  We study the non-Markovian decoherence and disentanglement dynamics of
dissipative quantum systems with special emphasis on non-Gaussian continuous
variable systems. The dynamics are described by the Hu-Paz-Zhang master
equation of quantum Brownian motion. The time evolution of the decoherence
function of a single-mode superposition is compared to the concurrence of a
two-mode entangled state. It is verified that moderate non-Markovian influences
slow down the decay of interference fringes and quantum correlations, while
strong non-Markovian effects resulting from an out-of-resonance bath can even
accelerate the loss of coherence, compared to predictions of Markovian
approximations. Qualitatively different scenarios including exponential,
Gaussian or algebraic decay of the decoherence function are analyzed. It is
shown that partial revivals of coherence can occur in case of non-Lindblad-type
dynamics.
