The new discovery is pretty exciting, because it’s been 50 years in the making. That’s when excitonium was first theorized, but proving it existed has been a bit tricky because it looked remarkably like another kind of electron movement called a Peierls phase.
Basically, it’s all about how the electrons move around the nucleus, but don’t get too electrified, let’s back up a second. Thanks to new measurement techniques, excitonium’s existence has been conclusively demonstrated. So now we know it exists, but what exactly is it?
Excitonium is a condensate, a collection of particles that exhibit quantum phenomena like superconductivity or superfluidity on a macroscopic scale. The particles that make up excitonium are, naturally, called excitons. Excitons are bosons, the category of particles that includes such hits as the photon, the gluon, and of course the higgs-boson.
Excitons are composite particles. A composite particle is something made up of two or more elementary particles. But, with excitons it’s actually not that simple. They’re made up of an electron that has jumped to a higher energy level from the crowded outermost shell of an atom and the hole that electron left behind.