A bright source of telecom single photons based on quantum frequency conversion

Abstract

On-demand indistinguishable single-photon sources are essential for quantum networking and communication. Semiconductor quantum dots are among the most promising candidates, but their typical emission wavelength renders them unsuitable for use in fiber networks. Here, we present quantum frequency conversion of near-infrared photons from a bright quantum dot to the telecommunication C-band, allowing integration with existing fiber architectures. We use a custom-built, tunable 2400\u2009nm seed laser to convert single photons from 942\u2009nm to 1550\u2009nm in a difference-frequency generation process. We achieve an end-to-end conversion efficiency of ≃35%, demonstrate count rates approaching 1\u2009MHz at 1550\u2009nm with g ( 2 ) ( 0 ) = 0.043 ( 1 ), and achieve Hong-Ou-Mandel (HOM) visibilities of 60%. We expect this scheme to be preferable to quantum dot sources directly emitting at telecom wavelengths for fiber-based quantum networking.