Events Archive

Mar
11
2014
Wetting and Adhesion at Soft Interfaces
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
2014
Ultrafast Molecular Dynamics probed by Vacuum Ultraviolet Pulses
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
2014
Photonic topological insulators and pseudomagnetism
  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
2014
Probing Quantum Many-body Systems at the Single-particle Level
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
2014
Quantum Simulation Using Cold Atoms and a "Brighter" Future
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
2014
Probing the Origin of Supermassive Black Holes with Dwarf Galaxies
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
2014
Untying the Knot: Experimental Topology in Fluid Flows
  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
12
2014
Predictive, causal modeling in the era of Big Data and High-Performance Computing
Feb
10
2014
All Optical Approaches in Attosecond Science
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Feb
07
2014
A Thouless formula for quasi-periodic long-range Schrödinger operators
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.

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