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 that describe phase-damping and amplitude-damping channels are briefly reviewed.