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Thermofield Dynamics of Time-Dependent Boson and Fermion Systems

Sang Pyo Kim·F. C. Khanna
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Abstract

We formulate the thermofield dynamics for time-dependent systems by combining the Liouville-von Neumann equation, its invariant operators, and the basic notions of thermofield dynamics. The new formulation is applied to time-dependent bosons and fermions by using the time-dependent annihilation and creation operators that satisfy the Liouville-von Neumann equation. It is shown that the thermal state is the time- and temperature-dependent vacuum state and a general formula is derived to calculate the thermal expectation value of operators.

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Sang Pyo Kim, F. C. Khanna. 2003-08-09. Thermofield Dynamics of Time-Dependent Boson and Fermion Systems. https://arxiv.org/abs/quant-ph/0308053

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