Quantum phases of Bose-Einstein condensates with synthetic spin - orbital-angular-momentum coupling

TL;DR

This paper investigates the complex quantum phases of Bose-Einstein condensates with synthetic spin-orbital-angular-momentum coupling, revealing rich interaction-driven structures and guiding future experiments.

Contribution

It introduces a detailed study of BECs with SOAM coupling in a realistic, inhomogeneous setting, highlighting the interplay between interactions and spin-orbit effects.

Findings

Discovery of stripe phases in spin-resolved distributions

Identification of immiscible states due to SOAM coupling

Deviation from single-particle predictions in the strongly interacting regime

Abstract

The experimental realization of emergent spin-orbit coupling through laser-induced Raman transitions in ultracold atoms paves the way for exploring novel superfluid physics and simulating exotic many-body phenomena. A recent proposal with the use of Laguerre-Gaussian lasers enables another fundamental type of coupling between spin and orbital angular momentum (SOAM) in ultracold atoms. We hereby study quantum phases of a realistic Bose-Einstein condensate (BEC) with this synthetic SOAM coupling in a disk-shaped geometry, respecting radial inhomogeneity of the Raman coupling. We find that the experimental system naturally resides in a strongly interacting regime in which the phase diagram significantly deviates from the single-particle picture. The interplay between SOAM coupling and interaction leads to rich structures in spin-resolved position and momentum distributions, including a stripe phase and various types of immiscible states. Our results would provide a guide for an experimental investigation of SOAM-coupled BECs.