Spin Diffusion and Relaxation in Solid State Spin Quantum Computer
  The processes of spin diffusion and relaxation are studied theoretically and numerically for quantum computation applications. Two possible realizations of a spin quantum computer (SQC) are analyzed: (i) a boundary spin chain in a 2D spin array and (ii) an isolated spin chain. In both cases, spin diffusion and relaxation are caused by a fast relaxing spin located outside the SQC. We have shown that in both cases the relaxation can be suppressed by an external non-uniform magnetic field. In the second case, our computer simulations have revealed various types of relaxation processes including the excitation of a random distribution of magnetic moments and the formation of stationary and moving domain walls. The region of optimal parameters for suppression of rapid spin relaxation is discussed. 
G.P. Berman, B.M. Chernobrod, V.N. Gorshkov (Theoretical Division, Los   Alamos National Laboratory, Los Alamos, New Mexico)...