Topological Acoustic Diode

TL;DR

This paper introduces a new class of topological acoustic diodes that leverage three-dimensional topological phases to achieve nonlinear acoustic effects, with potential for advanced topological engineering applications.

Contribution

It uncovers topologically-induced nonlinear acoustic phenomena and links them to quantum geometric tensors, expanding the understanding of quantum geometry in nonlinear responses.

Findings

Demonstrates topological phases enabling acoustic diode behavior

Links nonlinear acoustic effects to momentum-space nonmetricity tensor

Suggests experimental realization using axion insulator vacua

Abstract

We show that certain three-dimensional topological phases can act as acoustic diodes realizing nonlinear odd acoustoelastic effects. Beyond uncovering topologically-induced anomalous acoustic second-harmonic generation and rectification, we demonstrate how such nonlinear responses are uniquely captured by the momentum-space nonmetricity tensor in the quantum state Hilbert-space geometry. In addition to completing the classification of quantum geometric observables in the quadratic response regime, our findings reveal unexplored avenues for experimental realizations of acoustic diodes using effective $\theta$ vacua of axion insulators adaptable for topological engineering applications.