We propose a technique that allows to simultaneously perform universal control of the evolution operator and compensate for the first order contribution of an arbitrary Hermitian constant noise. We show that, at least, a three-valued Hamiltonian is needed in order to protect the system against any such noise. This technique is illystrated by an explicit algorithm for a control sequence that is applied to numerically design a safe two-qubit gate.
@article{arxiv.0905.3254,
title = {Universal protection of unitary evolution from slow noise: dynamical control pushed to the extreme},
author = {G. Bensky and E. Brion and F. Carlier and V. M. Akulin and G. Kurizki},
journal= {arXiv preprint arXiv:0905.3254},
year = {2009}
}