Evidence of sympathetic cooling of Na+ ions by a Na magneto-optical trap in a hybrid trap

Abstract

A hybrid ion-neutral trap provides an ideal system to study collisional dynamics between ions and neutrals. This system provides a general cooling method that can be applied to species that do not have optically accessible transitions, and can also potentially cool internal degrees of freedom. The long range polarization potentials (V ∝ −α/r4 ) between ions and neutrals result in large scattering cross sections at cold temperatures, making the hybrid trap a favorable system for efficient sympathetic cooling of ions by collisions with neutral atoms. We present experimental evidence of sympathetic cooling of trapped Na+ ions, which are closed shell and therefore do not have a laser induced atomic transition from the ground state, by equal mass cold Na atoms in a magneto-optical trap (MOT).