Events at Physics
Events During the Week of September 25th through October 2nd, 2011
- Plasma Physics (Physics/ECE/NE 922) Seminar
- Time: 12:05 pm
- Place: 2317 Engineering Hall
- Speaker: Ben Longmeier, University of Huston
- Condensed Matter Theory Group Seminar
- Orbital ice: an exact Coulomb phase on diamond lattice
- Time: 4:30 pm
- Place: 5310 Chamberlin
- Speaker: Gia-Wei Chern, UW-Madison
- Abstract: I will talk about an exact orbital Coulomb phase which is an exact ground state of p-orbital exchange Hamiltonian on the diamond lattice. The Coulomb phase is an emergent state characterized by algebraic dipolar-like correlations and a gauge structure resulting from the local constraints (ice rules) of the underlying lattice models. For most ice models on the pyrochlore lattice, these local constraints are a direct consequence of minimizing the energy of each individual tetrahedron. On the contrary, the orbital ice rules are emergent properties arising from the quantum orbital dynamics. We show that there exists a one-to-one mapping between the orbital-ice states and the spin-ice states obeying the 2-in-2-out constraints on the pyrochlore lattice. We also discuss possible realization of the orbital ice model in optical lattices with p-band fermionic cold atoms.
- Host: Perkins
- Chaos & Complex Systems Seminar
- Bed bugs - They will rule the world
- Time: 12:05 pm
- Place: 4274 Chamberlin
- Speaker: Phil Pellitteri, UW Department of Entomology
- Abstract: Human bed bugs were a common problem until DDT was used in the early 1940's. The seemed to disappear until about 10 years ago and now have become a major issue worldwide that shows no signs of going away. There are a number of factors involved in the resurgence, and we expect the problem to continue to increase. I will be discussing the biological and social aspects to the problem. It is not just a poem anymore.
- Host: Clint Sprott
- Department Meeting
- Special Department Meeting
- Time: 12:15 pm
- Place: 5310 Chamberlin Hall
- Open discussion of Strategic Plan.
- R. G. Herb Condensed Matter Seminar
- Coupled modes and parametric quantum informationprocessing--from classical pendula to single photons
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Jose Aumentado, NIST Boulder
- Abstract: The simple harmonic oscillator is a fundamental building block of everyday physics, from playground swings to the state of light. However, energy dissipates in many of these systems in ways that can be well described by extending these oscillator-like systems through coupling to other oscillators. This kind of coupling can be intuitively understood from a classical standpoint, but it also forms the basis for the most basic linear optical element-- the beamsplitter. In this talk, I'll show how simple superconducting devices (SQUIDs and resonators) can be used to create this interaction with microwave light, coupling microwave Fock states between harmonic oscillator modes at different frequencies combining elements of both cavity-QED and linear quantum optics. This generalized beam-splitter process, although simple, can be used to swap unknown quantum states and even build up straightforward interferometers (like 'real' beam splitters) albeit in a more abstract frequency space. I will discuss the experimental verification of this process so far, as well as briefly discuss how systems like this might be extended to address other problems more traditionally addressed in quantum optics.
- Host: Robert McDermott
- NPAC (Nuclear/Particle/Astro/Cosmo) Forum
- Probing Dark Matter with Neutrinos
- Time: 2:30 pm
- Place: 4274 Chamberlin Hall
- Speaker: Ina Sarcevic, University of Arizona
- Abstract: Dark Matter particles can be captured in the core of the Sun or the Earth, or in the Galactic center, by interacting with the nuclei in the medium. The capture rate depends on the composition of the medium, dark matter mass and its local density. If the captured dark matter annihilate or decay into the Standard Model particles, there is a possibility of producing neutrinos which can be detected via muon tracks or showers. I will present theoretical predictions for the indirect detection of the dark matter particles via neutrino signals due to their annihilations in the core of the Sun/Earth and in the Galactic center. I will discuss how measurements of muons and/or showers by IceCube and KM3NeT may be able to distinguish between different dark matter models, such as gravitino, Kaluza-Klein particle or leptophilic dark matter.
- Host: Reina Maruyama
- Astronomy Colloquium
- Large-Scale Flows in Galaxies for the last 6 Billion Years"
- Time: 3:30 pm
- Place: 4421 Sterling Hall
- Speaker: Nicolas Lehner, University of Notre Dame
- Abstract: The general issue of how gas flows into and out of galaxies has become one of the most critical problems in understanding the evolution of galaxies and their fundamental properties. New observational results based on the powerful combination of the Hubble, LBT, and Keck spectroscopy and images have constrained the mass and chemical composition of the large scale flows in and out of galaxies. These significant advances signal major progress toward answering some of the key open questions in galaxy formation studies. I will present and discuss some of these recent and exciting developments.
- Graduate Introductory Seminar
- High Energy Phenomenology, String Theory, and Theoretical Cosmology
- Time: 5:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Barger, Chung, Everett, Hashimoto, Shiu
- Cosmology Journal Club
- An Informal discussion about a broad variety of arXiv papers related to Cosmology
- Time: 12:00 pm
- Place: 5242 Chamberlin Hall
- Abstract: This week we'll discuss...
papers that have not yet been determined
Please feel free to bring your lunch!
If you have questions or comments about this journal club, would like to propose a topic or volunteer to introduce a paper, please email Le Zhang (firstname.lastname@example.org). Please visit the following link for more details: http://cmb.physics.wisc.edu/journal/index.html
- Host: Peter Timbie
- Physics Department Colloquium
- Vibrations, Conical Intersections, and Reaction Dynamics in Gases and Liquids
- Time: 3:30 pm
- Place: 2241 Chamberlin Hall (coffee at 4:30 pm)
- Speaker: Fleming Crim, University of Wisconsin-Madison
- Abstract: Conical intersections between potential energy surfaces occur when the two electronic states become degenerate and, consequently, the Born-Oppenheimer approximation fails. Although long regarded as interesting curiosities, it is now clear that they are central to a large variety of molecular transformations. Photodissociation and photoisomerization often occur by passage of electronically excited molecules through a conical intersection, and the details of that passage control the partitioning of the products among competing pathways.
Ammonia is a prototypical molecule in which a conical intersection is important in excited-state dissociation. High resolution studies of the dissociation of isolated ammonia molecules show that excitation of selected vibrations changes the course of the dissociation dramatically, leading to the formation of electronically excited products at the expense of ground-state products. The key to this behavior is the influence of vibrational motion on passage of the system through the conical intersection.
Similar studies in solution require high time resolution rather than high spectral resolution, and it is possible to prepare vibrationally excited molecules in solution and monitor their evolution using 100-fs laser pulses. In these experiments an infrared pulse excites a vibration, an ultraviolet pulse transfers molecules to an excited state, and broadband continuum absorption monitors their evolution in the excited state. The competition between excited state vibrational relaxation and barrier crossing is the feature that determines the influence of vibrational excitation on the isomerization rate.
- Host: Gilbert