Optical response of the supersolid polaron

TL;DR

This paper investigates the optical response of a neutral impurity in a dipolar supersolid, revealing how excitation modes influence the optical spectrum and proposing experimental probes for supersolid excitations.

Contribution

It provides the first calculation of the optical response of an impurity in a dipolar supersolid, linking spectral features to supersolid excitation modes.

Findings

Identification of Van Hove singularities in the spectrum

Observation of a peak related to the roton minimum

Proposal of using impurity response as an experimental probe

Abstract

The ground-state properties of the supersolid polaron consisting of a neutral impurity immersed in a dipolar supersolid have recently been studied. Here, the optical response of an impurity in a dipolar supersolid is calculated and interpreted in terms of the contributions of the different excitation modes of the supersolid. The optical absorption spectrum reveals the two Van Hove singularities that correspond to the flattening of the two Goldstone modes of the supersolid at the Brillouin zone edge. A single peak is found in the superfluid regime corresponding to the roton minimum which diverges at the transition. We propose the response of an ionic impurity as an experimental probe for the supersolid excitations and show how this technique can be extended to neutral impurities with an electric or magnetic dipole moment.