Events at Physics
Events on Thursday, March 27th, 2014
- R. G. Herb Condensed Matter Seminar
- Superconducting qubits and cavities: sidebands and vortices
- Time: 10:00 am
- Place: 5310 Chamberlin Hall
- Speaker: Professor Britton Plourde, Syracuse University
- Abstract: There has been tremendous progress in recent years with the development of superconducting qubits and cavities. I will describe two recent efforts in this area at Syracuse University. We have implemented a frequency-modulated driving technique with asymmetric transmon qubits for generating first-order sideband transitions for the rapid exchange of excitations between qubits and cavities. There are a variety of loss mechanisms that can influence the performance of both superconducting cavities and qubits, including magnetic flux vortices and quasiparticles. We are working on experiments with structures for trapping a single vortex in a superconducting microwave cavity. For certain locations of the vortex in the cavity, we observe a decrease in the microwave loss, which we attribute to a reduction of the quasiparticle density due to interactions with the vortex core.
- Host: McDermott
- Faculty Candidate Seminar
- Radar Detection of HE Neutrinos in the Ice
- Time: 1:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Kael Hanson, UniversitÃ© Libre de Bruxelles
- Abstract: The recent IceCube measurement of an excess of neutrino events in the energy range of 30 TeV to 2 PeV is an extremely interesting result which points to the existence of a detectible neutrino signal from diffuse galactic and extragalactic cosmic ray acceleration sites. The limited data is most compatible with a power law flux with spectral index near -2, consistent with production via Fermi shock acceleration, however the limited dynamic range of the measurement renders a large error in the determination of the behavior of the energy spectrum and future accumulation of statistics in IceCube above a PeV will come slowly. Extensions to the IceCube optical detector array are being designed to increase the effective area by an order of magnitude. Antenna arrays for the detection of extremely high energy neutrinos by their radio emission are also being designed and built, however these facilities would not detect a significant number of neutrinos of this origin but are rather targeted toward the much higher energy cosmogenic neutrino fluxes. This presentation will explore the possibility of detection of PeV scale energy and higher neutrinos using bistatic radars which reflect off of plasmas created in the energetic electromagnetic neutrino-induced cascades in the ice.
- Host: Joynt/Halzen
- Astronomy Colloquium
- "Sizing up Kepler's exoplanets with Asteroseismology"
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Travis Metcalfe, Space Science Institute
- Abstract: The past two decades have witnessed accelerating progress on one of the most fundamental questions in astronomy: Are we alone in the Universe? Astronomers have already discovered hundreds of planets around distant stars. Some of them are nearly as small as the Earth and orbit in the Goldilocks of their parent star where liquid water can exist. It remains to be seen whether biological signatures of life or evidence of radio communications can be found in these planetary systems. Our current emphasis is to determine how common such planets might be, to find as many of them as possible, and to characterize those which have already been discovered. I will give an overview of NASA's Kepler space telescope, how it searches for planets around distant stars, and how we characterize those planets using the natural vibrations of their suns.
- Host: Robert Lindner
- Van Vleck Lecture
- Application of Orthogonalized Linear Combination of Atomic Orbital Methods to Complex Materials
- Time: 3:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Professor Wai-Yim Ching, Curatorâ€™s Professor, University of Missouri-Kansas City
- Abstract: In this lecture, I present the development and application of an ab initio electronic structure method based on density functional theory, the orthogonalized linear combination of atomic orbital (OLCAO) method. The OLCAO method was initially developed at UW-Madison in mid-70s. Over the years, the method has been steadily improved, refined and withstood the test of time, and emerged as an extremely effective computational tool for complex materials. I will present three examples of its recent applications: (1) Densification of a near-perfect continuous random network model of amorphous SiO2 glass (Fig.1); (2) Genomic approach for the mechanical properties and electronic structure in a novel class of layered ternary compounds, the MAX phases (Mn+1AX2) (M = a transition metal, A= mostly Al or other group III, IV, V elements, X = C or N) (Fig.2); (3) Application to biomolecular systems and large proteins such as brome mosaic virus (1js9) (Fig.3). These examples illustrate the versatility of the OLCAO method in addressing specific problems of different material systems in diversified scientific and engineering fields. Further applications and limitations of the method will also be discussed.
- Host: Chun Lin