Enhanced Valley Splitting in Si Layers with Oscillatory Ge Concentration

Abstract

The valley degeneracy in Si qubit devices presents problems for their use in quantum information processing. It is possible to lift this degeneracy by using the Wiggle Well architecture, in which an oscillatory Ge concentration couples the valleys. This paper presents the basic theory of this phenomenon together with model calculations using the empirical pseudopotential theory to obtain the overall magnitude of this effect and its dependence on the wavelength of the concentration oscillations. We derive an important selection rule which can limit the effectiveness of the Wiggle Well in certain circumstances.

arXiv comment12 pages, 4 figures

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• Spin-orbit enhancement in Si/SiGe heterostructures with oscillating Ge concentration
• Coupling conduction-band valleys in SiGe heterostructures via shear strain and Ge concentration oscillations
• Valley splitting depending on the size and location of a silicon quantum dot
• Theory of Valley Splitting in Si/SiGe Spin-Qubits: Interplay of Strain, Resonances and Random Alloy Disorder
• Valley splitting by extended zone effective mass approximation incorporating strain in silicon
• Valley Splitting Correlations Across a Silicon Quantum Well Containing Germanium
• Electrical Interconnects for Silicon Spin Qubits
• Micromagnet-free operation of electron spin qubits in Si/Si${}_{1-x}$Ge${}_x$ vertical double quantum dots
• Wide Electrical Tunability of the Valley Splitting in a Doubly gated Silicon-on-Insulator Quantum Well
• Exact Multi-Valley Envelope Function Theory of Valley Splitting in Si/SiGe Nanostructures