  We show how to eliminate the first-order effects of the spin-orbit
interaction in the performance of a two-qubit quantum gate. Our procedure
involves tailoring the time dependence of the coupling between neighboring
spins. We derive an effective Hamiltonian which permits a systematic analysis
of this tailoring. Time-symmetric pulsing of the coupling automatically
eliminates several undesirable terms in this Hamiltonian. Well chosen pulse
shapes can produce an effectively isotropic exchange gate, which can be used in
universal quantum computation with appropriate coding.
