Charge transfer in ultracold gases via Feshbach resonances

TL;DR

This paper explores controlling charge-exchange in ultracold atom-ion collisions using Feshbach resonances, demonstrating the ability to tune reaction rates for quantum simulation applications.

Contribution

It introduces a quantum scattering approach to predict Feshbach resonances in heteroisotopic atom-ion systems, enabling control over charge-exchange processes.

Findings

Charge-exchange rate can be increased by tuning magnetic fields near a Feshbach resonance.

Predicted narrow resonance at 322 G significantly enhances charge-exchange rates.

Method applicable to alkali and alkaline-earth metal atom-ion pairs.

Abstract

We investigate the prospects of controlling charge-exchange in ultracold collisions of heteroisotopic combinations of atoms and ions of the same element. The treatment, readily applicable to alkali or alkanine-earth metals, is illustrated in the process $^9$Be$^{+}$ + $^{10}$Be $\leftrightarrow$ $^{9}$Be + $^{10}$Be$^{+}$, which exhibits favorable electronic, nuclear, and hyperfine structure. Feshbach resonances are obtained from quantum scattering calculations in a standard coupled-channel formalism with non-BO terms originating from the nuclear kinetic operator. Near a narrow resonance predicted at 322 G, we find the charge-exchange rate coefficient to rise from practically zero to values larger than $10^{-12}$ cm$^3$/s. Our results suggest controllable charge-exchange reactions between different isotopes of suitable atom-ion pairs with potential applications to quantum systems engineered to study charge diffusion in trapped cold atom-ion mixtures and emulate many-body physics.