Capture Dynamics of Ultracold Atoms in the Presence of an Impurity Ion

TL;DR

This paper investigates the quantum dynamics of ultracold bosonic atoms in one dimension after an ion is suddenly introduced, revealing complex many-body behaviors including oscillations, coherence, and correlation effects.

Contribution

It provides a detailed, correlation-inclusive analysis of atom-ion interactions and their impact on ultracold atomic dynamics, using advanced numerical and analytical methods.

Findings

Atomic ensemble separates into bound and unbound fractions

Oscillations in atomic density due to atom-ion interactions

Collapse and revival phenomena from two-particle correlations

Abstract

We explore the quantum dynamics of a one-dimensional trapped ultracold ensemble of bosonic atoms triggered by the sudden creation of a single ion. The numerical simulations are performed by means of the ab initio multiconfiguration time-dependent Hartree method for bosons which takes into account all correlations. The dynamics is analyzed via a cluster expansion approach, adapted to bosonic systems of fixed particle number, which provides a comprehensive understanding of the occurring many-body processes. After a transient during which the atomic ensemble separates into fractions which are unbound and bound with respect to the ion, we observe an oscillation in the atomic density which we attribute to the additional length and energy scale induced by the attractive long-range atom-ion interaction. This oscillation is shown to be the main source of spatial coherence and population transfer between the bound and the unbound atomic fraction. Moreover, the dynamics exhibits collapse and revival behavior caused by the dynamical build-up of two-particle correlations demonstrating that a beyond mean-field description is indispensable.