Quantum Transport Through Nanostructures PDF Download

One-dimensional (1D) electronic nanostructures comprise a class of systems that boast tremendous promise for both technological innovation as well as fundamental scientific discovery. To fully harness their potential, it is crucial to understand transport through 1D systems at the most fundamental, quantum level. In this thesis, we describe our investigations down three avenues of quantum transport in 1D: (1) ballistic transport in quantum wires, (2) quantum capacitance measurements of nanostructures, and (3) tunneling measurements in carbon nanotubes. First, we discuss measurements and modeling of hole transport in ballistic quantum wires fabricated by GaAs/AlGaAs cleaved-edge overgrowth, where we find strong g-factor anisotropy, which we associate with spin-orbit coupling, and evidence for the importance of charge interactions, indicated by the observation of "0.7" structure. Additionally, we present the first experimental observation of a predicted spin-orbit gap in the 1D density of states, where counter-propagating spins constituting a spin current are accompanied by a clear signal in the conductance. Next, we present the development of a highly sensitive integrated capacitance bridge for quantum capacitance measurements to be used as a novel probe of 1D systems. We demonstrate the utility of our bridge by measuring the capacitance of top-gated graphene devices, where we cleanly resolve the density of states, and also present preliminary measurements of carbon nanotube devices, where we ultimately aim to extract their mobility. Finally, we discuss a set of transport measurements in carbon nanotubes designed to probe interactions between fermions in 1D in which top gates are used to introduce tunable tunnel barriers.