One normally makes a distinction between quantum mechanics and quantum physics. Quantum physics is concerned with those processes that involve discrete energies, and quanta (such as photons). Quantum Mechanics concerns the study of a specific part of quantum physics, those quantum phenomena described by Schrödinger's equation.
Quantum physics plays a rôle on small (atomic and subatomic)
scales (say length scales of the order of
10-9m) and below.
You can see whether an expression has a quantum-physical
origin as soon as it contains Planck's constant in one of its two
guises
| h | = | 6.626 . 10-34Js, | |
| = | h/2 |
(1.1) |