Anderson localization of acoustic waves in three dimensional resonant microbead suspensions

Anderson localization is one of the most fascinating wave phenomena that may occur in strongly scattering heterogeneous media. Since the 1980s, the experimental search for this halt of diffusive transport in 3-D disordered systems has continued to be the focus of intense research, whether for quantum particles or classical waves. In the latter case, the experimental demonstration remains challenging for light waves, contrary to ultrasonic elastic waves, for which it has already been proven without ambiguity. In this talk, I will describe a new set of two independent time- and position-resolved experiments, using techniques that were first developed to clearly establish the existence of localized regimes in mesoglasses made of sintered beads. Here, I will focus on scalar acoustic waves and report unambiguous evidence of the transitions between diffusion and localization in suspensions made of soft metallic resonant beads, inspired by recent advances in the field of soft acoustic metamaterials. These experiments allow us to determine the mobility edges of the localization regimes with high precision. Finally, as it is easy to vary the concentration in our model system, we will show that there is an optimal intermediate concentration beyond which localization disappears.