Wisconsin Alumni Research Foundation

Mark A Eriksson

Max G Lagally

Mark Gregory Friesen

Zhenqiang Ma

Hao-Chih Yuan

Paul Gregory Evans

Guogong Wang

Robert J Joynt

Susan Nan Coppersmith

Donald E Savage

Daniel Warren Van Der Weide

Paul Powell Rugheimer

Daniel R Ward

Arnold Melvin Kiefer

Todd R Narkis

Matt S Marcus

John King Gamble

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 quantum computing system and method for performing quantum computation is provided. In some aspects, the system includes at least one charge qubit comprising a quantum dot assembly prepared with a symmetric charge distribution, wherein the symmetric charge distribution is configured to reduce a coupling between the charge qubit and a charge noise source. The system also includes a controller for controlling the at least one charge qubit to perform a quantum computation. The system further includes an output for providing a report generated using information obtained from the quantum computation performed.

System and method for quantum computation using symmetrical charge qubits

A quantum semiconductor device is provided. The quantum semiconductor device includes a quantum heterostructure, a dielectric layer, and an electrode. The quantum heterostructure includes a quantum well layer that includes a first 2DEG region, a second 2DEG region, and a third 2DEG region. A first tunnel barrier exists between the first 2DEG region and the second 2DEG region. A second tunnel barrier exists between the second 2DEG region and the third 2DEG region. A third tunnel barrier exists either between the first 2DEG region and the third 2DEG region. The dielectric layer is formed on the quantum heterostructure. The electrode is formed on the dielectric layer directly above the first tunnel barrier.

Direct tunnel barrier control gates in a two-dimensional electronic system

This invention provides thin film devices that have been processed on their front- and backside. The devices include an active layer that is sufficiently thin to be mechanically flexible. Examples of the devices include back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

Front and backside processed thin film electronic devices

This invention provides methods for fabricating thin film electronic devices with both front- and backside processing capabilities. Using these methods, high temperature processing steps may be carried out during both frontside and backside processing. The methods are well-suited for fabricating back-gate and double-gate field effect transistors, double-sided bipolar transistors and 3D integrated circuits.

A quantum-well photoelectric device, such as a quantum cascade laser, is constructed of monocrystalline nanoscale membranes physically removed from a substrate and mechanically assembled into a stack.

Quantum-well photoelectric device assembled from nanomembranes

Carbon nanotube Schottky barrier photovoltaic cells and methods and apparatus for making the cells are provided. The photovoltaic cells include at least one contact made from a first contact material, at least one contact made from a second contact material and a plurality of photoconducting carbon nanotubes bridging the contacts. A Schottky barrier is formed at the interface between the first contact material and the carbon nanotubes while at the interface between the second contact material and the carbon nanotubes, a Schottky barrier for the opposite carrier is formed, or a small, or no Schottky barrier is formed. It is the Schottky barrier asymmetry that allows the photo-excited electron-hole pairs to escape from the carbon nanotube device.

Carbon nanotube Schottky barrier photovoltaic cell

Method for double-sided processing of thin film transistors

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.

Growing community of inventors

Madison, WI, United States of America

Mark A Eriksson