In quantum mechanics we have different models like the infinite and finite square well, potential barrier, etc. What I don't understand is how these are applicable to real life situations. For example, in a one dimensional potential well we have two points where the potential goes to infinity. Now, if we were to apply this in real life situations then what would these "potentials" be? Can we take the example of two parallel plates with large voltage and a single particle between them? If yes, then in what other ways can this model be used? Also, does the potential used in the model refer only to the electrostatic potential or can it mean something else in other situations.
Edit: I am not looking for only the one dimensional potential well and took the example here just to explain my doubts. I just want to know how real life situations can be solved with quantum modelling. Also, what does negative energy in a quantum system mean?