@article{de6cea473157471f8a38628d05779d52,
title = "Three-Dimensional Acoustic Double-Zero-Index Medium with a Fourfold Degenerate Dirac-like Point",
abstract = "We report the first realization of a three-dimensional (3D) acoustic double-zero-index medium (DZIM) made of a cubic lattice of metal rods. While the past decade has seen several realizations of 2D DZIM, achieving such a medium in 3D has remained an elusive challenge. Here, we show how a fourfold degenerate point with conical dispersion can be induced at the Brillouin zone center, such that the material becomes a 3D DZIM with the effective mass density and compressibility simultaneously acquiring near-zero values. To demonstrate the functionalities of this new medium, we have fabricated an acoustic waveguide of 3D DZIM in form of a {"}periscope{"} with two 90° turns and observed tunneling of a normally incident planar wave through the waveguide yielding undistorted planar wave front at the waveguide exit. Our findings establish a practical route to realize 3D DZIM as an effective acoustic {"}void space{"} that offers unprecedented control over acoustic wave propagation.",
author = "Changqing Xu and Guancong MA and Chen, {Ze Guo} and Jie Luo and Jinjie Shi and Yun Lai and Ying Wu",
note = "Funding Information: We thank Dunjian Wang and Pengqi Li for assisting with the experiments, Professor C. T. Chan and Dr. Ruoyang Zhang for helpful discussions, Dr. Aigars Ekers for advice on the presentation, and anonymous referees for their valuable comments and suggestions. The work described here was partially supported by the King Abdullah University of Science and Technology (KAUST) Office of Sponsored Research (OSR) under Grant No. OSR-2016-CRG5-2950 and KAUST Baseline Research Fund BAS/1/1626-01-01. G. M. was supported by the Hong Kong Research Grants Council (Grants No. RGC-ECS 22302718 and No. GRF 12300419), the National Natural Science Foundation of China (Grant No. 11802256), and by the Hong Kong Baptist University through FRG2/17-18/056, RC-SGT2/18-19/SCI/006. Y. L. was supported by the National Key R&D Program of China (2017YFA0303702) and the National Natural Science Foundation of China (Grants No. 61671314, No. 11974176, and No. 11634005).",
year = "2020",
month = feb,
day = "19",
doi = "10.1103/PhysRevLett.124.074501",
language = "English",
volume = "124",
journal = "Physical Review Letters",
issn = "0031-9007",
publisher = "American Physical Society",
number = "7",
}