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Journal of Mathematical Physics

Large deviations in a semi-infinite layered ferromagnet with mean-field interactions: Classical and quantum models

N. Angelescu, M. Bundaru, Joseph V. Pulé

Published Sep 1, 1995• 0 citations
Publisher

Abstract

We consider the probability distribution in a classical semi-infinite layered ferromagnet with mean-field interactions and prove that this satisfies a large deviation principle, giving the rate function explicitly. For an analogous quantum system we show that the limiting states are product states, which are completely characterized by the classical mean-field solutions.

DOI
10.1063/1.530919

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The mean-field approximations of many-boson dynamics are known to be effective in many physical relevant situations. The mathematical justifications of such approximations rely generally on specific considerations which depend too much on the model and on the initial states of the system which are required to be well-prepared. In this article, using the method of Wigner measures, we prove in a fairly complete generality the accuracy of the mean-field approximation. Roughly speaking, we show that the dynamics of a many-boson system are well approximated, in the limit of a large number of particles, by a one particle mean-field equation if the following general principles are satisfied: ∙\bullet∙ The Hamiltonian is in a mean-field regime (i.e.: The interaction and the free energy parts are of the same order with respect to the number of particles). ∙\bullet∙ The interaction is relatively compact with respect to a one particle and it is dominated by the free energy part. ∙\bullet∙ There exists at most one weak solution for the mean-field equation for each initial condition.The convergence towards the mean field limit is described in terms of Wigner (probability) measures and it holds for any initial quantum states with a finite free energy average. The main novelty of this article lies in the use of fine properties of uniqueness for the Liouville equations in infinite dimensional spaces.