Shadow-wall lithography as a novel approach to Majorana devices

The development of quantum computers is perhaps one of the most exciting innovations of our time. The most investigated quantum computers, however, suffer from the fact that quantum information is lost due to interaction between the quantum bits and their environment. As a radically different approach, it has been proposed that one can instead...

Conformational and Spin Effects in Single-Molecule Electronic Transport

This dissertation presents the experimental work on singlemolecule charge transport, particularly on the aspects of spin and orbital conformational effects in singlemolecule junctions. In this dissertation, we employ and develop various singlemolecule techniques, the mechanically controlled break junction (MCBJ), thermoelectric electromigrated...

Carrier multiplication and cooling in semiconductor quantum dots

In semiconductor quantum dots (QDs), charge carrier cooling is in direct competition with carrier multiplication (CM), a process in which one absorbed photon excites two or more electrons that may improve the light conversion efficiency of photovoltaic devices. CM by an initially hot charge carrier occurs in competition with cooling, with the...

Electrical Control, Read-out and Initialization of Single Electron Spins

An electron, in addition to its electric charge, possesses a small magnetic moment, called spin. The spin of an electron can point parallel (spin-up) or antiparallel (spin-down) to the magnetic field. These two states are analogous to zero and one of the logical bit in current digital electronic devices. However, according to the laws of quantum...

Photogeneration Diffusion and Decay of Charge Carriers in Quantum-Dot Solids

Semiconductor nanocrystals (NCs), which can have a variety of sizes, shapes and chemical compositions, will be a large and important family of future advanced materials.This thesis focuses on colloidal semiconductor NC solids, also called quantum-dot (QD) solids, which are promising materials for many applications, such as photo-detectors, field...

Photoconductivity of Quantum Dot Films Towards Third-Generation Solar Cells

Colloidal semiconductor nanoparticles, also called quantum dots, have unique opto-electronic properties that make them promising candidates for many applications such as solar cells, light–emitting diodes, lasers, or biological imaging. One of the most interesting features is that the bandgap energy can be tuned by changing the particle size....

Electron spins in nanowire quantum dots

For small magnetic memories, the ultimate limit is a single magnetic particle, a single electron spin. A lot of research is put in developing devices that can utilize such a single spin memory. At the same time, there is also interest from a more fundamental point of view: on these small scales, Quantum Mechanics starts to play a role. Devices...

Quantum Dots in Vertical Nanowire Devices

The research described in this thesis is aimed at constructing a quantum interface between a single electron spin and a photon, using a nanowire quantum dot. Such a quantum interface enables information transfer from a local electron spin to the polarization of a photon for long distance readout. Important aspects for the realization of such a...

Opto-electronics on Single Nanowire Quantum Dots

An important goal for nanoscale opto-electronics is the transfer of single electron spin states into single photon polarization states (and vice versa), thereby interfacing quantum transport and quantum optics. Such an interface enables new experiments in the field of quantum information processing. Single and entangled photon-pair generation...

Quantum transport in molecular devices and graphene

As a result of progress in nanotechnology, smaller and smaller electronic circuits can be made. The stage of electrically contacting even a single molecule has now been reached. This stimulates both fundamental and applied research alike. Molecular electronics is hence a booming new field that draws a lot of attention. In this research project...

Effects and detection of quantum noise

This thesis is about random fluctuations over time (or noise) of electric currents and voltages occuring in small (mesoscopic) electronic devices with typical sizes of micro- to nanometre. Even though the theory presented is of a more general nature, research into such systems has been greatly pushed forward by the prospect of building a quantum...

Electron spins in few-electron lateral quantum dots

This thesis describes a series of experiments aimed at understanding and controlling single electron spins confined in semiconductor lateral quantum dots, with the long-term goal of creating of a small-scale quantum computer. The confinement of these electrons results in a quantized energy spectrum, and therefore, the quantum dots can be...

Electron Spins in Semiconductor Quantum Dots

This thesis describes a series of experiments aimed at understanding and controlling the behavior of the spin degree of freedom of single electrons, confined in semiconductor quantum dots. This research work is motivated by the prospects of using the electron spin as a quantum bit (qubit), the basic building block of a quantum computer. Here,...