Dlaczego w dylemat więźnia warto grać kwantowo?

The Prisoner's Dilemma [PD] is the best known example of a two-person, simultaneous game, for which the Nash equilibrium is far from Pareto-optimal solutions. In this paper we define a quantum PD, for which player's strategies are defined as rotations of the SU(2) group, parameterized by three angles. Quantum strategies are correlated through the mechanism of quantum entanglement and the result of the game is obtained by the collapse of the wave function. Classic PD is a particular case of the quantum game for which the set of rotations is limited to one dimension. Each quantum strategy can be, by appropriate choice of counter-strategy, interpreted as a "cooperation" or "defection". Quantum PD has Nash equilibria that are more favorable than the classic PD and close to the Pareto optimal solutions. With proper selection of strategies, quantum PD can be reduced to the classic, zero-sum, "matching pennies" game. In this paper we show examples of economic phenomena (price collusion, the chess strategy) that mimics the Nash equilibria of quantum PD.