Unconventional magnetism via optical pumping of interacting spin systems

TL;DR

This paper predicts new magnetic phases in strongly interacting spin systems driven by optical pumping, revealing nonequilibrium phase transitions and quantum correlations, with potential experimental realizations in ultracold atoms and trapped ions.

Contribution

It introduces the concept of novel steady-state magnetic phases arising from the interplay of coherent and dissipative processes in optically pumped spin systems.

Findings

Discovery of ferromagnetic, antiferromagnetic, and spin-density-wave steady states.

Identification of nonequilibrium phase transitions at a Lifshitz point.

Observation of spin squeezing associated with quantum correlations.

Abstract

We consider strongly interacting systems of effective spins, subject to dissipative spin-flip processes associated with optical pumping. We predict the existence of novel magnetic phases in the steady-state of this system, which emerge due to the competition between coherent and dissipative processes. Specifically, for strongly anisotropic spin-spin interactions, we find ferromagnetic, antiferromagnetic, spin-density-wave, and staggered-XY steady states, which are separated by nonequilibrium phase transitions meeting at a Lifshitz point. These transitions are accompanied by quantum correlations, resulting in spin squeezing. Experimental implementations in ultracold atoms and trapped ions are discussed.