Quantum computers based on electron spins controlled by ultra-fast,   off-resonant, single optical pulses
  We describe a fast quantum computer based on optically controlled electron spins in charged quantum dots that are coupled to microcavities. This scheme uses broad-band optical pulses to rotate electron spins and provide the clock signal to the system. Non-local two-qubit gates are performed by phase shifts induced by electron spins on laser pulses propagating along a shared waveguide. Numerical simulations of this scheme demonstrate high-fidelity single-qubit and two-qubit gates with operation times comparable to the inverse Zeeman frequency. 
Susan M. Clark, Kai-Mei C. Fu, Thaddeus D. Ladd, Yoshihisa Yamamoto