A two-photon double-slit experiment
R. W. Menzel, Axel Heuer, Dirk Puhlmann, K. Dechoum, Mark S. Hillery, M.J.A. Spähn, Wolfgang P. Schleich · Journal of Modern Optics · 2012
We employ a photon pair created by spontaneous parametric down conversion (SPDC) where the pump laser is in the TEM01 mode to perform a Young's double-slit experiment. The signal photon illuminates the two slits and displays interference fringes in the far-field while the idler photon measured in the near-field in coincidence with the signal photon provides us with ‘which-slit’ information. We explain the results of these experiments with the help of an analytical expression for the second-order correlation function derived from an elementary model of SPDC. Our experiment emphasizes the crucial role of the mode function in the quantum theory of radiation.