Global ETD Search
Search theses and dissertations gathered from participating repositories worldwide. Every result links back to the library that holds it. No account is needed.
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Showing 1 to 11 of 11 for “"quantum point contacts"”.
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FCS for superconducting quantum point contacts
… of the full counting statistics (FCS) for quantum mechanical systems has attracted much attention in recent years. In this thesis the FCS for superconducting quantum point contacts have been calculated. Such quantum point contacts frequently occur in modern microelectronic devices, which …
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Electronic and Spin Correlations in Asymmetric Quantum Point Contacts
<p>A quantum point contact (QPC) is a quasi-one dimensional electron system, for which the conductance is quantized in unit of $2e^2/h$. This conductance quantization can be explained in a simple single particle picture, where the electron density of states cancels the electron velocity to a …
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Bandstructure calculations for holes in GaAs and simulations of dc conductance in electron quantum point contacts
… We simulated data for a parabolic QPC saddle-point potential at T=0 K and analyse the data using methods based on the AC conductance and on the DC conductance. We show that the two methods are compatible and accurate to ±4 % for the ideal simulated data set, which is free of experimental …
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Zigzag Phase Transition in Quantum Wires and Localization in the Inhomogeneous One-Dimensional Electron Gas
… is described by Luttinger Liquid theory. We use Quantum Monte Carlo methods to study two situations that are beyond Luttinger Liquid theory --- the quantum phase transition from a linear 1D electron system to a quasi-1D zigzag arrangement, and electron localization in quantum point contacts. …
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Epitaxial aluminium gates in ultra-shallow GaAs/AlxGa1-xAs heterostructures for low disorder nanoelectronics
… we turn to investigating these systems for quantum electronic devices. We fabricate quantum point contacts and evidence the compatibility of these all-epitaxial systems with quantum device fabrication by demonstrating robust and reproducible 1D quantisation. Secondly, we show extremely low …
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Engineering superconductivity in ballistic semiconductor nanowires
… are promising materials for studying novel quantum devices. Following proposals to use 1D nanostructure to realize Majorana zero modes, quasiparticles that are relevant for topological quantum computing, many groups have attempted to engineer these modes in hybrid …
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Tunable spin polarization and conductance anomalies in mesoscopic one-dimensional systems
… – for instance, the “0.7” conductance anomaly in quantum point contacts – have remained unexplained. In this dissertation, we present a comprehensive theoretical model for electronic transport in quasi-1D systems, accounting for many-body effects and neglecting spin–orbit couplings. Then, with …
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Electron transport in confined structures in very high mobility GaAs in perpendicular magnetic fields
… one focusing on properties in the integer quantum Hall effect the second looking at properties in the fractional quantum Hall effect at filling fraction v = 5/2. Both sets of experiments employ electrostatically defined quantum point contacts (QPCs) fabricated on a high mobility GaAs/AlGaAs …
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Determining Energy Relaxation Length Scales in Two-Dimensional Electron Gases
… techniques include using the thermopower of quantum point contacts and the Coulomb blockade of quantum dots. However, these techniques have issues with the ease and reliability of fabrication of the thermocouples, and the complexity of their subsequent oper- ation. This thesis presents a …
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SAW-driven single-photon sources and photon detectors fabricated on an undoped GaAs/AlGaAs quantum well
… few decades there has been strong interest in quantum information systems based on photonic qubits. Devices able to emit pure single-photon states on demand and detect incoming single photons in the system are fundamental building blocks for the realisation of a quantum photonic scheme. …
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The curious case of the inverted oscillator: On the dynamics and symmetries of quadratic potentials in the lowest Landau level
Submission original under an indefinite embargo labeled 'Open Access'. The submission was exported from vireo on 2023-12-04 without embargo terms