von Neumann entropy

Named after John von Neumann.

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

von Neumann entropy

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