Uniqueness of Nash equilibria in a quantum Cournot duopoly game

A quantum Cournot game whose 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. PACS numbers: 03.67.−a, 02.50.Le (Some figures in this article are in colour only in the electronic version)