**algebraic quantum field theory** (perturbative, on curved spacetimes, homotopical)

**quantum mechanical system**, **quantum probability**

**interacting field quantization**

The theory of quantum physics (quantum mechanics, quantum field theory) is at its heart probabilistic (see at *hidden variable theory*). Any quantum observable in a given quantum state has a probability distribution with some finite width around its mean value. A measurement will find the observable with given probability in any one of its possible values, and hence it seems as if it “fluctuates”. This intrinsic randomness in quantum physics is referred to as *quantum fluctuation*. (See also at *measurement problem*.)

In particular the above holds for the vacuum state of any quantum system. Hence even when a quantum system is a little “excited” as possible, it still quantum fluctuation. These are therefore also called *vacuum fluctuations*.

See also:

- Wikipedia,
*Quantum fluctuation*

In view of thermodynamics:

- Akira Sone, Kanu Sinha, Sebastian Deffner,
*Thermodynamic perspective on quantum fluctuations*, in*Encyclopedia of Mathematical Physics 2nd ed*, Elsevier (2024) [arXiv:2308.04951]

Last revised on March 26, 2024 at 19:32:05. See the history of this page for a list of all contributions to it.