Experimental Realization of a Three-Qubit Entangled W State

Abstract

The experimental observation of the three-photon polarization-entangled W state was reported. Spontaneous parametric down conversion (SPDC) was used to create polarization-entangled multiphoton states. The polarization measurements on three photons showed the characteristic threefold quantum correlations violating a three-particle Mermin inequality. It was also shown that the correlations occurred in other analysis directions, and that they contained substantial two-photon entanglement.