The Wigner-Yanase entropy is not subadditive

Frank Hansen

Research output: Contribution to journalArticlepeer-review

24 Citations (Scopus)


Wigner and Yanase introduced in 1963 the Wigner-Yanase entropy defined as minus the skew information of a state with respect to a conserved observable. They proved that the Wigner-Yanase entropy is a concave function in the state and conjectured that it is subadditive with respect to the aggregation of possibly interacting subsystems. While this turned out to be true for the quantum-mechanical entropy, we negate the conjecture for the Wigner-Yanase entropy by providing a counter example.

Original languageEnglish
Pages (from-to)643-648
Number of pages6
JournalJournal of Statistical Physics
Issue number3
Publication statusPublished - 2007 Feb


  • Subadditivity
  • Wigner-Yanase entropy

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Mathematical Physics


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