Abstract
We report experimental evidence of Sisyphus cooling in atoms with a ground state. Since any cooling mechanism which requires multiple sublevels can only occur in the isotopes which have nuclear spin Ytterbium has seven stable isotopes and offers a unique system in which we can study cooling on and depending on the selection of isotope. We have trapped each of the seven stable isotopes of ytterbium in a magneto-optical trap (MOT) using the strong transition, and transferred them into a second MOT which uses the much narrower intercombination transition. We have measured the temperature of isotopes and in the MOT, as a function of the intensity and detuning of the trapping laser. The temperature of was found to increase more rapidly with intensity than predicted by Doppler cooling theory, in agreement with earlier work on alkaline-earth atoms. In the odd isotopes the temperature was found to decrease with increasing angular momentum, as observed in earlier experiments and three-dimensional simulations.
- Received 20 March 2003
DOI:https://doi.org/10.1103/PhysRevA.68.011403
©2003 American Physical Society