Characterization of charge-exchange collisions between ultracold $\rm{^6Li}$ atoms and $\rm{^{40}Ca^+}$ ions

TL;DR

This study measures how charge-exchange collision rates between ultracold $^6$Li atoms and $^{40}$Ca$^+$ ions depend on energy and internal states, confirming Langevin behavior and linking cross sections to ion states.

Contribution

It provides the first detailed characterization of charge-exchange collisions between ultracold $^6$Li atoms and $^{40}$Ca$^+$ ions, including energy and internal-state dependence.

Findings

Collision cross sections follow Langevin model.

Cross section magnitude varies with ion internal state.

Energy dependence consistent with theoretical predictions.

Abstract

We investigate the energy dependence and the internal-state dependence of the charge-exchange collision cross sections in a mixture of $^6$Li atoms and $^{40}$Ca$^+$ ions in the collision energy range from 0.2 mK to 1 K. Deliberately excited ion micromotion is used to control the collision energy of atoms and ions. The energy dependence of the charge-exchange collision cross section obeys the Langevin model in the temperature range of the current experiment, and the measured magnitude of the cross section is correlated to the internal state of the $^{40}$Ca$^+$ ions. Revealing the relationship between the charge-exchange collision cross sections and the interaction potentials is an important step toward the realization of the full quantum control of the chemical reactions at an ultralow temperature regime.