Oscillator phase states, thermal equilibrium and group representations

Y. Aharonov*, E. C. Lerner, H. W. Huang, J. M. Knight

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

44 Scopus citations


Eigenstates of the annihilation type operator U = C + iS, where C and S are the "cosine" and "sine" operators for harmonic oscillator phase, are shown to be closely related to thermal equilibrium states of the oscillator and to provide a new interpretation of the thermal equilibrium density operator. The problem of creating such states is considered and a general theorem is established leading to the construction of interaction Hamiltonians which transform the eigenstates of U among themselves and, in particular, create them from the oscillator ground state. These Hamiltonians lead to representations of the Lie algebras of O(2,1) and O(3). It is suggested that the mathematical technique used, in which generalized U-type operators provide the link between a group and its representations, has its own intrinsic interest for the study of Lie groups.

Original languageEnglish
Pages (from-to)746-756
Number of pages11
JournalJournal of Mathematical Physics
Issue number6
StatePublished - 1973


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