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### Quantum

A quantum is the minimum amount of any physical property involved in an interaction.

##### Explanation

The magnitude of a physical property can take on only discrete values consisting of integer multiples of one quantum.

##### Example 1

The Planck constant *h* is the quantum of electromagnetic action.

##### Example 2

Dirac's constant ℏ is a quantum of angular momentum, including spin. It is the smallest unit of information.

##### Example 3

A photon ɣ is the quantum of energy as a form of electromagnetic radiation.

##### Example 4

A phonon is the quantum of energy in vibrations that occur in periodic arrangements of atoms or molecules.

##### Example 5

A magnon is the quantum of a spin wave. It is an excitation associated with the spin structure of electrons in a crystal lattice.

##### Example 6

A plasmon is the quantum of plasma oscillation.

##### Example 7

A roton is a quantum of angular momentum. It is an excitation that describes the macroscopic rotational states of suprafluids.

##### Example 8

The elementary charge *e* of a proton is a quantum of electric charge.

##### Example 9

The hypothetical graviton is the energy quantum of gravitational waves.

##### Example 10

According the loop quantum gravity theory, interactions create space quanta.