Magnetic solitons in Rabi-coupled Bose-Einstein condensates

TL;DR

This paper investigates magnetic solitons in Rabi-coupled Bose-Einstein condensates, identifying two types with distinct phase behaviors, and explores their dynamics, properties, and stability in trapped systems.

Contribution

It introduces and characterizes two novel types of magnetic solitons, $2 ext{ extpi}$ and $0 ext{ extpi}$, in Rabi-coupled BECs, including their dynamics and transformations in trapping potentials.

Findings

Identification of $2 ext{ extpi}$ and $0 ext{ extpi}$ solitons with distinct phase properties.

Numerical demonstration of soliton transformation within harmonic traps.

Analysis of effective mass, critical velocity, and confinement effects on soliton behavior.

Abstract

We study magnetic solitons, solitary waves of spin polarization (i.e., magnetization), in binary Bose-Einstein condensates in the presence of Rabi coupling. We show that the system exhibits two types of magnetic solitons, called $2\pi$ and $0\pi$ solitons, characterized by a different behavior of the relative phase between the two spin components. $2\pi$ solitons exhibit a $2\pi$ jump of the relative phase, independent of their velocity, the static domain wall explored by Son and Stephanov being an example of such $2\pi$ solitons with vanishing velocity and magnetization. $0\pi$ solitons instead do not exhibit any asymptotic jump in the relative phase. Systematic results are provided for both types of solitons in uniform matter. Numerical calculations in the presence of a one-dimensional harmonic trap reveal that a $2\pi$ soliton evolves in time into a $0\pi$ soliton, and vice versa, oscillating around the center of the trap. Results for the effective mass, the Landau critical velocity, and the role of the transverse confinement are also discussed.