Recent experiments on silicon-based nanostructures have seen breakthroughs toward quantum information processing. The valley degree of freedom of the electrons plays a fundamental role in these devices, and the lowest two single-electron energy eigenstates of such a quantum dot can form a so-called "valley qubit". In the talk, I will characterize the interaction of such a qubit with external and phonon-induced electric fields, discuss how that interaction can be utilized to coherently control and measure the qubit state, and how the same interactions can lead to the loss of information encoded in the qubit.