Accessing the quantum world through electronic transport in carbon nanotubes

Abstract

In this thesis we will focus on (a) superconducting electrodes attached to carbon nanotube quantum dots in order to study the effects of superconducting correlations on quantum systems and (b) local gate control of carbon nanotubes in order to define and control double quantum dot systems in carbon nanotubes. As it turns out, local gates are an important tool for increasing the control over quantum states in nanotubes. The thesis is structured as follows: • Chapter 1 gives a brief introduction to the chemical and electronic properties of carbon nanotubes and the experimental procedures necessary for manufacturing electrical devices with single carbon nanotubes. • In Chapter 2 selected topics of charge transport in mesoscopic systems, such as single and coupled quantum dots, are reviewed. • In Chapter 3 we present electrical transport measurements through a carbon nanotube coupled to a normal and a superconducting lead - a test system for the exploration of the nature of many-particle correlations. • Chapter 4 describes how to achieve local gate control over semiconducting carbon nanotubes by adding top-gate electrodes. • In Chapter 5 double quantum dots are defined and controlled inside a carbon nanotube. The system allows for the observation of molecular states induced by a large tunnel coupling of the dots; an artificial molecule is defined inside a real one.