Coherent electrical rotations of valley states in Si quantum dots using   the phase of the valley-orbit coupling
  A gate electric field has a small but non-negligible effect on the phase of the valley-orbit coupling in Si quantum dots. Finite interdot tunneling between valley eigenstates in a double quantum dot is enabled by a small difference in the phase of the valley-orbit coupling between the two dots, and it in turn allows controllable rotations of two-dot valley eigenstates at a level anticrossing. We present a comprehensive analytical discussion of this process, with estimates for realistic structures. 
Yue Wu and Dimitrie Culcer
cond-mat.mes-hall