Global control and fast solid-state donor electron spin quantum   computing
  We propose a scheme for quantum information processing based on donor electron spins in semiconductors, with an architecture complementary to the original Kane proposal. We show that a naive implementation of electron spin qubits provides only modest improvement over the Kane scheme, however through the introduction of global gate control we are able to take full advantage of the fast electron evolution timescales. We estimate that the latent clock speed is 100-1000 times that of the nuclear spin quantum computer with the ratio $T_{2}/T_{ops}$ approaching the $10^{6}$ level. 
Charles D. Hill, L. C. L. Hollenberg, A. G. Fowler, C. J. Wellard, A.   D. Greentree, H.-S. Goan