Topological Phases of Sound and Light

TL;DR

This paper proposes creating a tunable topological phonon insulator in solid-state systems using optomechanical interactions, enabling robust, chiral phonon transport controlled by light.

Contribution

It introduces a method to realize a Chern insulator of phonons in a dielectric slab with optically tunable topological properties, combining photons and phonons.

Findings

Topologically protected phonon edge states can be optically probed.

Tunable topological phases emerge from photon-phonon interactions.

Strong mixing regimes lead to diverse topological phases.

Abstract

Topological states of matter are particularly robust, since they exploit global features insensitive to local perturbations. In this work, we describe how to create a Chern insulator of phonons in the solid state. The proposed implementation is based on a simple setting, a dielectric slab with a suitable pattern of holes. Its topological properties can be wholly tuned in-situ by adjusting the amplitude and frequency of a driving laser that controls the optomechanical interaction between light and sound. The resulting chiral, topologically protected phonon transport along the edges can be probed completely optically. Moreover, we identify a regime of strong mixing between photon and phonon excitations, which gives rise to a large set of different topological phases. This would be an example of a Chern insulator produced from the interaction between two physically very different particle species, photons and phonons.