Compact dual MOT apparatus of K and Rb for optical tweezer experiment

The optical tweezer experiment with neutral atoms is widely used for quantum information research. Here, we present a compact dual magneto-optical trap (MOT) setup for a two-species optical tweezer. Rubidium (Rb) atoms are directly captured using a vapor MOT, while potassium (K) atoms are collected via a 2-stage MOT. Both the quadratic and gradient magnetic fields required for the MOT and Zeeman slower are created by permanent magnets. With the help of the Zeeman slower, the K MOT loading efficiency is enhanced by a factor of three. After the MOT stage, we apply D₁ gray molasses to reduce the temperature of the K atoms to 9 μK. Using this apparatus, both Rb and K are loaded into the optical tweezer.