Events at Physics |
Events During the Week of September 6th through September 13th, 2009
Monday, September 7th, 2009
- Labor Day
Tuesday, September 8th, 2009
- Atomic Physics Seminar
- Observation of ultra long-range Rydberg molecules
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Johannes Nipper, Universitaet Stuttgart, Germany
- Abstract: At ultralow temperatures highly excited Rydberg atoms can form exotic molecules bound by a novel binding mechanism. First proposed by C. Greene and co-workers, these molecules are bound by low energy scattering of Rydberg electrons from polarizable ground state atoms. The resulting giant molecules can have an internuclear separation of several thousand Bohr radii, which places them among the largest known dimers to date.
Here we report on the experimental observation of the Rb(5S)-Rb(nS) dimer in a dense cloud of magnetically trapped Rubidium. The excitation spectra show the ground state and vibrationally excited states as well as trimer states, where two ground state atoms are bound to one Rydberg atom in a three body photoassociation process. The measured binding energies coincide with theoretical calculations taking into account s- and p-wave scattering. Lifetime measurements for the pure Rydberg state and the molecular dimer state show a decreased lifetime of the molecular state. Decay channels for the molecules are discussed. The coherent excitation dynamics of the dimer and the Rydberg state are studied in rotary echo experiments. - Host: Mark Saffman
- Chaos & Complex Systems Seminar
- HIV/AIDS, What we know and how we learned it
- Time: 12:05 pm
- Place: 4274 Chamberlin (Refreshments will be served)
- Speaker: Pete Cohen, UW Department of Medicine
- Abstract: AIDS/HIV disease is arguably the most important disease in the world. I will attempt in 45 minutes to review how current understanding of how the disease evolved.
- Astronomy Colloquium
- NCG 205 and M32, Understanding Andromeda's Tidally Distorted Satellites
- Time: 3:30 pm
- Place: 3425 Sterling Hall
- Speaker: Kirsten Howley, Univeristy of California - Santa Cruz
- Abstract: <br>
NGC 205 and M32 are close satellites of the Andromeda (M31) galaxy, and are our nearest examples of a dwarf elliptical (dE) and compact elliptical (cE) galaxy, respectively. Photometric observations strongly suggest NGC 205 and M32 are currently undergoing tidal distortion from their interaction with M31. In NGC 205, this conclusion is strengthened by the observation of an unusual velocity profile. Despite earlier attempts, the orbit and progenitor properties of NGC 205 are not well known. We perform an optimized search for these unknowns by combining a genetic algorithm with restricted N-body simulations of the interaction. Using NGC 205's photometric and kinematic observations as constraints, we carry out an effective exploration of the parameter space that defines the orbit and internal structure/dynamics of the progenitor satellite. We find that orbits best matching the observables place NGC 205 on primarily radial orbits moving from the Northwest to the Southeast with the satellite currently residing just behind M31. NGC 205's velocity appears near escape velocity, signifying it is likely on its first M31 passage. We also present Keck DEIMOS observations of M32's stellar kinematics well beyond the r < 4 arc sec region probed in previous studies. The task is made challenging by the fact that M32 is projected against the bright/complicated inner regions of M31. Long-slit integrated light spectroscopy is used to measure the rotation curve of M32 out to a radius of about 1 arcmin. Beyond this radius, we present constraints based on multislit spectroscopy of resolved stars. The velocity distributions from the latter data set reveal a distinct M32 component. A by-product of our M32 study, is the characterization of the kinematics of the underlying M31 disk and inner spheroid.<br>
- Host: Laura Chomiuk
Wednesday, September 9th, 2009
- No events scheduled
Thursday, September 10th, 2009
- R. G. Herb Condensed Matter Seminar
- Emulating the dynamics of a quantum spin using a superconducting phase qudit
- Time: 10:00 am
- Place: 5310 Chamberlin
- Speaker: Matthew Neeley, University of California - Santa Barbara
- Abstract: Quantum computers are typically thought of as being composed of qubits, or two-level quantum systems. However, one can also use qutrits (three-level systems) or general qudits (d-level systems) in quantum information processing, which can simplify certain computational tasks. Like many physical realizations of qubits, the superconducting phase qubit is a quantum system with multiple energy levels that is usually operated as a qubit by restricting it to the lowest two energy states. Here, we relax this restriction and instead use the higher levels to operate this device as a qudit up to d=5. We show how to manipulate and measure the qudit state, and then use it to emulate the dynamics of single spins with principal quantum number s=1/2, 1 and 3/2. In particular, we use this emulation to show the even (odd) parity of integer (half-integer) spins under 2pi rotation.
- Host: Robert McDermott
- Introductory Graduate Seminar
- Astrophysics I: Astrophysics and cosmology
- Time: 5:30 pm
- Place: 2223 Chamberlin Hall
- Speaker: Faculty, University of Wisconsin Department of Physics
- Abstract: Balantekin, Barger, Chung, Halzen, Heeger, Karle, McCammon, Montaruli, Ogelman, Ramsey-Musolf, Timbie, Westerhoff, Zweibel
Friday, September 11th, 2009
- Theory/Phenomenology Seminar
- Prospects for Supersymmetry during Year 1 of the LHC
- Time: 2:30 pm - 3:30 pm
- Place: 5280 Chamberlin Hall
- Speaker: Howie Baer, University of Oklahoma
- Host: V. Barger
- Physics Department Colloquium
- Anderson Localization: looking forward
- Time: 4:00 pm
- Place: 2241 Chamberlin Hall (coffee at 3:30 pm)
- Speaker: Boris Altshuler, Columbia University
- Abstract: Localization of the eigenfunctions of quantum particles in a random potential was discovered by P.W. Anderson more than 50 years ago. In spite of its respectable age and rather intensive theoretical and experimental studies this field is by far not exhausted. Anderson localization was originally discovered and studied in connection with spin relaxation and charge transport in disordered conductors. Later this phenomenon was observed for light, microwaves, sound, and more recently for cold atoms. Moreover, it became clear that the domain of applicability of the concept of localization is much broader. For example, it provides an adequate framework for discussing the transition between integrable and chaotic behavior in quantum systems. This talk is an introduction into the current understanding of the Anderson localization and its manifestation in different systems. In particular, we will see that the ideas developed for understanding quantum mechanics of a single particle can be extended to attack many-body problems in the presence of disorder.
- Host: Chubukov