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Calendar of Physics Talks Vienna
| From Matrices to Quantum Geometry |
| Speaker: | Harold Steinacker (Uni Wien) |
| Abstract: | Based on simple examples of quantized spaces described in terms of matrices, we explore the idea that physical space-time might be described in terms of similar quantum spaces and quantum geometry. The emphasis of this talk is to explain how geometry can arise from matrices, based on the analogy with quantum mechanics. |
| Date: | Tue, 25.06.2013 |
| Time: | 12:30 |
| Duration: | 60 min |
| Location: | Univ. of Vienna, Faculty of Physics, Boltzmanngasse 5, 5th floor, Erwin Schrödinger Lecture Hall |
| Contact: | Philipp Köhler, Albert Georg Passegger - www.univie.ac.at/lunch-seminar |
| Ab initio studies of Graphene-Metal Interfaces |
| Speaker: | Dipl.-Ing. Andreas Garhofer (TU Wien, IAP, CMS) |
| Abstract: |
Graphene (Gr) is a 2D allotrope of carbon with unique electronic and mechanical properties. The isolation of graphene in 2004 has led to a remarkable surge of interest in the scientific community. High quality graphene sheets can be produced via epitaxial growth on metal substrates. The Gr-metal interaction has either been classified as “weak” interaction, e.g. on Au, Ag, Cu, and Pt with merely shifted Gr pibands, or as “strong”, e.g. on Ni, Ti, and Co, with strongly perturbed graphene bands. However, the interaction of graphene with a metallic surface is still not well understood on a fundamental level. In this talk, I will present density function (DFT) theory calculations of different Grmetal interfaces. Gr/Ni(111) usually grows in 1x1 structures, because of a negligible lattice mismatch. |
| Date: | Tue, 25.06.2013 |
| 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. Josef Redinger |
| Speaker: | Werner Zeilinger (Vienna) |
| Abstract: | im Rahmen des Literaturseminars |
| Date: | Thu, 27.06.2013 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe: Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock |
| Contact: | P. Chrusciel |
| Hadronic Top Pair Production close to Threshold |
| Speaker: | Johann Kühn (Univ. Karlsruhe) |
| Abstract: | um Rahmen des Teilchenphysikseminars |
| Date: | Thu, 27.06.2013 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, H. Neufeld |
| Quantum Stochastic Processes |
| Speaker: | Lukas Hingerl (Univ.Wien) |
| Abstract: | im Rahmen der gemeinsam veranstalteten Seminare "Komplexe Stochastische
Systeme" (Univ.Wien) und "Analyse Komplexer Systeme" (Medizinische Univ.
Wien) |
| Date: | Fri, 28.06.2013 |
| Time: | 14:15 |
| Duration: | 45 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | H. Hüffel, Stefan Thurner |
| Advanced Infrared and THz beamLine Exploited for Spectrocopy (AILES) and its research program |
| Speaker: | Pascale Roy (Synchrotron SOLEIL, THz and IR beamline AILES, France) |
| Abstract: | At the AILES beamline of SOLEIL synchrotron (France), the combined intensity, stability and wide range (0.2-20 THz) has led to an optimal use of spectroscopy in the Infrared and THz range, hitherto unusable for a wide range of demanding experiments. In particular, condensed matter research under extreme conditions (temperature, pressure, …) and high resolution molecular studies. The coherent synchrotron emission allows an extension to the THz domain for experiments demanding an intense beam such as near field subwavelength microspectroscopy. We will describe the main characteristics of the beamline and will illustrate its performances with applications. |
| Date: | Fri, 28.06.2013 |
| Time: | 14:30 |
| Duration: | 45 min |
| Location: | Seminar Room CBEG02 (387, Photonics); Gußhausstraße 27 |
| Contact: | Andrei Pimenov |
| Measuring technological complexity of music styles |
| Speaker: | Gamaliel Esau Percino-Figueroa (Med.Univ.Wien) |
| Abstract: | im Rahmen der gemeinsam veranstalteten Seminare "Komplexe Stochastische
Systeme" (Univ.Wien) und "Analyse Komplexer Systeme" (Medizinische Univ.
Wien) |
| Date: | Fri, 28.06.2013 |
| Time: | 15:00 |
| Duration: | 45 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | H. Hüffel, Stefan Thurner |
| Coherent forward multiple scattering of waves in the Anderson localization regime |
| Speaker: | Christian MINIATURA (Institut Non Linéaire de Nice, UNS, CNRS) |
| Abstract: | The concepts of random walks and Brownian motion were developed at the beginning of the 20th century after groundbreaking founding works on the kinetic theory of gases. They could successfully explain numerous statistical phenomena ranging from the transport of classical particles (Boltzmann's kinetic equation, Drude's electronic transport) in physics to the migration of mosquitoes in a forest in biology.
The propagation of waves in complex media did not escape this description, as exemplified by Lord Rayleigh's pioneering works in acoustics (Rayleigh's law) or those of Chandrasekhar and Milne in astrophysics (radiative transfer theory). Within this framework, a wave packet propagating in a disordered medium is multiply scattered in all directions by the heterogeneities of the medium. The scattered partial waves acquire random phases and, on average, the interference between these partial waves are smoothed out although the initial wave packet can be perfectly coherent. In turn, the memory of the initial propagation direction is rapidly lost and the wave packet spreads diffusively in space, just like the swarm of mosquitoes in a forest.
This powerful and fruitful description of propagation in a random medium was nevertheless questioned in the late 50s when Anderson showed that disorder could bring wave transport to a halt, an interference phenomenon known as strong localization. In fact, we now know that phase coherence is not completely scrambled even far from the localization regime as exemplified by weak localization corrections to the diffusion constant, universal conductance fluctuations and by the celebrated coherent backscattering (CBS) phenomenon. The latter manifests itself as an interference peak in the momentum distribution of the wave packet centered in the direction opposite to the initial propagation direction. Even if the CBS effect has been thoroughly studied, both experimentally and theoretically, its fate in the strong localization regime was largely unknown.
This is what we have studied in a recent paper [PRL 109, 190601, (2012), arXiv :1204.3451]. We have performed a numerical study of the time evolution of the momentum distribution of a quasi-monochromatic matter wave packet evolving in a speckle potential. Much to our surprise, we have found that a new multiple scattering interference effect is triggered by strong localization in the forward direction. It manifests itself as a coherent forward peak (CFS) which starts to grow when strong localization sets in and it raises on the time scale of the Heisenberg time of the system. In the end, both CBS and CFS appear as twin peaks. I will present and explain these results in as much simple terms as possible.
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| Date: | Fri, 28.06.2013 |
| Time: | 15:30 |
| Location: | TU Wien Atominstitut, Hörsaal, Stadionallee 2, 1020 Wien |
| Contact: | J. Schmiedmayer |
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