But what about those coming from a field other than physics who have taken many physics courses (almost in all areas, except classical mechanics but I'll take it next semester), like me (I am a materials science student from Greece) having research experience in photonics theory and projects similar to those of research groups in physics departments?
I want to do my phD on photonics, quantum optics or both of them (a combination!).
Let me now introduce my self since this is the "nature" of this thread.
Materials Science dept. (4th final year of my BSc) from Greece
GPA : 8.43/10.0 (highest GPA since the foundation of the department)
Letter of recomendation from a faculty member of a physics department in the US (my thesis advisor) plus two others very good recomendation letters
Research experience: photonics and plasmonics theory (1.5 years since now, having 1 year more),
2 poster presentations
Tests:
GRE: Q : 750/800...had problem with time in the exam (going to retake it in few days aiming 800)
V : I don't wan't to say....didn't study for that

. Let's hope that's going to be better in my second attempt.
W : expected score between 4 and 5
PGRE: in November
TOEFL : results in few days (expecting > 100)
I'm aiming for schools in a diversity of areas (electrical engineering (top10), physics (top50) and materials science(top10)) for phD. So, what are my chances of getting admitted in a physics program in top20?