Quantum Electronics in Si/SiGe

Mark A. Eriksson
University of Wisconsin, Madison

Silicon has been studied intensively for decades, and it is the basis for the integrated electronics technology that pervades modern life. Perhaps surprisingly in the face of this ubiquity, many interesting and important questions about silicon and its basic physical properties remain open. This is particularly true in areas such as quantum electronics, in which silicon, in spite of its long history, is beginning to play a new, agile role that was hard to imagine just a few years ago. This talk will focus on some of these recent advances and the many challenges that remain, and it will attempt to describe something of the role that silicon might conceivably play in a future quantum electronics. As a starting point, I will present a brief overview of the current state of low-temperature silicon quantum electronics, focusing especially quantum dots in heterostructures and donor bound electrons. I will then focus on three areas in which our work has played a role. First, I will discuss results demonstrating that quantum phenomena such as the Kondo effect and the Fano effect can be realized in Si/SiGe heterostructure-based quantum dots [1]. Second, I will discuss an interesting interplay between random atomic steps and the valley states in silicon quantum wells [2]. This interplay leads to a prediction of a simple but unexpected method to lift the valley degeneracy in silicon quantum wells. Finally, I will describe a recent experiment studying the conduction mechanisms in ultra-thin silicon, this time at room temperature [3]. Implications of these results for future directions in silicon quantum electronics will be discussed.

[1] Coulomb blockade and Kondo effect in a few-electron silicon/silicon-germanium quantum dot, L.J. Klein, D.E. Savage, and M.A. Eriksson, Appl. Phys. Lett. 90, 033103 (2007).

[2] Controllable Valley Splitting in Si/SiGe Quantum Devices, Srijit Goswami, et al., Nature Physics 3, 41 (2007).

[3] Surface Electronic Transport in Nanometer-Scale Silicon-on-Insulator, Pengpeng Zhang, et al., Nature 439, 703 (2006).

For more information: Quantum Computing in Silcon web site and Eriksson Group and Mark A. Eriksson web site