Cambalache 3,14 - La vidriera irrespetuosa

Quantum correlations are contextual yet, in general, nothing prevents the existence of even more contextual correlations. We identify and test a simple noncontextual inequality in which the quantum violation cannot be improved by any hypothetical post-quantum resource, and use it to experimentally obtain correlations in which the maximum noncontextual content, defined as the maximum fraction of noncontextual correlations, is less than 0.06. Our correlations are experimentally generated from the outcomes of sequential compatible measurements on a four-state quantum system encoded in the polarization and path of a single photon.