This thesis describes a study from both a theoreticaL and an experimental point of view.

Promotor: Prof.dr. E. Eliel, Co-Promotor: M.J.A. de Dood

In this thesis, we study systems of electrons in which strong correlations give rise to emergent exotic physics.

Promotores: Prof.dr. J. Aarts, Prof.dr. J.M. van Ruitenbeek

The theoretical explanation of cosmic acceleration is nowadays one of the biggest puzzles in cosmology.

Mechanical forces are known to play an important role in bacterial colonies. In this dissertation, we study the self-organization at various stages of growing bacterial colonies, and focus on the mechanical effects of cell growth.

Mechanical metamaterials are carefully engineered materials whose properties are controlled by their structure, not by their composition, which allows using metamaterials to study and control physical effects in detail⁠.

DNA carries various forms of information. Out of these forms of information the most well-known is classical genetic information.

Promotor: Prof.dr. C.W.J. Beenakker

This dissertation is an experimental study of laser-generated, atmospheric pressure, transient toroidal helium plasmas.

Onderwijs over quantum is ontzettend belangrijk. Daarom ontwikkelt Quantum Leiden onderwijs en voorlichting over de quantumtechnologie, op alle niveaus, van middelbare school tot Masters-studie. Zo leiden we de onderzoekers van de toekomst op, en bereiden we de jeugd voor op een quantumtoekomst.

Scattering of light in the presence of nano-structured materials, i.e. with features in the order of the wavelength of the light or smaller, reveals details of how light interacts with matter at the nanoscale.

Promotor: T. Schmidt, Co-Promotor: B.E. Snaar-Jagalska

This thesis describes how to scale down concepts of macroscopic mechanical metamaterials to the thermal scale using a system of flexibly-linked colloids.

Stochastic resetting is simple enough to be approached analytically, yet modifies stochastic processes in a non-trivial way.

The overarching goal of this thesis is to set the foundations, but also make the first essential steps towards establishing a comprehensive, mesoscopic, hydrodynamic theory of epithelial tissues. The stage is set by an exhaustive study of topological defects in passive p-atic liquid crystals, singularities…

Promotor: A. Achúcarro, Co-promotor: A. Boyarsky

Promotor: Prof.dr. J.M. van Ruitenbeek, Prof.dr. R.M. Tromp

One of the most important correlation functions in physics, especially in cosmology, is the energy density, which describes how much energy is present at each point in spacetime due to matter fields. A key contribution to the energy density of the primordial universe comes from gravitational waves (GWs),…

In this thesis we investigate cosmology and the large scale structure of the Universe using cosmological simulations.

The human body consists of hundreds, perhaps thousands of different types of cells, each with different morphologies and functions, despite having the same genome.

Promotores: J. Zaanen, A. Parnachev

Promotor: T.H. Oosterkamp

This thesis investigates how cell shape and collective behavior influence the dynamics and structure of biological tissues, which are crucial for understanding processes like embryonic development, tissue regeneration, and metastasis.

In this thesis unconventional tools based on fluidic interfaces were developed to study the surface and interfacial chemistry of graphene, to characterize the intrinsic properties of graphene, to disentangle the effects of substrate and of the environmental factors, and to improve handling protocols…

Promotor: T. Schmidt, Co-promotor: S. J.T. van Noort

Promotor: J. Zaanen, Co-Promotor: V. Juricic

Promotor: Prof.dr. T. Schmidt

In the early universe, the dynamics of the Higgs field can give rise to many interesting phenomena.

This thesis presents insights from our study of various correlated electron systems with a scanning tunneling microscope (STM). In ordinary metals, electron-electron interactions exist, but get substantially screened due to the sheer number of electrons.

The elementary excitations of magnets are called spin waves, and their corresponding quasi-particles are known as magnons. The rapidly growing field of Magnonics aims at using them as information carriers in a new generation of electronic devices, (almost) free of electric currents.

Promotor: Prof.dr. A. Achucarro

In some condensed matter systems, such as the surface of a 3D topological insulator, the electrons are effectively massless and we must necessarily use the massless Dirac equation to describe them.

Materials with strongly correlated electrons show some of the most mysterious and exotic phases of quantum matter, such as unconventional superconductivity, quantum criticality and strange metal phase.

This thesis explores how electron paramagnetic resonance (EPR) spectroscopy can be used to investigate key biochemical processes.

Understanding interactions in quantum many-body systems remains one of the most profound and difficult challenges in condensed matter physics.

There are many interpretations of quantum mechanics, and ultimately experiments are needed to verify or falsify these interpretations.

In condensed matter systems electron-electron interactions, negligible in everyday metals, can dramatically alter the electronic behavior of the system. Examples of such altered behavior include high-temperature superconductivity and modulation of the electron density.

Molecular materials have been a subject of interest in fundamental research and applications for decades, and have been studied as bulk crystals, (thin) films and as individual molecules, due to the large variety in their properties. This dissertation explores pentacene crystals near the two-dimensional…

The energy system is at the heart of two of the greatest challenges of the 21st century: decreasing CO2 emissions to meet the ambitions of the Paris agreement while fulfilling the growing energy demand associated with the economic aspirations of a growing world population.

Geometric phases lead to a nontrivial interference result when an electron's different quantum mechanical paths choices encircle a magnetic coil in an Aharonov-Bohm experiment.

In this thesis, we show how MRFM can usefully contribute to the field of condensed-matter.

We find ourselves in an era of transition, not just towards a more computing- and data-driven society but also away from unsustainable fossil fuels as an energy source.

This dissertation combines the use of defined microenvironments, high-resolution fluorescence microscopy, and time-resolved analysis, to study intracellular and cellular motility.

Surface plasmons (SPs) are surface waves at the interface between a dielectric and a good metal, and are formed by the interaction between light and the free electrons at the metal-dielectric interface. They provide strong field confinement for optical fields, opening new possibilities for enhanced…

Spectroscopic studies on fluorescent single molecules in organic condensed matter does not only provide information about the molecule itself, but also its near environment. By suppression of phonon-induced broadening of spectral lines through cooling to low temperatures, small changes in the spectral…

Promotor: J. Aarts

In this thesis, we describe the latest advances in SQUID-detected Magnetic Resonance Force Microscopy (MRFM).

Promotor: M.L. van Hecke

The Standard Model (SM) of particle physics fails to explain several observed phenomena and is incomplete. In order to resolve this problem, one may extend the SM by adding new particles.