Simple Non-Markovian Microscopic Models for the Depolarizing Channel of   a Single Qubit
  The archetypal one-qubit noisy channels ---depolarizing, phase-damping and amplitude-damping channels--- describe both Markovian and non-Markovian evolution. Simple microscopic models for the depolarizing channel, both classical and quantum, are considered. Microscopic models which describe phase damping and amplitude damping channels are briefly reviewed. 
K. M. Fonseca Romero and R. Lo Franco
quant-ph