Mar
11
Teaser:

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.

Mar
10
Teaser:

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...

Mar
03
Teaser:

 

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...

Feb
27
Teaser:

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...

Feb
24
Teaser:

Advances of quantum control in atomic and optical physics have made it possible to study intriguing phenomena originally discussed in condensed matter, nuclear, and gravitational physics. In quantum gas experiments, new insights are derived from out-of-equilibrium dynamics of novel quantum many-body phases. In the first part of my talk, I will...

Feb
20
Teaser:

Over the past decade we have come to appreciate that essentially every giant galaxy, including our own Milky Way, harbors a supermassive black hole at its center.  These monster black holes, with masses of millions or even billions of times the mass of the Sun, play an important role in the evolution of galaxies and the appearance of the observable Universe.  However, unlike stellar-mass black holes that result from the collapse of massive stars at the end of their lives, the origin of supermassive black holes is largely unknown. While direct observations of the first "seeds" of supermassive black holes in the infant Universe are unobtainable with current...

Feb
17
Teaser:

 

ABSTRACT: The idea that the knottedness of field lines represents a
conserved physical quantity has a long history, having been applied to
fluids, plasmas, and other physical fields.  Testing these ideas in
the laboratory, however, has proven difficult: it requires the ability
to generate and measure dynamically evolving knotted fields.  We have
developed methods for doing precisely this in a fluid, resulting in
the first observation of isolated linked and knotted vortices.
Measuring the subsequent evolution of these vortices leads to
surprising insights about the decay of...
Feb
07
Teaser:

This talk is devoted to quasi-periodic Schrödinger operators beyond the Almost Mathieu, with more general potentials and interactions. The  links
between the spectral properties of these operators and the dynamical properties of the associated quasi-periodic linear skew-products rule the
game. In particular, we present a Thouless formula  and some consequences of Aubry duality.

Feb
05
Teaser:

Please note this is a WEBINAR

Feb
03
Teaser:

High-energy neutrinos are thought to be emitted by astronomical objects
such as active galactic nuclei, gamma-ray bursts, and supernova
remnants. However, due to their small predicted flux and large
backgrounds from neutrinos and muons created in the atmosphere, they had
not been observed until now. The IceCube Neutrino Observatory
instruments a cubic kilometer of ice at the South Pole to detect
neutrinos mainly above 100GeV. In a high-energy (>20TeV) data set from
the first couple of years of the full detector,  an excess above
atmospheric backgrounds is observed. These neutrino events are
incompatible in energy spectrum and...

Jan
31
Teaser:

The unification of the four fundamental forces remains one of the most important issues in theoretical particle physics. In this talk, I will first give a short introduction to Non-Commutative Spectral Geometry, a bottom-up approach that unifies the (successful) Standard Model of high energy physics with Einstein's General theory of Relativity. The model is built upon almost-commutative spaces and I will discuss the physical implications of the choice of such manifolds. I will show that even though the unification has been...

Jan
31
Teaser:

When the light interacts with low-dimensional systems, new optical phenomena can arise because of the reduced dimensionality. Classic examples include discrete electronic energy levels quantum dots or plasmon resonances of metallic nanoparticles. In addition to the dimensionality or shape, the light-matter interaction can be further tuned by using optical nonlinearities. Typically, the induced polarization currents depend linearly on the intensity of the radiation field. However, when the linear relationship breaks down new interesting phenomena arise like frequency conversion or intensity dependent refractive index. We combine these new possibilities with the interesting properties of...

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