Decoherence and dissipation of an open quantum system with a squeezed and frequency-modulated heat bath

The functional integral formalism is used to provide a unified treatment of the effect of squeezing of the bath and frequency modulation of the system–bath coupling on the decoherence and dissipation properties of an open quantum system. The system chosen is a standard one consisting of a particle in a harmonic oscillator potential interacting with a bath of harmonic oscillators by a coupling of the position–position kind. Using an Ohmic bath and the high-temperature limit, the coefficients of the master equation describing dissipation and decoherence are obtained and analyzed.