Artificial Gauge Fields and Dimensions in a Polariton Hofstadter Ladder

TL;DR

This paper demonstrates the use of artificial gauge fields and polarisation as an artificial dimension to realize topological edge states and non-reciprocal transport in a polariton lattice, avoiding the need for strong magnetic fields.

Contribution

It introduces a novel method to induce topological edge states in polariton systems using polarisation as an artificial dimension and engineered gauge fields, bypassing magnetic field requirements.

Findings

Realization of the topological Hall effect in a polariton chain

Polarisation-dependent edge-state propagation demonstrated

Non-reciprocal transport of polariton pseudospins achieved

Abstract

Artificial gauge fields allow uncharged particles to mimic the behavior of charged particles subjected to magnetic fields, providing a powerful platform for exploring topological physics. Neutral particles, like photons, are typically unaffected by real magnetic fields. However, it is possible to introduce artificial gauge fields that control the effective dynamics of these neutral particles. Topological exciton-polariton lasers have attracted considerable interest, in part due to the wide range of tunable system parameters, but often require strong magnetic fields to realise propagating topological edge states. Here we show, that by using an artificial gauge field the topological Hall effect in a micron-scale micropillar chain is experimentally realised, exploiting the circular polarisation of polaritons as an artificial dimension. By careful rotational alignment of elliptical micropillars, we introduce an effective plaquette phase that induces strictly polarisation-dependent edge-state propagation, demonstrating non-reciprocal transport of the polariton pseudospins. Our results demonstrate that the dimensionality limitation of topological interface states as well as requirements for strong external magnetic fields in coupled topological laser arrays can be overcome by utilizing polarisation effects and careful engineering of the potential landscape. Our results open new ways towards the implementation of topological polariton lattices and related optically active devices with additional artificial dimension.