# Observation of edge waves in a two-dimensional Su-Schrieffer-Heeger acoustic network

## TL;DR

This paper experimentally demonstrates topological edge waves in a 2D acoustic network modeled after the SSH system, revealing topological band gaps and edge states in audible sound frequencies.

## Contribution

It provides the first experimental realization of 2D SSH topological acoustic waves without tight binding approximation, using a simple air channel network.

## Key findings

- Observation of topological band gap in acoustic network
- Detection of edge waves within the band gap
- Validation of topological properties in a zero Berry curvature system

## Abstract

In this work, we experimentally report the acoustic realization the two-dimensional (2D) Su-Schrieffer-Heeger (SSH) model in a simple network of air channels. We analytically study the steady state dynamics of the system using a set of discrete equations for the acoustic pressure, leading to the 2D SSH Hamiltonian matrix without using tight binding approximation. By building an acoustic network operating in audible regime, we experimentally demonstrate the existence of topological band gap. More supremely, within this band gap we observe the associated edge waves even though the system is open to free space. Our results not only experimentally demonstrate topological edge waves in a zero Berry curvature system but also provide a flexible platform for the study of topological properties of sound waves.