DECOHERENCE AND INITIAL CORRELATIONS IN QUANTUM BROWNIAN-MOTION

We analyze the evolution of a quantum Brownian particle starting from an initial state that contains correlations between this system and it s environment. Using a path-integral approach, we obtain a master equa tion for the reduced density matrix of the system finding relatively s imple expressions for its time-dependent coefficients. We examine the evolution of delocalized initial states (Schrodinger cat) investigatin g the effectiveness of the decoherence process. Analytic results are o btained for an Ohmic environment (Drude's model) at zero temperature.