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Events During the Week of November 17th through November 23rd, 2019

Monday, November 18th, 2019

Plasma Physics (Physics/ECE/NE 922) Seminar
Consistent Closures for Plasma Fluid Equations
Time: 12:05 pm - 12:55 pm
Place: 2241 Chamberlin Hall
Speaker: Eric Held, Utah State
Host: John Sarff
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Tuesday, November 19th, 2019

Chaos & Complex Systems Seminar
Will global precipitation trends be observable in our lifetime?
Time: 12:05 pm - 1:00 pm
Place: 4274 Chamberlin (refreshments will be served)
Speaker: Tristan L'Ecuyer, UW Department of Atmospheric and Oceanic Sciences
Abstract: Simple energy balance arguments indicate that warming from human activities is likely to cause an increase in worldwide precipitation but it is very unlikely that these changes will be felt uniformly around the globe. Climate models indicate, for example, that in a warmer climate “the wet will get wetter and the dry will get drier” – in other words, rainfall is expected to increase in areas that already receive above average rainfall while arid regions may become even drier. Most predictive models also suggest that, as global temperatures rise, the frequency and amount of snowfall in the middle latitudes (where a large fraction of the world’s population resides) will decrease, impacting water availability in areas that depend critically on runoff from winter snow packs. These changes could have significant (and often undesirable) consequences that may require substantial investment to mitigate but developing cost-effective strategies for coping with changing global precipitation patterns must be based on reliable forecasts. Given the transient nature of precipitation, however, evaluating precipitation changes in climate models using the snapshots provided by Earth-observing satellites is a very challenging problem. This presentation will outline a robust statistical method for assessing how long it will take for predicted rain and snowfall trends to emerge from natural year-to-year variations and, therefore, become testable with satellite data records. Utilizing this new strategy, we will reveal a surprisingly robust climate change metric that may be observable by the middle of the next decade.
Host: Clint Sprott
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Wednesday, November 20th, 2019

Theory Seminar (High Energy/Cosmology)
Aspects of Neutrino Masses
Time: 4:00 pm - 5:00 pm
Place: 5280 Chamberlin Hall
Speaker: Jessica Turner, Fermilab
Abstract: The origin of neutrino masses remains unknown. In the first half of the talk I will discuss a theory which connects the baryon asymmetry of the Universe, light neutrino masses and the dynamical generation of the electroweak scale. In the second half of the talk I will discuss the generation of neutrino mass from enhanced gravitational effects.
Host: Nicholas Orlofsky
Presentation: Madison_2019.pdf
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Thursday, November 21st, 2019

No events scheduled

Friday, November 22nd, 2019

Physics Department Colloquium
Looking for excitations with fractional statistics in the quantum Hall regime
Time: 3:30 pm
Place: 2241 Chamberlin Hall
Speaker: Mike Manfra, Purdue University
Abstract: The fractional quantum Hall effect (FQHE) occurs when a two-dimensional electron gas (2DEG) is subjected to a large perpendicular magnetic field at low temperatures. At certain magnetic field values determined by the density of the electron gas, the system forms highly correlated ground states with a gap to low-lying excitations. In these states, the transverse Hall resistance is quantized to rational fractions of h/e2 and the longitudinal resistance vanishes. Remarkably, theory predicts that the excitations of the FQHE carry fractional charge and fractional statistics, possibly even non-Abelian statistics in certain cases. The search for “topological” materials with fractional charge and unusual statistics is currently an exciting branch of condensed matter physics spanning many different physical systems. Here I will describe how we create extremely high quality 2DEGs in AlGaAs/GaAs heterostructures using molecular beam epitaxy and the basics of electron transport experiments we use to study them. Building on this knowledge, I will discuss how we currently attempt to probe statistics in the FQHE via Aharonov-Bohm interference in small electronic Fabry-Perot interferometers. We have recently demonstrated highly coherent Aharonov-Bohm oscillations in the fractional quantum Hall regime. This result indicates we may have a viable platform for measurement of particle statistics in a condensed matter system.
Host: Mark Eriksson
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