Quarter-Flux Hofstadter Lattice in Qubit-Compatible Microwave Cavity Array

TL;DR

This paper presents a novel microwave cavity array platform that simulates a topological Hofstadter model with controllable flux, enabling exploration of topological and strongly correlated quantum phenomena in a synthetic system.

Contribution

It introduces a low-loss, qubit-compatible microwave cavity lattice with engineered flux and broken time-reversal symmetry, demonstrating site-resolved spectroscopy and edge channel dynamics.

Findings

Successful implementation of a quarter-flux Hofstadter model in microwave cavities

Observation of edge channel dispersion and dynamics

Platform flexibility demonstrated with tunnel barriers

Abstract

Topological- and strongly-correlated- materials are exciting frontiers in condensed matter physics, married prominently in studies of the fractional quantum hall effect [1]. There is an active effort to develop synthetic materials where the microscopic dynamics and ordering arising from the interplay of topology and interaction may be directly explored. In this work we demonstrate a novel architecture for exploration of topological matter constructed from tunnel-coupled, time-reversalbroken microwave cavities that are both low loss and compatible with Josephson junction-mediated interactions [2]. Following our proposed protocol [3] we implement a square lattice Hofstadter model at a quarter flux per plaquette ({\alpha} = 1/4), with time-reversal symmetry broken through the chiral Wannier-orbital of resonators coupled to Yttrium-Iron-Garnet spheres. We demonstrate site-resolved spectroscopy of the lattice, time-resolved dynamics of its edge channels, and a direct measurement of the dispersion of the edge channels. Finally, we demonstrate the flexibility of the approach by erecting a tunnel barrier investigating dynamics across it. With the introduction of Josephson-junctions to mediate interactions between photons, this platform is poised to explore strongly correlated topological quantum science for the first time in a synthetic system.