In the text book of quantum mechanics, it’s stated that bosons and fermions, two types of elementary particles that build the universe, behave in a drastically different way. For example, bosons can share the same quantum state while fermions of the same kind cannot but fill available quantum states one by one.
![](https://scx1.b-cdn.net/csz/news/tmb/2020/1-physicistsqu.jpg)
Source:
https://phys.org/news/2020-12-physicists-quantum-simulate-fermions-multiple.html