Thermal degree of freedom in thermo field dynamics

H. Umezawa*, Y. Yamanaka

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

16 Citations (Scopus)


The view of the thermal degree of freedom for the quantum field system, using the language of thermo field dynamics, is elaborated in this paper: the thermal degree of freedom is the degree of freedom to move through degenerate thermal vacua associated with spontaneous breakdown of a certain symmetry (Ĝ-symmetry). Based on this view, we study a quasi-particle picture, in which the Ĝ-transformation becomes the thermal Bogoliubov transformation.

Original languageEnglish
Pages (from-to)75-82
Number of pages8
JournalPhysics Letters A
Issue number2-3
Publication statusPublished - 1991 May 6
Externally publishedYes

ASJC Scopus subject areas

  • Physics and Astronomy(all)


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