Events Archive

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.
Feb
07
2014
TCAN Seminar: Introduction to Supermassive Black Hole Formation
Feb
05
2014
Measuring Happiness, Health, and Social Stories
Please note this is a WEBINAR
Feb
03
2014
The Birth of Neutrino Astronomy with IceCube
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
2014
Particle Physics and Cosmology from Almost Commutative Manifolds
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
2014
Nonlinear Optics at Reduced Dimensions
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...
Jan
30
2014
Dynamics of ferromagnets: averaging methods, bifurcation diagrams, and thermal noise effects
Driving nanomagnets by spin-polarized currents offers exciting prospects in magnetoelectronics, but the response of the magnet to such currents remains poorly understood. For a single domain ferromagnet, I will show that an averaged equation describing the diffusion of energy on a graph captures the low-damping dynamics of these systems. In particular, I compute the mean times of thermally assisted magnetization reversals in the finite temperature system, giving explicit expressions for the effective energy barriers conjectured to exist. I will then outline the problem of extending the analysis to...

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