For the other question on measurement, it depends on the underneath technology. The key concept is to understand the energy gaps which will get excited in one state but not the other according to quantum mechanics. For trapped ion, ions fluorescence or go dark depends on such a state when a laser of a specific frequency is shone on it. That will be captured by CCD. There are a lot of details with Physics. Even the Ion trap can be a Ph.D. thesis already.
For me, I read through people’s thesis and research papers to get the information I want. I don’t think I have a good answer for you. But you may check out major research groups in the academic for courses and info. For example, in trapped ions, you can start with this http://iontrap.umd.edu/
For superconducting quantum computer: https://web.physics.ucsb.edu/~martinisgroup/
This paper is nice. It also answers some of your questions in more detail for ion trapped QC.