dc.contributor.advisor Marcus, Charles Masamed dc.contributor.author Churchill, Hugh Olen Hill dc.date.accessioned 2012-08-17T14:15:25Z dc.date.issued 2012-08-17 dc.date.submitted 2012 dc.identifier.citation Churchill, Hugh Olen Hill. 2012. Quantum Dots in Gated Nanowires and Nanotubes. Doctoral dissertation, Harvard University. en_US dc.identifier.other http://dissertations.umi.com/gsas.harvard:10412 en dc.identifier.uri http://nrs.harvard.edu/urn-3:HUL.InstRepos:9414563 dc.description.abstract This thesis describes experiments on quantum dots made by locally gating one-dimensional quantum wires. The first experiment studies a double quantum dot device formed in a Ge/Si core/shell nanowire. In addition to measuring transport through the double dot, we detect changes in the charge occupancy of the double dot by capacitively coupling it to a third quantum dot on a separate nanowire using a floating gate. We demonstrate tunable tunnel coupling of the double dot and quantify the strength of the tunneling using the charge sensor. The second set of experiments concerns carbon nanotube double quantum dots. In the first nanotube experiment, spin-dependent transport through the double dot is compared in two sets of devices. The first set is made with carbon containing the natural abundance of $^{12}C$ (99%) and $^{13}C$ (1%), the second set with the 99% $^{13}C$ and 1% $^{12}C$. In the devices with predominantly $^{13}C$, we find evidence in spin-dependent transport of the interaction between the electron spins and the $^{13}C$ nuclear spins that was much stronger than expected and not present in the $^{12}C$ devices. In the second nanotube experiment, pulsed gate experiments are used to measure the timescales of spin relaxation and dephasing in a two-electron double quantum dot. The relaxation time is longest at zero magnetic field and goes through a minimum at higher field, consistent with the spin-orbit-modified electronic spectrum of carbon nanotubes. We measure a short dephasing time consistent with the anomalously strong electron-nuclear interaction inferred from the first nanotube experiment. en_US dc.description.sponsorship Physics en_US dc.language.iso en_US en_US dash.license LAA dc.subject carbon nanotubes en_US dc.subject charge sensing en_US dc.subject germanium silicon nanowires en_US dc.subject quantum dots en_US dc.subject quantum transport en_US dc.subject spin qubits en_US dc.subject quantum physics en_US dc.subject condensed matter physics en_US dc.subject nanoscience en_US dc.title Quantum Dots in Gated Nanowires and Nanotubes en_US dc.type Thesis or Dissertation en_US dash.depositing.author Churchill, Hugh Olen Hill dc.date.available 2012-08-17T14:15:25Z thesis.degree.date 2012 en_US thesis.degree.discipline Physics en_US thesis.degree.grantor Harvard University en_US thesis.degree.level doctoral en_US thesis.degree.name Ph.D. en_US dash.contributor.affiliated Churchill, Hugh Olen Hill
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