We report a violation of Bell’s inequality using one photon from a pulsed parametric down-conversion pair and a second photon from a weak coherent state. The experiment relied on post-selected three-photon interference effects that also have direct applications in linear optics quantum computing.
We report a violation of Bell's inequality using one photon from a parametric down-conversion source and a second photon from an attenuated laser beam. The two photons were entangled at a beam splitter using the postselection technique of Shih and Alley [Phys. Rev. Lett. 61, 2921 (1988)]]. A quantum interference pattern with a visibility of 91% was obtained using the photons from these independent sources, as compared with a visibility of 99.4% using two photons from a central parametric down-conversion source.