Regensburg 2007 – wissenschaftliches Programm

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TT: Fachverband Tiefe Temperaturen

TT 28: Transport - Poster Session

TT 28.50: Poster

Donnerstag, 29. März 2007, 14:00–17:45, Poster A

Spin-boson dynamics in a structured environment: A path integral approach — •Johannes Hausinger, Francesco Nesi, and Milena Grifoni — Universität Regensburg

In our work we examine the dynamics of a spin-boson Hamiltonian coupled to a reservoir featuring a peaked spectral density.This system has become relevant to investigate e. g. relaxation and dephasing in flux qubits coupled to a dc-SQUID detector [1].

We investigate that system using the real-time path integral approach of Feynman and Vernon.

We consider the case of a symmetric as well as of a biased two-level system (TLS). In the symmetric case the so-called noninteracting-blip approximation (NIBA), being perturbative in the tunneling coupling Δ, well describes the TLS dynamics. In particular the related power spectrum exhibits Rabi-vacuum splitting in the proper parameter regime. In the biased case however, the NIBA fails [2] in the low temperature and damping regime.

We present a novel approximation scheme capable to deal with bath-induced correlations in such a low temperature regime.

[1] M. Thorwart, E. Paladino, M. Grifoni, Chem. Phys. 296, 333 (2004)

[2] U. Weiss, Quantum Dissipative Systems, 2nd ed. (World Scientific, Singapore, 1999)