Seminars in Spring 2013
All seminars are held at 4:10 PM in Bio 19, unless otherwise noted.
Refreshments will be served at 4:00 PM.
Rick Watkins, Willamette University
New Perspectives on the Expansion of the Universe
The Doppler shift of light from a distant galaxy is caused by both the relative motion of the galaxy and by the expansion of the space through which the light has been traveling. In disentangling these two effects, it is usually assumed that space expands at the same rate at all locations. However, since the gravitation of matter leads to a deceleration of the expansion, local variations in the density should lead to different expansion rates at different locations. For example, our galaxy is on the edge of a large, empty void, which should be expanding slightly faster than the more dense walls that surround it. After giving an overview of the Big Bang theory, I will describe recent work which reexamines galaxy redshift and distance data in a framework that doesn't assume a uniform expansion. This work suggests that the dipole of the Cosmic Background Radiation, which has long been believed to be a result of our motion relative to a cosmic rest frame, may in fact be mostly due to a larger than average expansion rate in the direction of the local void.
Christof Teuscher, Portland State University
From Intrinsic to Designed Computation
The computing disciplines face difficult challenges by further scaling down CMOS technology. One solution path is to use an innovative combination of novel devices, compute paradigms, and architectures to create new information processing technology. Emerging biological and non-biological devices typically exhibit extreme physical variation, have a partially or entirely unknown structure with limited functional control, and often behave in time-dependent nonlinear ways, beyond a simple on/off switching behavior. In this talk I will present our latest research that focuses harnessing the intrinsic dynamics of device networks for performing useful computation.
Nicholas Wheeler, A. A. Knowlton Professor (emeritus), Reed College
Introduction to the Quantum Theory of Open Systems
The impression conveyed by textbooks notwithstanding, "isolated quantum systems" do not exist, except to a degree of approximation that quite well serves most practical applications. In recent decades it has come to be realized that there exist problem areas---relating often to foundational matters---in which explicit provision must be made for the sometimes profound consequences of "interaction with the environment." This circumstance has led to development of a "quantum theory of open systems."
Wheeler will sketch a couple of elementary mathematical notions that are basic to the quantum theory of "composite sytems" (of which "open systems" comprise a special class), then sketch the application of open system theory to (1) decoherence (the "evaporation of information" and emergence of the classical world); (2) dissipation (the "evaporation of energy"); (3) the quantum theory of measurement (and more particularly: the simultaneous measurement of conjugate observables, which standard interpretations of the Heisenberg uncertainty principle hold to be impossible). In the first two of those subject areas the "unitary state evolution" of standard quantum theory gives way---surprisingly---to a "non-unitary state evolution" of a particularly interesting type.
Wheeler's objective will be simply to alert students to the existence of some quite accessible (if conceptually challenging) aspects of quantum theory which, though they lie presently beyond the reach of present-day textbooks, are almost certain to be standard to the pedagogical literature by the time the "New Quantum Theory" (Heisenberg , Schrödinger et al) celebrates its Centennial (2025).
Moira Gresham, Whitman College
Will the top quark topple the Standard Model?
The Standard Model (SM) of particle physics provides a remarkably accurate description of physical phenomena probed at subatomic scales and high energies in the laboratory. It has predicted phenomena amazingly well thus far, yet physicists know it is incomplete---it's not the whole story about the fundamental constituents of matter and their interactions. With each new particle physics experiment we hope to reveal shortcomings of the SM that will serve as clues about a more complete description of particle physics. Until recently it seemed that experiments were yielding no such clues, but before its recent shutdown the Tevatron collider at Fermilab may have uncovered anomalous behavior in top quark pair production events.
The CDF and D0 collaborations at Fermilab might be seeing a rare hint of phenomena unexplained by the SM; both collaborations report larger-than-expected top quark pair forward-backward asymmetries. I'll tell the story of these puzzling top quark measurements and discuss some of my recent work that has helped to clarify their implications.
Andrew Dawes, Pacific University
Quantum State Tomography of Slow and Stored Light
Quantum information can be transferred from a beam of light to a cloud of atoms and controllably released at a later time. Prior experiments have stored light in a variety of systems, including cold atom clouds, warm atomic vapor, solid state materials, and optical fibers. To extend these successful investigations, we propose to measure the quantum states of stored-and-retrieved multimode light. We apply array-detection techniques developed for quantum state reconstruction to experimental stored-light systems. Preliminary results of this program will be presented along with a roadmap to achieve a complete understanding of the quantum state of light before and after storage.
Harry Yeh, Oregon State University
Tsunamis: Interplay between Observation and Theory
Tsunami is a translational long wave created by seafloor displacement. Here we focus on the tsunamis that are triggered by co-seismic fault rupture. Characteristics of tsunami generation, propagation, and runup of the 2011 Tohoku/East-Japan Tsunami are presented. Examples of close interplay between theory and application are presented. First, we demonstrate that a mathematical recipe for cylindrical wave equation can yield a very practical and surprisingly accurate estimate for the directivity of tsunami energy emission. The analytical solution predicts well the initial tsunami source of the 2004 Indian Ocean Tsunami, matching with the prediction made by the seismic wave inversion.
When a solitary wave – a popular waveform for modeling tsunamis – impinges obliquely onto a reflective vertical wall, it can take the formation of a Mach reflection (a geometrically similar reflection from acoustics). The theory predicts that the wave at the reflection can amplify not twice, but as high as four times the incident wave amplitude. Nevertheless, this four-fold amplification has not been verified by numerical or laboratory experiments. We discuss the discrepancies between the theory and the experiments.
Lastly, we introduce some tsunami-related unsolved problems. Those are the topics of undular bores, tsunami splash-up, and some peculiar tsunami waveforms that were observed in the 2011 Tohoku/East-Japan Tsunami.
Noah Muldavin, Alan Baur, Mike Vignal, Luke Howard
Noah Muldavin, “N-Body Simulation of Galaxy Dynamics”
Alan Baur, “Chasing Pinwheels: Measuring the Force of the Electric Wind”
Mike Vignal, “A Thermal Mapping of the Reed Reactor’s Core”
Luke Howard, “A Numerical Approach to an Intractable Problem: Water Waves Over a Non-Trivial Bottom Surface”
Julius Monello, Zach Brown, Cole Perkinson, Neil Anderson
Julius Monello: "2-D Stable Configurations of BuckyBalls®"
Zach Brown: "Condensation Phase Transition of a Chipping Model"
Cole Perkinson: “A Spectroelectrochemical Investigation of Tunable Photoluminescence in CdSe and Mn:ZnSe Quantum Dots”
Neil Anderson: “A Reggeized model for eta/eta' meson production in proton proton collisions”
Jon Kindem, Julia Fisk, Chrissy Porter, Bibek Kafle
Jon Kindem: “An Investigation of Optical Precursors in Trapped Rubidium”
Julia Fisk: “Fluorescence Intermittency in Quantum Dots”
Chrissy Porter: “Structure and Dynamics of Laboratory Ball Lightning Produced Via Electrical Arcing Through Doped Silicon”
Bibek Kafle: “Electronic Structure Calculations for Artificial Quasicrystals Composed of Semiconductor Quantum Dots”
Victor Lowney, Will Eichelberger, Andre Frankenthal, Lindsay Sonderhouse
Victor Lowney: “Optimizing the Grid Structure of the Active Walker Model”
Will Eichelberger: “A Numerical Model for the Partial Coalescence of Small Fluid Drops”
Andre Frankenthal: “A Quantum-Mechanical Study of the de Sitter Potential”
Lindsay Sonderhouse: “Amplitude and Phase Instability in an Optoelectronic Oscillator with Delayed Self-Feedback”
Connor Wallace, Lukas Kuczynski, Xueping Long
Connor Wallace: “Non-Hermitian Perturbations of Two-Dimensional Fermion Systems”
Lukas Kuczynski: “Extending piecewise-linear chaos to ultra-high-frequencies in a time-delay device”
Xueping Long: “Implementation of a nonlinear differential equation using an electromechanical oscillator”
Lucas Johns, Elisabeth Thomas, Halley Vrijmoet, Carolynn Polanchek
Lucas Johns: “Exploring the Conformal Equivalence of Metrics”
Elisabeth Thomas: “Microwave Absorption in DNA”
Halley Vrjimoet: “Numerically Levitating Objects with Rockets”
Carolynn Polanchek: “Configuring Cavities: Stringing 19 Tones Into One Octave”
Alec Jackson, Phillip Norfleet, Max Gurewitz, Ian Flower
Alec Jackson: “Observing Optical Flux Variability of BL Lac Object MRK 421”
Phillip Norfleet: “Conductance Quantization in Gold Nanowires”
Max Gurewitz: “Early Stopping for Regularization in Multilayer Perceptrons”
Ian Flower: “Blue Hue: Visualizing the Color of Cerenkov Radiation in New Media”