Sub-Doppler deep-cooled bosonic and fermionic isotopes of potassium in a compact 2D⁺–3D MOT set-up

We report the sub-Doppler deep-cooled three-dimensional magneto-optical trap (3D MOT) of the fermionic 40K and bosonic 39K isotopes of potassium loaded by a very compact 2D+ MOT with a novel optical design feature. The set-up is meant for studies on the quantum dynamics of a few fermionic and bosonic atoms in an optical dipole trap near and well within quantum degeneracy. The loading rate and atom numbers achieved in the compact simple set-up are comparable to those in the previous set-ups with more elaborate vacuum design. We attained relatively low temperatures of 34 and 30 µK for 39K and 40K after the sub-Doppler cooling process.