Indistinguishable Photons from a Single Molecule
  We report the results of coincidence counting experiments at the output of a Michelson interferometer using the zero-phonon-line emission of a single molecule at $1.4 K$. Under continuous wave excitation, we observe the absence of coincidence counts as an indication of two-photon interference. This corresponds to the observation of Hong-Ou-Mandel correlations and proves the suitability of the zero-phonon-line emission of single molecules for applications in linear optics quantum computation. 
A. Kiraz, M. Ehrl, Th. Hellerer, O. E. Mustecaplioglu, C. Brauchle,   and A. Zumbusch