Events at Physics |
Events on Thursday, January 29th, 2015
- Atomic Physics Seminar
- Observation of ultracold Cs Rydberg molecules with kiloDebye dipole moments
- Time: 2:00 pm
- Place: 5310 Chamberlin
- Speaker: Donald Booth, University of Oklahoma
- Abstract: We present results on our Cs ultracold Rydberg atom experiments involv-<br>
ing two classes of ultralong-range Rydberg molecules known as trilobite" and<br>
butter<br>
y" molecules. These molecules are predicted to have giant, body- xed<br>
permanent dipole moments on the order of 1000 Debye. The two classes of<br>
molecules are distinguished by the relative dominance of the s-wave and p-wave<br>
electron scattering. We present spectra for (nS1=2 +6S1=2)3 molecules, where<br>
n = 37, 39 and 40, and measurements of the Stark broadenings of selected<br>
trilobite states in Cs due to the application of a constant external electric eld.<br>
Additionally, we present measurements of spectra and Stark splittings for p-<br>
wave dominated (nS1=2 + 6S1=2)3 molecules, where n = 31 and 32.<br>
- Host: Saffman
- Astronomy Colloquium
- Puzzles in Massive Galaxy Assembly
- Time: 3:30 pm - 5:00 pm
- Place: 4421 Sterling Hall
- Speaker: Nicholas McConnell, Ifa, University of Hawaii
- Abstract: Do giant elliptical galaxies represent the final outcome of a common sequence of galaxy growth and merging, or are they the relics of exceptional objects that formed violently in the early universe? I will describe observational efforts to understand two features of the most massive ellipticals: their stellar populations and their supermassive black holes. (1) The Black Hole Safari is a campaign to measure stellar kinematics and central black hole masses (MBH) in over 30 giant elliptical
galaxies, spanning a range of cosmic environments. The resulting census of black holes in the local universe will assess whether the linear relation between MBH and stellar spheroid mass arises naturally from hierarchical merging, and it may shed light upon the origins of recently-discovered overmassive black holes. (2) The most massive elliptical galaxies exhibit an extremely bottom-heavy stellar initial mass function (IMF), at odds with
galaxy formation models where they are assembled from mergers of lower-mass systems. One possible means of reconciliation would be the detection of radial gradients in the IMF. I will present new measurements of IMF-sensitive spectral features with unprecedented radial coverage, suggesting that massive ellipticals' extreme are indeed confined to small radii. - Host: Prof Tremonti
- R. G. Herb Condensed Matter Seminar
- Faculty Candidate Seminar
- Noise in superconducting circuits: microscopic theory and open questions
- Time: 4:00 pm - 5:00 pm
- Place: 4274 Chamberlin
- Speaker: Lara Faoro, Laboratoire de Physique Theorique et Hautes Energies
- Abstract: I review the main sources of noise in superconducting circuits: charge noise, critical current noise, quasiparticle poisoning and flux noise. I discuss the microscopic mechanism for these noises and show that charge and critical current noise are accounted for by the microscopic model that assumes the presence of localized electron states at the Superconductor Insulator interfaces. Due to the large electron electron interaction these states form resonances close to the Fermi surface. These states serve as traps where the quasiparticles live for a long time. The spins of the quasiparticles in these states produce flux noise of the right magnitude and frequency dependence. However the correlation between the magnetization and susceptibility noise observed by R. McDermott remains unexplained.
- Host: Coppersmith