Overview

The quantum world is fascinating. Scientists discover electron properties and atom behaviors that are strange and uncanny to us, common people. The enormous variety of phenomena defying our intuition and understanding of reality occurs in an infinitesimally small space where matter and energy intermingle. Using predictions, models, and cutting-edge technology, a recent study has rendered a cloud of atoms invisible, and the applications could be unimaginable.

The science and other stuff to know

The Pauli Exclusion Principle is a physical postulate that asserts the electrons in an atom must be distributed in the atomic orbitals so that they “fill the seats orderly.” That is, the orbital levels close to the nucleus (with higher energy) are filled first and then the following ones. This principle is what explains the stability of atoms and, therefore, of matter on a large scale.

Thirty years ago, MIT professor David Pritchard predicted that this principle should become apparent if you took a cloud of atoms, cooled it to temperatures comparable to the interstellar vacuum, and squeezed the atoms together, they would begin to behave as if they were electrons, following the Pauli Exclusion Principle. If a beam of light were then shone on them, the photons would not be able to sneak between the atoms, making scattering impossible. For the eyes of an observer, this would be equivalent to not seeing the cloud of electrons because the light could not penetrate it.

Yair Margalit, the lead author of the study published in Science, explains how they used a cloud of ultracold lithium atoms at 20 microkelvins (100,000 times colder than outer space) and densified it using a laser to disperse almost 40% light. As a result, they managed to make the cloud 40% more transparent.

“We’re actually counting a few hundred photons, which is really amazing. A photon is a small amount of light, but our equipment is so sensitive that we can see them as a small drop of light in the camera,” he said in an official statement from MIT.

So what?

Wolfgang Ketterle is a co-author of the article. He considers the contributions behind this new physical phenomenon to be significant. For example, it can fave the way for further refinement and understanding of the Standard Model of Particle Physics. Furthermore, technological applications mainly related to quantum computing may optimize information storage processes in quantum circuits.

Ketterle says: “Any time we control the quantum world, like in quantum computers, light scattering is a problem, and it means that information is leaking out of your quantum computer. This is a way to suppress light scattering, and we are contributing to the general theme of controlling the atomic world.”

What’s next?

The researchers expect that at lower temperatures and higher densities, clouds will lose more and more scattering ability. So that at a temperature of 0° K (absolute zero), they become completely transparent. But there are still technical challenges to overcome before they can replicate this in the laboratory: they must develop technologies that allow them to cool and densify atomic clouds enough to reduce scattering to 100% and make matter completely invisible for the first time.