I don't know if it applies to an uni interview, but the folk I've been talking to about applying for their work placements all say the same thing. Basically they assume you know your soykaf what they look for is a genuine interest in the subject. So yes, mention your skills/ qualifications so they can tick that box but talk about why you are interested in doing, what are your goals, what excites you, what projects are you working on etc.
Make sure you do your research on the uni and have lots of questions for them. That includes their past, present and future. Ask about clubs and the like so they at least have the pretence that you are a normal social humanoid even if you aren't. Also on that note have a repository of things you cant talk about that are wholly unrelated to physics, sports, holidays, cinema, music and the like.
Finally be confident about yourself, obviously its ok to be nervous in the interview but with out being a dick let them know, that you know, "I'm the best fuarrrking guy on the list and this is why".
You probably aren't but if two people come in with the same sheet saying they've done X,Y,Z which one are they going to give it to. the guy who goes>uhh, oh ye X. That was ok I didn't have much to do with it I just helped out.
or the guy who goes>X was great, here's what I did, this is what I got out of it, this is how I saved the day, is there anything like X here I can get involved in?