noun
quantum mechanics
The branch of physics dealing with atomic and subatomic systems. Often contrasted with 古典力学 (classical mechanics).
See also: 古典力学
量子力学は、原子や電子の振る舞いを説明する理論です。
Quantum mechanics is a theory that explains the behavior of atoms and electrons.
彼は大学で量子力学を専攻している。
He is majoring in quantum mechanics at university.