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Calendar of Physics Talks Vienna
| Melting Transitions of Hard Disks |
| Speaker: | Prof. Dr. Werner Krauth (Laboratoire de Physique Statistique, École normale supérieure in Paris Cedex, France) |
| Abstract: | The hard‐disk model has exerted outstanding influence on computational physics and statistical mechanics. Decades ago, hard disks were the first system to be studied by Markov-chain Monte Carlo methods and by molecular dynamics. It was in hard disks, through numerical simulations, that a two-dimensional melting transition was first seen to occur even though such systems cannot develop long‐range crystalline order. Analysis of the system was made difficult by the absence of powerful simulation methods.
In recent years, we have developed a number of powerful Monte Carlo algorithms for hard disks and related systems. I will in particular show how the powerful event-chain Monte Carlo algorithm which has allowed us to prove that hard disks melt with a first-order transition from the liquid to the hexatic and a continuous transition from the hexatic to the solid. |
| Date: | Mon, 23.01.2012 |
| Time: | 16:00 |
| Location: | SemR 138C, TU Wien, |
| Contact: | SC-CMS / CMS / ViCoM |
| Schrödinger's chip: Designs for solid state quantum processors using electron spins |
| Speaker: | Charles Marcus (Department of Physics, Harvard University) |
| Abstract: | Schrödinger’s cat, half-alive, half-dead, existing in its sealed box in this dual state, illustrates the counterintuitive role of measurement in quantum mechanics, but also how the preservation of quantum properties, which dominate at atomic scales (even at room temperature), become less familiar and even absurd for large multi-particle objects. Building computer chips that can take advantage of quantum coherence and entanglement to allow improvements in computation and simulation is much like the challenge of trying to build Schrödinger's cat, using components that operate near absolute zero. This talk will review progress toward this endeavor, and the interesting new physics that arises in fighting decoherence in solid-state systems. |
| Date: | Mon, 23.01.2012 |
| Time: | 17:30 |
| Location: | TU Wien Freihaus, Hörsaal 5 (2. Stock, grüner Bereich), Wiedner Hauptstr. 8, 1040 Wien |
| Contact: | Prof. J. Schmiedmayer |
| Neutron Stars as Laboratory for Dense Matter |
| Speaker: | Laura Tolos (Universidad Autonoma de Barcelona) |
| Abstract: | Neutron stars are an excellent laboratory for testing matter under extreme conditions. In particular, a lot of emphasis has been invested in understanding the interior of neutron stars and the equation of state of the different possible phases since its direct consequences for the mass-radius relationship of neutron stars as well as cooling processes. I will review some results for nucleonic, kaonic and hyperonic matter together with superfluidity and their consequences for cooling processes. I will comment on possible constraints not only from neutron stars observations but also from back-to-Earth experiments, such as heavy-ion collisions. I will finally outline future prospects to be tested in neutron stars laboratory. |
| Date: | Tue, 24.01.2012 |
| Time: | 12:30 |
| Duration: | 60 min |
| Location: | TU Wien (Wiedner Hauptstrasse 8-10/136, 1040 Wien, yellow area, 10th floor, seminar room 136) |
| Contact: | Sabine Ertl |
| A UNIFIED VIEW OF THE DISCRIMINATION PROBLEM OF QUANTUM STATES |
| Speaker: | Janos Bergou (Hunter College of the City University of New York, Department of Physics and Astronomy, USA) |
| Abstract: | State discrimination is a fundamental measurement primitive in quantum information processing. It is the key element in quantum key distribution, security analyses and probabilistic quantum algorithms. State discrimination deals with the following problem [1]: One is given a quantum system that was prepared in one of N known quantum states, but we don't know which. The task is to identify the state of the system as well as allowed by the laws of quantum mechanics. If the possible states are not mutually orthogonal the problem is highly nontrivial and optimization with respect to some reasonable criteria leads to complex measurement strategies often involving generalized measurements. Finding the optimum measurement strategy is the subject of state discrimination. |
| Date: | Tue, 24.01.2012 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | IQOQI Vienna, Seminar Room, 2nd Floor, Boltzmanngasse 3, 1090 Vienna |
| Contact: | Anton Zeilinger |
| Bose-Einstein Kondensation in niedrigen Dimensionen |
| Speaker: | Veronika Baumann (Univ.Wien) |
| Abstract: | im Rahmen des Seminars für Mathematische Physik |
| Date: | Tue, 24.01.2012 |
| Time: | 15:30 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien |
| Contact: | J. Yngvason |
| Improvements in understanding the energy transport in multi-layer insulations |
| Speaker: | Dr. Gerald Richter (Technische Universität Wien, Institut für Angewandte Physik) |
| Abstract: | As part of the research project "Ultimal" efforts were made to better understand some details in the functioning of Multi-layer insulations (MLIs) as they are long used in space and terrestrial cryogenic applications. It was the goal of this study to pave the way for a replacement of the "empirical black-box approach" that is mostly used in designing MLIs up until now, while attempting to shed some light on discovered unexpected behavior of these materials which can not be explained in a straightforward manner.
This talk will give a summary on the closed study, the experimental efforts that were made and some conclusions that can be drawn from it.
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| Date: | Tue, 24.01.2012 |
| 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. Wolfgang Werner |
| Quantum Matter with Strong Correlations - From Hot Superconductors to Cold Atoms |
| Speaker: | Prof. Dr. Antoine Georges (Centre de Physique Théorique, Collége de France and École Polytechnique in Palaiseau Cedex, France) |
| Abstract: | From copper-oxide superconductors to rare‐earth compounds, materials with strong electronic correlations have focused enormous attention over the last two decades. Solid‐state chemistry, new elaboration techniques and improved experimental probes are constantly providing us with examples of novel materials with surprising electronic properties, the latest example being the recent discovery of iron-based high-temperature superconductors.
In this colloquium, I will emphasize that the classic paradigm of solid-state physics, in which electrons form a gas of wave-like quasiparticles, must be seriously revised for strongly correlated materials. Instead, a description accounting for both atomic-like excitations in real‐space and quasiparticle excitations in momentum space is requested. I will review how Dynamical Mean-Field Theory - an approach that has led to significant advances in our understanding of strongly correlated materials - fulfills this goal.
New frontiers are also opening up, which bring together condensed-matter physics and quantum optics. `Artificial materials' made of ultra-cold atoms trapped by laser beams can be engineered with a remarkable level of controllability, and allow for the study of strong-correlation physics in previously unexplored regimes. |
| Date: | Tue, 24.01.2012 |
| Time: | 17:15 |
| Location: | Lecture Hall P2, Graz University of Technology (TU Graz), Petersgasse 16, A-8010 Graz, AUSTRIA |
| Contact: | SC-CMS / CMS / ViCoM |
| Quarkonium Phenomenology in Vacuum |
| Speaker: | Denis Parganlija (Vienna University of Technology) |
| Abstract: | The scalar mesons have been one of the most debated issues of
low-energy QCD for decades. The experimental data show the existence of
six scalar isosinglet states - next to the famous sigma meson, there are
five states with the same quantum numbers but higher energies than the
energy of the sigma. If we consider the u and d quarks as degenerate and
work in a theoretical framework that inlcudes strange states as well,
then we can construct two scalar \bar q - q states. Thus constructed
scalars can, of course, describe at most two out of the mentioned six
experimentally known states - but the question is: Which two?
I will present a model with (pseudo)scalar and (axial-)vector mesons that
allows us to answer this question. The scalar (and other) mesons are
important not only in vacuum but also at finite temperatures and densities
as they build order parameters for the chiral transition. |
| Date: | Thu, 26.01.2012 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | SEM 136 (Freihaus, Wiedner Hauptstrasse 8-10), Institute for Theoretical Physics, Vienna University of Technology |
| Contact: | Andreas Schmitt |
| Nonrelativistic high-energy physics: Precision calculations for top and squark production at the LHC |
| Speaker: | Martin Beneke (RWTH Aachen) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Thu, 26.01.2012 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock, 1090 Wien |
| Contact: | A. Hoang, H. Neufeld |
| On the asymptotic dynamics of G2 cosmologies |
| Speaker: | Mark Heinzle (Univ.Wien) |
| Abstract: | im Rahmen des Literaturseminars |
| Date: | Thu, 26.01.2012 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe: Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock |
| Contact: | R. Beig |
| Progress Report on Group Formation and Dynamics in the Pardus Game |
| Speaker: | Benedikt Fuchs (Med.Univ. Wien) |
| Abstract: | im Rahmen der gemeinsam veranstalteten Seminare "Komplexe Stochastische Systeme"(Univ.Wien) und "Analyse Komplexer Systeme" (Med.Univ.Wien) |
| Date: | Fri, 27.01.2012 |
| Time: | 14:15 |
| Duration: | 90 min |
| Location: | Medizinische Univ., Bauteil 88, |
| Contact: | H. Hüffel, Stefan Thurner |
| Quantum-state tomography in many-body systems |
| Speaker: | Roman SCHMIED (Departement Physik, Universität Basel) |
| Abstract: | The quantum-mechanical states of large systems are difficult to measure experimentally because of the exponentially large number of variables involved. Yet in systems of indistinguishable bosons, this number is dramatically reduced, and a tomographic reconstruction of the exchange-symmetric density matrix is feasible even for thousands of particles. We present a practical method for experimentally performing this tomography for two-component Bose-Einstein condensates, and extend it to the tomographic determination of correlations between small numbers of particles within a condensate: such correlations can be stable even when the total atom number fluctuates between experimental runs. The tomographic reconstructions of Wigner functions, Glauber-Sudarshan P-representations, and Husimi-Q distributions on the Bloch sphere are compared.
As an application we present the quantum-state tomography of spin-squeezed states of a two-component 87Rb Bose-Einstein condensate. Such states can be used for interferometric metrology beyond the standard quantum limit.
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| Date: | Fri, 27.01.2012 |
| Time: | 15:30 |
| Location: | Hörsaal Atominstitut, Stadionallee 2. 1020 Wien |
| Contact: | Prof. J. Schmiedmayer |
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