Calendar of Physics Talks Vienna

Calorimetry of a Bose-Einstein condensed photon gas
Speaker:Liang Qi (Univerität Bonn)
Date: Mon, 27.10.2014
Time: 14:00
Duration: 60 min
Location:Semiarraum, Atominstitut, Stadionallee 2, Wien 2
Contact:WU RuGway

Quantum Nanophotonics with Quantum Dots in Photonic Crystals
Speaker:Peter Lodahl (Niels Bohr Institute, University of Copenhagen, Denmark)
Abstract:The efficient coupling of a quantum emitter to a propagating mode is eagerly sought after since it would enable a number of new opportunities in quantum optics and quantum-information processing. Such a setting would not only constitute a near-ideal deterministic single-photon source, but also enable giant nonlinearities that are sensitive at the level of just a few photons. Quantum-dot sources have in recent years matured significantly and are now capable of producing highly indistinguishable and high-purity single photons. Combined with the ability to enhance light-matter interaction with photonic nanostructures this opens for a realm of novel opportunities for all-solid-state integrated quantum-information processing [1]. We review the recent experimental progress on research using quantum dots coupled to photonic-crystal waveguides.
Date: Tue, 28.10.2014
Time: 10:00
Duration: 60 min
Location:Atominstitut, Stadionallee 2, Wien 2, Seminarraum
Contact:Arno Rauschenbeutel

Atomic resolution in air with a home-built qPlus atomic force microscope
Speaker:Daniel Wastl (University of Regensburg, Institute of Experimental and Applied Physics, Regensburg/Germany)
Abstract:Since its invention in 1986 the atomic force microscope (AFM) has been shown to be a powerful tool in surface science and surface chemistry. Up to now the most impressive results are achieved with AFM’s running in UHV and at low temperature. I want to show the audience how one can achieve resolution comparable to UHV and low temperature systems in air or liquids. The qPlus sensor is based on quartz tuning forks with stiffnesses of 1000 to 5000 N/m. This high stiffness allows stable oscillations with oscillation amplitudes as low as 10 pm in any environment. In ambient conditions, the relation between the oscillation amplitude and the drive signal reflects the environmental damping. By determining the effective quality factor, we can quantify the noise as a function of amplitude and optimize the scan parameters to reach the highest signal-to-noise ratio. I will show applications of this m
Date: Tue, 28.10.2014
Time: 16:00
Location:Technische Universität Wien, Institut für Angewandte Physik, Seminarraum 134A, Turm B (gelbe Leitfarbe), 5. OB, 1040 Wien, Wiedner Hauptstraße 8-10
Contact:Univ.Prof. Dr. Ulrike Diebold

C-Parameter with Massive Quarks
Speaker:Moritz Preißer (Univ. Wien)
Abstract:In recent years event-shapes for electron-positron annihilation to hadrons, such as thrust or the C-parameter, have been studied using Soft-Collinear Effective Theory (SCET). Within this framework it is possible to derive factorization theorems which allow to systematically resum occuring large logarithms. Using these methods it is possible to extract precise values for the strong coupling constant from experimental data. Traditionally this was done treating the involved particles as massless. In this talk I will therefore discuss primary heavy quark mass-effects in C-parameter studies. First I will introduce the used observable and give a brief review of SCET. Afterwards details on a recent calculation of the massive differential cross-section in QCD and SCET are shown.
Date: Tue, 28.10.2014
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:A. Hoang, H. Neufeld

AdS/CFT and Brownian Motion in anisotropic plasma
Speaker:Shankhadeep Chakrabortty (IISER Pune)
Abstract:We employ methods of gauge/string duality to analyze the Brownian motion and the concomitant Langevin equation of a heavy quark in a strongly coupled, thermal, anisotropic Yang-Mills plasma. We consider fluctuations both along and perpendicular to the direction of anisotropy and study the effects of anisotropy on the drag coefficient, the diffusion constant and the Langevin coefficient for both the directions. We also verify the fluctuation-dissipation theorem for Brownian motion in an anisotropic medium.
Date: Thu, 30.10.2014
Time: 16:00
Duration: 60 min
Location:SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna)
Contact:Daniel Grumiller