# Artificial gauge fields and dimensions in a polariton hofstadter ladder

## TL;DR

The study demonstrates a new way to create topological edge transport in polariton systems using artificial gauge fields, eliminating the need for strong magnetic fields.

## Contribution

A new method to achieve non-reciprocal transport in polariton lattices using an artificial gauge field and polarization as an artificial dimension.

## Key findings

- Non-reciprocal transport of polariton pseudospins was demonstrated in a micropillar chain.
- Artificial gauge fields enabled topological edge-state propagation without strong magnetic fields.
- The approach overcomes dimensionality and magnetic field limitations in topological polariton systems.

## Abstract

Artificial gauge fields allow uncharged particles such as photons to mimic the behaviour of charged particles subjected to magnetic fields, providing a powerful platform to alter the effective dynamics and exploring topological physics. Topological exciton-polariton lasers have attracted considerable interest, but often require strong magnetic fields to realise propagating topological edge states. Here we experimentally realise the topological Hall effect in a micron-scale micropillar chain by using an artificial gauge field, exploiting the circular polarisation of polaritons as an artificial dimension. Careful rotational alignment of elliptical micropillars 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. Our results open new ways towards the implementation of topological polariton lattices and related optically active devices with additional artificial dimension.

The study shows a micron-scale polariton structure where an artificial gauge field creates topological, non-reciprocal edge transport without strong magnetic fields, overcoming key limits for topological polariton lasers and devices.