Spin-orbital-angular-momentum coupled Bose-Einstein condensates

TL;DR

This paper demonstrates the coupling of atomic spin and orbital angular momentum in a Bose-Einstein condensate using Raman-dressing lasers, creating coreless vortices and revealing spin-OAM correlations with potential for topological quantum states.

Contribution

It introduces a novel method to couple spin and orbital angular momentum in BECs using Laguerre-Gaussian beams, enabling the creation of coreless vortices and new topological textures.

Findings

Observation of spin-OAM correlations in dressed states

Creation of stable coreless vortices in BECs

Potential for exploring new topological quantum states

Abstract

We demonstrate coupling between the atomic spin and orbital-angular-momentum (OAM) of the atom's center-of-mass motion in a Bose-Einstein condensate (BEC). The coupling is induced by Raman-dressing lasers with a Laguerre-Gaussian beam, and creates coreless vortices in a $F=1$ $^{87}$Rb spinor BEC. We observe correlations between spin and OAM in the dressed state and characterize the spin texture; the result is in good agreement with the theory. In the presence of the Raman field our dressed state is stable for 0.1~s or longer, and it decays due to collision-induced relaxation. As we turn off the Raman beams, the vortex cores in the bare spin $|m_F=1\rangle$ and $|-1\rangle$ split. These spin-OAM coupled systems with the Raman-dressing approach have great potential for exploring new topological textures and quantum states.