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This Week at Physics

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Events on Thursday, October 4th, 2012

R. G. Herb Condensed Matter Seminar
No Herb Seminar -- Atomic Seminar held at this time
Time: 10:00 am
Place: 5310 Chamberlin
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Atomic Physics Seminar
Atom Interferometry in an inductively coupled ring trap
Time: 10:00 am
Place: 5310 Chamberlin
Speaker: Jonathan Pritchard, University of Strathclyde, Glasgow
Abstract: Atom interferometry offers a number advantages to the field of precision metrology overt over optical interferometers due to the sensitivity of atoms to external electromagnetic fields and inertial forces. Utilising a circular waveguide has the further benefit of providing a strong common-mode rejection between paths and rotational sensitivity via the Sagnac effect, whilst also permitting longer interaction times compared to optical sensors. We present the first demonstration of a novel inductively coupled ring trap for cold atoms to create a circular waveguide of radius 5 mm. A uniform, ac magnetic field induces current in a copper ring, which creates an opposing magnetic field that is time-averaged to produce a smooth cylindrically symmetric ring trap. This resolves the issue of perturbations due to electrical connections and benefits from averaging out corrugation of the potential due to current meandering. A laser-cooled atomic sample is used to characterise the loading efficiency and adiabaticity of the magnetic potential, achieving a vacuum-limited lifetime in the trap. This technique is suitable for creating scalable toroidal waveguides for applications in matterwave interferometry, with a large enclosed area and long interaction times. Development of a second generation apparatus to utilise the ac ring trap for Sagnac interferometry with Bose (87Rb) and Fermi (40K) quantum degenerate gases is described.
Host: Saffman
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Astronomy Colloquium
Probing the Gas Around Galaxies and Black Holes
Time: 3:30 pm
Place: 4421 Sterling Hall
Speaker: Aleks Diamond-Stanic, UC San Diego
Abstract: Our understanding of galaxy evolution centers around questions of how gas gets into galaxies, how it participates in star formation and black hole growth, and how it is returned to its galactic
surroundings via feedback. I will present results on the relationship between gas that forms stars and gas that accretes onto supermassive black holes, and the nature of feedback that is capable of removing gas from galaxies. These results have important implications for how radiation, momentum, and kinetic energy from stars and black holes regulate the cold gas supply in
galaxies. I will also discuss prospects for characterizing the physical properties of gaseous outflows and inflows using existing and future facilities.
Host: Christy Tremonti
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Graduate Introductory Seminar
High Energy Phenomenology String Theory & Theoretical Cosmology
Time: 5:45 pm
Place: 2223 Chamberlin Hall
Speaker: Bai, Barger, Chung, Everett, Hashimoto, Shiu, UW Madison
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