Theory of decoherence control in a fluctuating environment

Detailed studies are carried out for the problem of decoherence control by a successive application of pi-pulses when a relevant spin-1/2 (qubit) system is surrounded by a stochastically fluctuating environment. Specifically, considerations are given to two representative stochastic processes: a two-state-jump Markov process and a Gauss-Markov process. Exact analytical solutions are obtained for the decoherence control by the pi-pulse application even for non-stationary stochastic processes as well as for stationary processes. In view of recent advances in dynamical decoupling experiments with artificial (engineered) stochastic noise, the results are useful in analysing qubit systems under the influence of a fluctuating environment.