Nonreciprocal Transmission of Microwave Acoustic Waves in Nonlinear Parity-Time Symmetric Resonators

TL;DR

This paper demonstrates a tunable, nonlinear, parity-time symmetric acoustic system using lithium niobate, achieving nonreciprocal transmission and one-way circulation of 200-MHz acoustic waves at low power, advancing on-chip phononic control.

Contribution

It introduces a fully tunable nonlinear acoustic parity-time-symmetric system with nonreciprocal transmission using lithium niobate and electric circuitry.

Findings

Achieved 10 dB nonreciprocity at 200 MHz with 3 μW input power.

Demonstrated one-way circulation of acoustic waves.

Showcased potential for on-chip phononic processing and non-Hermitian physics exploration.

Abstract

Acoustic waves have emerged as versatile on-chip information carriers with applications ranging from microwave filters to transducers. Nonreciprocal devices are desirable for the control and routing of high-frequency phonons. This is challenging, however, due to the linear response of most acoustic systems. Here, we leverage the strong piezoelectricity of lithium niobate to demonstrate fully tunable gain, loss, and nonlinearity for surface acoustic waves using electric circuitry. This allows the construction of a nonlinear acoustic parity-time-symmetric system and enables nonreciprocal transmission. We achieve a nonreciprocity of 10 decibels for a 200-MHz acoustic wave at a low input power of 3 $\mu$W and further demonstrate one-way circulation of acoustic waves by cascading nonreciprocal devices. Our work illustrates the potential of this piezoelectric platform for on-chip phononic processing and exploration of non-Hermitian physics.