Erratum: An experimental test of non-local realism

The experimental values of correlation functions were measured at the difference angle ϕ = 20° (on the Poincaré sphere), rather than 18.8° as was stated in the original paper. The reported violation of 3.2 standard deviations refers to ϕ = 20°. In Supplementary Information II of the original paper the boundaries of all integrals over variables χ and ψ should be the following: χ varies from -2π to 2π; ψ varies from |χ|/2 to 2π - |χ|/2. Also, in equation (35) and what follows, should be replaced by . The final inequality of the paper and all its conclusions do not change. The errors arose from our attempt for a more concise notation, but were never used in our actual calculations. We thank Stephen Parrott for pointing out these errors.