I have about three fields that I am extremely interested in and would be happy spending years investigating them, but I am having trouble determining the exact field or branch of physics that I should be applying for in order to meet my interests.

Interest 1: One of my main interests is working with nuclear fusion. Particularly, I am interested in being part of the research involved with obtaining the renewable energy resource of nuclear fusion and development of commercial nuclear fusion reactors.

I see Ph.D fields of research in different subjects such as nuclear physics (experimental/theoretical), atomic physics (exp/theory), particle physics (exp/theory), high energy physics (exp/theory)... I am not sure which physics branch category that my interests would fall into.

Interest 2: I am also interested in other fields of physics as well (they may seem a little sci-fi and unrealistic, but very interesting to me). Particularly the quest behind finding the source of gravity, how to manipulate gravity or create artificial gravity or just explore the properties of this major force.

Interest 3: Another huge interest of mine is learning about space/time, like finding and exploring at least one thing on this earth that we can use to manipulate or interact with this space/time fabric. For instance, finding some way to bend and manipulate light like gravity does (bending space/time), but in some small scaled man-made alternative way on earth. I would like to explore or research some applications of theory of doing even the tiniest manipulations.

Again, I am not certain what official program branches Interests 2 and 3 would fall under in a graduate school programs. I'm assuming that they might be part of Quantum Field, which is 1 of the 4 major branches of physics and also the one that I never got to learn about in undergrad school?

Thanks