Manifestations of the Roton Mode in Dipolar Bose-Einstein Condensates

TL;DR

This paper explores how the roton mode manifests in dipolar Bose-Einstein condensates, revealing that small perturbations can cause significant density profile changes linked to roton-like excitations.

Contribution

It demonstrates the connection between the roton mode and density oscillations in dipolar BECs using perturbation theory, highlighting new insights into their structure.

Findings

Small perturbations induce large density oscillations in dipolar BECs.

Roton-like modes are responsible for these density features.

Density oscillations also appear in vortex states of dipolar BECs.

Abstract

We investigate the structure of trapped Bose-Einstein condensates (BECs) with long-range anisotropic dipolar interactions. We find that a small perturbation in the trapping potential can lead to dramatic changes in the condensate's density profile for sufficiently large dipolar interaction strengths and trap aspect ratios. By employing perturbation theory, we relate these oscillations to a previously-identified "roton-like" mode in dipolar BECs. The same physics is responsible for radial density oscillations in vortex states of dipolar BECs that have been predicted previously.