Acoustic twisted bilayer graphene

TL;DR

This paper introduces an acoustic metamaterial platform that mimics twisted bilayer graphene, enabling easier exploration of its quantum behaviors and revealing tunable mode localization and interaction effects at various twist angles.

Contribution

The authors develop a classical acoustic analog of twisted bilayer graphene, demonstrating tunable mode localization and strong interactions at adjustable twist angles, including a high magic angle of 6.01 degrees.

Findings

Mode localization at a magic angle of about 1.1 degrees

Achieved strong interactions three times higher than under pressure

Demonstrated a magic angle as high as 6.01 degrees

Abstract

Twisted van der Waals (vdW) heterostructures have recently emerged as an attractive platform to study tunable correlated electron systems. However, the quantum mechanical nature of vdW heterostructures makes their theoretical and experimental exploration laborious and expensive. Here we present a simple platform to mimic the behavior of twisted vdW heterostructures using acoustic metamaterials comprising of interconnected air cavities in a steel plate. Our classical analog of twisted bilayer graphene shows much of the same behavior as its quantum counterpart, including mode localization at a magic angle of about 1.1 degrees. By tuning the thickness of the interlayer membrane, we reach a regime of strong interactions more than three times higher than the feasible range of twisted bilayer graphene under pressure. In this regime, we find the magic angle as high as 6.01 degrees, corresponding to a far denser array of localized modes in real space and further increasing their interaction strength. Our results broaden the capabilities for cross-talk between quantum mechanics and acoustics, as vdW metamaterials can be used both as simplified models for exploring quantum systems and as a means for translating interesting quantum effects into acoustics.