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TT: Tiefe Temperaturen

TT 25: Correlated Electrons - Poster Session

TT 25.67: Poster

Mittwoch, 29. März 2006, 14:30–18:30, P1

Spin-boson model dynamics for non-equilibrium initial preparation — •Andreas Hackl¹ and Stefan Kehrein² — ¹Theoretische Physik III, Center for Electronic Correlations and Magnetism, Department of Physics, Universitaet Augsburg — ²Department of Physics, LMU Muenchen Theresienstr. 37, 80333 Muenchen

The spin-boson model as a paradigm for quantum dissipation is well-understood in equilibrium. [1] However, many interesting questions regarding its dynamics are still open if the spin-boson model is initially prepared in a quantum state that is not its ground state. We use infinitesimal unitary tranformations (flow equation method) [2] to eliminate the system-bath coupling in a controlled nonperturbative approximation. In this way we are able to solve the Heisenberg equations of motion for the spin operators analytically with good accuracy, which allows us to study such non-equilibrium dynamics. We discuss various correlation functions, their equilibration properties and the fluctuation-dissipation theorem for different classes of initial states.

[1] S. Kehrein und A. Mielke, Annalen der Physik (Leipzig) 6, 90 (1997)

[2] F. Wegner, Annalen der Physik (Leipzig) 3, 77 (1994)