Inelastic collision dynamics of a single cold ion immersed in a Bose-Einstein condensate

TL;DR

This study explores the inelastic collision processes of a single cold ion in a Bose-Einstein condensate, revealing rapid three-body recombination and molecular ion formation, with insights gained through an energy-resolved dissociation technique in a field-free environment.

Contribution

It introduces a novel method to investigate ion-atom interactions in a field-free setting using Rydberg excitation and energy-resolved dissociation, advancing understanding of impurity dynamics in ultracold gases.

Findings

Rapid three-body recombination leading to molecular ion formation

Secondary collisions quench rovibrational states to deeper binding energies

Good agreement between experimental results and Langevin capture simulations

Abstract

We investigate inelastic collision dynamics of a single cold ion in a Bose-Einstein condensate. We observe rapid ion-atom-atom three-body recombination leading to formation of weakly bound molecular ions followed by secondary two-body molecule-atom collisions quenching the rovibrational states towards deeper binding energies. In contrast to previous studies exploiting hybrid ion traps, we work in an effectively field-free environment and generate a free low-energy ionic impurity directly from the atomic ensemble via Rydberg excitation and ionization. This allows us to implement an energy-resolved field-dissociation technique to trace the relaxation dynamics of the recombination products. Our observations are in good agreement with numerical simulations based on Langevin capture dynamics and provide complementary means to study stability and reaction dynamics of ionic impurities in ultracold quantum gases.