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Finite size mean-field models

M. Fannes·C. Vandenplas
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Abstract

We characterize the two-site marginals of exchangeable states of a system of quantum spins in terms of a simple positivity condition. This result is used in two applications. We first show that the distance between two-site marginals of permutation invariant states on N spins and exchangeable states is of order 1/N. The second application relates the mean ground state energy of a mean-field model of composite spins interacting through a product pair interaction with the mean ground state energies of the components.

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M. Fannes, C. Vandenplas. 2006-05-25. Finite size mean-field models. https://doi.org/10.1088/0305-4470/39/45/001

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