Experimental Test of the Quantum Violation of the Noncontextuality Inequalities for the n-Cycle Scenario

TL;DR

This paper reports an experimental test demonstrating quantum violations of noncontextuality inequalities in the n-cycle scenario, confirming quantum contextuality for systems with up to 14 observables.

Contribution

It provides the first experimental verification of maximum quantum violations of n-cycle inequalities for even n from 4 to 14, using photonic qubits.

Findings

Confirmed quantum contextual correlations for n=4,6,8,10,12,14.

Achieved maximum quantum violation of inequalities for all tested n.

Used two-photon encoding in a four-dimensional Hilbert space.

Abstract

The inequalities that separate contextual from noncontextual correlations for the n-cycle scenario (consisting of n dichotomic observables Oj, with j = 0, ..., n-1 and such that Oj and Oj+1 are jointly measurable) have been recently identified [arXiv:1206.3212 (2012)]. Here we report the results of an experiment designed to reach the maximum quantum violation of these inequalities for any even number of observables ranging from 4 to 14. The four dimensional Hilbert space required for the test was spanned by two photonic qubits encoded in the transversal path of photon pairs, and the joint measurability of the observables is guaranteed by measuring correlations between observables from different modes. Our results show contextual correlations as predicted by quantum mechanics.