von Neumann entropy

English

Etymology

Named after John von Neumann.

Pronunciation

• IPA^(key): /vɔn ˈnoɪ.mən ˈɛn.tɹə.pi/

Noun

von Neumann entropy

1. (quantum mechanics) The entropy of a quantum state. If the state is expressed as a quantum density matrix $\rho$, then this entropy can be expressed mathematically as $S=-{\text{tr}}(\rho \log \rho )$ where ${\text{tr}}$ is the trace operator and the logarithm is natural.