Intervalley interactions in Si quantum dots

In this paper, we studied the intervalley interactions between the orbital functions associated with multivalley of silicon (Si) quantum dots. Numerical calculations show that the intervalley coupling between orbital functions increases rapidly with an applied electric field. We also considered the potential applications to quantum bit operation utilizing controlled intervalley interactions. Quantum bits are the multivalley symmetric and antisymmetric orbitals. Evolution of these orbitals would be controlled by an external electric field which turns on and off the intervalley interactions. Estimates of the decoherence time are made for the longitudinal-acoustic-phonon process. Elementary single- and two-qubit gates are also proposed.