Spin-Nematic Vortex States in Cold Atoms

TL;DR

This paper introduces a novel spin-nematic vortex state in high-spin cold atom systems, coupling spin tensors with orbital angular momentum, leading to topologically quantized phases and expanding the landscape of topological quantum matter.

Contribution

It proposes a simple scheme to couple spin tensors with orbital angular momentum in spin-1 cold atoms, revealing a new topological spin-nematic vortex phase.

Findings

Discovery of spin-nematic vortex states with quantized topological numbers

Coupling scheme between spin tensor and orbital angular momentum

Potential for new topological phases in high-spin cold atom systems

Abstract

The (pseudo-)spin degrees of freedom greatly enriches the physics of cold atoms. This is particularly so for systems with high spins (i.e., spin quantum number larger than 1/2). For example, one can construct not only the rank-1 spin vector, but also the rank-2 spin tensor in high spin systems. Here we propose a simple scheme to couple the spin tensor and the center-of-mass orbital angular momentum in a spin-1 cold atom system, and show that this leads to a new quantum phase of the matter: the spin-nematic vortex state that features vorticity in an SU(2) spin-nematic tensor subspace. Under proper conditions, such states are characterized by quantized topological numbers. Our work opens up new avenues of research in topological quantum matter with high spins.