Decoherence control for high-temperature reservoirs

We investigate the decoherence control coupled to a rather general environment, i.e., without using the Markov approximation. Markovian errors generally require high-energy excitations (of the reservoir) and tend to destroy the scalability of the adiabatic quantum computation. Especially, we find that deriving optimal control using the Pontryagin maximum principle, the decoherence can be suppressed even in high-temperature reservoirs. The influences of Ohmic reservoir with Lorentz-Drude regularization are numerically studied in a two-level system under ωc ≪ ω0 condition, here ω0 is the characteristic frequency of the quantum system of interest, and ωc the cut-off frequency of Ohmic reservoir. It implies that designing some engineered reservoirs with the controlled coupling and state of the environment can slow down the decoherence rate and delay the decoherence time. Moreover, we compared the non-Markovian optimal decoherence control with the Markovian one and find that with non-Markovian the engineered artificial reservoirs are better than the Markovian approximate in controlling the decoherence of open, dissipative quantum systems.