Crossed-Beam slowing to enhance narrow-line Ytterbium Magneto-Optic Traps

Abstract

We demonstrate a method to enhance the atom loading rate of a ytterbium (Yb) magneto-optic trap (MOT) operating on the 556 nm ${{}^{1}S}_0\to {{}^{3}P}_1$ intercombination transition (narrow linewidth $\hat{I}{“}_g=2\ddot{I}€\times 182$ kHz). Following traditional Zeeman slowing of an atomic beam near the 399 nm ${{}^{1}S}_0\to {{}^{1}P}_1$ transition (broad linewidth $\hat{I}{“}_p=2\ddot{I}€\times 29$ MHz), two laser beams in a crossed-beam geometry, frequency tuned near the same transition, provide additional slowing immediately prior to the MOT. Using this technique, we observe an improvement by a factor of 6 in the atom loading rate of a narrow-line Yb MOT. The relative simplicity and generality of this approach make it readily adoptable to other experiments involving narrow-line MOTs. We also present a numerical simulation of this two-stage slowing process which shows good agreement with the observed dependence on experimental parameters, and use it to assess potential improvements to the method.