Volume 80, Number 4, November 2007
Article Number 40005
Number of page(s) 6
Section General
Published online 18 October 2007
EPL, 80 (2007) 40005
DOI: 10.1209/0295-5075/80/40005

Spin-boson dynamics: A unified approach from weak to strong coupling

F. 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