  Microscopic Hamiltonian models of the composite system "open system +
environment" typically do not provide the operator-sum Kraus form of the open
system's dynamical map. With the use of a recently de- veloped method [16], we
derive the Kraus operators starting from the mi- croscopic Hamiltonian model,
i.e. from the proper master equation, of the one-qubit depolarizing channel.
Those Kraus operators generalize the stan- dard counterparts, which are widely
used in the literature. Comparison of the standard and the here obtained Kraus
operators is performed via inves- tigating dynamical change of the Bloch sphere
volume, entropy production and the open system's state trace distance. We find
that the standard depo- larizing channel is more deteriorating than the
generalized one.
