Sub-Doppler laser cooling of ${}^{39}$K via the 4S$\to$5P transition

Govind Unnikrishnan, Michael Gröbner, Hanns-Christoph Nägerl

We demonstrate sub-Doppler laser cooling of ${}^{39}$K using degenerate Raman sideband cooling via the 4S${}_{1/2}\to$5P${}_{1/2}$ transition at 404.8 nm. By using an optic…