Experimental demonstration of Greenberger-Horne-Zeilinger correlations using nuclear magnetic resonance - art. no. 022106

The Greenberger-Horne-Zeilinger (GHZ) effect provides an example of quantum correlations that cannot be explained by classical local hidden variables. This paper reports on the experimental realization of GHZ correlations usi ng nuclear magnetic resonance (NMR). The NMR experiment differs from the or iginally proposed GHZ experiment in several ways: it is performed on mixed states rather than pure states, and instead of being widely separated, the spins on which it is performed are all located in the same molecule. As a r esult, the NMR version of the GHZ experiment cannot entirely rule out class ical local hidden variables. It nonetheless provides an unambiguous demonst ration of the "paradoxical" GHZ correlations, and confirms the predictions of quantum mechanics.