Quasiparticles: what are(n’t) they?
How the absence of a particle gives rise to particle-like behavior
The phenomenon of quasiparticles is fascinating, albeit counterintuitive. Nevertheless, it is real and what allows you to read this very text, at this very moment, on the device you are holding.
What are they?
Inside your smartphone or computer screen, there is a constant traffic of electrons through the diodes and transistors that ultimately make them work. But, at the same time that the electrons jump from atom to atom, if you look at it more broadly, not only do you have a traveling stream of negatively charged particles, but also an opposite one of positive charges.
This opposing stream of positive charges is mostly due to the empty locations left by the electrons in the Valence Shells of the atoms: as an electron jumps from one silicon atom to the next, it leaves a vacant, positively charged, “hole” in the previous silicon atom.
These “holes” with a positive charge are a type of “quasiparticle”, the curious object of this article.
Even though they are not real particles, they give rise to real phenomena with real-world applications.
