Quantization of a real scalar field by Ciro Santilli 34 Updated Created
This is one of the first examples in most quantum field theory.
It usually does not involve any forces, just the interpretation of what the quantum field is.
www.youtube.com/watch?v=zv94slY6WqY&list=PLSpklniGdSfSsk7BSZjONcfhRGKNa2uou&index=2 Quantization Of A Free Real Scalar Field by Dietterich Labs (2019)