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Calendar of Physics Talks Vienna
| Two-dimensional electronic spectroscopy: Coherence, entanglement and photosynthesis |
| Speaker: | Prof. Dr. Graham Fleming (Department of Chemistry, University of California, Berkeley) |
| Date: | Mon, 19.10.2009 |
| Time: | 17:30 |
| Duration: | 60 min |
| Location: | Lise-Meitner-Hörsaal, Strudlhofgasse 4, 1st floor, 1090 Wien |
| Contact: | Markus Arndt |
| Two-dimensional electronic spectroscopy: coherence, entanglement and photosynthesis |
| Speaker: | Graham R. Fleming (Department of Chemistry, University of California Berkeley and Physical Biosciences Division, Lawrence Berkeley National Laboratory) |
| Abstract: | Two-dimensional (2D) electronic spectra contain information about the combined spatial, energetic and temporal landscapes of condensed phase systems. Because they are recorded at the amplitude level, they are directly sensitive to the presence of quantum coherence. In addition, differing sequences of polarizations of the four fields involved can suppress or enhance specific features in the spectra. An example is given by a sequence which reveals only peaks that have arisen through coherence transfer as opposed to population transfer. In this talk these ideas will be applied to natural photosynthetic light harvesting systems. These pigment-protein complexes contain chlorophyll molecules at very high spatial density, leading to delocalized excited states. The experiments reveal long-lived quantum electronic coherence and substantial coherence transfer leading to speculations about the physiological consequences of quantum effects, and the potential applications in quantum theory. New theoretical methods are required to address these questions and a formally exact, reduced hierarchy approach will be used to describe the experiments and explore more subtle quantum mechanical questions such as the presence of entanglement in natural systems. |
| Date: | Mon, 19.10.2009 |
| Time: | 17:30 |
| Location: | Universität Wien, Lise Meitner Hörsaal, Strudlhofg. 4, 1090 Wien |
| Contact: | Prof. J. Schmiedmayer |
| Graphene: two-dimensional massless Dirac Fermions |
| Speaker: | Florian Libisch (TU Wien ) |
| Abstract: | Graphene, a honeycomb-lattice of carbon atoms, has attracted considerable attention since its first experimental realization in 2004. In particular, the linear dispersion relation near the Fermi energy connects the dynamics of electrons in graphene to the ultrarelativistic Dirac equation. We discuss the implications and limitations of this analogy: we compare predictions based on the Dirac picture (e.g. Klein tunneling or suppressed backscattering) to a tight-binding simulation of realistic graphene quantum dots. In particular we study the influence of confinement and lattice defects on the electronic structure of graphene-based nanodevices. We find that the Dirac properties of graphene are very sensitive to breaking of the sublattice symmetry, in particular at the edges of the sample. Experimental realizations of Dirac physics in graphene nanoelectronics will thus depends on a smooth edge confinement. Lunch Club Overview |
| Date: | Tue, 20.10.2009 |
| Time: | 12:30 |
| Duration: | 60 min |
| Location: | TU Vienna, Inst. f. Theoretical Physics, Freihaus, Wiedner Hauptstr. 8-10, 10. OG, SEM136 |
| Contact: | Max Attems, David Burke, Marcus Huber |
| Das klassische Klein-Gordon Feld auf gekrümmten Raumzeiten |
| Speaker: | Jakob Yngvason (Univ. Wien) (Fakultät für Physik) |
| Abstract: | im Rahmen des Seminars für Mathematische Physik |
| Date: | Tue, 20.10.2009 |
| Time: | 14:30 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | J. Yngvason |
| Theory of magnetostrictions in Invar materials |
| Speaker: | Dr. Sergii Khmelevskyi (Technische Universität Wien, Institut für Angewandte Physik) |
| Abstract: | The origin of the large value of the spontaneous volume magnetostriction in Invar materials is investigated using first-principle methods of electronic structure calculations. It is shown a common nature of the Invar effect in various sistems such as Fe-based alloys, including classical Invars Fe-Ni and Fe-Pt, and Rare-Earth intermetallics. The origin of existance of various competing theories of Invar effect is analized with particular emphasis on the Fe-Ni alloys and comparison of them to the Laves Phase (Zr,Nb)Fe2 Invar-type alloys. |
| Date: | Tue, 20.10.2009 |
| 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. Peter Mohn |
| Holomorphic properties of form factors |
| Speaker: | Jürg Gasser (Univ. Bern) (Fakultät für Physik) |
| Abstract: | 2. Vorlesung im Rahmen der Schrödinger-Gastprofessur 2009 |
| Date: | Tue, 20.10.2009 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien |
| Contact: | H. Neufeld |
| Vortrag im Rahmen der Chemisch-Physikalischen Gesellschaft: Mysterious Water |
| Speaker: | Thomas Loerting (Universität Innsbruck) |
| Abstract: | Water shows many anomalous properties, which
includes its rich polymorphism and its "amorphous
polymorphism". In this talk I will introduce the
sixteen crystalline and three amorphous phases of
ice. I will discuss how we prepare them in the
laboratory, what their molecular structure is, where
they can be found in nature and how one
amorphous and three crystalline phases were
discovered in Innsbruck in the last few years. I will
discuss our experiments on the highly disputed
question whether or not the amorphous phases are
glasses in the sense of vitrified liquids. If they are
indeed glasses, which our research suggests, the
consequence is that water can be separated into
three liquids in the deeply supercooled state (of
composition H2O and densities of 0.92, 1.15 and
1.26 g/cm3). In fact, we recently achieved to observe
coexistence of two glassy water phases differing by
25% in density, which suggests that indeed a first
order liquid-liquid phase transition may be at the
origin of the thermodynamic anomalies of water in
the supercooled region. |
| Date: | Tue, 20.10.2009 |
| Time: | 17:00 |
| Location: | Lise-Meitner-Hörsaal (ehem. Großer Hörsaal der
Experimentalphysik), Fakultät für Physik, Universität Wien, 1090 Wien,
Strudlhofgasse 4/Boltzmanngasse 5, 1. Stock |
| Contact: | Christl Langstadlinger |
| Plasma oscillations and the generation and detection of THz radiation |
| Speaker: | Prof. Dr. Hartmut Roskos, Johann Wolfgang Goethe-Universität Frankfurt (ADLIS Seminar) |
| Date: | Fri, 23.10.2009 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Seminarraum CBEG02, Institut f. Photonik, Gußhausstr. 27 |
| Contact: | Heike Höller, SFB ADLIS Sekretariat, Tel: 58801 13625 |
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