Sisyphus Cooling in Ytterbium Intercombination MOT

We report the first evidence of Sisyphus cooling in the ground state of alkaline-earth like atoms. Ytterbium and alkaline-earth atoms have J = 0 in the ground state (^1S_0) and the even isotopes (nuclear spin I = 0) are ideal for testing pure Doppler cooling. Sisyphus cooling, which requires multiple sub-levels, can be tested in isotopes with I >0. Ytterbium has seven stable isotopes and offers a unique system in which we can study cooling on the F =0 arrow 1 (^168, 170, 172, 174, 176Yb), F =1/2 arrow 3/2 (^171Yb), and F =5/2 arrow 7/2 (^173Yb) transitions, depending on isotope selection. We have trapped each of the seven stable isotopes of ytterbium in a magneto-optical trap (MOT) using the ^1S₀ - ^1P₁ transition, and transferred them into a second MOT which uses the ^1S₀ - ^3P₁ transition. The temperature of even isotopes, of which ^174Yb was the most carefully studied, was found to deviate significantly from Doppler cooling theory. The temperature of isotopes ^171Yb and ^173Yb was measured as a function of the intensity and detuning of the trapping lasers. The dependence on ground state angular momentum, laser intensity, and detuning was found to be in agreement with theoretical models of Sisyphus cooling. Further progress and possible future experiments including photoassociation spectroscopy and quantum degeneracy will be presented.