Kelvon-roton instability of vortex lines in dipolar Bose-Einstein condensates

TL;DR

This paper investigates how dipolar interactions influence vortex line stability in Bose-Einstein condensates, revealing conditions under which a roton minimum causes vortex instability, thus opening new research avenues.

Contribution

It introduces the concept of roton-induced instability in vortex lines within dipolar Bose-Einstein condensates, highlighting the impact of nonlocal interactions on vortex dynamics.

Findings

Dipolar interactions significantly affect vortex stability.

A roton minimum can develop in the vortex spectrum.

Vortex instability can occur due to roton softening.

Abstract

The physics of vortex lines in dipolar condensates is studied. Due to the nonlocality of the dipolar interaction, the 3D character of the vortex plays a more important role in dipolar gases than in typical short-range interacting ones. In particular, the dipolar interaction significantly affects the stability of the transverse modes of the vortex line. Remarkably, in the presence of a periodic potential along the vortex line, a roton minimum may develop in the spectrum of transverse modes. We discuss the appropriate conditions at which this roton minimum may eventually lead to an instability of the straight vortex line, opening new scenarios for vortices in dipolar gases.