Realization of Green MOT for Ytterbium Atoms

We report the experimental realization of a magneto-optical trap (MOT) of ¹⁷⁴Yb atoms operating on the ¹S₀-³P₁ intercombination transition at 555.8nm. The green MOT is loaded by a Zeeman-slowed atomic beam. In order to increase the capture velocity of the MOT, we use the trapping laser beams consisting of five discrete frequency components obtained by modulating the laser light through an electro-optic modulator. The trapped atomic number of the ¹⁷⁴Yb isotope is about 6.2× 10⁵, and the temperature of the cold atomic cloud is estimated to be about 100μK. The success of the green MOT is an important step towards the goal of an ytterbium optical clock.