Strong-coupling Bose polarons in 1D: Condensate deformation and modified Bogoliubov phonons

TL;DR

This paper investigates the behavior of Bose polarons in one-dimensional systems, revealing that impurity-induced condensate deformation significantly alters polaron properties, and introduces a model that accounts for this backaction, aligning well with quantum Monte-Carlo results.

Contribution

The study develops a new model for 1D Bose polarons that incorporates condensate backaction, extending beyond the traditional Fröhlich model and accurately matching numerical simulations.

Findings

Polaron energies and masses agree with quantum Monte-Carlo simulations.

Condensate deformation plays a crucial role in 1D Bose polarons.

The model improves understanding of impurity-condensate interactions in low dimensions.

Abstract

We discuss the interaction of a quantum impurity with a one-dimensional degenerate Bose gas forming a Bose-polaron. In three spatial dimensions the quasiparticle is typically well described by the extended Fr\"ohlich model, in full analogy with the solid-state counterpart. This description, which assumes an undepleted condensate, fails however in 1D, where the backaction of the impurity on the condensate leads to a self-bound mean-field polaron for arbitrarily weak impurity-boson interactions. We present a model that takes into account this backaction and describes the impurity-condensate interaction as coupling to phonon-like excitations of a deformed condensate. A comparison of polaron energies and masses to diffusion quantum Monte-Carlo simulations shows very good agreement already on the level of analytical mean-field solutions and is further improved when taking into account quantum fluctuations.