There are a number of proposals that involve single electrons in multiple quantum dot systems, using either electron spin or dot location to store and manipulate information for quantum computation. In this dissertation a technique for fabricating double quantum dot systems potentially useful for quantum computation is described. This method allows single charge electrometers to be fabricated close to the dots so that measurement of the charge states can be made, which is a requirement for quantum computation. Low temperature measurements of the charge transport through these quantum dot structures are presented for a variety of different double dot structures. A number of phenomena observed in the experiments are described. These include period doubling and peak splitting of the Coulomb oscillations, carrier energy filtering effects due to energy level misalignment, observation of the double dot stability diagram, and magnetic field dependence of the Coulomb oscillations. Other measurements in a dilution refrigerator reveal that photon assisted tunnelling from black body radiation within the refrigerator - a source of decoherence for quantum computation, can take place. The device can be used as a sensitive radiation detector to ensure that the radiation is minimized or reduced for measurements of quantum coherence. Single hole electrometers fabricated very close to the double dot structures are shown to be sensitive enough to measure the charge states in the double dot structure.
| Identifer | oai:union.ndltd.org:bl.uk/oai:ethos.bl.uk:597215 |
| Date | January 2002 |
| Creators | Cain, P. |
| Publisher | University of Cambridge |
| Source Sets | Ethos UK |
| Detected Language | English |
| Type | Electronic Thesis or Dissertation |
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