ENTANGLED NONLOCAL QUANTUM INTERFEROMETRY

A novel quantum optical interference experiment based on a delayed cor relation technique and involving photons prepared in a polarization-en tangled state is presented. The resulting phenomenology is found to be determined by the simultaneous realization of several non-classical i nterference processes of distinct nature albeit strictly interrelated. A formal interpretation of the results is attempted by a standard qua ntum analysis and by the adoption of a set of interfering Feynman diag rams. In addition, a physical interpretation at a deeper level is unde rtaken by introducing for the system the basic theoretical background of a new concept in quantum optics: entangled interferometry. As a rel evant application of this new paradigm, a novel two-photon welcher-weg argument within a delayed-choice experiment is presented. It leads to an unexpected complementarity puzzle which expresses the manifestatio n of the EPR non-locality within the general context of interferometry . PACS numbers: 03.65.Bz, 42.50.-p, 42.50.Wm.