A General Method to Design Acoustic Higher-Order Topological Insulators

TL;DR

This paper introduces a universal method for designing acoustic higher-order topological insulators using a kagome lattice, linking theoretical models with practical acoustic system implementations.

Contribution

It derives a Hamiltonian for acoustic systems from topological crystalline insulators, establishing a direct correspondence between theoretical models and acoustic device design.

Findings

Exact Hamiltonian derivation from acoustic perspective

Soft boundary conditions correspond to generalized chiral symmetry

Platform enables construction of versatile topological devices

Abstract

Acoustic systems that are without limitations imposed by the Fermi level have been demonstrated as significant platform for the exploration of fruitful topological phases. By surrounding the nontrivial domain with trivial "environment", the domain-wall topological states have been theoretically and experimentally demonstrated. In this work, based on the topological crystalline insulator with a kagome lattice, we rigorously derive the corresponding Hamiltonian from the traditional acoustics perspective, and exactly reveal the correspondences of the hopping and onsite terms within acoustic systems. Crucially, these results directly indicate that instead of applying the trivial domain, the soft boundary condition precisely corresponds to the theoretical models which always require generalized chiral symmetry. These results provide a general platform to construct desired acoustic topological devices hosting desired topological phenomena for versatile applications.