Calendar of Physics Talks Vienna

Euklidische Quantenfeldtheorie / Teil 2
Speaker:Jakob Yngvason (Univ.Wien)
Abstract:im Rahmen des Seminars für Mathematische Physik
Date: Tue, 12.03.2013
Time: 14:15
Duration: 60 min
Location:Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:J. Yngvason

Secondary electron emission studied by secondary electron electron energy loss coincidence spectrometer (SE2ELCS)
Speaker:Rahila Khalid (Technische Universität Wien, Institut für Angewandte Physik)
Abstract:To investigate the mechanisms responsible for the emission of secondary electrons, a reflection (e,2e) coincidence spectrometer named Secondary Electron Electron Energy Loss Coincidence Spectrometer (SE2ELCS) has been developed which allows one to uncover the relation between the features in the spectra which are due to energy losses and true secondary electron emission structures. Correlated electron pairs are measured with a hemispherical mirror analyzer (HMA) and a time of flight analyzer (TOF) by employing a continuous electron beam. An effort has been made to increase the coincidence count rate by increasing the effective solid angle of the TOF analyzer and optimizing the experimental parameters to get optimum energy resolution. Double differential coincidence spectra for free electron metals (Al, Si), noble metals (Ag, Au) and highly oriented pyrolytic graphite (HOPG) have been mea
Date: Tue, 12.03.2013
Time: 16:00
Location:Technische Universität Wien, Institut für Angewandte Physik, Seminarraum 134A, Turm B (gelbe Leitfarbe), 5. OG, 1040 Wien, Wiedner Hauptstraße 8-10
Contact:Ao.Univ.Prof. Dr. Wollfgang Werner

Flat Space Holography as a limit of AdS/CFT
Speaker:Reza Fareghbal (IPM Teheran)
Abstract:The asymptotic group of symmetries at null infinity of flat spacetimes in three and four dimensions is the infinite dimensional Bondi-Metzner-Sachs (BMS) group. This group is isomorphic to a non-relativistic limit of conformal group. We will argue that this non-relativistic limit of CFT is equivalent to the flat space limit of AdS space-times. Using this correspondence we propose a method for the study of flat-space holography as a limit of AdS/CFT.
Date: Wed, 13.03.2013
Time: 15:00
Duration: 60 min
Location:SEM 136 (Freihaus, Wiedner Hauptstrasse 8-10), Institute for Theoretical Physics, Vienna University of Technology
Contact:Daniel Grumiller

Magneto-optics of graphene-based materials
Speaker:A.B. Kuzmenko (University of Geneva)
Abstract:Graphene attracts much attention as a novel optical and plasmonic material. Its electromagnetic response is exceptionally sensitive to a magnetic field due to the small cyclotron mass of the Dirac-like charge carriers. This does not only make infrared magneto-optics (infrared Hall effect) a valuable characterization tool, but also gives rise to giant magneto-optical effects, potentially interesting for terahertz applications. I’ll overview our magneto-transmission and Faraday rotation studies of large-scale single- and multilayer graphene grown epitaxially on the Si- and C-faces of silicon carbide respectively [1,2,3]. I’ll consider peculiarities of the cyclotron resonance in quasiclassical and quantum regimes and touch upon the important effect of nanoscale inhomogeneites, such as terrace steps and thermal wrinkles.
Date: Wed, 13.03.2013
Time: 16:00
Duration: 45 min
Location:TU Wien, Freihaus Seminarraum 138B, Turm C, 7. OG (rote Leitfarbe)
Contact:Andrei Pimenov

Logarithmic Conformal Field Theory
Speaker:Thomas Creutzig (TU Darmstadt)
Abstract:Logarithmic two-dimensional CFT appears in both condensed matter physics and the AdS/CFT correspondence. Together with David Ridout, a method to study such theories has been developed. I will illustrate our ideas in the well-known and non-logarithmic example of the free boson before turning to the logarithmic singlet theory at central charge minus two.
Date: Thu, 14.03.2013
Time: 16:00
Duration: 60 min
Location:SEM 136 (Freihaus, Wiedner Hauptstrasse 8-10), Institute for Theoretical Physics, Vienna University of Technology
Contact:Daniel Grumiller

Advanced methods of optical manipulations with microparticles and nanoparticles
Speaker:Pavel ZEMÁNEK (Institute of Scientific Instruments of the ASCR, Brno)
Abstract:Optical micro-manipulation techniques have been using for more than 30 years to transfer the momentum from light to microparticles or nanoparticles and influence their movement in liquid, on surface, or in air. These days such techniques become more developed and frequently used in physics, chemistry and biology to manipulate, trap, rotate, or sort various types of microparticles and nanoparticles, including living cells in a contactless and gentle way [1]. I will briefly introduce the principle and “classical” methods of optical micromanipulations, such as optical tweezers, holographic optical tweezers, and their combinations with selected diagnostics methods (i.e. Raman tweezers [2]). I will mainly focus on physical background and experimental demonstration of novel micromanipulation methods that cover synchronous delivery of thousands of confined microobjects (e.g. optical conveyor belts) [3], utilization of non-Gauassian beams and passive optical sorting [4]. Increasing number of particles confined in the beam leads to their interaction via scattered light (so called optical binding) and their spatial self-organization into optically bound matter. The principle and utilization of the optical “tractor” beam [6] will be presented as an example that combines all the phenomena mentioned above. [1] Jonas, A., Zemanek, P., (2008) Electrophoresis 29, 4813-4851. [2] Petrov, D.V. J. Opt. A (2007) Pure Appl. Opt. 9, S139–S156. [3] Cizmar, T. et al. (2006) Appl. Phys. B 84, 197. [4] Dholakia, K. et al. (2007) Methods in Cell Biology 82, 467-495. [5] Dholakia, K., Zemanek, P., (2010) Rev. Mod. Phys. 82, 1767-1791. [6] Brzobohaty, O. et al. (2013) Nature Photonics 7, 123-127.
Date: Fri, 15.03.2013
Time: 15:30
Location:TU Wien Atominstitut, Hörsaal, Stadionallee 2, 1020 Wien
Contact:Arno Rauschenbeutel