Zeeman-insensitive cooling of a single atom to its two-dimensional motional ground state in tightly focused optical tweezers

Abstract

We combine near-deterministic preparation of a single atom with Raman sideband cooling, to create a push-button mechanism to prepare a single atom in the motional ground state of tightly focused optical tweezers. In the two-dimensional (2D) radial plane, we achieve a large ground-state fidelity for the entire procedure (loading and cooling) of ∼0.73, while the ground-state occupancy is ∼0.88 for realizations with a single atom present. For 1D axial cooling, we attain a ground-state fraction of ∼0.52. The combined 3D cooling provides a ground-state population of ∼0.11. Our Raman sideband cooling variation is indifferent to magnetic field fluctuations, allowing widespread unshielded experimental implementations. Our work provides a pathway towards a range of coherent few-body experiments.