Polaronic properties of an impurity in a Bose-Einstein condensate in reduced dimensions

TL;DR

This paper investigates how reducing the dimensionality of Bose-Einstein condensates affects polaron properties, using variational methods to predict enhanced polaronic features and experimental observability.

Contribution

It extends polaron theory to reduced dimensions and applies the Jensen-Feynman variational principle to calculate ground state and response properties.

Findings

Reduced dimensions lead to larger polaronic features.

Enhanced experimental observability of polaronic properties in lower dimensions.

Tuning polaronic coupling via Feshbach and confinement-induced resonances.

Abstract

The application of optical lattices allows a tuning of the geometry of Bose-Einstein condensates to effectively reduced dimensions. In the context of solid state physics the consideration of the low-dimensional Fr\"ohlich polaron results in an extension of the polaronic strong coupling regime. With this motivation we apply the Jensen-Feynman variational principle to calculate the ground state properties of the polaron consisting of an impurity in a Bose-Einstein condensate in reduced dimensions. Also the response of this system to Bragg scattering is calculated. We show that reducing the dimension leads to a larger amplitude of the polaronic features and is expected to facilitate the experimental observation of polaronic properties. In optical lattices not only Feshbach resonances but also confinement-induced resonances can be used to tune the polaronic coupling strength. This opens up the possibility to experimentally reveal the intermediate and strong polaronic coupling regimes and resolve outstanding theoretical questions regarding polaron theory.