Rotons and their damping in elongated dipolar Bose-Einstein condensates

TL;DR

This paper investigates how rotons in elongated dipolar Bose-Einstein condensates are damped at finite temperatures, revealing that many excitation branches influence damping rates and that rotons can remain stable even with very small energy gaps.

Contribution

It introduces a detailed analysis of roton damping mechanisms in elongated dipolar BECs, highlighting the role of multiple excitation branches and stability conditions.

Findings

Many excitation branches contribute to increased damping rates.

Rotons with very small energy gaps can remain stable.

Finite temperature effects significantly influence roton stability.

Abstract

We discuss finite temperature damping of rotons in elongated Bose-condensed dipolar gases, which are in the Thomas-Fermi regime in the tightly confined directions. The presence of many branches of excitations which can participate in the damping process, is crucial for the Landau damping and results in significant increase of the damping rate. It is found, however, that even rotons with energies close to the roton gap may remain fairly stable in systems with the roton gap as small as 1nK.