Magnetic Phase Diagram of Light-mediated Spin Structuring in Cold Atoms

TL;DR

This paper investigates how cold atoms form complex 2D spin and light structures under laser illumination and magnetic fields, revealing new phases involving dipolar and quadrupolar magnetic moments.

Contribution

It introduces the observation of spontaneous 2D spin and light structuring in cold atoms, including novel quadrupolar magnetic phases induced by optical coherence.

Findings

Observation of high contrast spatial modulations in light and atomic spins.

Identification of phases related to dipolar and quadrupolar magnetic moments.

Demonstration of spontaneous quadrupolar magnetic structures in cold atoms.

Abstract

When applying a red-detuned retro-reflected laser beam to a large cloud of cold atoms, we observe the spontaneous formation of 2D structures in the transverse plane corresponding to high contrast spatial modulations of both light field and atomic spins. By applying a weak magnetic field, we explore the rich resulting phase space and identify specific phases associated with both dipolar and quadrupolar terms of the atomic magnetic moment. In particular we demonstrate spontaneous structures in optically induced ground state coherences representing magnetic quadrupoles.