John Bush (MIT)

Hydrodynamic quantum analogs

Since Yves Couder’s discovery in 2005 that droplets may self-propel along the surface of a vibrating liquid bath, numerous studies have shown that these walking droplets exhibit features previously thought to be exclusive to the microscopic, quantum realm. The walking droplet system represents a macroscopic realization of wave-particle duality, and of a pilot-wave dynamics of the form proposed for microscopic quantum particles by Louis de Broglie in the 1920s. Experimental and theoretical results allow us to explore its potential and limitations as a quantum analog, and so redefine the boundary between classical and quantum. Theoretical descriptions of the hydrodynamic system allow us to forge links with existing quantum pilot-wave theories. Fledgling, trajectory-based descriptions of quantum dynamics, informed by the hydrodynamic system, are explored. Particular attention is given to illustrating how the non-Markovian droplet dynamics give rise to features taken as evidence of quantum nonlocality in their microscopic counterparts.