Abstract

We investigate the potential of light forces to confine atoms with respect to all spatial coordinates and at the same time provide cooling to temperatures in the microkelvin range. This leads to atomic samples highly ordered in three-dimensional periodic lattices on a micrometer length scale. The physics describing such a sample resembles that of an ultracold and very dilute solid. We report the experimental realization of such an atomic crystal bound by light. The trapping of atoms in three-dimensional microscopic cavities might open a novel path toward the observation of collective absorption and emission processes and collisions in systems of two or more closely spaced atoms. To achieve trapping and efficient cooling of the atoms at the same time, polarization gradients in the light are necessary. In one dimension the configuration of two counterpropagating laser beams with orthogonal polarization (i.e., the lin⊥lin scheme) is appropriate. In three dimensions the situation is more complex and requires control of the rime phase differences between the standing waves used.

© 1993 Optical Society of America