Topic: Acoustic levitation

Ultrasound can levitate particles and create tunable interactions through sound scattered by nearby objects. In air, low viscosity permits underdamped collective dynamics far from equilibrium. Heinrich Jaeger discusses experiments that assemble small particles into freely suspended clusters and monolayer rafts while tracking their motion with high-speed video. Changing particle separation and acoustic energy transforms close-packed solids into soft lattices and unusual two-dimensional liquids. These experiments provide a platform for investigating non-reciprocal many-body forces and the collec

Granular matter can serve as a prototype for exploring the rich physics of many-body systems driven far from equilibrium. This talk will outline a new direction for granular physics with macroscopic particles, where acoustic levitation compensates the forces due to gravity and eliminates frictional interactions with supporting surfaces in order to focus on particle interactions. Levitating small particles by intense ultrasound fields in air makes it possible to manipulate and control their positions and assemble them into larger aggregates. The small air viscosity implies that the regime of un