Vortex phases and domain walls in trapped spinor Bose-Einstein condensates with inhomogeneous spin-orbital-angular-momentum coupling

TL;DR

This paper explores how inhomogeneous spin-orbital-angular-momentum coupling in spinor Bose-Einstein condensates leads to novel vortex phases and domain walls, revealing new quantum phase transitions and topological structures.

Contribution

It introduces a new vortex-necklace phase and an analytical model for domain wall radius in inhomogeneous SOAMC BECs, advancing understanding of topological phenomena.

Findings

Identification of stripe and vortex-necklace phases

Development of an analytical model for domain wall radius

Agreement between model predictions and numerical simulations

Abstract

We investigate the ground-state structures and vortex configurations in a two-component Bose-Einstein condensate (BEC) under the influence of spin-orbital-angular-momentum coupling (SOAMC) with a high spatial inhomogeneity and high characteristic orbital angular momentum. By modulating the coupling strength, we uncover two distinct quantum phases: a stripe phase at low coupling strengths and a new vortex-necklace phase at higher coupling intensities. The latter is characterized by vortices forming a ring-shaped structure that acts as a domain wall, a unique phase boundary between a central stripe phase and an outer single-momentum phase. For a better understanding of this new mixed phase of the system, we develop an analytical model to describe the domain wall radius as a function of coupling strength, which aligns well with numerical simulations. Our findings contribute to the understanding of SOAMC-driven quantum phase transitions and domain wall formation, offering new insights into topological phenomena in ultracold atomic systems.