Generation of a high-visibility four-photon entangled state and realization of a four-party quantum communication complexity scenario

Abstract

We obtain a four-photon polarization-entangled state with a visibility as high as $(95.35\ifmmode\pm\else\textpm\fi{}0.45)%$ directly from a single down-conversion source. A success probability of $(81.54\ifmmode\pm\else\textpm\fi{}1.38)%$ is observed by applying this entangled state to realize a four-party quantum communication complexity scenario, which comfortably surpasses the classical limit of 50%. As a comparison, two Einstein-Podolsky-Rosen pairs are shown to implement the scenario with a success probability of $(73.89\ifmmode\pm\else\textpm\fi{}1.33)%$. This four-photon state can also be used to fulfill decoherence-free quantum information processing and other advanced quantum communication schemes.