Tkachenko polarons in vortex lattices

TL;DR

This paper studies impurities in vortex lattices of ultracold bosons, revealing unique damping behaviors of Tkachenko polarons due to their interaction with collective modes, which can be experimentally observed.

Contribution

It derives an effective polaron model incorporating impurity interactions with Tkachenko modes, highlighting novel damping phenomena at zero temperature.

Findings

Lorentzian broadening of spectral function at small wave vectors

Anomalous damping of Tkachenko polarons

Potential for experimental detection via spectroscopy

Abstract

We analyze the properties of impurities immersed in a vortex lattice formed by ultracold bosons in the mean field quantum Hall regime. In addition to the effects of a periodic lattice potential, the impurity is dressed by collective modes with parabolic dispersion (Tkachenko modes). We derive the effective polaron model, which contains a marginal impurity-phonon interaction. The polaron spectral function exhibits a Lorentzian broadening for arbitrarily small wave vectors even at zero temperature, in contrast with the result for optical or acoustic phonons. The anomalous damping of Tkachenko polarons could be detected experimentally using momentum-resolved spectroscopy.