From the topological spin-Hall effect to the non-Hermitian skin effect in an elliptical micropillar chain

TL;DR

This paper demonstrates a system of elliptical micropillars that exhibits both the topological spin-Hall effect and the non-Hermitian skin effect, enabling robust polariton transport and vortex formation.

Contribution

It introduces a novel exciton-polariton lattice system that combines topological and non-Hermitian effects through polarization splitting and controlled decay rates.

Findings

Observation of topological spin-Hall effect in micropillar chain

Transition to non-Hermitian skin effect under incoherent pumping

Potential for robust polariton transport and vortex creation

Abstract

The topological spin-Hall effect causes different spins to propagate in opposite directions based on Hermitian physics. The non-Hermitian skin effect causes the localization of a large number of modes of a system at its edges. Here we propose a system based on exciton-polariton elliptical micropillars hosting both the effects. The polarization splitting of the elliptical micropillars gives rise to the topological spin-Hall effect in a one dimensional lattice. When a circularly polarized external incoherent laser is used to imbalance effective decay rates of the different spin polarizations, the system transits to a non-Hermitian regime showing the skin effect. These effects have implications for robust polariton transport as well as the deterministic formation of multiply charged vortices and persistent currents.