Double-structure potential due to multiphoton processes in a magneto-optical trap

We have derived ab initio analytical results for the shape of the double-st ructure potential well for a (3+5)-level atoms in the magneto-optical trap (MOT). We show that for a case of a (3+5)-level atom and a one-dimensional sigma(+)-sigma(-) laser held, the sharp bottom part of the MOT potential we ll results from the two-photon processes between the atomic ground-state ma gnetic sublevels. These nonlinear processes are, in particular, responsible for atomic temperatures below the Doppler limit which is due to the one-ph oton processes in the MOT. We also find that in more complicated atomic sch emes, even order multiphoton processes contribute to the sharp and narrow M OT potential well. [S1050-2947(99)01712-6].