|
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 |
| Contact: | ESI |
| 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 |
| 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 |
| Contact: | ESI |
| 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 |
|