BRIGHT OPTICAL LATTICES IN A LONGITUDINAL MAGNETIC-FIELD - EXPERIMENTAL-STUDY OF THE OSCILLATING AND JUMPING REGIMES

All the bright optical lattices studied so far have been designed to o btain a circularly polarized light at the bottom of the optical potent ial wells. This condition minimizes the departure rate of the atoms fr om the fundamental adiabatic surface and permits an oscillating regime in a large range of parameters. We present here an experimental study of cesium atoms in a three-dimensional optical lattice, where the lig ht is linearly polarized at the bottom of the potential wells. Tempera ture measurements and pump-probe spectroscopy give similar results for this lattice and for the conventional lin perpendicular to lin lattic e (which have circular polarizations at the bottom of the wells) despi te the fact that one lattice operates in the jumping regime and the ot her in the oscillating regime. We study the behaviour of the two types of lattices in a longitudinal magnetic field, with particular emphasi s on the zero field and strong field regimes. The strong field situati on is very simple because the eigenstates are then almost pure Zeeman substates and the adiabatic and diabatic potential surfaces are identi cal. The comparison between the zero-field and the high-field situatio ns shows that the diabatic potentials are more appropriate to account for experimental observations in the novel lattice.