We investigate theoretically donor-based charge qubit operation driven by external electric fields. The basic physics of the problem is presented by considering a single electron bound to a shallow-donor pair in GaAs: This system is closely related to the homopolar molecular ion H_2^+. In the case of Si, heteropolar configurations such as PSb^+ pairs are also considered. For both homopolar and heteropolar pairs, the multivalley conduction band structure of Si leads to short-period oscillations of the tunnel-coupling strength as a function of the inter-donor relative position. However, for any fixed donor configuration, the response of the bound electron to a uniform electric field in Si is qualitatively very similar to the GaAs case, with no valley quantum interference-related effects, leading to the conclusion that electric field driven coherent manipulation of donor-based charge qubits is feasible in semiconductors.
@article{arxiv.cond-mat/0510520,
title = {Electric field driven donor-based charge qubits in semiconductors},
author = {Belita Koiller and Xuedong Hu and S. Das Sarma},
journal= {arXiv preprint arXiv:cond-mat/0510520},
year = {2007}
}