Combine EPR and two-slit experiments: Interference of advanced waves

A nonclassical interference effect, using two-photon correlations in nonlinear optical interactions, is discussed. The apparent nonlocality could be conveniently interpreted in terms of advanced waves, emitted by one detector toward the other. A new Bell-type experiment is proposed, in which the measured photon's parameter is the wave-vector (instead of the polarisation), so that the observable can take more than two possible values.