Polarons and bipolarons in Rydberg-dressed extended Bose-Hubbard model

TL;DR

This paper explores how impurities behave as polarons or bipolarons in a Rydberg-dressed extended Bose-Hubbard model, revealing phase-dependent properties and bound states relevant for ultracold gas experiments.

Contribution

It provides a detailed analysis of impurity ground states across different phases, highlighting the formation of bound impurity pairs without explicit interaction.

Findings

Impurities form polaron-like quasiparticles in the superfluid phase.

Impurities regain particle-like behavior in the insulating phase.

Two impurities can form a bound state without explicit coupling.

Abstract

Impurities immersed in hard-core Bose gases offer exciting opportunities to explore polaron and bipolaron physics. We investigate the ground state properties of a single and a pair of impurities throughout the superfluid and insulating (charge density wave) phases of the bosonic environment. In the superfluid phase, the impurity exhibits polaron-like behavior, forming a dressed quasiparticle. In contrast, in the insulating phase, the impurity regains its particle-like character, moving through a potential landscape shaped by the charge density wave order. Moreover, we show that two impurities can form a bound state even in the absence of an explicit impurity-impurity coupling. We establish the stability of this bound state within both the superfluid and insulating phases. Our results offer valuable insights for ongoing lattice polaron experiments with ultracold gases.