title: Experimental violation of a spin-1 bell inequality using maximally entangled four-photon states.
abstract: We demonstrate the experimental violation of a spin-1 Bell inequality. The spin-1 inequality is based on the Clauser, Horne, Shimony, and Holt formalism. For entangled spin-1 particles, the maximum quantum-mechanical prediction is 2.55 as opposed to a maximum of 2, predicted using local hidden variables. We obtained an experimental value of 2.27+/-0.02 using the four-photon state generated by pulsed, type-II, stimulated parametric down-conversion. This is a violation of the spin-1 Bell inequality by more than 13 standard deviations.
authors.affiliation: Centre for Quantum Computation, Clarendon Laboratory, University of Oxford, Parks Road, Oxford OX1 3PU, United Kingdom.
authors.forename: John C
authors.initials: JC
authors.lastname: Howell
authors.forename: Antia
authors.initials: A
authors.lastname: Lamas-Linares
authors.forename: Dik
authors.initials: D
authors.lastname: Bouwmeester