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Calendar of Physics Talks Vienna
| Speaker: | Patrice Bertet (Quantronics group, SPEC/CEA Saclay, Paris) |
| Abstract: | Bridging the gap between quantum-optical and solid-state implementations of quantum information is currently one of the major challenges in the field. Microscopic quantum systems have long coherence times, whereas artificial superconducting atoms can be manipulated and entangled very rapidly and with high fidelity; it is therefore appealing to combine them to form “hybrid” quantum circuits. In a first set of experiments towards this goal, we have demonstrated the strong coupling between an ensemble of electronic spins and a frequency tunable superconducting resonator [1]. The spins are Nitrogen-Vacancy centers in a diamond crystal. I will also present recent experiments demonstrating the storage and retrieval of a small microwave field in the spin ensemble, as well as our current efforts to couple the spins to a superconducting qubit.
[1] Y. Kubo et al., Phys. Rev. Lett. 105, 140502 (2010)
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| Date: | Mon, 23.05.2011 |
| Time: | 15:30 |
| Duration: | 60 min |
| Location: | Universität Wien, Lise Meitner Hörsaal, Strudlhofgasse 4, 1st floor, 1090 Wien |
| Contact: | Dr. Christiane Losert / University of Vienna |
| SU(3) x SU(2) x U(1) Vacua in F-theory |
| Speaker: | Kang Sin Choi (Korean Institute for Advanced Study) |
| Abstract: | The Standard Model group and matter spectrum is obtained in vacua of F-theory, without resorting to an intermediate unification group. The group SU(3) x SU(2) x U(1)_Y is the commutant to SU(5)_t \times
U(1)_Y structure group in E_8 and is geometrically realized as a deformation of I_5 singularity. Lying along the unification groups of E_n, our vacua naturally inherit their unification structure. We can
distinguish Higgses from lepton doublets by matter parity U(1)_B-L. Turning on universal G-flux preserving SO(10) relation, the spectrum contains three generations of quarks and leptons, as well as vectorlike pairs of electroweak and colored Higgses. Minimal Yukawa couplings is obtained at the renormalizable level.
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| Date: | Mon, 23.05.2011 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | SEM 136 (Freihaus, Wiedner Hauptstrasse 8-10), Institute for Theoretical Physics, Vienna University of Technology |
| Contact: | Ching-Ming Chen and Daniel Grumiller |
| Listening to the universe with Einstein's gravitational waves |
| Speaker: | Karsten DANZMANN (Max Planck Institute for Gravitational Physics (Albert Einstein Institut) and Leibniz Universität Hannover) |
| Abstract: | More than 90 years ago, Einstein predicted the existence of Gravitational Waves as a consequence of his theory of General Relativity. They are minute distortions of space and time, created by rapidly accelerating large masses, and propagating at the the speed of light. So far, they have never been directly detected. Several kilometer-size laser-interferometric gravitationl wave detectors are currently operating on the earth, and one of them is GEO600 near Hannover. They will soon be joined by space detectors with armlengths of millions of kilometers, in particular the ESA/NASA space mission LISA. These mysterious waves are emitted by coalescing binary stars, neutron stars, supernovae, Black Holes and the Big Bang itself, and their observation requires modern laser technology and measurements at the quantum mechanical detection limit. |
| Date: | Mon, 23.05.2011 |
| Time: | 17:00 |
| Location: | Universität Wien, Lise Meitner Hörsaal, Strudlhofg. 4, 1090 Wien |
| Contact: | H.-J. Schmiedmayer |
| Ground states for a Semi-Relativistic Model in QED |
| Speaker: | Martin Könenberg (Univ. Wien) |
| Abstract: | im Rahmen des Seminars für Mathematische Physik |
| Date: | Tue, 24.05.2011 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | J. Yngvason |
| Axions - Theoretical motivation, cosmological role and experimental searches |
| Speaker: | Georg Raffelt (MPI, München) |
| Abstract: | 4. Vorlesung im Rahmen der Schrödinger-Gastprofessur 2011 |
| Date: | Tue, 24.05.2011 |
| Time: | 16:15 |
| Duration: | 90 min |
| Location: | Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien |
| Contact: | W. Grimus, H. Neufeld |
| Experimentally-friendly detection of entanglement |
| Speaker: | Tomasz Paterek (CQT Singapore) |
| Abstract: | im Rahmen des FWF Projekts P21947N16 |
| Date: | Wed, 25.05.2011 |
| Time: | 13:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Teilchenphysik, Kleiner Seminarraum, Boltzmanngasse 5, 5. Stock |
| Contact: | B.C. Hiesmayr |
| Weak antilocalization in HgTe quantum wells and topological surface states |
| Speaker: | Grigory Tkachov (Universität Würzburg) |
| Abstract: | HgTe quantum wells and surfaces of three-dimensional topological insulators support Dirac fermions with a single-valley band dispersion. In the presence of disorder they experience weak antilocalization, which has been observed in recent transport experiments. In this work we conduct a comparative study of the weak antilocalization in HgTe quantum wells and topological surface states. The difference between these two single-valley systems comes from a finite band gap (effective Dirac mass) in HgTe quantum wells in contrast to gapless (massless) surface states in topological insulators. The finite effective Dirac mass implies a broken internal symmetry, leading to suppression of the weak antilocalization in HgTe quantum wells at times larger than certain t_M, inversely proportional to the Dirac mass. This corresponds to the opening of a relaxation gap 1/t_M in the Cooperon diffusion mode which we obtain from the Bethe-Salpeter equation including relevant spin degrees of freedom. We demonstrate that the relaxation gap exhibits an interesting nonmonotonic dependence on both carrier density and band gap, vanishing at a certain combination of these parameters. The weak-antilocalization conductivity reflects this nonmonotonic behavior which is unique to HgTe QWs and absent for topological surface states. On the other hand, the topological surface states exhibit specific weak-antilocalization magnetoconductivity in a parallel magnetic field due to their exponential decay in the bulk. |
| Date: | Wed, 25.05.2011 |
| Time: | 16:00 |
| Location: | TU Wien, Freihaus Seminarraum 138B, Turm C, 7. OG (rote Leitfarbe) |
| Contact: | Andrei Pimenov |
| Predicting signal and background for ttH production at the LHC |
| Speaker: | Stefan Dittmaier (Univ. Freiburg) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Thu, 26.05.2011 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien |
| Contact: | G. Ecker, H. Neufeld |
| Black holes in higher dimensions: exact solutions and classification theorems |
| Speaker: | Stoytcho Yazadjiev (Sofia) |
| Abstract: | im Rahmen des Literaturseminars |
| Date: | Thu, 26.05.2011 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe: Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock |
| Contact: | R. Beig |
| Topics on 3d gravity and AdS/CFT |
| Speaker: | Alan Garbarz (Physics Department, University of Buenos Aires) |
| Abstract: | In this talk we will discuss some aspects of three dimensional gravity and the recent attempts to construct its quantum version in a consistent manner via AdS/CFT correspondence. We will start reviewing seminal results in the field, such as Brown-Henneauxs work on asymptotic symmetries, which will play a main role in the discussion. The main idea of Wittens work of 2007 will also be commented due to its
importance in triggering the recent study of others (than GR) gravitational theories in three dimensions. Among these theories, we will discuss the so-called Chiral Gravity, its cousin dubbed Log Gravity, and the more recent New Massive Gravity. These theories are intended to give alternatives for a possible quantum theory of gravity in three dimensions, with notable differences in comparison with GR, such as novel black holes solutions and deformed AdS asymptotics. In addition, possible physically sensible contributions to the partition function will be mentioned, like particle-like singularities and
space-times with torsion.
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| Date: | Thu, 26.05.2011 |
| 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 |
| Ultracold quantum gases: Exploring strongly interacting matter at pico-eV |
| Speaker: | Rudolf Grimm (Institut für Experimentalphysik und Institut für Quantenoptik und Quanteninformation, Universität Innsbruck) |
| Abstract: | Atomic ensembles, cooled down to temperatures in the nanokelvin range and trapped in op-tical potentials, represent ideal model systems to study a great variety of quantum phenomena. After a short introduction into the general ideas and methods of the field, I will present a few examples how [..] |
| Date: | Thu, 26.05.2011 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | SMI, Seminar room, Boltzmanngasse 3, 1090 Wien, Room 2.08 |
| Contact: | Roland Gsell |
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