Observation of acoustic Landau quantization and quantum-Hall-like edge states

TL;DR

This paper demonstrates the first experimental realization of giant uniform pseudomagnetic fields in acoustic graphene, revealing Landau levels and quantum-Hall-like edge states, thus opening new avenues for sound manipulation using artificial gauge fields.

Contribution

It introduces a simple uniaxial deformation method to create large pseudomagnetic fields in acoustic systems, enabling observation of Landau levels and edge states in acoustics.

Findings

Observation of acoustic Landau levels in frequency spectra

Visualization of quantum-Hall-like edge states

Establishment of a framework for artificial pseudomagnetic fields in acoustics

Abstract

Many intriguing phenomena occur for electrons under strong magnetic fields. Recently, it was proposed that an appropriate strain texture in graphene can induce a synthetic gauge field, in which the electrons behave like in a real magnetic field. This opened the door to control quantum transport by mechanical means and to explore unprecedented physics in high-field regime. Such studies have been achieved in molecular and photonic lattices. Here we report the first experimental realization of giant uniform pseudomagnetic field in acoustics by introducing a simple uniaxial deformation to acoustic graphene. Benefited from the controllability of our macroscopic platform, we observe the acoustic Landau levels in frequency-resolved spectroscopy and their spatial localization in pressure-field distributions. We further visualize the quantum-Hall-like edge states (connected to the zeroth Landau level), which have been elusive before owing to the challenge in creating large-area uniform pseudomagnetic fields. These results, highly consistent with our full-wave simulations, establish a complete framework for artificial structures under constant pseudomagnetic fields. Our findings, conceptually novel in acoustics, may offer new opportunities to manipulate sound.