Hydrodynamic Quantum Analogs: Classical Insight into Quantum Systems

Massachusetts Institute Of Technology, Cambridge MA

Investigators

Abstract

In 2005, Yves Couder discovered that a milimetric droplet may self-propel along the surface of a vibrating bath through a resonant interaction with its own guiding or ‘pilot’ wave field. Notably, the walking droplet system bears a strong resemblance to the quantum pilot-wave theory researched in the 1920s by Louis de Broglie, who envisaged microscopic particles as oscillators that generate a propulsive pilot-wave field. Remarkably, the walking droplets exhibit many features previously thought to be exclusive to the microscopic, quantum realm. Thus, they have provided the basis for the burgeoning field of hydrodynamic quantum analogs, the goal of which is to demarcate clearly the line between those features of quantum mechanics that can and cannot be understood from a classical perspective. The approach is progressive: the establishment of each new hydrodynamic quantum analog moves this line. Specifically, the walking-droplet system has suggested classical reinterpretations of a number of the most beguiling quantum notions, including wave-particle duality, wave function collapse, superposition of states, orbital quantization, single-particle diffraction and interference, uncertainty and nonlocality. The award supports the PI's integrated experimental and theoretical investigation of hydrodynamic quantum analogs, as will naturally inform the viability of classical pilot-wave dynamics as the basis for a realist quantum theory. The intellectual merit of this research is that it will thus both question and inform the philosophical foundations of modern physics. The award supports the PI's investigations of hydrodynamic quantum analogs, that include the discovery of new analog systems in the laboratory, the theoretical modeling thereof, and critical comparison with the quantum analog of interest. Experimental studies will explore a new class of hydrodynamic quantum analogs on the frontiers of the subject, including superradiant photon emission, particle creation and annihilation, and the Aharanov-Bohm effect. Theoretical developments will be directed towards advancing and exploring a generalized classical pilot-wave framework that captures the key common features of the walking-droplet system and de Broglie’s pilot-wave theory. In addition to providing a platform for exploring a remarkably rich new dynamical system, this classical theoretical framework might ultimately provide a mathematical bridge between models of wave-particle interactions on the macroscopic and microscopic scales. Both experimental and theoretical components of the research will give particular attention to elucidating the manner in which apparently non-local features may arise through local, pilot-wave interactions, with focus on the possibility of achieving non-separable states and entanglement with classical pilot-wave dynamics. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.