Finite size mean-field models

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.

20 pages

References in corpus (2)

• Entanglement in a second order quantum phase transition
• Entanglement in a first order quantum phase transition

Cited by in corpus (3)

• Entanglement and permutational symmetry
• On Exchangeable Continuous Variable Systems
• Additivity of the Renyi entropy of order 2 for positive-partial-transpose-inducing channels