155 research outputs found
Optical investigations of nanostructured oxides and semiconductors
This work is motivated by the prospect of building a quantum computer: a device that would allow physicists to explore quantum mechanics more deeply, and allow everyone else to keep their credit card numbers safe on the internet. In this thesis we explore materials that are relevant to a proposed quantum computer architecture.Systems with a ferroelectric to paraelectric transition in the vicinity of room temperature areuseful for devices. Adjusting the ferroelectric transition temperature is traditionally accomplished by chemical substitution, as in barium strontium titanate. We investigate strained-strontium titanate, which is ferroelectric at room-temperature, and a composite material of barium strontium titanate and magnesium oxide.We present optical techniques to measure electron spin dynamics with GHz dynamical bandwidth,transform-limited spectral selectivity, and phase-sensitive detection. We demonstrate the technique with a measurement of GHz-spin precession in n-GaAs. We also describe our efforts to measure single quantum dots optically.Nanoscale devices with photonic properties have been the subject of intense research over the past decade. Potential nanophotonic applications include communications, polarization-sensitive detectors, and solar power generation. Here we show photosensitivity of a nanoscale detectorwritten at the interface between two oxides
Gigahertz Optical Spin Transceiver
We present a time-resolved optical technique to measure electron spin dynamics with GHz dynamical bandwidth, transform-limited spectral selectivity, and phase-sensitive (lock-in) detection. Use of a continuous-wave (CW) laser and fast optical bridge enables greatly improved signal-to-noise characteristics compared to traditional optical sampling (pump-probe) techniques. We demonstrate the technique with a measurement of GHz-spin precession in n-GaAs. This approach may be applicable to other physical systems where stroboscopic techniques cannot be used because of either noise or spectral limitations
The Microbial Flora of Acid Mine Water and its Relationship to Formation and Removal of Acid
(print) viii, 124 p. illus. 28 cm.Title Page -- Table of Contents -- List of Tables -- List of Figures -- I: Introduction -- II: The Influence of Acid Water on Aerobic Heterotrophs of A Normal Stream -- III: The Relative Influence of Iron, Sulfate and Hydrogen Ions on the Microflora of A Non-Acid Stream -- IV: Aerobic Heterotrophs Indigenous to pH 2.8 Mine Water -- V: A Microbial Dissimilatory Sulfur Cycle -- VI: Microbial Sulfate Reduction in Acidic Mine Water and Its Potential Utility as A Water Pollution -- VII: General Summary and Conclusions -- VIII: Recommendations -- IX: Publications Resulting from this Research Projec
Spin-orbit-assisted electron pairing in 1D waveguides
Understanding and controlling the transport properties of interacting
fermions is a key forefront in quantum physics across a variety of experimental
platforms. Motivated by recent experiments in 1D electron channels written on
the / interface, we analyse how the
presence of different forms of spin-orbit coupling (SOC) can enhance electron
pairing in 1D waveguides. We first show how the intrinsic Rashba SOC felt by
electrons at interfaces such as / can be
reduced when they are confined in 1D. Then, we discuss how SOC can be
engineered, and show using a mean-field Hartree-Fock-Bogoliubov model that SOC
can generate and enhance spin-singlet and triplet electron pairing. Our results
are consistent with two recent sets of experiments [Briggeman et al.,
arXiv:1912.07164; Sci. Adv. 6, eaba6337 (2020)] that are believed to engineer
the forms of SOC investigated in this work, which suggests that metal-oxide
heterostructures constitute attractive platforms to control the collective spin
of electron bound states. However, our findings could also be applied to other
experimental platforms involving spinful fermions with attractive interactions,
such as cold atoms.Comment: 12 pages, 7 figure
- …