A fascinating manifestation of collective quantum phenomena in condensed matter is the emergence of elementary excitations – or quasiparticles – carrying quantum numbers that are fractions of those of a non-interacting system. Low-dimensional and frustrated magnetic materials, built from localized spins 1/2, display a diversity of such many-body phenomena. Moreover, they allow detailed experimental investigations, quantitative comparisons with theoretical predictions,...
Liquids and solids tend to stick to each other. When a liquid droplet sticks to a solid surface we call it wetting. When a solid particle sticks to a solid surface we call it adhesion. The classic coarse-grained descriptions of these two phenomena are distinct from each other. Both descriptions assume that solid objects undergo very little deformation during wetting and adhesion. In this talk, I will show how this assumption breaks down when the solids are soft enough and how wetting and adhesion really are not that different after all.
I will present time-resolved measurements of the relaxation dynamics, in a small molecular system, following ultraviolet (UV) photoexcitation. We probe these excitations through photoionization and velocity map imaging (VMI) spectroscopy. Vacuum and extreme ultraviolet (VUV/XUV) pump and probe pulses are created by exploiting strong-field high harmonic generation (HHG) from our state-of-the-art 30 mJ, 1 kHz laser system. Three dimensional photoelectron and photoion momentum images recorded with our VMI spectrometer reveal non-Born Oppenheimer dynamics in the vicinity of a conical intersection, and allow us track the state of the...
I will present two examples in which ‘fictitious fields’ lead to surprising photonic effects that would be difficult (if not impossible) to achieve with real fields. Firstly, I will present the first observation of the topological protection of light - a ‘Photonic...
The manipulation and detection of individual quantum excitations forms the basis of modern quantum optics experiments. However, most of these experiments have been restricted to systems composed of only a few particles.
In recent years, tremendous experimental progress has been made in probing strongly interacting many-body systems at the level of individual particles. This was achieved using single-site- and...