Atomic, molecular, and optical physics is the study of matter-matter and light-matter interactions on the scale of single atoms or structures containing a few atoms. The three areas are grouped together because of their interrelationships, the similarity of methods used, and the commonality of the energy scales that are relevant. Physicists sometimes abbreviate the field as AMO physics. All three areas include both classical and quantum treatments.

Atomic physics

Atomic physics studies the electron hull of atoms. This branch of physics is distinct from nuclear physics, despite their association in the public consciousness. Atomic physics is not concerned with the intra-nuclear processes studied in nuclear physics, although properties of the nucleus can be important in atomic physics (e.g., hyperfine structure). Current research focuses on activities in quantum control, cooling and trapping of atoms and ions, low-temperature collision dynamics, the collective behavior of atoms in weakly interacting gases (Bose-Einstein Condensates and dilute Fermi degenerate systems), precision measurements of fundamental constants, and the effects of electron correlation on structure and dynamics.Atomic physics is that branch of physics which deals with the study of atom, particularly extra-nuclear particles like electrons and their behaviour in atom-like interactions with protons, neutrons in the nucleus.

Molecular physics

Molecular physics focuses on multi-atomic structures and their internal and external interactions with matter and light.

Optical physics

Optical physics is distinct from optics in that it tends to focus not on the control of classical light fields by macroscopic objects, but on the fundamental properties of optical fields and their interactions with matter in the microscopic realm.