Abstract

Our present theoretical understanding of laser cooling below the Doppler limit is based on the interplay of a degenerate ground state and spatially varying light polarizations, providing a very efficient cooling mechanism. Some of these theoretical ideas have been tested by measuring the dependence of the temperature on laser intensity and detuning in Na¹ and Cs² optical molasses. There remains, however, the question of the dependence of the cooling on the degree of degeneracy of the ground state. Using ³⁵Ub and ⁸⁷Rb, one can perform a clean comparison of two transitions that are virtually identical except for the angular momentum of the ground and excited states. Possible effects of a change in the recoil shift or the linewidth can be eliminated. More important, since the experiments can be done in the same apparatus, a large number of systematic effects (e.g., calibrations, beam profiles) would not affect the comparison.

© 1992 Optical Society of America