We present a protocol to evaluate the expectation value of the correlations of measurement outcomes for ensembles of quantum systems, and use it to experimentally demonstrate--under an assumption of fair sampling--the violation of an inequality that is satisfied by any non-contextual hidden-variables (NCHV) theory. The experiment is performed on an ensemble of molecular nuclear spins in the solid state, using established Nuclear Magnetic Resonance (NMR) techniques for quantum information processing (QIP).
@article{arxiv.0912.0485,
title = {Testing contextuality on quantum ensembles with one clean qubit},
author = {O. Moussa and C. A. Ryan and D. G. Cory and R. Laflamme},
journal= {arXiv preprint arXiv:0912.0485},
year = {2010}
}