a schematic of the interface formed by swapping the large and small tubes. b Measured real-space interface wave propagation excited by a point-like source at the Dirac frequency. The position of the sound source is indicated by a red star. c Fourier-transformed equifrequency contours for the data in b. The black spheres represent the projections of the Dirac points. d Interface band dispersion for kz = 0, 0.2π/h and 0.4π/h. The green solid lines represent the simulated interface states. The shaded areas represent the calculated projected bulk bands. e Schematic of the interface formed by swapping the large and small tubes and inverting the chirality of slanted tubes of the Weyl sonic crystal. f, g Equifrequency contours at f WP1 frequency and at g Dirac frequency.
by Boyang Xie, Hui Liu, Hua Cheng, Zhengyou Liu, Jianguo Tian, and Shuqi Chen