Calendar of Physics Talks Vienna

Generation of squeezed light and its use in quantum communication
Speaker:Christoph Marquardt (Max Planck Institute for the Science of Light Universität Erlangen)
Abstract:In this talk I will present sources of squeezed light that can be used in quantum communication systems. Whispering gallery mode resonators (WGMR) have proven to be useful in nonlinear optics. The large second order nonlinearity provided in a crystalline whispering gallery mode resonator made from lithium niobate is used to achieve optical paramatric oscillations. The high Q‐factor of the WGMR results in an extremely low pump power threshold. We observed two‐mode squeezing and single mode squeezing in the parametric beams generated in a WGMR for the first time. Another nonlinear medium for the effective generation of squeezed states are optical fibres. I will present the generation of squeezed azimuthally polarized modes in a specially tailored photonic crystal fibre. Due to the complex vectorial structure of these modes one can generate continuous variable entanglement between different degrees of freedom (namely polarization and spatial modes). Finally I will present the first realistic optical free space link for the distribution of continuous variable quantum states. This link in a metropolitan environment will be used for the investigation of CV quantum communication protocols including squeezed and entangled states.
Date: Mon, 09.05.2011
Time: 17:30
Duration: 60 min
Location:Atominstitut, großer Hörsaal, Stadionallee 2, 1020 Wien
Contact:Dr. Christiane Losert

Symmetries of Strings and Branes (part 4)
Speaker:Peter West (King’s College)
Abstract:I will begin by explaining electro-magnetic duality symmetries in the context of supersymmetric Yang-Mills theories. I will then discuss S, T and U dualities of string theory and their implications for branes. The conjectured E11 symmetry will also be considered.
Date: Tue, 10.05.2011
Time: 10:00
Duration: 120 min
Location:TU Wien (Wiedner Hauptstr. 8-10), yellow area, 10th floor, seminar room E136
Contact:Sabine Ertl

Stability of solutions of the Camassa-Holm equation
Speaker:Katrin Grunert (University of Vienna)
Date: Tue, 10.05.2011
Time: 11:00
Location:Erwin Schrödinger International Institute, Boltzmanngasse 9, 1090 Wien, Schrödinger lecture hall

Quantum kinetics of non-perturbative electron-positron production - The influence of temporal and spatial inhomogeneities
Speaker:Florian Hebenstreit (Uni Graz)
Abstract:Non-perturbative electron-positron pair creation in electric fields (Schwinger effect) has been a long-standing but still unobserved prediction of QED. Due to the advent of a new generation of high-intensity laser systems such as the European XFEL or the Extreme Light Infrastructure (ELI) it might, however, become possible to observe this effect within the next decades. Previous investigations led to a good understanding of the general mechanisms behind the pair creation process, however, realistic electric fields as they might be present in upcoming experiments have not been fully considered yet. In this talk I focus on various aspects of the Schwinger effect in the presence of inhomogeneous electric fields: First, I consider the pair creation process in the presence of a spatially homogeneous, time-dependent electric field. Most notably, the momentum distribution of created particles in the presence of a pulsed electric field with sub-cycle structure, which serves as a simple model of the time-dependence of a realistic laser pulse, is presented. Moreover, I introduce a formalism by means of which the Schwinger effect in the presence of space- and time-dependent electric fields can be treated properly. Finally, I present the time evolution of various observable quantities (charge distribution, momentum spectrum, number of created particles) in the presence of a simple space- and time-dependent electric field which have been calculated for the first time.
Date: Tue, 10.05.2011
Time: 12:30
Duration: 60 min
Location:Uni Wien ( Boltzmanngasse 5, 5th floor, Schrödinger HS / large seminar room )
Contact:Sabine Ertl

The art and science of atomic force microscopy
Speaker:Prof. Dr. Franz J. Giessibl (Institute of Experimental and Applied Physics, University of Regensburg/Germany)
Abstract:For a long time, it was generally accepted that the spatial resolution of atomic force microscopy [1] is inferior to the resolution of scanning tunnelling microscopy. However, this paradigm has been challenged by experimental evidence showing that AFM can obtain subatomic spatial resolution [2] and a direct comparison of constant-height data of forces and tunnelling currents clearly showed that AFM can obtain higher spatial resolution than STM [3]. Recently, pentacene - an organic molecule consisting of five carbon hexagons - has been imaged with unprecedented resolution by AFM [4]. These breakthroughs in spatial resolution became possible by a detailed analysis of the physics underlying force microscopy and the transfer of the theoretical findings into an experimental device – the qPlus sensor - a force sensor based on a quartz tuning fork [5]. This sensor not only allows high-resolution force microscopy, it also enables combined STM and AFM measurements. These combined measurements show that on weakly conducting samples, a partial breakdown of the tunnelling barrier can occur – indicated by a reduced attractive electrostatic force component [6]. [1] S. Morita, R. Wiesendanger, E. Meyer (eds.) Noncontact Atomic Force Microscopy, Springer, Berlin (2002); S. Morita, F.J. Giessibl, R. Wiesendanger (eds.) NCAFM II, Springer, Berlin (2009). [2] F.J. Giessibl, S. Hembacher, H. Bielefeldt, J. Mannhart, Science 289, 422 (2000). [3] S. Hembacher, F.J. Giessibl, .J. Mannhart, Science 305, 1066 (2004). [4] L. Gross, F. Mohn, N. Moll, P. Liljeroth, G. Meyer, Science 325, 1110 (2009). [5] F.J. Giessibl, Appl. Phys. Lett. 73, 3956 (1998). [6] A. J. Weymouth, T. Wutscher, J. Welker, T. Hofmann, F.J. Giessibl, arxiv 1103.2226 (2011)
Date: Tue, 10.05.2011
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. Friedrich Aumayr, Univ.Prof. Dr. Ulrike Diebold

Supernova neutrinos
Speaker:Georg Raffelt (MPI, München)
Abstract:2. Vorlesung im Rahmen der Schrödinger-Gastprofessur 2011
Date: Tue, 10.05.2011
Time: 16:15
Duration: 90 min
Location:Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien
Contact:W. Grimus, H. Neufeld

Festveranstaltung zu Ehren von emer.O.Univ.Prof. Dr. Walter Thirring und emer.O.Univ.Prof. Dr. Karl Lintner
Speaker:emer.O.Univ.Prof. Dr. Walter Thirring, Univ.Prof. Dr. Brigitte Weiss (Laudatio für Prof Lintner), Ao.Univ.Prof. Dr. Gerhard Ecker (Laudatio für Prof Thirring) (Fakultät für Physik der Universität Wien und Chemisch-Physikalische Gesellschaft)
Abstract:Die Fakultät für Physik der Universität Wien und die Chemisch-Physikalische Gesellschaft laden zu einer Festveranstaltung anlässlich der Geburtstagsfeiern von emer.O.Univ.Prof. Dr. Walter Thirring und emer.O.Univ.Prof. Dr. Karl Lintner. Die Begrüßung und einleitende Worte erfolgen durch den Dekan der Fakultät für Physik, Univ.Prof. Dr. Christoph Dellago, und den Präsidenten der Chemisch-Physikalischen Gesellschaft, Ao.Univ.Prof. Dr. Peter Mohn. Die Laudatio für Prof. Karl Lintner hält Univ.Prof. Dr. Brigitte Weiss, Physik Nanostrukturierter Materialien. Die Laudatio für Prof. Walter Thirring hält Ao.Univ.Prof. Dr. Gerhard Ecker, Teilchenphysik. Den Abschluss der Festveranstaltung bildet ein Vortrag von Prof. Walter Thirring über "Die Physik über den Eisernen Vorhang hinweg - 1954 bis 1989".
Date: Tue, 10.05.2011
Time: 17:00
Location:Christian-Doppler-Hörsaal, Universität Wien, Fakultät für Physik, 1090 Wien, Boltzmanngasse 5/Strudlhofgasse 4, 3. Stock
Contact:Christl Langstadlinger

Speaker:Harvey Segur (University of Colorado, Boulder)
Date: Thu, 12.05.2011
Time: 11:00
Location:Erwin Schrödinger International Institute, Boltzmanngasse 9, 1090 Wien, Schrödinger lecture hall

The role of transverse gauge links in soft-collinear effective field theory
Speaker:Ignazio Scimemi (Universidad Complutense de Madrid)
Date: Thu, 12.05.2011
Time: 14:15
Location:Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:André Hoang

On the weight of the heaviest known elementary particle
Speaker:Andre Hoang (Teilchenphysik Universität Wien)
Abstract:The mass and the other properties of the top quark are important since they might tell us about the currently unknown mechanism of spontaneous symmetry breaking. In particular, precise measurements of the top quark mass are a crucial ingredient for indirect searches for the mechanism of [...]
Date: Thu, 12.05.2011
Time: 16:00
Duration: 60 min
Location:SMI, Seminar room, Boltzmanngasse 3, 1090 Wien, Room 2.08
Contact:Roland Gsell

Physik und Technologie von Graphen
Speaker:Hans Kuzmany (Univ.Wien)
Abstract:im Rahmen der gemeinsam veranstalteten Seminare "Komplexe Stochastische Systeme" (Univ.Wien) und "Analyse Komplexer Systeme" (Med.Univ.Wien)
Date: Fri, 13.05.2011
Time: 14:00
Duration: 90 min
Location:Medizinische Univ., Bauteil 88, Informatikbibliothek, Ebene 3 (Zugang über Spitalgasse 23)
Contact:H. Hüffel, Stefan Thurner

Non-Equilibrium Quantum Dynamics in Optical Lattices and Thermalization: Landau-Zener Sweeps and Quantum Quenches
Speaker:Stefan TROTZKY (LMU München)
Date: Fri, 13.05.2011
Time: 15:30
Location:TU Wien Atominstitut, Hörsaal, Stadionallee 2, 1020 Wien
Contact:A. Rauschenbeutel