Cavity-assisted generation of entangled photon pairs by a quantum-dot cascade decay

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 emission rate reduces the effect of dot dephasing and excitonic fine structure on the concurrence. However, strong dot-cavity couplings, as well as low detection efficiencies, increase the detrimental effect of multiple cascades. This affects the merits of the entangled photon-pair source, beyond what is estimated by quantum tomography.