# Analyzing a Bose polaron across resonant interactions

## TL;DR

This paper investigates Bose polarons in a condensate, disentangling experimental effects, comparing theoretical models, and developing a semi-classical theory to better understand their properties across interaction strengths.

## Contribution

It provides a detailed analysis of polaron energies, dynamics, and loss mechanisms, reconciling experimental results with advanced theoretical calculations.

## Key findings

- Good agreement between experiments and quantum Monte-Carlo calculations
- Development of a semi-classical model for polaron dynamics and losses
- Consistency established between different experimental observations

## Abstract

Recently, two independent experiments reported the observation of long-lived polarons in a Bose-Einstein condensate, providing an excellent setting to study the generic scenario of a mobile impurity interacting with a quantum reservoir. Here, we expand the experimental analysis by disentangling the effects of trap inhomogeneities and the many-body continuum in one of these experiments. This makes it possible to extract the energy of the polaron at a well-defined density as a function of the interaction strength. Comparisons with quantum Monte-Carlo as well as diagrammatic calculations show good agreement, and provide a more detailed picture of the polaron properties at stronger interactions than previously possible. Moreover, we develop a semi-classical theory for the motional dynamics and three-body loss of the polarons, which partly explains a previously unresolved discrepancy between theory and experimental observations for repulsive interactions. Finally, we utilize quantum Monte-Carlo calculations to demonstrate that the findings reported in the two experiments are consistent with each other.