Nonlinear engineering of Hong-Ou-Mandel interference with structured light

Abstract

A pair of photons entering a Hong-Ou-Mandel interferometer will bunch or anti-bunch depending on the symmetry of their state in the measured degree of freedom, resulting in constructive or destructive interference. For photon pairs generated through spontaneous parametric down-conversion, this symmetry can be engineered through linear transformations and projections applied to the photon pairs, or by tailoring the pump field. Here, we adopt the latter approach to demonstrate that the pump's parity affects the shape and frequency of the transition from constructive to destructive interference. We demonstrate this concept theoretically and experimentally using a rotating structured pump mode encoded in the Hermite-Gaussian and Laguerre-Gaussian bases. In the former case, we show that the transition exhibits a rich structure unique to the mode family, resulting in enhanced sensitivity as the mode order increases. In the latter case, we demonstrate, as with NOON states, an integer enhancement in angular resolution by a factor proportional to the orbital angular momentum content, thereby opening the possibility of Hong-Ou-Mandel-enhanced rotation sensing.