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
Revised: 14 October 2003
Published online: 8 June 2004
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.
PACS: 72.20.Dp – General theory, scattering mechanisms / 05.30.-d – Quantum statistical mechanics
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2004