Dipolar dark solitons

TL;DR

This paper investigates the properties of dark soliton-like excitations in a dipolar quantum gas, revealing their interactions, bound states, energy loss mechanisms, and spontaneous formation in thermal conditions.

Contribution

It introduces the existence and dynamics of dipolar dark solitons, highlighting their interactions, stability, and spontaneous emergence in thermal dipolar gases.

Findings

Dipolar dark solitons interact and form bound states.

They emit phonons and lose energy during collisions.

Solitons can spontaneously appear in thermal samples.

Abstract

We numerically generate, and then study the basic properties of dark soliton-like excitations in a dipolar gas confined in a quasi one dimensional trap. These excitations, although very similar to dark solitons in a gas with contact interaction, interact with each other and can form bound states. During collisions these dipolar solitons emit phonons, loosing energy, but accelerating. Even after thousands of subsequent collisions they survive as gray solitons and finally reach dynamical equilibrium with background quasiparticles. Finally, in the frame of classical field approximation, we verified, that these solitons appear spontaneously in thermal samples, analogously to the type II excitations in a gas of atoms with contact interaction.