Switching Topics Once in Graduate School
At this stage it doesn't matter, so you can choose whatever you like (or whatever you think is more promising etc) and switch (or not switch) later.It is quite common for phd students in cond-mat to do both (some) theory and (some) experiments during their phd. I'd also not be worried about being &quot;ethical&quot; here because people do change their interests, and it is totally unreasonable to expect a student to choose a line of research for their entire life.