Dark-bright solitons in Bose-Einstein condensates at finite temperatures

TL;DR

This paper investigates the finite-temperature dynamics of dark-bright solitons in Bose-Einstein condensates, revealing how the bright component stabilizes dark solitons and analyzing their interactions and thermal effects.

Contribution

It develops a perturbation theory for two-component dissipative Gross-Pitaevskii equations to describe soliton dynamics and stability at finite temperatures.

Findings

Bright component stabilizes dark solitons against thermal dissipation.

Dark-bright soliton molecules exhibit expanding oscillations.

Analytical results agree with numerical simulations.

Abstract

We study the dynamics of dark-bright solitons in binary mixtures of Bose gases at finite temperature using a system of two coupled dissipative Gross-Pitaevskii equations. We develop a perturbation theory for the two-component system to derive an equation of motion for the soliton centers and identify different temperature-dependent damping regimes. We show that the effect of the bright ("filling") soliton component is to partially stabilize "bare" dark solitons against temperature-induced dissipation, thus providing longer lifetimes. We also study analytically thermal effects on dark-bright soliton "molecules" (i.e., two in- and out-of-phase dark-bright solitons), showing that they undergo expanding oscillations while interacting. Our analytical findings are in good agreement with results obtained via a Bogoliubov-de Gennes analysis and direct numerical simulations.