Spin and charge in semiconductor nanowires

The research in this thesis is motivated by an interest in quantum physics and by the prospect of new applications based on the spin of electrons or holes. This work focuses on confining single spins in quantum dots, which can serve as building blocks of a future quantum computer. Such a computer exploits the unique features of quantum mechanics...

Coherence and control of a single electron spin in a quantum dot

An electron does not only have an electric charge, but also a small magnetic moment, called spin. In a magnetic field, the spin can point in the same direction as the field (spin-up) or in the opposite direction (spin-down). However, the laws of quantum mechanics also allow the spin to exist in both states at the same time (so-called...

Carbon nanotube quantum dots

Low temperature electron transport measurements on individual single wall carbon nanotubes are described in this thesis. Carbon nanotubes are small hollow cylinders made entirely out of carbon atoms. At low temperatures (below ~10 K) finite length nanotubes form quantum dots. Because of its small size a quantum dot has a discrete set of energy...

Quantum transport in semiconductor nanowires

This thesis describes a series of experiments aimed at understanding the low-temperature electrical transport properties of semiconductor nanowires. The semiconductor nanowires (1-100 nm in diameter) are grown from nanoscale gold particles via a chemical process called vapor-liquid-solid (VLS) growth. The huge versatility of this material system...

Quantum transport in carbon nanotubes

Electronic transport through nanostructures can be very different from trans- port in macroscopic conductors, especially at low temperatures. Carbon na- notubes are tiny cylinders made of carbon atoms. Their remarkable electronic and mechanical properties, together with their small size (a few nm in diameter), make them very attractive for...

Noise and Spin in Nanostructures

Electron spin and charge in semiconductor quantum dots

In this thesis, the spin and charge degree of freedom of electrons in semiconductor lateral and vertical quantum dots are experimentally investigated. The lateral quantum dot devices are defined in a two-dimensional electron gas (2DEG) below the surface of a GaAs/AlGaAs heterostructure, by metallic surface gates. The vertical quantum dots are...

Nuclear Spins in Quantum Dots

The main theme of this thesis is the hyperfine interaction between the many lattice nuclear spins and electron spins localized in GaAs quantum dots. This interaction is an intrinsic property of the material. Despite the fact that this interaction is rather weak, it can, as shown in this thesis, strongly influence the dynamics of electron spins...

The Delft intense slow positron beam 2D-ACAR facility for analysis of nanocavities and quantum dots

Positron annihilation spectroscopy is a powerful method to study materials containing very small concentrations of atomic defects and embedded quantum dots. Depending on the method of producing positrons, there are bulk spectroscopies using fast positrons and depth profiling spectroscopies using slow positrons. Both types of spectroscopies are...

Electron transport and coherence in semiconductor quantum dots and rings

A number of experiments on electron transport and coherence in semiconductor vertical and lateral quantum dots and semiconductor rings is described. Quantum dots are often referred to as "artificial atoms", because of their similarities with real atoms. Examples of such atom-like properties that have been studied, are spin-singlet-triplet...