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Events on Friday, August 6th, 2010

R. G. Herb Condensed Matter Seminar
Silicon enhancement mode nanostructures for few electron spin devices
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Malcolm Carroll, Sandia National Laboratory
Abstract: Promising coherent control of single electron spins in modulation doped, depletion mode, GaAs quantum dots has been demonstrated [1] with spin decoherence times order of 30 ms with Hahn echo [2]. Spin decoherence times orders of magnitude longer, > 0.6 seconds, have been measured in ensemble spin measurements in silicon but have not yet been realized in single spin silicon nanostructures although numerous groups are showing rapid progress towards this goal. Achieving single electron spin control with long decoherence times will likely require low charge and magnetic disordered silicon devices. This has represented a long standing challenge to the community resulting in the examination of numerous materials, device design and process integration approaches. This talk will describe a silicon metal oxide semiconductor (MOS), open-lateral gated design that produces a confined potential for electrons at the SiO2/Si interface that allows sufficient tunability to both form well behaved double quantum dots (DQD) and overcome some electrostatic non-uniformity in the nanostructure. This structure further provides the ability to implant the quantum dot structures with impurities (Sb), which provides an alternate path to obtaining single electron potentials that can couple and be manipulated by the DQD structure. Electrical transport of both low disorder MOS quantum dots and impurity implant induced resonances will be presented. Modeling of the electrostatics and the excited state spectroscopy of these systems is used to begin to clarify the source of the single electron transport. The effects of processing induced defects and background impurities in the metal oxide semiconductor (MOS) system on electrostatic and magnetic effects on the qubit will also be discussed if time permits.

We wish to acknowledge the research funding support provided by the laboratory directed research and development (LDRD) program at Sandia National Laboratories. Sandia National Labs is a multi-program laboratory operated by Sandia Corporation, a Lockheed Martin Company, for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

[1] J. Petta et al., Science 309, 2180 (2005)
[2] H. Bluhm et al., arXiv: 1005.2995 (2010)
Host: Mark Eriksson
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