Efficient generation of near infra-red single photons from the zero-phonon line of a single molecule

Using the zero-phonon line (ZPL) emission of a single molecule, we realized a triggered source of near-infra-red (lambda=785 nm) single photons at a high repetition rate. A Weierstrass solid immersion lens is used to image single molecules with an optical resolution of 300 nm (~0.4*lambda) and a high collection efficiency. Because dephasing of the transition dipole due to phonons vanishes at liquid helium temperatures, our source is attractive for the efficient generation of single indistinguishable photons.