Shot-by-shot imaging of Hong-Ou-Mandel interference with an intensified sCMOS camera

We report the first observation of Hong-Ou-Mandel (HOM) interference of highly indistinguishable photon pairs with spatial resolution. Direct imaging of two-photon coalescence with an intensified sCMOS camera system clearly reveals spatially separated photons appearing pairwise within one of the two modes. With the use of the camera system we quantified the number of pairs and recovered the full HOM dip yielding 96.3% interference visibility, as well as retrieved the number of coalesced pairs. We retrieved the spatial mode structure of both interfering photons by performing a proof-of-principle demonstration of a new, low noise high resolution coincidence imaging scheme.