Spin-boson dynamics: A unified approach from weak to strong couplingF. Nesi1, E. Paladino2, M. Thorwart3 and M. Grifoni1
1 Theoretische Physik, Universität Regensburg - 93040 Regensburg, Germany
2 MATIS INFM-CNR & Dipartimento di Metodologie Fisiche e Chimiche, Università di Catania 95125 Catania, Italy
3 Institut für Theoretische Physik, Heinrich-Heine-Universität Düsseldorf - 40225 Düsseldorf, Germany
received 22 June 2007; accepted in final form 21 September 2007; published November 2007
published online 18 October 2007
We present a novel approximation scheme to describe the influence of a harmonic bath on the dynamics of a two-level particle over almost the whole regime of temperatures and coupling to the environment, for a wide class of bath spectral densities. Starting from the exact path integral solution for the two-level system density matrix, effective intra-blip correlations are fully included, while inter-blip and blip-sojourn interactions are considered up to first order. In the proper regimes, an excellent agreement with conventional perturbative approaches and ab initio path-integral results is found.
05.30.-d - Quantum statistical mechanics.
03.65.Yz - Decoherence; open systems; quantum statistical methods.
© Europhysics Letters Association 2007