The effective medium representation is fundamental in providing a performance-to-design approach for many devices based on metamaterials. While there are recent works in extending the effective medium concept into the temporal domain, a direct implementation is still missing. Here, we construct an acoustic metamaterial dynamically switching between two different configurations with a time-varying convolution kernel, which can now incorporate both frequency dispersion of metamaterials and temporal modulation. We establish the effective medium formula in temporally averaging the compressibilities, densities and even Willis coupling parameters of the two configurations. A phase disorder between the modulation of different atoms is found negligible on the effective medium. Our realization enables a high-level description of metamaterials in the spatiotemporal domain, making many recent proposals, such as magnet-free non-reciprocity, broadband slow-light and Fresnel drag using spatiotemporal metamaterials possible for implementations in future.
Chiral Landau levels induced by two in-plane pseudomagnetic fields in underwater acoustic metamaterials
Jiangsu Key Laboratory for Design and Manufacturing of Precision Medicine Equipment, School of Mechanical Engineering, Southeast University（东南大学机械工程学院精密医疗器械设计与制造江苏省重点实验室）；Key Laboratory of Underwater Acoustic Signal Processing (Southeast University), Ministry of Education（教育部水下声学信号处理重点实验室（东南大学））；Advanced Ocean Institute of Southeast University Nantong（东南大学南通海洋研究院）；State Key Laboratory of Acoustics and Marine Information, Institute of Acoustics, Chinese Academy of Sciences（中国科学院声学研究所声学与海洋信息国家重点实验室）；Modern Matter Laboratory and Advanced Materials Thrust, The Hong Kong University of Science and Technology (Guangzhou)（香港科技大学（广州）现代物质实验室先进材料课题组）
