Topological states in partially-PT-symmetric azimuthal potentials

TL;DR

This paper introduces partially-PT-symmetric azimuthal potentials supporting stable vortex solitons with properties dependent on topological charge, revealing directional asymmetries and distinct internal current distributions in nonlinear media.

Contribution

It presents a novel class of partially-PT-symmetric potentials with topological states, highlighting their unique asymmetric vortex dynamics and stability properties.

Findings

Stable vortex solitons exist in pPT-symmetric potentials.

Vortex properties depend on the sign of topological charge.

Internal current distributions differ between pPT- and PT-symmetric potentials.

Abstract

We introduce partially-parity-time-symmetric (pPT-symmetric) azimuthal potentials composed from individual PT-symmetric cells located on a ring, where two azimuthal directions are nonequivalent in a sense that in such potentials excitations carrying topological dislo-cations exhibit different dynamics for different directions of energy circulation in the initial field distribution. Such non-conservative ratchet-like structures support rich families of stable vortex solitons in cubic nonlinear media, whose properties depend on the sign of the topological charge due to the nonequivalence of azimuthal directions. In contrast, oppositely charged vortex solitons remain equivalent in similar fully PT-symmetric potentials. The vortex solitons in the pPT- and PT-symmetric potentials are shown to feature qualitatively different internal current distributions, which are described by different discrete rotation symmetries of the intensity profiles.