# Quantum superposition |  | **Quantum superposition** is a fundamental principle of quantum mechanics. In classical mechanics, things like position or momentum are always well-defined. It may not be known what they are at any given time, but that is an issue of understanding and not an issue of the physical system. A quantum system interacts in ways that can be explained with superposition of different discrete states. Measurements of quantum systems give a statistical result corresponding to any one of the possible states appearing at random. | |-|-| | | wikipedia:: [Quantum superposition](https://en.wikipedia.org/wiki/Quantum_superposition) |