Late to the party, but was also going to recommend Griffiths. Not difficult if you have the mathematical background (mainly just calculus and linear algebra). Covers vanilla quantum mechanics, no relativistic QM or quantum field theory.
>an effect of quantum physics called electron degeneracy.
quantum physics, all right then. For a moment I thought you are talking politics and politicians.
I had this book and it was great:
Introduction to Quantum Mechanics, 3rd Ed, David J. Griffiths
He uses useful analogies, explains step by step, uses language that is not overly complicated, and mixes the occasional joke in.
Prerequisite maths, like others said. I think calculus and linear algebra are the most important. You'll be lost without them. Pick up a book if you must.
Probability and statistics are useful for the interpretation. But you don't need a MSc degree in statistics, mainly some intuition about probability distributions and so on. Maybe you can look up these topics as you go along.
This was the book that really made things click for me …
There are some good links and FAQs in the subreddit wiki:
https://www.reddit.com/r/QuantumPhysics/wiki/index
If you want a mathematical/practical introduction to QM (without most of the philosophical interpretation stuff talked about here) then the introductory undergraduate textbooks are the way to go e.g. David J. Griffiths and Darrell F. Schroeter (you can probably find it online for free to see if you want to buy it physically)
If you want philosophy and less maths I quite like the Stanford Encyclopedia of Philosophy pages as a detailed introduction e.g Consistent Histories The articles are generally written by real experts for each topic. For the Consistent Histories interpretation Robert Griffiths has most of his book available online for free here.
There are plenty of easier popular science books/articles out there than the ones I've linked, but I'm less familiar with which ones are good. I've focused on the Consistent Histories interpretation in the example links, but this is just one possible interpretation of QM.
https://en.wikipedia.org/wiki/Interpretations_of_quantum_mechanics
Momentum is the value that the momentum operator gives you. It will be related to the time evolution of the field, as you would expect for a quantity classically related to velocity. In coherent states, which are mixtures of states in any bases that are sufficiently localized in space, the classical limit is recovered.
Spin is the result of another operator, but what it gives you is the angular momentum of an electron. Everybody agrees on this. No physicist thinks it's actually spinning because they're not dense and have enough imagination to know a vector quantity can exist all on its own. Here are two experts that agree on this definition - I know this because all the experts agree on the definition, because they're all working with the exact same mathematical model.
This is literally first year stuff, as in actual first years taking physics classes in college will learn it. Occasionally, they will delay it to their second year - I suppose that was my ego at play.
Has anyone checked out the recently released 3rd edition of Introduction to Quantum Mechanics by Griffiths? Also here