Fast and dense magneto-optical traps for strontium

Abstract

We improve the efficiency of sawtooth-wave adiabatic-passage cooling for strontium atoms in three dimensions and combine it with standard narrow-line laser cooling. With this technique, we create strontium magneto-optical traps with $6\ifmmode\times\else\texttimes\fi{}{10}^{7}$ bosonic $^{88}\mathrm{Sr}$ ($1\ifmmode\times\else\texttimes\fi{}{10}^{7}$ fermionic $^{87}\mathrm{Sr}$) atoms at phase-space densities of $2\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}3}$ ($1.4\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$). Our method is simple to implement and is faster and more robust than traditional cooling methods.