I'm trying to do a personal research project on a field, e.g. "quantum physics" and wanted to analyse which keywords are the most important or have the most papers in a field. Is there any way to achieve this?
If you are looking for the last 5 years a good chance would be
a current textbook/PhD thesis (many are published on university servers and open access) on that field that has a glossary
browsing/downloading the most cited papers on journal websites (there are often tags, keywords for every paper added by the authors) and noting them down
doing text analytics/statistics on your own with such tools after converting PDF to text:
You may want to check out the free software tool VOSviewer http://www.vosviewer.com/:
VOSviewer is a software tool for constructing and visualizing bibliometric networks. These networks may for instance include journals, researchers, or individual publications, and they can be constructed based on citation, bibliographic coupling, co-citation, or co-authorship relations. VOSviewer also offers text mining functionality that can be used to construct and visualize co-occurrence networks of important terms extracted from a body of scientific literature.