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arXiv · 1506.05263

De Finetti theorems, mean-field limits and Bose-Einstein condensation

Nicolas Rougerie
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Abstract

These notes deal with the mean-field approximation for equilibrium states of N-body systems in classical and quantum statistical mechanics. A general strategy for the justification of effective models based on statistical independence assumptions is presented in details. The main tools are structure theorems {\`a} la de Finetti, describing the large N limits of admissible states for these systems. These rely on the symmetry under exchange of particles, due to their indiscernability. Emphasis is put on quantum aspects, in particular the mean-field approximation for the ground states of large bosonic systems, in relation with the Bose-Einstein condensation phenomenon. Topics covered in details include: the structure of reduced density matrices for large bosonic systems, Fock-space localization methods, derivation of effective energy functionals of Hartree or non-linear Schr{\"o}dinger type, starting from the many-body Schr{\"o}dinger Hamiltonian.

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Nicolas Rougerie. 2015-06-17. De Finetti theorems, mean-field limits and Bose-Einstein condensation. https://arxiv.org/abs/1506.05263

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