Cavity-assisted fast generation of entangled photon pairs through the biexciton-exciton cascade

We present a scheme for the fast cavity-assisted generation of entangled photon pairs from a single quantum dot coupled to a planar photonic crystal that support two orthogonally polarized cavity modes. We discuss “within generation” and “across generation” of entangled photons when both the biexciton to exciton, and the exciton to ground-state transitions, are coupled through cavity modes. In the across generation, the photon entanglement is restored through a time delay between the photons. The concurrence, which is a measure of the entanglement between two photons, is greater than 0.7 and 0.8 using experimentally achievable parameters in across generation and within generation, respectively. We also show that the entanglement can be distilled in both cases using a simple spectral filter. ©2009 The American Physical Society