  This article presents microscopic derivation of the Kraus operators for (the
generalized) amplitude and phase damping process. Derivation is based on the
recently developed method [Andersson et al, J. Mod.Opt. 54, 1695 (2007)] which
concerns finite dimensional systems (e.g. qubit). The form of these operators
is usually estimated without insight into the microscopic details of the
dynamics. The behavior of the qubit dynamics is simulated and depicted via
Bloch sphere change.
