We consider a gas of $N$ bosons in a box with volume one interacting through a two-body potential with scattering length of order $N^{ -1}$ (Gross-Pitaevskii limit). Assuming the (unscaled) potential to be sufficiently small, we show that the ground state of the system and all states with relatively small excitation energy exhibit complete Bose-Einstein condensation, with a uniform (i.e. $N$ independent) bound on the number of excitations.
Categories: math-ph math.AP math.MP