Interference scheme to measure light-induced nonlinearities in   Bose-Einstein condensates
  Light-induced nonlinear terms in the Gross-Pitaevskii equation arise from the stimulated coherent exchange of photons between two atoms. For atoms in an optical dipole trap this effect depends on the spatial profile of the trapping laser beam. Two different laser beams can induce the same trapping potential but very different nonlinearities. We propose a scheme to measure light-induced nonlinearities which is based on this observation. 
K. V. Krutitsky, K.-P. Marzlin, J. Audretsch