From the Topological Spin-Hall Effect to the Non-Hermitian Skin Effect in an Elliptical Micropillar Chain

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.