  Dynamical decoupling techniques are the method of choice for increasing gate
fidelities. While these methods have produced very impressive results in terms
of decreasing local noise and increasing the fidelities of single qubit
operations, dealing with the noise of two qubit gates has proven more
challenging. The main obstacle is that the noise time scale is shorter than the
two qubit gate itself so that refocusing methods do not work. We present a
measurement and feedback based method to refocus two qubit gates which cannot
be refocused by conventional methods. We analyze in detail this method for an
error model which is relevant for trapped ions quantum information.
