Collisional cooling of light ions by co-trapped heavy atoms

TL;DR

This study demonstrates that light ions can be cooled through collisions with co-trapped heavier neutral atoms, extending the potential for ion cooling techniques across various atom-ion mass ratios.

Contribution

It provides experimental evidence that localized ultracold neutral atoms can cool trapped light ions, regardless of their mass ratio, broadening ion cooling applications.

Findings

Longer trap lifetime of $^{39}$K$^{+}$ ions with $^{85}$Rb atoms

Cooling of $^{85}$Rb$^{+}$ ions by ultracold $^{133}$Cs atoms

Cooling mechanism effective for any mass ratio

Abstract

We experimentally demonstrate cooling of trapped ions by collisions with co-trapped, higher mass neutral atoms. It is shown that the lighter $^{39}$K$^{+}$ ions, created by ionizing $^{39}$K atoms in a magneto-optical trap (MOT), when trapped in an ion trap and subsequently allowed to cool by collisions with ultracold, heavier $^{85}$Rb atoms in a MOT, exhibit a longer trap lifetime than without the localized $^{85}$Rb MOT atoms. A similar cooling of trapped $^{85}$Rb$^{+}$ ions by ultracold $^{133}$Cs atoms in a MOT is also demonstrated in a different experimental configuration to validate this mechanism of ion cooling by localized and centered ultracold neutral atoms. Our results suggest that cooling of ions by localized cold atoms holds for any mass ratio, thereby enabling studies on a wider class of atom-ion systems irrespective of their masses.