Disorder-induced valley-orbit hybrid states in Si quantum dots

Quantum dots in silicon are promising candidates for the implementation of solid-state quantum information processing. It is important to understand the effects of the multiple conduction band valleys of silicon on the properties of these devices. Here we present a systematic effective mass theory of valley-orbit coupling in disordered silicon systems. This theory reveals valley-orbit hybridization effects that are detrimental for storing quantum information in the valley degree of freedom, including nonvanishing dipole matrix elements between valley states and altered intervalley tunneling.