Barnett effect in rotating spinor dipolar quantum droplets

TL;DR

This paper explores how the Barnett effect can stabilize vortex states in dipolar Bose-Einstein condensate droplets by inducing spontaneous magnetization and enabling controlled rotation.

Contribution

It introduces a novel mechanism for stabilizing vortex states through spin degrees of freedom and spontaneous magnetization in dipolar quantum droplets.

Findings

Spontaneous magnetization arises via the Barnett effect when a vortex is embedded.

Applying an external magnetic field induces the entire droplet to rotate.

Stable bound states of droplets form due to attractive interactions between magnetized droplets.

Abstract

We propose releasing the spin degree of freedom to stabilize the vortex state in self-bound droplets of dipolar Bose-Einstein condensates. When a vortex is embedded into the droplet, spontaneous magnetization arises in the axial direction via a mechanism similar to the Barnett effect; that is, the orbital angular momentum is transferred to the spin angular momentum. When an external magnetic field is applied to the spontaneously magnetized droplet, the entire atomic cloud starts to rotate without changing its shape, which can be regarded as mechanical Larmor precession of a macroscopic object. A chirally different pair of droplets can form a stable bound state because of the attractive interaction between the spontaneously magnetized droplets.