Engineering spin-orbit coupling for photons and polaritons in microstructures

TL;DR

This paper demonstrates the engineering of spin-orbit coupling for photons and polaritons in semiconductor microstructures, revealing new wavefunction behaviors and opening avenues for quantum simulation of complex interactions.

Contribution

It introduces a novel method to induce spin-orbit coupling in photons and polaritons using coupled micropillars in a microcavity, with experimental observation of resulting wavefunction phenomena.

Findings

Observation of helical polariton condensate wavefunctions

Spin-orbit coupling effects visible in polarization patterns

Potential for quantum simulation with polariton fluids

Abstract

One of the most fundamental properties of electromagnetism and special relativity is the coupling between the spin of an electron and its orbital motion. This is at the origin of the fine structure in atoms, the spin Hall effect in semiconductors, and underlies many intriguing properties of topological insulators, in particular their chiral edge states. Configurations where neutral particles experience an effective spin-orbit coupling have been recently proposed and realized using ultracold atoms and photons. Here we use coupled micropillars etched out of a semiconductor microcavity to engineer a spin-orbit Hamiltonian for photons and polaritons in a microstructure. The coupling between the spin and orbital momentum arises from the polarisation dependent confinement and tunnelling of photons between micropillars arranged in the form of a hexagonal photonic molecule. Dramatic consequences of the spin-orbit coupling are experimentally observed in these structures in the wavefunction of polariton condensates, whose helical shape is directly visible in the spatially resolved polarisation patterns of the emitted light. The strong optical nonlinearity of polariton systems suggests exciting perspectives for using quantum fluids of polaritons11 for quantum simulation of the interplay between interactions and spin-orbit coupling.