A far-off-resonance optical trap for a Ba$^+$ ion

TL;DR

This paper demonstrates optical trapping of a Ba+ ion without rf fields, significantly reducing photon scattering and recoil heating, and introduces a method for precise stray electric field compensation, advancing ultracold ion-atom research.

Contribution

It presents the first optical trapping of a Ba+ ion in a far-detuned trap and a novel stray field compensation technique, enabling lower temperatures for quantum experiments.

Findings

Photon scattering suppressed by three orders of magnitude

Recoil heating reduced by four orders of magnitude

Stray electric field compensation below 9 mV/m achieved

Abstract

Optical trapping and ions combine unique advantages of independently striving fields of research. Light fields can form versatile potential landscapes, such as optical lattices, for neutral and charged atoms, avoiding detrimental implications of established radiofrequency (rf) traps while mediating interaction via long range Coulomb forces, controlling and detecting motional and electronic states on the quantum level. Here we show optical trapping of $^{138}$Ba$^{+}$ ions in the absence of rf fields in a far-detuned dipole trap, suppressing photon scattering by three and the related recoil heating by four orders of magnitude. To enhance the prospects for optical as well as hybrid traps, we demonstrate a novel method for stray electric field compensation to a level below 9 mV/m. Our results will be relevant, for example, for ion-atom ensembles, to enable four to five orders of magnitude lower common temperatures, accessing the regime of ultracold interaction and chemistry, where quantum effects are predicted to dominate.