Quantum computing is to quantum physics as electrical engineering is to electromagnetism. Having a deep understanding helps, and most graduate programs will require you to take courses in those areas, but it’s not necessary to get started.
You don’t need much besides linear algebra, which most STEM majors learn.
Check out these books:
Or this game: Steam Community :: Quantum Odyssey
A different issue entirely is what will make you a competitive applicant for quantum computing graduate programs - for that, Physics, electrical engineering, or math would be your best bet.