Atomic fountain of laser-cooled Yb atoms for precision measurements

Abstract

We demonstrate launching of laser-cooled Yb atoms in a cold atomic fountain. Atoms in a collimated thermal beam are first cooled and captured in a magneto-optical trap (MOT) operating on the strongly allowed ${{}^{1}S}_{0}\ensuremath{\rightarrow}{{}^{1}P}_{1}$ transition at 399 nm (blue line). They are then transferred to a MOT on the weakly allowed ${{}^{1}S}_{0}\ensuremath{\rightarrow}{{}^{3}P}_{1}$ transition at 556 nm (green line). Cold atoms from the green MOT are launched against gravity at a velocity of around 2.5 m/s using a pair of green beams. We trap more than ${10}^{7}$ atoms in the blue MOT and transfer up to $70%$ into the green MOT. The temperature for the odd isotope $^{171}\mathrm{Yb}$ is $~1 \mathrm{mK}$ in the blue MOT, and reduces by a factor of 40 in the green MOT.