# von Neumann entropy

## EnglishEdit

### EtymologyEdit

Named after John von Neumann.

### PronunciationEdit

- IPA
^{(key)}: /vɔn ˈnoɪ.mən ˈɛn.tɹə.pi/

### NounEdit

**von Neumann entropy**

- (quantum mechanics) The entropy of a quantum state. If the state is expressed as a quantum density matrix , then this entropy can be expressed mathematically as where is the trace operator and the logarithm is natural.