基于合成磁场的声学非互易

Sound non-reciprocity based on synthetic magnetism

通过设计特定的时空调制,合成磁性的概念最近被提出以实现对光子和声子等电荷中性粒子的非互易操控,但现有方案存在着隔离度低、信号频率变化等问题.本文设计了一种新型耦合共振腔系统,其中动态耦合的相位作为实现声学合成磁场的新机制并打破了系统的时间反演对称性,最终取得了优异的声波非互易传输.基于旋转波近似方法,作者严格推导出了实现系统强非互易声传输的参数条件.通过优化动态耦合之间的相位差以及耦合强度,实验展示了隔离度达45-dB和正向传输率达0.85的优异单向声传输.此外,这种单向声传输具有始末态频率不变和隔离方向可电控等重要特性.该研究突破了现有声波单向操控机制在效率和隔离度方面的局限,并为实现弗洛奎和非线性声学拓扑绝缘体提供了新途径.

Synthetic magnetism has been recently realized using spatiotemporal modulation patterns,producing non-reciprocal steering of charge-neutral particles such as photons and phonons.Here,we design and experimentally demonstrate a non-reciprocal acoustic system composed of three compact cavities interlinked with both dynamic and static couplings,in which phase-correlated modulations induce a synthetic magnetic flux that breaks time-reversal symmetry.Within the rotating wave approximation,the transport properties of the system are controlled to efficiently realize large non-reciprocal acoustic transport.By optimizing the coupling strengths and modulation phases,we achieve frequency-preserved unidirectional transport with 45-dB isolation ratio and 0.85 forward transmission.Our results open to the realization of acoustic non-reciprocal technologies with high efficiency and large isolation,and offer a route towards Floquet topological insulators for sound.