There are four different departments who offer courses in physics:
> Courses in Physics
> More courses in Physics
> Courses in astrophysics > courses in synchrotrone light physics (at MAX-lab)
Please note that you always need to apply to next term's courses formally - even if you already are a programme student. Apply through:
https://www.universityadmissions.se/intl/start
Application deadline for Spring courses are October 15, and April 15 for Autumn courses. Non-Swedish speakers may find the following booklet helpful:
Instructons for non-Swedes on how to apply for B.Sc. and M.Sc. programmes given at Lund University
(On page 9 you simply search for the course you want to take instead of the programmes mentioned.)