10,851 research outputs found
Quantum Cooperative Games
We study two forms of a symmetric cooperative game played by three players,
one classical and other quantum. In its classical form making a coalition gives
advantage to players and they are motivated to do so. However in its quantum
form the advantage is lost and players are left with no motivation to make a
coalition.Comment: Revised in the light of referee's comments. Submitted to Physics
Letters A. LaTex, 9 pages, 1 figure. Parts of this paper are rewritte
Stability of mixed Nash equilibria in symmetric quantum games
In bi-matrix games the Bishop-Cannings theorem of the classical evolutionary
game theory does not permit pure evolutionarily stable strategies (ESSs) when a
mixed ESS exists. We find the necessary form of two-qubit initial quantum
states when a switch-over to a quantum version of the game also changes the
evolutionary stability of a mixed symmetric Nash equilibrium.Comment: 8 pages, no figure, to appear in Communications in Theoretical
Physic
Backwards-induction outcome in a quantum game
In economics duopoly is a market dominated by two firms large enough to
influence the market price. Stackelberg presented a dynamic form of duopoly
that is also called `leader-follower' model. We give a quantum perspective on
Stackelberg duopoly that gives a backwards-induction outcome same as the Nash
equilibrium in static form of duopoly also known as Cournot's duopoly. We find
two qubit quantum pure states required for this purpose.Comment: Revised in the light of referee's comments. Latex, 16 pages, 2
figures, To appear in Phy. Rev.
Topological spin liquids: Robustness under perturbations
We study the robustness of the paradigmatic kagome Resonating Valence Bond
(RVB) spin liquid and its orthogonal version, the quantum dimer model. The
non-orthogonality of singlets in the RVB model and the induced finite length
scale not only makes it difficult to analyze, but can also significantly affect
its physics, such as how much noise resilience it exhibits. Surprisingly, we
find that this is not the case: The amount of perturbations which the RVB spin
liquid can tolerate is not affected by the finite correlation length, making
the dimer model a viable model for studying RVB physics under perturbations.
Remarkably, we find that this is a universal phenomenon protected by
symmetries: First, the dominant correlations in the RVB are spinon
correlations, making the state robust against doping with visons. Second,
reflection symmetry stabilizes the spin liquid against doping with spinons, by
forbidding mixing of the initially dominant correlations with those which lead
to the breakdown of topological order.Comment: v2: accepted versio
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