title: Modeling heat transport through completely positive maps.
abstract: We investigate heat transport in a spin-1/2 Heisenberg chain, coupled locally to independent thermal baths of different temperature. The analysis is carried out within the framework of the theory of open systems by means of appropriate quantum master equations. The standard microscopic derivation of the weak-coupling Lindblad equation in the secular approximation is considered, and shown to be inadequate for the description of stationary nonequilibrium properties like a nonvanishing energy current. Furthermore, we derive an alternative master equation that is capable of describing a stationary energy current and, at the same time, leads to a completely positive dynamical map. This paves the way for efficient numerical investigations of heat transport in larger systems based on Monte Carlo wave function techniques.
authors.affiliation: Fachbereich Physik, Universität Osnabrück, Barbarastrasse 7, D-49069 Osnabrück, Germany. hwichter@uni-osnabrueck.de
authors.forename: Hannu
authors.initials: H
authors.lastname: Wichterich
authors.forename: Markus J
authors.initials: MJ
authors.lastname: Henrich
authors.forename: Heinz-Peter
authors.initials: HP
authors.lastname: Breuer
authors.forename: Jochen
authors.initials: J
authors.lastname: Gemmer
authors.forename: Mathias
authors.initials: M
authors.lastname: Michel