Rotation of cold molecular ions inside a Bose-Einstein condensate

TL;DR

This paper applies angulon theory to analyze the rotational behavior of molecular ions in Bose-Einstein condensates, revealing observable many-body effects and proposing a new pseudopotential construction method.

Contribution

It introduces a detailed theoretical study of molecular ion rotation in BECs, including the rotational Lamb shift, fine structure, and a novel pseudopotential construction approach.

Findings

Large rotational Lamb shift and fine structure effects predicted

Effects are experimentally observable with current technology

New method for constructing pseudopotentials from ab initio data

Abstract

We use recently developed angulon theory [Phys. Rev. Lett. 114, 203001 (2015)] to study the rotational spectrum of a cyanide molecular anion immersed into Bose-Einstein condensates of rubidium and strontium. Based on $\textit {ab initio}$ potential energy surfaces, we provide a detailed study of the rotational Lamb shift and many-body-induced fine structure which arise due to dressing of molecular rotation by a field of phonon excitations. We demonstrate that the magnitude of these effects is large enough in order to be observed in modern experiments on cold molecular ions. Furthermore, we introduce a novel method to construct pseudopotentials starting from the $\textit {ab initio}$ potential energy surfaces, which provides a means to obtain effective coupling constants for low-energy polaron models.