An impurity in a heteronuclear two-component Bose mixture

TL;DR

This paper investigates the behavior of an impurity in a heteronuclear Bose mixture, exploring various phases including miscible, immiscible, and self-bound droplets, revealing new impurity localization phenomena.

Contribution

It provides a comprehensive theoretical analysis of impurity dynamics in a heteronuclear BEC mixture, including novel impurity localization states in quantum droplets.

Findings

Impurity localizes at the center or surface of a quantum droplet.

Distinct impurity behaviors in miscible and immiscible regimes.

Identification of exotic impurity states in self-bound droplets.

Abstract

We study the fate of an impurity in an ultracold heteronuclear Bose mixture, focusing on the experimentally relevant case of a $^{41}$K-$^{87}$Rb mixture, with the impurity in a $^{41}$K hyperfine state. Our work provides a comprehensive description of an impurity in a BEC mixture with contact interactions across its phase diagram. We present results for the miscible and immiscible regimes, as well as for the impurity in a self-bound quantum droplet. Here, varying the interactions, we find novel, exotic states where the impurity localizes either at the center or at the surface of the droplet.