Engineered valley-orbit splittings in quantum confined nanostructures in silicon

Abstract

An important challenge in silicon quantum electronics in the few electron regime is the potentially small energy gap between the ground and excited orbital states in 3D quantum confined nanostructures due to the multiple valley degeneracies of the conduction band present in silicon. Understanding the "valley-orbit" (VO) gap is essential for silicon qubits, as a large VO gap prevents leakage of the qubit states into a higher dimensional Hilbert space. The VO gap varies considerably depending on quantum confinement, and can be engineered by external electric fields. In this work we investigate VO splitting experimentally and theoretically in a range of confinement regimes. We report measurements of the VO splitting in silicon quantum dot and donor devices through excited state transport spectroscopy. These results are underpinned by large-scale atomistic tight-binding calculations involving over 1 million atoms to compute VO splittings as functions of electric fields, donor depths, and surface disorder. The results provide a comprehensive picture of the range of VO splittings that can be achieved through quantum engineering.

4 pages, 4 figures

References in corpus (6)

• Transport spectroscopy of a single dopant in a gated silicon nanowire
• Valley Polarization in Si(100) at Zero Magnetic Field
• Physical mechanisms of interface-mediated intervalley coupling in Si
• Quantum control of donor electrons at the Si-SiO2 interface
• Valley splitting of Si/SiGe heterostructures in tilted magnetic fields
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