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.

Indistinguishable near infra-red single photons from an individual organic molecule

By using the zero-phonon line emission of an individual organic molecule, we realized a source of indistinguishable single photons in the near infrared. A Hong-Ou-Mandel interference experiment is performed and a two-photon coalescence probability of higher than 50% at 2 K is obtained. The contribution of the temperature-dependent dephasing processes to the two-photon interference contrast is studied. We show that the molecule delivers nearly ideal indistinguishable single photons at the lowest temperatures when the dephasing is nearly lifetime limited. This source is used to generate post-selected polarization-entangled photon pairs, as a test-bench for applications in quantum information.