Physics

Seminars in Fall 2014

All seminars are held at 4:10 PM in Bio 19, unless otherwise noted.
Refreshments will be served at 4:00 PM.

Upcoming Seminar

September 17, 2014

Summer Internship Talks

Sept 3

Thesis Start-Up Meeting

Sept 10

Summer Internship Talks

Yudan Guo, Self-Consistent Tomography of a Superconducting Qubit

Dan Herman, Examining Energy Transport in Solar Flares Using EUV/SXR Peak Flux Timing

Liese Maynard, Using Jet Asymmetry to Distinguish Quark 3-Pronged Decays from Background

Anna Nuxoll, Myths and Science: Research on Inclusive Climate

Sept 17

Summer Internship Talks

Miguel Conner, Regolith-Atmosphere Water Vapor Transfer on Mars: Comparison between Phoenix and MSL Data

Naomi Gendler, Inference on Populations of Binary Neutron Stars

Elizabeth Grace, Sensitivity Study: Measurement of Reactor Electron Antineutrino Disappearance in the Double Chooz Experiment 

Kai Nalipinski/Jack Flowers, An Investigation of Lowest Energy Levels on a Square Lattice

Julia Selker, A New Method and Instrument for Cryo-Electron Microscopy Sample Preparation

Sept 24

Spencer Chang, University of Oregon

Dark Matter Direct Detection Experiments and Inelastic Dark Matter

In this talk, I will give an introductory overview of dark matter direct detection experiments, a class of underground experiments searching for dark matter in our galaxy. There is an elegant dark matter framework called the weakly interacting massive particle (WIMP), which suggests a detectable scattering cross section for dark matter off target nuclei. An overview of interesting past and future experiments will be given, focusing on a longstanding observation by the DAMA experiment of an annual modulation that is suggestive of dark matter. I will review both dark matter and background explanations of this modulation. In particular, I will show that cosmic ray muons, which are known to modulate, cannot be solely responsible for the signal.  As a potential signal, I will discuss a scenario where the dark matter inelastically scatters with nuclei, which I will show is still allowed by current limits and should be tested in the near future.

Oct 1

Andrew Essin, Caltech

Exotic Quantum Numbers in Exotic Phases of Matter

Symmetries imply conservation laws and therefore provide meaningful and useful ways to label and classify states of particles and matter. Condensed matter physics traditionally classifies phases of matter by patterns of symmetry breaking.  One of the most exciting areas of current research is the study of phases which break no symmetries, because the distinctions between them cannot be captured within the traditional scheme.  I will focus on exotic phases of matter that are host to "fractional excitations," and will describe how fractional excitations can carry "fractional quantum numbers."
Oct 8

Summer Internship Talks/CAT Presentation

Jay Collins, Simulating Information Transmission at Auditory Hair Cell Synapses

Will Holdhusen, Comparing Earth's Gravity Field to Antarctic Seasonal Patterns

Nick Irvin, The Vortex Emitted from a Wind Turbine

Oct 15

Matthew Graham, Oregon State University

Micro-Femto Energetics; Nano-Physics in the Twinkling of an Eye

When light and matter interact, electron micro-femto energetics begin.  Our just-constructed lab is able ‘film’ the excited electron’s energetic journey from light absorption to photocurrent generation with sub-micron (<10-6 m) spatial resolution and femtosecond (~10-15 s) time-resolution.  By 'filming' how electrons move and relax at nanoscale interfaces, we identify the bottlenecks that inherently limit the efficiency of solar voltaics and photosensors.  We will show how our ultrafast ‘moives’ give a time-space resolved microscopy map of the electronic population in materials such as graphene and single atomic layer dichalcogenides devices.  For graphene, our measurements reveal how electrons relax near the Fermi energy through a radically accelerated supercollision mechanism. The discovery of this novel electronic mechanism provides the missing link required to predict current generation from electronic population in graphene.

Oct 22

Fall Break

Oct 29

Ian Coddington, National Institute of Standards and Technology, Boulder

Frequency Comb Measurements Outside the Laboratory

Frequency combs are a novel laser source that have been exploited in an exciting range of laboratory-bound precision measurements. I will discuss development of a fieldable frequency comb, and experiments that send comb light across outdoor air paths to explore both accurate atmospheric measurements of greenhouse gasses and optical time-frequency transfer to support navigation and geodesy.

Nov 5

Robert Knapp, Evergreen College

Physics and Sustainable Buildings

Buildings account for roughly 40% of energy use and large fractions of water, materials and other dimensions of the national and global sustainability challenge. Physics imposes limits and creates opportunities for reducing resource demands and impacts while maintaining high performance. Using measured energy flows in instrumented buildings as one guide, and fundamental physics as another, this talk will highlight key aspects of the critical thermal, optical, fluid and electrical processes used in the current generation of high-performing buildings such as the Packard Foundation’s and Bullitt Foundation’s new “net zero” office buildings. Topics will include heat engines and heat exchangers, blackbody and selective absorption and radiation, and photovoltaic performance.

Nov 12

Anne Trehu, Oregon State University

Physics of Earthquakes and Tsunamis

Nov 19

Ben McMorran, University of Oregon

Experiments with Free Electron Vortices

Electron vortex beams are composed of free electrons in quantized orbital states. Each electron wave packet in the beam has a helical shape, with a resulting quantized orbital angular momentum (OAM) and a corresponding magnetic moment. To produce such states, we use nanofabricated diffraction gratings to holographically “sculpt” a phase vortex onto free electron matter waves in a transmission electron microscope (TEM). We also use this approach to place free electrons in coherent superpositions of orbital states. These beams can interact with surfaces and materials in unique, albeit subtle, ways. For example, electron vortex beams can transfer quantized OAM to another system through inelastic scattering. In the TEM this can result in OAM-dependent signals and images that can provide new magnetic, plasmonic, and structural information about a material. These applications, the new technologies developed to achieve them, and the fundamental physics of free electron orbital states will be discussed.

Nov 26

Thanksgiving Break

Dec 3

Alex Emerman Thesis Talk/Phil Mass, Lightcraft Technology

Dec 10

Max Schlosshauer, University of Portland

A New "No-Go" Result for Quantum Mechanics

I describe a new theorem that shows that whenever you consider a pair of quantum systems, the whole is different from the sum of the parts even in the absence of entanglement. (Reference: Phys. Rev. Lett. 112, 070407 (2014), arXiv:1306.5805 [quant-ph])