Synthetic gauge flux and Weyl points in acoustic systems

TLDR: In this paper, it was shown that inversion symmetry breaking can be used to create acoustic analogues of the topological Haldane model and an effective gauge flux in a reduced two-dimensional system by engineering interlayer couplings.

Abstract: Realizing non-trivial topological effects is challenging in acoustic systems. It is now shown that inversion symmetry breaking can be used to create acoustic analogues of the topological Haldane model. Following the discovery of the quantum Hall effect1,2 and topological insulators3,4, the topological properties of classical waves began to draw attention5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21. Topologically non-trivial bands characterized by non-zero Chern numbers are realized through either the breaking of time-reversal symmetry using an external magnetic field5,6,7,15,16 or dynamic modulation8,17. Owing to the absence of a Faraday-like effect, the breaking of time-reversal symmetry in an acoustic system is commonly realized with moving background fluids20,22, which drastically increases the engineering complexity. Here we show that we can realize effective inversion symmetry breaking and create an effective gauge flux in a reduced two-dimensional system by engineering interlayer couplings, achieving an acoustic analogue of the topological Haldane model2,23. We show that the synthetic gauge flux is closely related to Weyl points24,25,26 in the three-dimensional band structure and the system supports chiral edge states for fixed values of kz.