Observation of Coherent Perfect Acoustic Absorption at an Exceptional Point

TL;DR

This paper demonstrates the experimental realization of coherent perfect acoustic absorption at an exceptional point in a two-channel waveguide with active loss modulation, revealing high sensitivity and opening new avenues in non-Hermitian physics for acoustics.

Contribution

It introduces the first experimental demonstration of CPA at an exceptional point in acoustics using active components for loss control.

Findings

Achieved full absorption at a specific real frequency.

Demonstrated high sensitivity to incident phase variations.

Opened new possibilities for non-Hermitian acoustic devices.

Abstract

Non-Hermitian systems have recently shown new possibilities to manipulate wave scattering by exploiting loss, yet coherent perfect absorption at an exceptional point (CPA EP) remains elusive in acoustics. Here we demonstrate it based on a two-channel waveguide with compact lossy resonators. We realize imbalanced losses crucial for CPA EP by using active components to independently modulate the non-Hermiticity. The CPA EP experimentally manifests as full absorption at a unique real frequency and shows high sensitivity to the incident phase variations.Our findings open an avenue to explore novel non-Hermitian physics for classical waves and develop innovative acoustic singularity-based devices.