Fast and dense magneto-optical traps for Strontium

We improve the efficiency of sawtooth-wave-adiabatic-passage (SWAP) 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 $6\times 10^7$ bosonic $^{88}$Sr ($1\times 10^7$ fermionic $^{87}$Sr) atoms at phase-space densities of $2\times 10^{-3}$ ($1.4\times 10^{-4}$). Our method is simple to implement and is faster and more robust than traditional cooling methods.