Asymmetric frequency conversion with acoustic non-Hermitian space-time varying metamaterial

TL;DR

This paper demonstrates the experimental realization of non-Hermitian space-time varying acoustic metamaterials that enable efficient, asymmetric frequency conversion and quantum interference analogies through software-defined, gain-loss balanced modulation.

Contribution

It introduces a novel experimental approach using virtualized, software-defined metamaterials to achieve non-Hermitian space-time modulation for asymmetric frequency conversion.

Findings

Achieved efficient asymmetric frequency conversion with gain-loss balance.

Demonstrated control of quantum interference analogies in acoustic systems.

Enhanced side band conversion efficiency through space-time modulation.

Abstract

Space-time modulated metamaterials support extraordinary rich applications, such as parametric amplification, frequency conversion and non-reciprocal transmission. However, experimental realization of space-time modulation is highly non-trivial, hindering many interesting physics that are theoretically predicted to be experimentally demonstrated. Here, based on the proposed virtualized metamaterials with software-defined impulse response, we experimentally realize non-Hermitian space-time varying metamaterials for efficient and asymmetric frequency conversion by allowing material gain and loss to be tailor-made and balanced in the time domain. In the application of frequency conversion, the combination of space-time varying capability and non-Hermiticity allows us to diminish the main band through gain-loss balance and to increase the efficiency of side band conversion at the same time. In addition, our approach of software-defined metamaterials is flexible to realize the analogy of quantum interference in an acoustic system with design capability. Applying an additional modulation phase delay between different atoms allows to control such interference to get asymmetric amplification in frequency conversion.