Violation of Bell's inequality by a generalized Einstein-Podolsky-Rosen state using homodyne detection

Using homodyning with weak coherent fields and photon counting, we have obs erved violations of Bell-type inequalities by the generalized Einstein-Podo lsky-Rosen state produced in a pulsed nondegenerate optical parametric ampl ifier, as predicted by Grangier et al. [Phys. Rev. A 38, 3132 (1988)]. The maximum observed visibility of the interference pattern was (89 +/- 4)%. Th is interference can be regarded as a manifestation of nonlocality in the se nse described by Banaszek and Wodkiewicz [Phys. Rev. A 58, 4345 (1998)]. We have investigated the interference both theoretically and experimentally a nd have measured the influence of dispersion and phase matching.