Quantum contextuality in a Young-type interference experiment

arejointly measurable) have been recently identi ed [arXiv:1206.3212 (2012)]. Here we report the resultsof an experiment designed to reach the maximum quantum violation of these inequalities for anyeven number of observables ranging from 4 to 14. The four dimensional Hilbert space required forthe test was spanned by two photonic qubits encoded in the tranversal paths of photon pairs, and thejoint measurability of the observables is guaranteed by measuring correlations between observablesfrom di erent modes. Our results show contextual correlations as predicted by quantum mechanics.