Can someone link me some sort of article or journal that lays out the general process of preparing a mixed state of let's say an electron. I was curious as to how exactly you could know it is in one in the first place.
Electrons tend to have short decoherence times. It's tricky.
If you want a simple(r) illustration of preparing and manipulating mixed states, I'd suggest a book on NMR techniques, which are very often all about putting a system into a known state, letting it evolve into a mixed state over time, and then measuring it again.