Energy spectrum of extremal invariant states

Richard H. Herman, Daniel Kastler

Research output: Contribution to journalArticlepeer-review


For an extremal invariant state ω of a weakly asymptotically abelian dynamical system we prove that the corresponding energy spectrum is either one-sided or the whole reals, or a periodic subgroup. The latter case implies abelianness of the algebra in the representation generated by ω.

Original languageEnglish (US)
Pages (from-to)87-90
Number of pages4
JournalCommunications in Mathematical Physics
Issue number1
StatePublished - Feb 1977
Externally publishedYes

ASJC Scopus subject areas

  • Statistical and Nonlinear Physics
  • Mathematical Physics


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