Ultracold magnetically tunable interactions without radiative charge transfer losses between Ca$^+$, Sr$^+$, Ba$^+$, and Yb$^+$ ions and Cr atoms

TL;DR

This paper proposes ultracold ion-atom systems involving Ca$^+$, Sr$^+$, Ba$^+$, and Yb$^+$ ions with Cr atoms, demonstrating magnetically tunable interactions without charge transfer losses, supported by detailed ab initio calculations.

Contribution

It introduces a new class of ultracold heteronuclear systems with controllable interactions and provides comprehensive electronic structure data using advanced quantum chemistry methods.

Findings

Potential energy curves and dipole moments computed for molecular ions.

Magnetic Feshbach resonances identified for ion-atom pairs.

Systems are feasible for quantum simulations without radiative losses.

Abstract

The Ca$^+$, Sr$^+$, Ba$^+$, and Yb$^+$ ions immersed in an ultracold gas of the Cr atoms are proposed as experimentally feasible heteronuclear systems in which ion-atom interactions at ultralow temperatures can be controlled with magnetically tunable Feshbach resonances without charge transfer and radiative losses. \textit{Ab initio} techniques are applied to investigate electronic-ground-state properties of the (CaCr)$^+$, (SrCr)$^+$, (BaCr)$^+$, and (YbCr)$^+$ molecular ions. The potential energy curves, permanent electric dipole moments, and static electric dipole polarizabilities are computed. The spin restricted open-shell coupled cluster method restricted to single, double, and noniterative triple excitations, RCCSD(T), and the multireference configuration interaction method restricted to single and double excitations, MRCISD, are employed. The scalar relativistic effects are included within the small-core energy-consistent pseudopotentials. The leading long-range induction and dispersion interaction coefficients are also reported. Finally, magnetic Feshbach resonances between the Ca$^+$, Sr$^+$, Ba$^+$, and Yb$^+$ ions interacting with the Cr atoms are analyzed. The present proposal opens the way towards robust quantum simulations and computations with ultracold ion-atom systems free of radiative charge transfer losses.