  A quantum Cournot game of which classical form game has multiple Nash
equilibria is examined. Although the classical equilibria fail to be Pareto
optimal, the quantum equilibrium exhibits the following two properties, (i) if
the measurement of entanglement between strategic variables chosen by the
competing firms is sufficiently large, the multiplicity of equilibria vanishes,
and, (ii) the more strongly the strategic variables are entangled, the more
closely the unique equilibrium approaches to the optimal one.
