Abstract

The light-shifts of an atom in a standing wave are generally space dependent because of the gradient of polarization or intensity in the standing wave. These spatially modulated light shifts appear as a periodic optical potential in which quantization of atomic motion can occur. The occurrence of quantized vibrational states for the external degrees of freedom was first demonstrated in the one-dimensional (1-D) case¹ in the case of the 6S_1/2(F = 4)-6P_3/2(F = 5) transition. The occurrence of narrow lines and long damping times associated with the evolution of the external degrees of freedom was observed and interpreted.² More recent experiments showed that similar results are obtained in the 2-D and 3-D cases.³ Several beam geometries were used to realize this goal, leading to different patterns for the location of cold atoms. We describe experiments performed with beams aligned along a regular or a stretched tetrahedron, which lead to optical lattices having various symmetries (triclinic, orthorombic, tetragonal, or cubic) depending on the beams geometry. Investigation of the vibrational frequencies of cesium atoms in these optical potentials as well as temperature measurements will be presented. We finally describe the problems (density, atomatom interaction etc. …) that are encountered in these lattices and we show that it is possible to overcome some of these difficulties by developing a new kind of lattices (magneto-optical lattice) working on a transition connecting two levels having the same angular momentum (for which there is a dark state in absence of motional and magnetic couplings).

© 1994 IEEE