Universality of quantum Brownian motion

Are Markovian master equations for quantum Brownian motion independent of m odel assumptions used in the derivation and, thus, universal? With the aim of answering this question, we use a random band-matrix model for the syste m-bath interaction to derive Markovian master equations for the time evolut ion of one-dimensional quantum systems weakly coupled to a heat bath. We st udy in detail two simple systems, the harmonic oscillator and the two-level system. Our results are in complete agreement with those of earlier models , like the Caldeira-Leggett model and, in the large-band limit, with the Ag arwal equations (both with and without rotating-wave approximation). This p roves the universality of these master equations. (C) 1999 Elsevier Science B.V. All rights reserved.