Extracting density–density correlations from in situ images of atomic quantum gases

We present a complete recipe to extract the density–density correlations and the static structure factor of a two-dimensional (2D) atomic quantum gas from in situ imaging. Using images of non-interacting thermal gases, we characterize and remove the systematic contributions of imaging aberrations to the measured density–density correlations of atomic samples. We determine the static structure factor and report the results on weakly interacting 2D Bose gases, as well as strongly interacting gases in a 2D optical lattice. In the strongly interacting regime, we observe a strong suppression of the static structure factor at long wavelengths. 3 Author to whom any correspondence should be addressed. New Journal of Physics 13 (2011) 075019 1367-2630/11/075019+15$33.00 © IOP Publishing Ltd and Deutsche Physikalische Gesellschaft