physicist
A scientist who studies or works in physics.
He is a famous physicist.
To become a physicist, you must be good at mathematics.
物理学 is the field of physics, while 物理学者 is a person who works in that field.
科学者 is a general term for scientist; 物理学者 specifically refers to a physicist.
Compound of 物理 (physics) + 学者 (scholar, -ist).