What should one consider while signing up for a Physics PhD program, with an focus on experimental Quantum/Molecular optics, program at either university if both of them offer?
I understand there are many factors to take into account when choosing a school for research (advisor, research fit and funding to name a few), but these are on the individual.
Any Physicists on HN?
As others have pointed out, your prospective advisor(s) are the most important thing to consider. You can't go wrong with either school.
That said, when choosing an advisor:
* Pay attention to where the advisor's former students ended up. The former students are a natural "network" for you when you graduate. If you can, ask relatively recent grads about their experience.
* Meet the prospective advisor's current students and post-docs - are they happy? Will you fit in with them? Do they graduate in a reasonable amount of time? Ask other grad students about the professor as well. Trust me, each professor is going to have a reputation.
* If you want to stay in academia, mid-career advisors are the "safest" - an assistant prof may be working on something exciting, but the research will probably be more risky, and the professor might even have to leave mid-way through your thesis work if they don't get tenure. A late-career advisor may presently sit on a lot of committees and be more well-known, but by the time you need their recommendation for jobs/tenure they may have considerably less influence (that happened to me, although it was fine in the end.)
Read Feibelman's "A PhD is not enough" - still lots of good advice even though written 30+ years ago.