Noise suppression via generalized-Markovian processes*

It is by now well established that noise itself can be useful for performing quantum information processing tasks.
We present results which show how one can effectively reduce the error rate associated with a noisy quantum channel, by counteracting its detrimental effects with another form of noise.
In particular, we consider the interplay between a purely Markovian (Lindblad) dynamics, and a more general form of dissipation, which we refer to as generalized-Markovian noise. This noise has an associated memory kernel and the resulting dynamics is described by an integro-differential equation (i.e., it has a non-Markov character).
The overall dynamics are characterized by decay rates which depend not only on the original dissipative time-scales, but also on the new integral kernel. We find that one can engineer this kernel such that the overall rate of decay is lowered by the addition of such a noise term.
We provide numerical results for several physical models, including a dephasing channel, and qubit in a thermal environment.
These results help to qualitatively explain the physical mechanism behind this error suppression scheme, whereby the system is periodically decoupled from the background noise.