  Quantum optimal control theory allows to design accurate quantum gates. We
employ it to design high-fidelity two-bit gates for Josephson charge qubits in
the presence of both leakage and noise. Our protocol considerably increases the
fidelity of the gate and, more important, it is quite robust in the disruptive
presence of 1/f noise. The improvement in the gate performances discussed in
this work (errors of the order of 10^{-3}-10^{-4} in realistic cases) allows to
cross the fault tolerance threshold.
