Extended topological mode in a one-dimensional non-Hermitian acoustic crystal

Abstract

In Hermitian topological systems, topological modes (TMs) are bound to interfaces or defects of a lattice. Recent discoveries show that non-Hermitian effects can reshape the wavefunctions of the TMs and even turn them into extended modes occupying the entire bulk lattice. In this letter, we experimentally demonstrate such an extended TM (ETM) in a one-dimensional (1D) non-Hermitian acoustic topological crystal. The acoustic crystal is formed by a serie of coupled acoustic resonant cavities, and the non-Hermiticity is introduced as the non-reciprocal coupling coefficient using active electroacoustic controllers (AECs). Our work highlights the potential universality of ETMs in different physical systems and resolves the technical challenges in the further study of ETMs in acoustic waves.

8 pages, 3 figures

References in corpus (6)

• Making Sense of Non-Hermitian Hamiltonians
• Non-Hermitian Topology and Exceptional-Point Geometries
• Topological acoustics
• Acoustic non-Hermitian skin effect from twisted winding topology
• Non-Hermitian Morphing of Topological Modes
• Delocalization of topological edge states

Cited by in corpus (5)

• Realization and Topological Properties of Third-Order Exceptional Lines Embedded in Exceptional Surfaces
• Anderson transition at complex energies in one-dimensional parity-time-symmetric disordered systems
• Higher-order Skin Effect through a Hermitian-non-Hermitian Correspondence and Its Observation in an Acoustic Kagome Lattice
• Extended imaginary gauge transformation in a general nonreciprocal lattice
• Exceptional point rings and $PT$-symmetry in the non-Hermitian XY model