German Title: Dissipative Quantensysteme und Flussgleichungen
Translation of abstract (English)
This work investigates dissipative quantum systems by means of Flow Equations for Hamiltonians. We start with the Spin-Boson Model including one bosonic mode. The Flow Equation results for the ground-state energy and for the transformation of the Pauli spin matrices are compared with the numerically exact solution. For the Spin-Boson Model with an arbitrary number of bosonic modes and explicitly broken reflection symmetry, general Flow Equations are set up using a truncation scheme which involves an l-dependent normal ordering procedure. Furthermore, observations on universal asymptotic behaviour are discussed. The remaining chapter investigates quantum Brownian motion in a periodic potential with broken reflection symmetry - employing the previous procedures. In this context we also include results for the Tomonaga-Luttinger Model with impurity.
|Supervisor:||Mielke, Prof. Dr. Andreas|
|Date of thesis defense:||20 February 2002|
|Faculties / Institutes:||The Faculty of Physics and Astronomy > Institute for Theoretical Physics|
|Controlled Keywords:||Dissipation, Brownsche Bewegung, Magnetische Phasenumwandlung, Renormierungsgruppe, Feldtheorie|
|Uncontrolled Keywords:||Flussgleichung , Spin-Boson-Modell , Rauschinduzierter Transportflow equation , spin-boson model , noise induced transport|