We here present the results of a semester project to assemble a piezoelectric droplet generator to produce millimetric oil drops for use in experimental research of a macroscopic system analogous to Louis de Broglie’s pilot wave theory of quantum mechanics. The 3D-printed droplet generator is an inexpensive alternative to commercially-produced equipment and may be fabricated from readily available components. This droplet generator was constructed according to a design by Dr. Daniel Harris of the Massachusetts Institute of Technology’s Harris Lab. We discuss the function and assembly of the droplet generator and recommend a modification to improve performance and ease of use.
We here present the results of a semester project to assemble a piezoelectric droplet generator to produce millimetric oil drops for use in experimental research of a macroscopic system analogous to Louis de Broglie’s pilot wave theory of quantum mechanics. The 3D-printed droplet generator is an inexpensive alternative to commercially-produced equipment and may be fabricated from readily available components. This droplet generator was constructed according to a design by Dr. Daniel Harris of the Massachusetts Institute of Technology’s Harris Lab. We discuss the function and assembly of the droplet generator and recommend a modification to improve performance and ease of use.
A millimetric droplet can be induced to bounce on the surface of a fluid bath by vibrating the bath near the droplet's resonant frequency (Figure 1(a) ). [superscript 1–3] The localized field of Faraday waves excited by the bouncing droplet can cause it to propel itself laterally across the surface, moving in resonance with its guiding wave field (Figure 1(b) ). [superscript 4,5] These walking droplets, or “walkers,” generally move in a straight line at constant speed; however, they can be diverted through interaction with boundaries or external forces. This hydrodynamic system represents a macroscopic realization of the pilot-wave theory of quantum dynamics proposed by Louis de Broglie, according to which microscopic particles are propelled through a resonant interaction with a wave field generated by the particle's internal vibration. [superscript 6] Coincidentally, it exhibits many behaviors once thought to be exclusive to the microscopic quantum realm, including single-particle diffraction, [superscript 7] tunneling, [superscript 8] quantized orbits, [superscript 9] and orbital-level splitting. [superscript 10]
A millimetric droplet bouncing on the surface of a vibrating fluid bath can self-propel by virtue of a resonant interaction with its own wave field. This system represents the first known example of a pilot-wave system of the form envisaged by Louis de Broglie in his double-solution pilot-wave theory. We here develop a fluid model of pilot-wave hydrodynamics by coupling recent models of the droplet’s bouncing dynamics with a more realistic model of weakly viscous quasi-potential wave generation and evolution. The resulting model is the first to capture a number of features reported in experiment, including the rapid transient wave generated during impact, the Doppler effect and walker–walker interactions.
Recently, the properties of bouncing oil droplets, also known as `walkers', have attracted much attention because they are thought to offer a gateway to a better understanding of quantum behaviour. They indeed constitute a macroscopic realization of wave-particle duality, in the sense that their trajectories are guided by a self-generated surrounding wave. The aim of this paper is to try to describe walker phenomenology in terms of de Broglie-Bohm dynamics and of a stochastic version thereof. In particular, we first study how a stochastic modification of the de Broglie pilot-wave theory, à la Nelson, affects the process of relaxation to quantum equilibrium, and we prove an H-theorem for the relaxation to quantum equilibrium under Nelson-type dynamics. We then compare the onset of equilibrium in the stochastic and the de Broglie-Bohm approaches and we propose some simple experiments by which one can test the applicability of our theory to the context of bouncing oil droplets. Finally, we compare our theory to actual observations of walker behavior in a 2D harmonic potential well.
Yves Couder, Emmanuel Fort, and coworkers recently discovered that a millimetric droplet sustained on the surface of a vibrating fluid bath may self-propel through a resonant interaction with its own wave field. This article reviews experimental evidence indicating that the walking droplets exhibit certain features previously thought to be exclusive to the microscopic, quantum realm. It then reviews theoretical descriptions of this hydrodynamic pilot-wave system that yield insight into the origins of its quantum-like behavior. Quantization arises from the dynamic constraint imposed on the droplet by its pilot-wave field, and multimodal statistics appear to be a feature of chaotic pilot-wave dynamics. I attempt to assess the potential and limitations of this hydrodynamic system as a quantum analog. This fluid system is compared to quantum pilot-wave theories, shown to be markedly different from Bohmian mechanics and more closely related to de Broglie's original conception of quantum dynamics, his double-solution theory, and its relatively recent extensions through researchers in stochastic electrodynamics.
A pilot-wave hydrodynamic system consists of a small droplet of viscous fluid that is propelled across a vibrating bath of the same fluid. Bouncing vertical motion and "walking" horizontal motion of the droplet can be achieved with careful control over the frequency and amplitude of the bath's oscillation. The droplet avoids merging with the fluid from which it was generated and exhibits intricate motion across the fluid surface. Of particular importance, the observed walking motion is due to the droplet's interaction with the waves it generates as it bounces off of the vibrating liquid surface. With each rebound, it receives transverse kicks in its motion dependent on the waves generated by its previous bounces. Ultimately, it is the droplet's interaction with the superposition of these waves that produce the complex motion observed. With variations in bath geometries and subsurface structures, the droplet's trajectory can be manipulated to induce fascinating behavior. Over short timescales, a droplet will exhibit seemingly random trajectories. However, when the droplet is observed over long timescales, patterns in the cumulative motion of the droplet begin to emerge. The patterns this system maps out over long timescales represent a compelling macroscopic analog to Louis de Broglie's double-solution theory of quantum mechanics. In order to analyze this behavior, a novel imaging scheme and data acquisition system has been developed, enabling observations of droplet behavior over various timescales simultaneously. An exploration into the development of a pilot-wave hydrodynamic system, and the pilot-wave hydrodynamic experiments conducted thereafter, is presented.