Electric field driven donor-based charge qubits in semiconductors

TL;DR

This paper theoretically explores how external electric fields can manipulate donor-based charge qubits in semiconductors like GaAs and Si, demonstrating feasibility despite complex band structures.

Contribution

It provides a comparative analysis of charge qubit behavior in GaAs and Si, highlighting the impact of multivalley conduction bands and confirming the potential for electric field control.

Findings

Electric fields can coherently manipulate donor charge qubits in GaAs and Si.

Multivalley effects cause oscillations in tunnel coupling in Si but do not hinder electric control.

Electric field response in Si is similar to GaAs despite complex band structures.

Abstract

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.