Experimental demonstration of quantum gain in a zero-sum game

We propose and experimentally demonstrate a zero-sum game which is in a fair Nash equilibrium for classical players, but a quantum player can always win using an appropriate strategy. The gain of the quantum player is measured experimentally under different quantum strategies and input states. It is found that the quantum gain is maximized under a maximally entangled state, but does not reduce to zero when entanglement disappears. Instead, it links with another kind of quantum correlation described by discord for the qubit case.