How do I find out if I want to switch to experimental physics for PhD with little experience?

Question

I finished my master in physics and now want to pursue a PhD (or its equivalent), both in Germany. I did my master thesis (1 year) in the field of quantum computing at a research institute, where I continued working and now could do the PhD. This work is at the intersect of computer science and theoretical physics. I like the work and I feel like I get a lot of opportunities there. But I also feel like I lack the excitement about the work that it takes to do a PhD. I always get very excited when hearing about experimental physics. But I am not sure if I had that excitement when working there or if it is rather in the context of listing to other people only. And I feel like I risk a good job that I have for sure now. Also, I have almost no training in experimental matters. I touched maybe twice an oscilloscope. Although, I have read about a number of examples where it worked out despite a lack of experience.

On top of that, I don't want my current boss to know about my doubts about continue working in his group. I feel like it could affect our relationship very badly and maybe I want to continue working with him. He is very well connected in the community and I am afraid that if I contact someone he will hear about that.

So, there are basically two questions: 1) How do I find out if I really want to switch to experimental physics, while working a full-time job? 2) How do I do it without my boss noticing?

Answer 1

If your goal is "excitement," do not get a PhD. "Exciting" research results require a lot of background work that is not exciting. Maybe try a career in sales. Sales is an example of a field of work where projects reach rapid conclusions.

If you are considering switching from theoretical physics to tabletop experimental physics, ask yourself:

• Do I like working with my hands?
• Do I like broken stuff?
• Can I tolerate relying on other people? Even if they are weird people?
• Can I tolerate continuing to do my existing tasks like calculating and writing? (Yes, experimentalists have to do those too.)

I would not recommend getting a PhD in tabletop experimental physics unless the answer to all the questions is yes.

Answer 2

Here's an example of what it's like to work in experimental physics. If you pump atoms into a vacuum with a specific magnetic field & laser beams, you should end up with a magneto-optical trap. So you set up your atom source, your vacuum chamber, your electromagnets, etc., yet when you look at your detector there are no atoms. Something's clearly wrong, but what? Some possibilities could be:

• Maybe the atom source has run out and there are no more atoms left.
• Maybe there's a leak in the vacuum chamber.
• Maybe the laser beams are of slightly incorrect frequency.
• Maybe the laser beams aren't aligned properly.

Maybe you check all these things and find that there are still no atoms detected. Time to start thinking about what other things could've gone wrong:

• Maybe the vacuum isn't vacuum enough (i.e., the pressure is too high). But the vacuum pump can't bring the pressure any lower. Does the department have a better vacuum pump?
• Maybe the lab temperature is too high and this is affecting the trap (does this actually affect the trap? Better check the theory and see if there is an impact).
• Maybe the detector is broken. (Buying a new detector could cost a significant amount of money, not to mention paperwork, so are you sure it is broken?)

In the last case you could easily end up with this related problem:

• Ok, so the detector is broken and we've ordered a new one, but it will take a couple of weeks to arrive. What do I do in the meantime?

These are the kinds of problems that you'll be solving in an experimental physics PhD. If you enjoy these - as oppose to enjoy reading about the results - then you can consider switching to experimental physics.