Suppression of 1/fα noise in one-qubit systems

We investigate the generation of quantum operations for one-qubit systems under classical Markovian noise with a 1/f(alpha) power spectrum, where 2 > alpha > 0. We present an efficient way to approximate the noise with a discrete multistate Markovian fluctuator. With this method, the average temporal evolution of the qubit state operator under 1/f(alpha) noise can be feasibly determined from recently derived deterministic master equations. We obtain qubit operations such as quantum memory and the NOT gate to high fidelity by a gradient- based optimization algorithm. For the NOT gate, the computed fidelities are qualitatively similar to those obtained earlier for random telegraph noise. In the case of quantum memory, however, we observe a nonmonotonic dependency of the fidelity on the operation time, yielding a natural access rate of the memory.