Proposal for generating telecommunication-wavelength entangled photon pairs from a quantum dot by frequency down-conversion.

Fine-structure splitting of the exciton energy levels in a quantum dot introduces an energy difference between the two biexciton decay paths. This energy difference greatly reduces the entanglement of the photon pairs generated via biexciton recombination. Here, we propose a feasible method to eliminate the "which-path" information by using a fast frequency down-conversion technique, which substantially improves the entanglement of the photon pairs. Moreover, the wavelengths of both of the entangled photons can be transferred to the telecommunication band, which makes this method further appropriate for quantum communication. [ABSTRACT FROM AUTHOR]