Events Archive

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...
Jan
27
2014
First Evidence of High-Energy Extraterrestrial Neutrinos at IceCube
The spectrum of cosmic rays includes the most energetic particles ever observed. The mechanism of their acceleration and their sources are, however, still mostly unknown. Observing astrophysical neutrinos can help solve this problem. Because neutrinos are produced in hadronic interactions and are neither absorbed nor deflected, they will point directly back to their source. This talk will cover searches for high-energy neutrinos (> 100 TeV) at the IceCube neutrino observatory, which have recently produced the first evidence for a flux beyond standard expectations from neutrinos generated in the Earth's atmosphere. This includes the detection of two events with energies above...
Jan
23
2014
Opening a window on the gravitational wave transient sky
A new observational era in gravitational wave astronomy is poised to begin in this decade, with the upcoming start of Advanced LIGO and Advanced Virgo.  These instruments will be capable of the direct detection of gravitational wave transients, which will yield new insights into the engines powering some of the most energetic astrophysical events: the coalescence of neutron star and/or black hole binary systems, core-collapse supernovae, and isolated neutron star instabilities. I will present the path towards this detection using the second generation of gravitational wave interferometers, and summarize the open analysis challenges, prospects for astrophysical inference and the...
Jan
16
2014
An Observational Search for Close, Supermassive Binary Black Holes
Jan
06
2014
Modeling living cell movement on soft substrates
Computational modeling of eukaryotic cells moving on substrates is an extraordinarily complex task: many physical processes, such as actin polymerization, action of motors, formation of adhesive contacts concomitant with both substrate deformation and recruitment of actin etc., as well as regulatory pathways are intertwined. Moreover, highly nontrivial cell responses emerge when the substrate becomes deformable and/or heterogeneous. Here we extended a computational model for motile cell fragments, based on an earlier developed phase field approach, to account for...
Jan
06
2014
Behaviour of miscible liquids under vibrations
Dec
10
2013
Topological interface physics in spin-1 atomic Bose-Einstein condensates
Dec
02
2013
Cosmic Rays: Alien Invaders from Outer Space
Cosmic rays are microscopic, charged particles that permanently bombard Earth from outer space. 100 years after their discovery their origin is still a mystery. It is also not clear how cosmic rays can obtain energies that are sometimes billion times larger than what can be produced in the most powerful particle accelerator on Earth, the LHC, where the Higgs particle was discovered last year. Possible particle accelerators that nature provides are very exotic sites in the universe like exploding stars, massive black holes, gamma-ray bursts, and pulsars. To find out more about these...
Dec
02
2013
Structured graphene: from ballistic transport to electronics

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