Quantum physics is physics that takes the postulate of the quantum as one of its foundations. It is mostly concerned with sub-atomic particles, atoms, and molecules, and the radiation that belongs to them. The postulate of the quantum is that change in Nature is through jumps between sub-atomic stationary states.
![Quantum Physics: Atoms, Molecules, Solids, Nuclei, and Particles – Robert Eisberg, Robert Resnick – 2nd Edition Quantum Physics: Atoms](https://www.tbooks.solutions/wp-content/archivos/2020/06/quantum-physics-atoms-molecules-solids-nuclei-and-particles-robert-eisberg-robert-resnick-1st-edition-250x325.jpg)