Nash equilibria in quantum games with generalized two-parameter strategies

In the Eisert protocol for 2 x 2 quantum games [J. Eisert, et aL, Phys. Rev. Lett. 83 (1999) 3077], a number of authors have investigated the features arising from making the strategic space a two-parameter subset of single qubit unitary operators. We argue that the new Nash equilibria and the classical-quantum transitions that occur are simply an artifact of the particular strategy space chosen. By choosing a different, but equally plausible, two-parameter strategic space we show that different Nash equilibria with different classical-quantum transitions can arise. We,generalize the two-parameter strategies and also consider these strategies in a multiplayer setting (C) 2006 Elsevier B.V All rights reserved.