Condensed Matter Physics, 2008, vol. 11, No. 4(56), p. 687697
DOI:10.5488/CMP.11.4.687
Title:
Annihilation operators associated with unstable vacua in nonequilibrium thermofield dynamics
Author(s):

K. Yoshida
(Graduate School of Pure and Applied Sciences, University of Tsukuba, 111 Tennoudai, Ibaraki 3058571, Japan)
,


T. Arimitsu
(Graduate School of Pure and Applied Sciences, University of Tsukuba, 111 Tennoudai, Ibaraki 3058571, Japan)

Out of thermal equilibrium state, the vacuum is unstable and evolves in time. Consequently, the annihilation operators associated with the unstable vacuum depend on time. This dissipative timeevolution of quantum systems can be systematically treated, within the canonical operator formalism referred to as nonequilibrium thermofield dynamics. Given is an alternative route to derive the timedependent annihilation operators within the formalism. As an example, timedependent annihilation operators for the systems of bosonic and fermionic semifree fields are derived.
Key words:
nonequilibrium thermofield dynamics, annihilation operator, unstable vacuum, dissipative quantum systems, timedependent Bogoliubov transformation
PACS:
11.10.Wx, 05.30.d
