A5055895069- Semiconductor Quantum Structures and Devices
- Advancements in Semiconductor Devices and Circuit Design
- Quantum and electron transport phenomena
- Semiconductor materials and devices
- Quantum Information and Cryptography
- Semiconductor materials and interfaces
- Photonic and Optical Devices
- Silicon Nanostructures and Photoluminescence
- Integrated Circuits and Semiconductor Failure Analysis
- Semiconductor Lasers and Optical Devices
- Nanowire Synthesis and Applications
- Magnetic Field Sensors Techniques
- Advanced MEMS and NEMS Technologies
- Advanced Sensor and Energy Harvesting Materials
- Species Distribution and Climate Change
- Amphibian and Reptile Biology
- Advanced Thermodynamics and Statistical Mechanics
- Spectroscopy and Quantum Chemical Studies
- Particle physics theoretical and experimental studies
- Silicon Carbide Semiconductor Technologies
- Quantum Dots Synthesis And Properties
- Advanced Research in Systems and Signal Processing
- Thin-Film Transistor Technologies
- Quantum Chromodynamics and Particle Interactions
- Low-power high-performance VLSI design
University of Wisconsin–Madison
2014-2021
US Forest Service
2019
Intel (United States)
2018
Delft University of Technology
2018
QuTech
2018
Texas Instruments (United States)
1961-2005
Identifying and ameliorating dominant sources of decoherence are important steps in understanding improving quantum systems. Here we show that the free induction decay time ($T_{2}^{*}$) Rabi rate ($\Gamma_{\mathrm{Rabi}}$) dot hybrid qubit can be increased by more than an order magnitude appropriate tuning parameters operating points. By spin-like regime this qubit, choosing increase qubit's resilience to charge noise (which is presently limiting source for qubit), achieve a Ramsey...
Multi-electron semiconductor quantum dots have found wide application in qubits, where they enable readout and enhance polarizability. However, coherent control such has typically been restricted to only the lowest two levels, strongly interacting regime not realized. Here we report of eight different resonances a silicon-based dot. We use qubit perform spectroscopy, revealing dense set energy levels with characteristic spacing far smaller than single-particle energy. By comparing full...
Atomic-scale disorder at the top interface of a Si quantum well is known to suppress valley splitting. Such may be inherited from underlying substrate and relaxed buffer growth, but can also arise due random SiGe alloy. Here, we perform activation energy (transport) measurements in Hall regime determine source affecting We consider three Si/SiGe heterostructures with nominally identical substrates different barriers well, including two samples pure-Ge interfaces. For all samples, observe...
Abstract Universal quantum computation requires high-fidelity single-qubit rotations and controlled two-qubit gates. Along with gates, strong efforts have been made in developing robust logic gates electrically gated dot systems to realise a compact nanofabrication-compatible architecture. Here we perform measurements of state-conditional coherent oscillations charge qubit. Using quadruple formed Si/SiGe heterostructure, show the first demonstration two-axis control double qubit undoped...
We present an improved fabrication process for overlapping aluminum gate quantum dot devices on Si/SiGe heterostructures that incorporates low-temperature inter-gate oxidation, thermal annealing of oxide, on-chip electrostatic discharge (ESD) protection and optimized interconnect budget considerations. This reduces gate-to-gate leakage, damage from ESD, dewetting formation undesired alloys in device interconnects. Additionally, cross-sectional scanning transmission electron microscopy (STEM)...
Valley splitting affects the energy dispersion of silicon quantum dot qubits, and occasionally manifests itself through some striking features. Here, authors observe a strong correlation between unexpected ``sweet spots'' ``hot in coherence rates quantum-dot hybrid qubit anomalous features dispersion. Through tight-binding simulations, they are able to attribute such effects disorder at quantum-well interface speculate on possibility harnessing enhance times.
Achieving controllable coupling of dopants in silicon is crucial for operating donor-based qubit devices, but it difficult because the small size donor-bound electron wavefunctions. Here we report characterization a quantum dot coupled to localized electronic state, and present evidence between state. A set measurements transport through this device enable determination most likely location consistent with an electronically active impurity well near edge dot. The experiments are gate-voltage...
We report the fabrication and characterization of a gate-defined double quantum dot formed in Si/SiGe nanomembrane. In past, all dots heterostructures were on top strain-graded virtual substrates. The strain grading process necessarily introduces misfit dislocations into heterostructure, these defects introduce lateral inhomogeneities, mosaic tilt, threading dislocations. use SiGe nanomembrane as substrate enables relaxation to be entirely elastic, eliminating need for However, this approach...
To assess possible improvements in the electronic performance of two-dimensional electron gases (2DEGs) silicon, SiGe/Si/SiGe heterostructures are grown on fully elastically relaxed single-crystal SiGe nanomembranes produced through a strain engineering approach. This procedure eliminates formation dislocations heterostructure. Top-gated Hall bar devices fabricated to enable magnetoresistivity and effect measurements. Both Shubnikov-de Haas oscillations quantum observed at low temperatures,...
The Sierra Nevada Yellow-Legged Frog (Rana sierrae) has generally been viewed as a lake species, but it increasingly found in streams, including the northern part of its range where is particularly at risk. Developing effective conservation strategies hindered by lack knowledge basic ecological requirements stream habitats. To address this information gap, we investigated demography, habitat use, and movements populations federally endangered species. We conducted capture–mark–recapture...
TUNNEL DIODE CIRCUITRY incorporating transistors has been used to gain advanced digital speeds while improving circuit reliability and stability. Major disadvantages in the use of tunnel diodes are: (1) common input-output, (2) inability obtain direct pulse inversion (3) bidirectional flow information, (4) difficulty stage-to-stage coupling caused by loading insufficient signal transfer. Circuitry using as emitter followers accomplishes steering impedance transformation. Nanosecond...
A discussion of various techniques usable in obtaining high-speed digital circuit operation is presented. To gain these advanced speeds, tunnel diodes have been incorporated into transistor circuitry. The fast rate change voltage and the bistable capabilities diode are characteristics which provide for higher speeds. Development has mainly applied to application GaAs circuitry because output available. Some ultimate speeds attainable circuits providing impedance transformation amplification...
The Cogar 1024-bit MOS read-write memory chip is fully decoded, has a 100-ns access time, and only 125 × mils in size. This small size made possible by the use of 4-device cell dimensional tolerances as 0.15 mil. chips are fabricated from 2.25-inch-diameter wafer that consists low-resistivity p-type substrate covered high-resistivity epitaxial layer. layer provides not for precise control surface impurity concentration, but also means reach-through type gate protection device. In addition,...
Buried layers are used in bipolar devices to lower collector resistance bulk silicon and SOI (silicon-on-insulator) technologies. They also with deep trench for isolating different types. This work investigates the effect of buried layer processing on CMOS capacitor reliability, comparing results between substrates. Opposing from technologies indicate degradation mechanisms at play. The starting material requires that metal contaminant gettering be taken account layers.
As semiconductor based quantum devices scale up from single to multiple qubits there is an increasing need integrate classical manage and generate control signals. We discuss progress on integrating field-effect transistors with planar dot achieve a high throughput of device testing by creating on-chip multiplexers for our devices. Using the we can overcome challenge limited number electrical connections available in typical dilution refrigerator while still working at milliKelvin...