View article

Recent explorations of topology in physical systems have led to a new paradigm of condensed matters characterized by topologically protected states and phase transition, for example, topologically protected photonic crystals enabled by magneto-optical effects. However, in other wave systems such as acoustics, topological states cannot be simply reproduced due to the absence of similar magneticsrelated sound–matter interactions in naturally available materials. Here, we propose an acoustic topological structure by creating an effective gauge magneticfield for sound using circularlyflowing air in the designed acoustic ring resonators. The created gauge magneticfield breaks the time-reversal symmetry, and therefore topological properties can be designed to be nontrivial with non-zero Chern numbers and thus to enable a topological sonic crystal, in which the topologically protected acoustic edge-state transport …