# Ultracold bosonic scattering dynamics off a repulsive barrier: coherence loss at the dimensional crossover

## TL;DR

This paper investigates how the dimensionality of a bosonic system affects scattering dynamics off a barrier, revealing mechanisms of coherence loss linked to particle and spatial correlations, with implications for quantum coherence control.

## Contribution

It introduces a detailed analysis of coherence loss mechanisms in bosonic scattering across different dimensional regimes, highlighting the role of correlations and aspect ratio effects.

## Key findings

- Coherence loss mechanisms depend on aspect ratio and correlations.
- Weaker transverse confinement results in stronger decay of center of mass oscillations.
- Integer aspect ratios amplify correlation effects.

## Abstract

We explore the impact of dimensionality on the scattering of a small bosonic ensemble in an elongated harmonic trap off a centered repulsive barrier, thereby taking particle correlations into account. The loss of coherence as well as the oscillation of the center of mass are studied and we analyze the influence of both particle and spatial correlations. Two different mechanisms of coherence losses in dependence of the aspect ratio are found. For small aspect ratios, loss of coherence between the region close to the barrier and outer regions occurs, due to spatial correlations, and for large aspect ratios, incoherence between the two density fragments of the left and right side of the barrier arises, due to particle correlations. Apart form the decay of the center of mass motion induced by the reflection and transmission, further effects due to the particle and spatial correlations are explored. For tight transversal traps, the amplitude of the center of mass oscillation experiences a weaker damping, which can be traced back to the population of a second natural orbital, and for a weaker transversal confinement, we detect a strong decay, due to the possibility of transferring energy to transversal excited modes. These effects are enhanced if the aspect ratio is integer valued.