Quantum information processing using localized ensembles of nuclear   spins
  We describe a technique for quantum information processing based on localized en sembles of nuclear spins. A qubit is identified as the presence or absence of a collective excitation of a mesoscopic ensemble of nuclear spins surrounding a single quantum dot. All single and two-qubit operations can be effected using hyperfine interactions and single-electron spin rotations, hence the proposed scheme avoids gate errors arising from entanglement between spin and orbital degrees of freedom. Ultra-long coherence times of nuclear spins suggest that this scheme could be particularly well suited for applications where long lived memory is essential. 
J. M. Taylor, G. Giedke, H. Christ, B. Paredes, J. I. Cirac, P.   Zoller, M. D. Lukin, and A. Imamoglu