Trap-assisted complexes in cold atom-ion collisions

TL;DR

This paper models how trap-assisted atom-ion complexes form and influence reactions in cold atom-ion systems, highlighting the roles of trap dynamics and atom mass in complex formation and stability.

Contribution

It introduces a theoretical framework for understanding trap-assisted complex formation in atom-ion collisions, emphasizing the effects of trap type and atom mass.

Findings

Complex formation is more pronounced with heavier atoms.

The micromotion amplitude strongly influences complex formation rates.

Complexes persist even in static harmonic traps, with higher formation rates.

Abstract

We theoretically investigate the trap-assisted formation of complexes in atom-ion collisions and their impact on the stability of the trapped ion. The time-dependent potential of the Paul trap facilitates the formation of temporary complexes by reducing the energy of the atom, which gets temporarily stuck in the atom-ion potential. As a result, those complexes significantly impact termolecular reactions leading to molecular ion formation via three-body recombination. We find that complex formation is more pronounced in systems with heavy atoms, but the mass has no influence on the lifetime of the transient state. Instead, the complex formation rate strongly depends on the amplitude of the ion's micromotion. We also show that complex formation persists even in the case of a time-independent harmonic trap. In this case, we find higher formation rates and longer lifetimes than the Paul trap, indicating that the atom-ion complex plays an essential role in atom-ion mixtures in optical traps.