Eur. Phys. J. B 38, 559-562 (2004)
https://doi.org/10.1140/epjb/e2004-00152-7

Dynamics of a two-level system coupled to Ohmic bath: a perturbation approach

Department of Physics, Shanghai Jiao Tong University, Shanghai 200030, P.R. China

Corresponding authors: ^a hzheng@mail.sjtu.edu.cn hzheng@online.sh.cn

Received: 24 April 2003
Revised: 14 October 2003
Published online: 8 June 2004

Abstract

The quantum dynamics, both non-equilibrium and equilibrium, of the dissipative two-level system is studied by means of the perturbation approach based on a unitary transformation. It works well for the whole parameter range and and our main results are: the coherence-incoherence transition is at ; for the non-equilibrium correlation ; the susceptibility is of a double peak structure for and the Shiba's relation is exactly satisfied; at the transition point the equilibrium correlation in the long time limit.