N-player quantum games in an EPR setting

TL;DR

This paper explores N-player quantum games within an EPR framework, analyzing how entanglement influences strategies and payoffs, and extends classical game concepts to quantum scenarios with explicit solutions for the Prisoners' Dilemma.

Contribution

It introduces a novel approach to N-player quantum games using EPR settings, deriving explicit Nash equilibria and payoffs for GHZ and W states, and reveals parity-based payoff differences.

Findings

Payoffs are equal for even number of players at Nash equilibrium.

For odd number of players, cooperating players receive higher payoffs.

The quantum game reduces to the classical game when entanglement is zero.

Abstract

The $N$-player quantum game is analyzed in the context of an Einstein-Podolsky-Rosen (EPR) experiment. In this setting, a player's strategies are not unitary transformations as in alternate quantum game-theoretic frameworks, but a classical choice between two directions along which spin or polarization measurements are made. The players' strategies thus remain identical to their strategies in the mixed-strategy version of the classical game. In the EPR setting the quantum game reduces itself to the corresponding classical game when the shared quantum state reaches zero entanglement. We find the relations for the probability distribution for $N$-qubit GHZ and W-type states, subject to general measurement directions, from which the expressions for the mixed Nash equilibrium and the payoffs are determined. Players' payoffs are then defined with linear functions so that common two-player games can be easily extended to the $N$-player case and permit analytic expressions for the Nash equilibrium. As a specific example, we solve the Prisoners' Dilemma game for general $ N \ge 2 $. We find a new property for the game that for an even number of players the payoffs at the Nash equilibrium are equal, whereas for an odd number of players the cooperating players receive higher payoffs.