Comment by potsandpans

Start here: https://youtu.be/F_Riqjdh2oM

You don't need to know quantum theory necessarily, but you will need to know some maths. Specifically linear algebra.

There are a few youtube courses on linear algebra

For a casual set of video: - https://youtube.com/playlist?list=PLZHQObOWTQDPD3MizzM2xVFit...

For a more formal approach:

- https://youtube.com/playlist?list=PL49CF3715CB9EF31D

And the corresponding open courseware

- https://ocw.mit.edu/courses/18-06-linear-algebra-spring-2010...

Linear algebra done right comes highly recommended

- https://linear.axler.net/