But since you are stuck as a CS Major, here are some areas that you might find interesting:
1. Security --- This is an arms race, so there is always something interesting to do
2. Machine Learning --- While this field is very hyped up right now, there are still many areas that need a lot of work. Things like robustness against adversarial attack
3. Quantum Computing --- Honestly, I don't have much experience with this. But this is one field where your interest in physics can complement your current major