3D Anderson localization of classical scalar waves

Anderson localization, first predicted in 1958, is one of the most fascinating and remarkable wave phenomena. The experimental search for this halt of diffusive transport in three-dimensional (3D) disordered systems, which is still very actively pursued for classical waves (light or sound), has never been demonstrated for the fundamental case of scalar waves. Inspired by recent advances in 3D metamaterials, we show that a locally resonant ultrasonic metafluid consisting of a suspension of soft metallic beads is the innovation needed for 3D Anderson localization of scalar acoustic waves to be definitively observed. By reporting two independent sets of time- and position-resolved ultrasonic experiments, we present clear evidence of Anderson transitions between diffusion and localization, accurately determining the mobility edges and the localization phase diagram.