A hydrodynamic analog of the Kapitza-Dirac effect

In 1933, Kapitza and Dirac predicted that a standing wave of light would diffract a beam of electrons—an effect experimentally confirmed only after the advent of lasers. In 2005, Couder and Fort discovered that millimetric droplets can self-propel along the surface of a vibrating liquid bath, guided by their own pilot-wave field. These walking droplets represent a macroscopic realization of wave-particle duality and have been shown to exhibit many features previously thought to be exclusive to the subatomic, quantum realm. We here examine a hydrodynamic analog of the Kapitza-Dirac effect through consideration of walking droplets interacting with a localized beam of standing Faraday waves, which is conditioned using submerged features in the liquid bath.