Wisconsin Alumni Research Foundation

Robert J Joynt

Mark A Eriksson

Mark Gregory Friesen

Donald E Savage

Daniel Warren Van Der Weide

Max G Lagally

Susan Nan Coppersmith

Paul Powell Rugheimer

Charles George Tahan

Paul Rugheimer

Semiconductor heterostructures, methods of making the heterostructures, and quantum dots and quantum computation devices based on the heterostructures are provided. The heterostructures include a quantum well of strained silicon seeded with a relatively low concentration of germanium impurities disposed between two quantum barriers of germanium or a silicon-germanium alloy. The quantum wells are characterized in that the germanium concentration in the wells has an oscillating profile that increases the valley splitting in the conduction band of the silicon quantum well.

Silicon-germanium heterostructures with quantum wells having oscillatory germanium concentration profiles for increased valley splitting

A semiconductor quantum dot device converts spin information to charge information utilizing an elongated quantum dot having an asymmetric confining potential along its length so that charge movement occurs during orbital excitation. A single electron sensitive electrometer is utilized to detect the charge movement. Initialization and readout can be carried out rapidly utilizing RF fields at appropriate frequencies.

Spin readout and initialization in semiconductor quantum dots

Semiconductor dot devices include a multiple layer semiconductor structure having a substrate, a back gate electrode layer, a quantum well layer, a tunnel barrier layer between the quantum well layer and the back gate, and a barrier layer above the quantum well layer. Multiple electrode gates are formed on the multi-layer semiconductor with the gates spaced from each other by a region beneath which quantum dots may be defined. Appropriate voltages applied to the electrodes allow the development and appropriate positioning of the quantum dots, allowing a large number of quantum dots be formed in a series with appropriate coupling between the dots.

Solid-state quantum dot devices and quantum computing using nanostructured logic gates

Growing community of inventors

Madison, WI, United States of America

Robert J Joynt