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Calendar of Physics Talks Vienna
| CoQuS Colloquium Seminar Talk by Jonathan Dowling |
| Speaker: | Jonathan Dowling (CoQuS) |
| Abstract: | "Schrödinger's Web - The Race to Build the Quantum Internet" Over the past 20 years bright sources of entangled photons have led to a renaissance in quantum optical interferometry. These photon sources have been used to test the foundations of quantum mechanics and implement some of the spooky ideas associated with quantum entanglement such as quantum teleportation, quantum cryptography, quantum lithography, quantum computing logic gates, and sub-shot-noise optical interferometers. I will discuss some of these advances and the unification of optical quantum imaging, metrology, and information processing. I will end with quantum communications and networks and highlight advances particularly in China. |
| Date: | Mon, 20.11.2017 |
| Time: | 16:30 |
| Duration: | 120 min |
| Location: | Lise-Meitner Hörsaal, Strudelhofgasse 4, 1090 Vienna |
| Contact: | CoQuS-Team |
| Double Field Theory and Membrane Sigma Models |
| Speaker: | Athanasios Chatzistavrakidis (Rudjer-Boskovic-Institute Zagreb) |
| Abstract: | Double Field Theory (DFT) promotes the T-duality for closed strings to a manifest
symmetry and it can describe the generalised geometries that a closed string may
experience. In this talk, we discuss the world volume theory and the geometry that
corresponds to the DFT structure. Utilizing the one-to-one correspondence between
Courant algebroids and a class of Membrane Sigma Models (MSMs), we construct
the MSM for DFT as a projection of a Courant sigma model over a doubled space.
This model contains all types of geometric and non-geometric fluxes as generalised
Wess-Zumino terms and its gauge structure gives rise to the DFT Bianchi identities
and the DFT strong constraint. Moreover, this offers a geometric description of DFT
as a structure that lies in between two Courant algebroids over different bases.
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| Date: | Tue, 21.11.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | TU Wien, Freihaus, SEM 136, 10. Stock, Wiedner Hauptstr. 8-10, 1040 Wien |
| Contact: | S. Fredenhagen, D. Grumiller |
| Physical properties of the CuMnAs alloy - a material promising for antiferromagnetic spintronics |
| Speaker: | František Máca (Institute of Physics ASCR, Praha) |
| Abstract: | Today, the CuMnAs alloy is an extensively studied material due to its promising properties for antiferromagnetic spintronics. However, CuMnX Heusler alloys cannot be grown without defects and estimating the precise stoichiometry by X-ray analysis is difficult due to the very similar X-ray scattering properties of Cu and Mn atoms. And since, up to now, reliable neutron diffraction data for real samples are also not available, computer simulations are an effective tool to find most probable defects and relate their concentrations to measured transport characteristics. The role of defects in the antiferromagnetic CuMnAs and in the prototype Heusler alloy CuMnSb has been investigated from first principles.
The calculations reveal that electron correlations play an important role for the phase stability and that both Mn/Cu exchange and vacancies on Mn- and Cu-sublattices are the most proba |
| Date: | Tue, 21.11.2017 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner Hauptstraße 8-10 Yellow Tower „B“, 5th floor, SEM.R. DB gelb 05 B |
| Contact: | Ao.Univ.Prof. Dr. J. Redinger |
| Soft and hard multiple interactions in hadronic collisions |
| Speaker: | Stefan Gieseke (KIT) |
| Abstract: | im Rahmen des Teilchenphysikseminars |
| Date: | Tue, 21.11.2017 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | H. Neufeld, S. Plätzer |
| General Sobolev metrics the on manifold of all Riemannian metrics |
| Speaker: | Peter Michor (Vienna) |
| Abstract: | For a compact manifold Mm equipped with a smooth fixed background
Riemannian metric bg we consider the space MetHs(bg)(M) of all Riemannian metrics of Sobolev class Hs for real s > m 2 with respect to bg. The L2-metric on MetC1(M) was considered by DeWitt, Ebin, Freed and Groisser, Gil-Medrano and Michor, Clarke. Sobolev metrics of integer order on MetC1(M) were considered in [M.Bauer, P.Harms, and P.W. Michor: Sobolev metrics on the manifold of all Riemannian metrics. J. Differential Geom., 94(2):187-208, 2013.] In this talk we consider variants of these Sobolev metrics which include Sobolev metrics of any positive real (not integer) order s > m 2 . We derive the geodesic equations and show that they are well-posed under some conditions and induce a locally diffeomorphic geodesic exponential mapping.
Based on collaborations with M.Bauer, M.Bruveris, P.Harms. |
| Date: | Thu, 23.11.2017 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| Non-linear supersymmetry and D-term breaking |
| Speaker: | Niccolo Cribiori (Padova University) |
| Abstract: | Non-linear realizations revealed to be a convenient tool for the analysis of models with broken supersymmetry, both in the global and in the local case. Particular attention has been devoted to the studying of inflation and to the description of de Sitter phases in supergravity and string theory.
One possible way to implement non-linear realizations of supersymmetry consists in imposing constraints on multiplets.
In this talk I am concentrating on N=1 supergravity in four dimensions and, after reviewing the main ingredients of the constrained multiplets formalism, I am going to to show how models with D-term breaking can be recast into equivalent ones with F-term breaking. |
| Date: | Thu, 23.11.2017 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | 10th floor seminar room in yellow tower of TU Wien Freihaus (Wiedner Hauptstrasse 8-10, A-1040 Vienna) |
| Contact: | Timm Wrase |
| Quantum Geometrodynamics of Einstein and Conformal Gravity |
| Speaker: | Claus Kiefer (University of Cologne) |
| Abstract: | I discuss the canonical quantization of general relativity and Weyl-squared gravity.
I present the classical and quantum constraints and discuss their similarities and differences.
I perform a semiclassical expansion and discuss the emergence of time for the two theories.
While in the first case semiclassical time has a scale and a shape part, in the second case it only has a shape part. I also address the relevance of these results for the general problem
of understanding quantum gravity.
Ref.: C. Kiefer and B. Nikolic, J.Phys.Conf.Ser. 880 (2017) no.1, 012002 (open access)
and references therein
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| Date: | Fri, 24.11.2017 |
| Time: | 11:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| Tunneling exit characteristics from classical backpropagation of an ionized electron wave packet |
| Speaker: | Hongcheng Ni (Max-Planck-Institut für Physik komplexer Systeme, Dresden) |
| Date: | Fri, 24.11.2017 |
| Time: | 11:00 |
| Location: | Dekanatsraum FH DA grün 09, Institute for Theoretical Physics – Vienna University of Technology, Wiedner Hauptstraße 8 – 10, 9th floor, Elevator to level 8, then stairway behind the green tower lift |
| Contact: | Univ.Prof. Dr. Joachim Burgdörfer |
| Atomtronics and cavity QED experiments in Auckland |
| Speaker: | Maarten Hoogerland (Department of Physics, University of Auckland) |
| Abstract: |
I will discuss two experiments at the University of Auckland. In the first experiment we consider a two dimensional Bose gas in an "atomtronic" circuit. We will look at the effects of Anderson localization and of quantum turbulence.
In the second experiment we consider an optical nanofiber, which is part of a fiberoptic ring resonator, interacting with atoms in a MOT. We see strong coupling between atoms and photons, and show saturation of the system for 13 photons in the resonator.
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| Date: | Fri, 24.11.2017 |
| Time: | 15:30 |
| Location: | Atominstitut, Hörsaal, Stadionallee 2, Wien 2 |
| Contact: | Arno Rauschenbeutel |
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