Small polarons in dilute gas Bose-Einstein condensates

TL;DR

This paper explores how a neutral impurity in a dilute Bose-Einstein condensate can become self-localized, forming a small polaron by distorting the surrounding condensate density, analyzed through a strong coupling approach.

Contribution

It introduces a strong coupling theoretical framework to describe impurity self-localization in dilute BECs, highlighting the formation of small polarons.

Findings

Impurity can form a bound, self-localized state in dilute BECs.

Self-localization results from impurity-induced density distortion.

The strong coupling approach effectively models the polaron formation.

Abstract

A neutral impurity atom immersed in a dilute Bose-Einstein condensate (BEC) can have a bound ground state in which the impurity is self-localized. In this small polaron-like state, the impurity distorts the density of the surrounding BEC, thereby creating the self-trapping potential minimum. We describe the self-localization in a strong coupling approach.