Engineering topological materials in microwave cavity arrays

TL;DR

This paper proposes a scalable microwave cavity array architecture that enables the study of interacting topological photon phases, including non-reciprocal flux, topological band structures, and fractional quantum Hall states, using circuit QED techniques.

Contribution

It introduces a novel, scalable architecture combining microwave cavities, ferrites, and superconducting qubits to realize and explore interacting topological phases of photons.

Findings

Realizes various topological band structures including Hofstadter model

Demonstrates the creation of a bosonic Laughlin state with photon interactions

Shows robustness of the architecture against experimental disorder

Abstract

We present a scalable architecture for the exploration of interacting topological phases of photons in arrays of microwave cavities, using established techniques from cavity and circuit quantum electrodynamics. A time-reversal symmetry breaking (non-reciprocal) flux is induced by coupling the microwave cavities to ferrites, allowing for the production of a variety of topological band structures including the $\alpha=1/4$ Hofstadter model. Effective photon-photon interactions are included by coupling the cavities to superconducting qubits, and are sufficient to produce a $\nu=1/2$ bosonic Laughlin puddle. We demonstrate by exact diagonalization that this architecture is robust to experimentally achievable levels of disorder. These advances provide an exciting opportunity to employ the quantum circuit toolkit for the exploration of strongly interacting topological materials.