Quantum phases of spin-orbital-angular-momentum coupled bosonic gases in optical lattices

TL;DR

This paper explores the emergence of diverse quantum phases in ultracold bosonic gases with spin-orbital-angular-momentum coupling in optical lattices, revealing complex spin textures and many-body states driven by engineered laser interactions.

Contribution

It introduces a novel scheme combining SOAM coupling with strong correlations, uncovering new quantum phases and spin textures in the Mott-insulating regime of ultracold gases.

Findings

Rich quantum phases supported by SOAM coupling including spin and composite vortices

Effective exchange model shows Dzyaloshinskii-Moriya and Heisenberg interactions cause spin textures

Additional phases like canted-antiferromagnetic and stripe phases emerge with combined couplings

Abstract

Spin-orbit coupling plays an important role in understanding exotic quantum phases. In this work, we present a scheme to combine spin-orbital-angular-momentum (SOAM) coupling and strong correlations in ultracold atomic gases. Essential ingredients of this setting is the interplay of SOAM coupling and Raman-induced spin-flip hopping, engineered by lasers that couples different hyperfine spin states. In the presence of SOAM coupling only, we find rich quantum phases in the Mott-insulating regime, which support different types of spin defects such as spin vortex and composite vortex with antiferromagnetic core surrounded by the outer spin vortex. Based on an effective exchange model, we find that these competing spin textures are a result of the interplay of Dzyaloshinskii-Moriya and Heisenberg exchange interactions. In the presence of both SOAM coupling and Raman-induced spin-flip hopping, more many-body phases appear, including canted-antiferromagnetic and stripe phases. Our prediction suggests that SOAM coupling could induce rich exotic many-body phases in the strongly interacting regime.