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Time-dependent Displaced and Squeezed Number States
Sang Pyo Kim
We generalize the wave functions of the displaced and squeezed number states, found by Nieto, to a time-dependent harmonic oscillator with variable mass and frequency. These time-d…
Thermofield Dynamics of Time-Dependent Boson and Fermion Systems
Sang Pyo Kim, F. C. Khanna
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 dyna…
Invariant Operators vs Heisenberg Operators for Time-Dependent Generalized Oscillators
Sang Pyo Kim
We investigate the relation between the invariant operators satisfying the quantum Liouville-von Neumann and the Heisenberg operators satisfying the Heisenberg equation. For time-d…
Exact Quantum-Statistical Dynamics of Time-Dependent Generalized Oscillators
Sang Pyo Kim, Don N. Page
Using linear invariant operators in a constructive way we find the most general thermal density operator and Wigner function for time-dependent generalized oscillators. The general…
Decoherence of Quantum Damped Oscillators
Sang Pyo Kim, Ademir E. Santana, F. C. Khanna
Quantum dissipation is studied within two model oscillators, the Caldirola-Kanai (CK) oscillator as an open system with one degree of freedom and the Bateman-Feshbach-Tikochinsky (…
One-Parameter Gaussian State of Anharmonic Oscillator: Nonlinear Realization of Bogoliubov Transformation
Jung Kon Kim, Sang Pyo Kim, Kwang-Gi Park
We find a one-parameter Gaussian state for an anharmonic oscillator with quadratic and quartic terms, which depends on the energy expectation value. For the weak coupling constant,…