Researchers show that carefully designed complex scattering media can perform non-Abelian braiding of acoustic modes

Sound waves (Courtesy: iStock/Sandipkumar Patel)

When waves travel through complex environments (such as acoustics), repeated scattering is usually a problem because it scrambles wavefronts and distorts the information they carry. As a result, most approaches seek to suppress or compensate for scattering. In this work, however, the researchers take the opposite approach and show that scattering itself can be harnessed to manipulate waves.

The challenge is to design a disordered medium so that multiple scattering produces a desired outcome. This is difficult because the scattering matrix, which describes how waves are transformed by the medium, depends sensitively on the positions of many individual scatterers. Finding a configuration that performs a target operation can therefore be like searching for a destination in a vast landscape.…