In physics , a quantum (from the Latin quantum , 'how big', 'how much') is an object that is created by a change of state in a system with discrete values of a physical quantity . Quantized quantities are described in the context of quantum mechanics and sub-areas of theoretical physics inspired by it, such as quantum electrodynamics . Quanta can only ever appear in certain portions of this physical quantity, they are therefore the quantization of these quantities.
The term quant
The physical term quantum is often associated with a particle character of the size under consideration. However, this is only part of the real meaning of the term. An example of a quantum that cannot be ascribed a particle character is the angular momentum quantum .
As a physical term, quantum is not used to denote the atomic structure of matter , although here, too, a smallest unit of quantity (quantization) occurs.
- The photon as a quantum of the electromagnetic field . Photons can have different discrete energy levels , but they can only be created or destroyed as a whole.
- The phonon as a quantum of mechanical distortion waves in the solid .
- The plasmon as a quantum of an excitation in the solid, in which the charge carriers oscillate against each other.
- The magnon as a quantum of magnetic excitations.
- The quantum of the angular momentum that is not interpreted as a particle.
- The gluon as a quantum of the force field that transmits the strong interaction .
- The graviton as a quantification of the gravitational field.
Jürgen Audretsch: Entangled World Fascination of the Quanta , Wiley-VCh, Weinheim 2002, ISBN 3-527-40318-3