Observation of topological valley Hall edge states in honeycomb lattices of superconducting microwave resonators

TL;DR

This paper demonstrates the experimental observation of topological valley Hall edge states in honeycomb microwave resonator lattices with broken inversion symmetry, confirming theoretical predictions through spatial mode imaging and dispersion relation analysis.

Contribution

It reports the first realization and imaging of topological valley edge states in microwave photonic honeycomb lattices with engineered inversion symmetry breaking.

Findings

Observation of topological valley edge states at lattice interfaces

Dispersion relations match tight-binding model predictions

Spatial imaging confirms mode localization along interfaces

Abstract

We have designed honeycomb lattices for microwave photons with a frequency imbalance between the two sites in the unit cell. This imbalance is the equivalent of a mass term that breaks the lattice inversion symmetry. At the interface between two lattices with opposite imbalance, we observe topological valley edge states. By imaging the spatial dependence of the modes along the interface, we obtain their dispersion relation that we compare to the predictions of an ab initio tight-binding model describing our microwave photonic lattices.