Experimental observation of quantum dispersion cancellation

Summary form only given. For many applications making use of photon interference, such as entanglement swapping or teleportation, a short pulse pumped source of photon pairs is required to enable multi-photon pair generation. However, timing information inherent in pulses affects the interference, and spectrally dispersive component media properties poses further fundamental effects on the degree of interference. In particular dispersion cancellation effects expected for CW pumped cases do not apply in general to pulse pumped applications. Theoretical models to account for such effects in a Hong-Ou-Mandel Interferometer (HOMI) have recently been published [Perina, PRA, 58, 2359 (1999); Franson, PRA, 45, 3126 (1992)]; the results presented here, give to our knowledge the first experimental observation of dispersive reduction of quantum interference, as well as the full restoration expected, when very large dispersion is balanced along the paths of the two photons.