Regensburg 2004 – wissenschaftliches Programm

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DY: Dynamik und Statistische Physik

DY 50: Entanglement and Decoherence

DY 50.5: Vortrag

Freitag, 12. März 2004, 11:30–11:45, H2

Is the Quantum Dynamics of an Open Quantum System always Linear? — •Peter Hänggi, Peter Talkner, and Karen M. Fonseca-Romero — Institut für Physik, Universität Augsburg, Universitätsstr. 1, D-86135 AUGSBURG

We study the influence of the preparation of an open quantum systerm on its reduced time evolution. In contrast to the widely studied case of an initial preparation where the total density matrix factorizes into a product of system density matrix and bath density matrix the time evolution generally is no longer governed by a linear map. Put differently, the evolution is truely nonlinear and cannot be cast into the form of a linear map plus a term that is independent of the initial denisty matrix of the open system (no affine time evolution). As a consequence, the inhomogeneity that emerges in formally exact generalized master equatins is in fact a nonlinear term that vanishes only for a factorizing initial state. The general results are elucidated with the example of two interacting spins prepared in thermal equilibrium with one spin subjected to external fields.