Zener tunneling of acoustic waves in a one-dimensional phononic crystal

We numerically study the Zener tunneling of acoustic waves in a one-dimensional phononic crystal (PC). The PC is designed to possess two minibands separated by a narrow frequency gap, which further form two acoustic Wannier-Stark ladders when an increasing gradient in the width of elementary cell of PC is introduced. Resonant tunneling between two Wannier-Stark states in different minibands is observed.