Quantum mechanics

branch of physics dealing with the descripiton of behavior of subatomic particles in terms of quanta

In physics, quantum mechanics is the study of the relationship between energy quanta (radiation) and matter, in particular that between valence shell electrons and photons. Quantum mechanics is a fundamental branch of physics with wide applications in both experimental and theoretical physics. The effects of quantum mechanics are typically not observable on macroscopic scales, but become evident at the atomic and subatomic level.  Quantum theory generalizes all classical theories, including mechanics and electromagnetism (except general relativity), and provides accurate descriptions for many previously unexplained phenomena such as black body radiation and stable electron orbits.
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Quantum mechanics, n the application of quantum theory to statistical mechanics to explain the properties of matter when examined at the subatomic [more]Quantum mechanics - Community and Resources

Noun
1. the branch of quantum physics that accounts for matter at the atomic level; an extension of statistical mechanics based on quantum theory (especially the Pauli exclusion principle)
(hypernym) quantum physics
(hyponym) wave mechanics

A branch of physics that describes the behavior of objects of atomic and subatomic size.