  Broadband noise represents a severe limitation towards the implementation of
a solid-state quantum information processor. Considering common spectral forms,
we propose a classification of noise sources based on the effects produced
instead of on their microscopic origin. We illustrate a multi-stage approach to
broadband noise which systematically includes only the relevant information on
the environment, out of the huge parametrization needed for a microscopic
description. We apply this technique to a solid-state two-qubit gate in a fixed
coupling implementation scheme.
