Temperature changes and squeezing properties of the system of time-dependent harmonic oscillators

Abstract

The density operator is defined as a function of a generalized invariant for the system of time-dependent harmonic oscillators. Applying this to the Hamiltonian with two asymptotic regions, we calculate the temperature change driven by a time-varying Hamiltonian. Furthermore, the squeezing properties of an eigenstate and a coherent state of the initial Hamiltonian are discussed.