TL;DR: First, all of this is happening in the US. I was a PhD student in X, in good standing, but had a shift of interest towards field Y, so I switched programs and universities to study Y. A year is passed since I switched, I'm currently in good standing in Y, but have come to the understanding that I really don't want to build my career in Y, and want to go back to X in my previous university. My request to go back was declined shortly after switching, but that was in different circumstances. I'm hoping there might be a chance now, but I don't know if there is any chance for a PhD student leaving a program for another to go back to the previous program by just saying "I made a mistake, I am sorry". Am I, in principle, qualified to return? What's the best way to go about this? Should I first make arrangements with potential advisors in my previous department, or should I first contact the department?
I was enrolled in a top-tier PhD program in field X, but I left it for another top-tier program at another university in field Y, sufficiently distant from X that switching post PhD would be practically impossible. When I left my previous program, I hadn't yet started my dissertation yet and hadn't advanced to candidacy, but I had a couple of (unsubstantial) publications, and was past my exams, and was overall in good standing with a high GPA and the department seemed overall satisfied with me at that point. But I had been experiencing a shift of interests, which I explored quite a bit, studied on Y, collaborated with researchers on Y, talked to a lot of people, and eventually decided I like to switch my field, despite the fact that all of my undergrad education and post-undergrad background was in X.
It's been a year since I left X and joined Y (immediately). I realized this change was a mistake for non-academic reasons quite early on, asked my previous department if I can go back after a semester, and they said no. Now, I'm past my core courses in Y, have a couple of papers going on, am in good standing again, but besides the personal reasons, I actually realize I'm not "compatible" with this field. I am interested in questions researchers ask in Y, but, coming from a background in X, the process of research in Y is fundamentally different from how I think about problems. The non-academic aspects are hopefully going to be fine in long-term, but in 5-10 years, I can't see myself doing Y for a living or even identifying my professional character with this field.
Now I want to go back to X, I don't know if I'm at all at a position to even try, and if I do, I don't know how to do it to maximize my chance. I am afraid of receiving a negative answer right away if I contact our department. I thought about first making arrangements with a prospective advisor, but I also don't want the department (i.e. chair and DGS) to think I'm going around them or trying to manipulate the system.
Does a person in my situation typically qualify for getting back to my previous program and continuing from where I left? If so, what is the best way to do this?
Keep in mind:
- Most PhD students in both departments are funded centrally, by the department. Occasionally some advisors might have their own funding in X, but I'd guess department typically tends to accept a student only if they can afford them disregarding advisor's funding.
- At least one current PhD student at my previous department dropped out recently, so I'm guessing they might have vacancies, but can't be sure about that, and don't know if they already filled that in in the regular admission cycle.
- This is in the US, and clearly past the regular admission cycle by a few months, and I want to ask if I can go back from this upcoming fall.
- I had some (completely unrelated) personal complications when I was a student in X, and my previous department was incredibly helpful and considerate, but that makes me think I've already bothered them enough and "used my tickets".
Review of other questions:
I looked at this, and this, but they are not asking about going back to a program after leaving it for another program, but rather going back to PhD after leaving the PhD and being out of academia for a while.