Does getting awarded your PhD in physics depend on the quality of university?
The quality of the university and the quality of the theses produced are not perfectly correlated. You are just as likely to end up with a "nothing special" thesis at a Cambridge as at a Random State University. The criterion for awarding a PhD is the completion of an independent and original contribution to the field of knowledge one is studying. There is no requirement that it be "groundbreaking." 

That said, given that the "top" universities also tend to have superior resources available to students, the likelihood that a "nothing special" thesis will be accepted by the advisor as suitable for a PhD thesis is also somewhat mitigated as a result.