Universal aspects of a strongly interacting impurity in a dilute Bose condensate

TL;DR

This paper investigates the universal behavior of a Bose polaron in a dilute Bose gas under strong impurity-boson interactions, revealing that key properties depend on a single potential parameter, extending understanding beyond weak interactions.

Contribution

It demonstrates that in the strong interaction regime, static quasiparticle properties depend universally on a single impurity-boson potential parameter, unlike the weak interaction case.

Findings

Static properties depend on a single potential parameter at unitarity.

Universal behavior extends beyond perturbative regimes.

Key quasiparticle properties are characterized by this universality.

Abstract

We study the properties of an impurity immersed in a weakly interacting Bose gas, i.e., of a Bose polaron. In the perturbatively-tractable of limit weak impurity-boson interactions many of its properties are known to depend only on the scattering length. Here we demonstrate that for strong (unitary) impurity-boson interactions all static quasiproperties of a Bose polaron in a dilute Bose gas, such as its energy, its residue, its Tan's contact and the number of bosons trapped nearby the impurity, depend on the impurity-boson potential via a single parameter.