, strong dot-cavity couplings and finite detection efficiencies are shown to reduce the relevance of the desired cascade decay with respect to that of competing processes. This affects the merits of the entangled photon-pair source, beyond what estimated by the quantum-tomography.