Chiral emission induced by optical Zeeman effect in polariton micropillars

TL;DR

This paper demonstrates that polarization-dependent interactions in microcavity polaritons can break time-reversal symmetry and induce chiral emission without external magnetic fields, enabling optical control of topological states.

Contribution

It reveals a novel mechanism for breaking time-reversal symmetry in polaritons via polarization interactions, leading to chiral emission without magnetic fields.

Findings

Polarization-dependent polariton interactions induce Zeeman-like splitting.

Circularly polarized excitation results in vortical, chiral emission.

Potential for optically controlling topological polariton states.

Abstract

The low sensitivity of photons to external magnetic fields is one of the major challenges for the engineering of photonic lattices with broken time-reversal symmetry. Here we show that time-reversal symmetry can be broken for microcavity polaritons in the absence of any external magnetic field thanks to polarization dependent polariton interactions. Circularly polarized excitation of carriers in a micropillar induces a Zeeman-like energy splitting between polaritons of opposite polarizations. In combination with optical spin-orbit coupling inherent to semiconductor microstructures, the interaction induced Zeeman splitting results in emission of vortical beams with a well-defined chirality. Our experimental findings can be extended to lattices of coupled micropillars opening the possibility of controling optically the topological properties of polariton Chern insulators.