Interactions and charge transfer dynamics of an Al$^+$ ion immersed in ultracold Rb and Sr atoms

TL;DR

This paper provides a theoretical analysis of the interactions and charge transfer dynamics of an Al$^+$ ion immersed in ultracold Rb and Sr atoms, with implications for atomic clock precision and cold hybrid ion-atom experiments.

Contribution

It introduces detailed potential energy curves and transition dipole moments for Al$^+$ interacting with Rb and Sr, including relativistic effects, and explores charge transfer and collision dynamics.

Findings

Charge transfer involves multiple electronic states influenced by spin-orbit coupling.

Long-range interaction coefficients are quantified for Al$^+$ with Rb and Sr.

Prospects for laser control and molecular ion formation are discussed.

Abstract

Atomic clocks based on an Al$^+$ ion sympathetically cooled by a laser-cooled alkaline-earth ion have achieved unprecedented accuracy. Here, we investigate theoretically interactions and charge transfer dynamics of an Al$^+$ ion immersed in an ultracold gas of Rb and Sr atoms. We calculate potential energy curves and transition electric dipole moments for the (Al+Rb)$^+$ and (Al+Sr)$^+$ ion-atom systems using coupled cluster and multireference configuration interaction methods with scalar relativistic effects included within the small-core energy-consistent pseudopotentials in Rb and Sr atoms. The long-range interaction coefficients are also reported. We use the electronic structure data to investigate cold collisions and charge transfer dynamics. Scattering of an Al$^+$ ion with alkali-metal or alkaline-earth-metal atom is governed by one potential energy curve whereas charge transfer can lead to several electronic states mixed by the relativistic spin-orbit coupling. We examine the branching ratios resulting from the interplay of the short- and long-range effects, as well as the prospects for the laser-field control and formation of molecular ions. We propose to employ the atomic clock transition in an Al$^+$ ion to monitor ion-atom scattering dynamics via quantum logic spectroscopy. The presented results pave the way for the application of atomic ions other than alkali-metal and alkaline-earth-metal ones in the field of cold hybrid ion-atom experiments.