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TT: Fachverband Tiefe Temperaturen

TT 12: Quantum Dynamics, Decoherence and Quantum Information (organized by DY)

TT 12.2: Vortrag

Montag, 31. März 2014, 10:00–10:15, HÜL 186

Adiabatic-Markovian Dynamics at Avoided Crossings — •Peter Nalbach — I. Institut für Theoretische Physik, Universität Hamburg, Jungiusstr. 9, 20355 Hamburg

In order to study Landau-Zener transitions at avoided crossings under the influence of environmental fluctuations we derive effective nonequilibrium Bloch equations. Thereby, we employ an adiabatic-Markovian approximation which results in effectively time-dependent relaxation and dephasing rates and a time-dependent quasi-equilibrium statistical operator to which the system is driven. At weak coupling, where in a static case a Markovian approximation is valid, we observe very good agreement for the full driving speed range between the nonequilibrium Bloch equations predictions and numerical exact data for the Landau-Zener transition and the excitation survival probability [1]. The nonequilibrium Bloch equations, thus, allow for an efficient tool to analyze and model the dynamics in driven double quantum dot [2] and other qubit realizations.
[1] P. Nalbach and M. Thorwart, Phys. Rev. Lett. 103, 220401 (2009) & Chem. Phys. 375, 234 (2010).
[2] P. Nalbach, J. Knörzer and S. Ludwig, Phys. Rev. B 87, 165425 (2013).