Hydrodynamic analogue of radiation from oil 17.02.2023

American and French scientists obtained in a vibrating vessel with oil a hydrodynamic analogue of radiation - an effect from quantum optics. Due to vibrations, waves formed on the surface of the oil, provoking the appearance of drops, just as ensembles of atoms are able to emit light through a collective interaction with each other. The experiment of physicists highlighted the features of the quantum effect, and will also find application in the calculations of hydrodynamic systems.

When the atoms in an ensemble are very close to each other, less than a wavelength apart, they interact with each other through an electromagnetic field, which allows them to collectively emit photons, and at a greater intensity than any individual atom. This phenomenon is called superradiance and is not only of theoretical interest to scientists, but also of practical interest, because it can be used in a variety of fields related to optics: from lasers to quantum information technologies.

In their work, physicists at the Massachusetts Institute of Technology demonstrated a phenomenon similar to superradiance, but in a vessel filled with oil.

The creation of hydrodynamic analogs of quantum phenomena, which are also based on waves, physicists have been doing for a long time. For example, there are hydrodynamic versions of the Casimir effect, the Aharonov-Bohm effect, and even experiments with dark holes. They make it possible to study phenomena that are difficult or even impossible to study directly. In their experiments, physicists managed to fix several essential features of super-radiation by reproducing it in a vibrating vessel with oil, in which cavities at the bottom acted as atoms, and radiation manifested itself in the appearance of drops on the surface from the wave connection between them.

For the study, scientists created a container with two recesses 6 millimeters deep and 7 millimeters in diameter, the distance between which was varied in the range from 8 to 12 millimeters. They served as resonators, over which oil was poured in a thin layer of 0,75 millimeters. The whole structure was subjected to vibrations with a frequency of 39 hertz with different amplitudes, which physicists selected to overcome the so-called Faraday boundary - the boundary beyond which ripples (Faraday waves) appeared on the surface. It turned out that even at such considerable distances, the wave field of the perturbation of one resonator can reach another, which makes it possible for them to carry out long-range interactions.

The mesentery manifested itself most intensely above the resonators, near which drops were detached from the surface. Since the waves of both resonators met and interfered, this also affected the formation of droplets. The number of physics drops formed per second was taken as radiation. In the system they created, the appearance of drops is analogous to the emission of a photon through the collective interaction of atoms.

In addition to radiation amplification, the hydrodynamic experiment with superradiance has several other key features in common with superradiance from quantum optics. Another geometry of the resonators would help to reproduce the sub-radiation. As the researchers write, the formation of drops in their system will become a new platform for studying the hydrodynamic analogues of the phenomenon of collective radiation of particles and further expanding the field of hydrodynamic analogues of quantum phenomena.