"Silicon Quantum Dots and Nanomembranes: Tools for Quantum Information?"

Mark A. Eriksson
University of Wisconsin-Madison

Abstract: Silicon has certain unusual properties, including a spin-0 nuclear isotope, that make quantum dots in this material excellent candidates for quantum information processing. Silicon can also form spectacular membranes, one hundred nanometers thick, centimeters across, and that bend like plastic sandwich wrap but retain their properties as beautiful single crystals. I will present results on silicon quantum dots fabricated using both Schottky gates and Atomic-Layer-Deposition MOS gates on Si/SiGe modulation-doped heterostructures. These dots have excellent charge stability, but their fabrication currently requires special processing. To attempt a leapfrog past these complexities, we have begun investigating ultra-thin silicon membranes. I will present recent results on such silicon membranes, a material that retains the excellent intrinsic properties of silicon, but that can be bent, strained, and rolled into tubes, allowing the use of strain in a defect-free system, and potentially leading to new ways to create quantum dots with few end-processing complexities. Finally, I will discuss results of a new spectroscopic measurement of the energy gap between the two lowest-lying valley states in silicon quantum wells. Understanding the physics of these states is a surprising open challenge in quantum electronics.