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Calendar of Physics Talks Vienna
| Topological defects in open string field theory |
| Speaker: | Prof. Martin Schnabl (Univ. Prag) |
| Abstract: | im Rahmen des Seminars für Mathematische Physik |
| Date: | Tue, 19.06.2018 |
| Time: | 13:45 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | S. Fredenhagen, D. Grumiller |
| Speaker: | Wolfgang Niedenzu (Institut für Theoretische Physik) |
| Abstract: | Heat engines were the basis of the industrial revolution and are still indispensable in our modern world. Originally designed as macroscopic machines that convert heat into mechanical work, the question naturally arises whether their operational principles can also be applied to the quantum domain and whether their performance can benefit from possible quantum advantages. In this overview talk I will present recent theoretical and experimental progress on quantum heat engines. |
| Date: | Tue, 19.06.2018 |
| Time: | 14:00 |
| Location: | Atominstitut, Seminarraum, Stadionallee 2, Wien 2 |
| Contact: | Philipp Haslinger |
| Create and Control Novel Phases in Heterostructures of Transition Metal Oxides |
| Speaker: | Milan Radovic (Photon Science Department, Paul Scherrer Institut, Villigen PSI., Switzerland) |
| Abstract: | Transition Metal Oxides (TMOs) exhibit unique and multifunctional physical phenomena (such as high-temperature superconductivity, colossal magnetoresistance, metal-insulator transitions, etc.) directly related to the spin and orbital degrees of freedom of the transition metal d-states and their interplay with the lattice. Importantly, the iso-structure of TMOs permits realization of hetero-structures generating at their surfaces and interfaces new physical matters that radically differ from those of the constituent bulk materials. Therefore, to fully explore the potential of modern quantum and hybrid materials based on TMO the first worldwide experimental setup combining Pulse Laser Deposition and Angle Resolved Photoemission (ARPES) has been designed at the SIS beamline (Swiss Light Source, Paul Scherrer Institut). Presently, this set up is being extended with Molecular Beam Epitaxy (MB |
| Date: | Tue, 19.06.2018 |
| Time: | 16:00 |
| Location: | Technische Universität Wien, Institut für Angewandte Physik, E134 yellow tower „B“, 5th floor, Sem.R. DB gelb 05 B (room number DB05L03), 1040 Wien, Wiedner Hauptstraße 8-10 |
| Contact: | Univ.Prof. Dr. Ulrike Diebold |
| Dispersion forces in inhomogeneous planar cavities |
| Speaker: | Johannes Fielder (Universität Freiburg ) |
| Abstract: | Dispersion forces such as van der Waals forces between neutral particles and Casimir forces between dielectric bodies are caused by the ground-state fluctuations of the electromagnetic field which lead to attractive forces between the interacting objects [1]. These forces are typically investigated in vacuum, e.g. by the diffraction of a molecular beam at a dielectric grating [2]. However, these forces play an important role in many natural systems. In particular they cause the binding of a wide range of molecules and are involved in several biological and chemical reactions. Such processes usually take place in an environment, e.g. in water. Thus, the impact of an environment on the dispersion forces is of great interest for current investigations. By considering a particle in a medium from a microscopic view one finds that the particle expels the surrounding medium from a certain volume. Taking such volumes with hard boundary conditions into account via cavity models leads to excess polarizabilities [3] creating several effects. Especially, the transition from attractive to repulsive forces strongly depends on the cavity’s size [4]. A closer look at the boundary of the cavity shows that the assumption of a hard boundary is not valid and cavities with continuous profiles has to be investigated.
In order to determine the impact of an inhomogeneous boundary condition of a cavity on the dispersion forces we analyse a one-dimensional analog system of a planar cavity with continuous boundary conditions [5]. We present an effective description of a particle and a dielectric slab embedded in a cavity with dielectric inhomogeneous boundaries by approximating the corresponding Riccati differential equation for the multiple reflection of light at a continuous profile. We determine the impact on van der Waals and Casimir forces and illustrate the results by the application to helium atoms and helium slabs in a planar cavity within water.
[1] S.Y. Buhmann, Dispersion forces I, Springer (Heidelberg, 2012).
[2] C. Brand, J. Fiedler et al., Ann. Phys. (Berlin) 527, 580 (2015).
[3] J. Fiedler et al., J. Phys. Chem. A 121, 9742 (2017).
[4] J. Fiedler et al., Phys. Rev. E, submitted, arXiv:1806.03505.
[5] J. Fiedler et al., Dispersion forces in inhomogeneous planarly layered media: A one-dimensional model for effective polarisabilities, Phys. Rev. A, submitted.
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| Date: | Wed, 20.06.2018 |
| Time: | 14:00 |
| Location: | Atominstitut, Stadionallee 2, Bibliothek, 1020 Wien |
| Contact: | Philipp Haslinger |
| Gravitational waves in deSitter background |
| Speaker: | Jahanur Hoque (Chennai) |
| Abstract: | Cosmological observations have established that our universe has positive cosmological constant. A positive cosmological constant profoundly alters the asymptotic structure of space-time. In this talk, we discuss the linearized gravitational field produced by compact sources in the background with positive cosmological constant -- de Sitter space. Using the covariant phase space formalism, we obtain the quadrupole formula in such a setting. We also show that the energy flux of gravitational waves measured at future null infinity is the same as that measured across the cosmological horizon of the compact source. To get an order of estimate we also discuss power radiated by a binary system in de Sitter background. |
| Date: | Thu, 21.06.2018 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel, D. Fajman |
| Finite coupling corrections to gauge fields in AdS/CFT |
| Speaker: | Sebastian Waeber (Uni Regensburg) |
| Abstract: | We compute finite 't Hooft coupling corrections to observables related to charged quantities in strongly coupled N=4 supersymmetric Yang-Mills plasma. The coupling corrected equations of motion of gauge fields are explicitly derived and differ from findings of previous works, which contained several small errors with large impact. As a consequence the O(γ)-corrections to the observables considered, including the conductivity, quasinormal mode frequencies, in and off equilibrium spectral density and photoemission rates, become much smaller. This suggests that infinite coupling results obtained within AdS/CFT are little modified for the real QCD coupling strength. |
| Date: | Thu, 21.06.2018 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | SEM136, Wiedner Hauptstr. 8-10, 10th floor (yellow), 1040 |
| Contact: | Anton Rebhan |
| Silicon Technologies for Future Collider Experiments |
| Speaker: | Florian Pitters (CERN) |
| Abstract: | Over the past 30 years, silicon as a detector material has steadily increased in importance for high energy physics. For future detectors, this trend seems to continue if not accelerate.
For CLIC, a future 3 TeV e+e- collider, the desired energy and momentum resolution together with the flavour tagging performance will require the vertex detector to provide around 3 µm spatial and 3 ns time resolution [..]. Several technologies [..] are currently under consideration to fulfill these requirements.
For the HL-LHC phase, the CMS endcap calorimeter upgrade will employ more than 600 m2 of silicon pad sensors. [..] precise timing capabilities and unprecedented radiation hardness is needed.
The role of silicon detectors in these two future collider experiments with very different experimental and technological challenges will be discussed.. [full abstract https://indico.smi.oeaw.ac.at/event272] |
| Date: | Thu, 21.06.2018 |
| Time: | 17:00 |
| Duration: | 60 min |
| Location: | Stefan-Meyer-Institut, Boltzmanngasse 3, 1090 Wien, Seminarraum 3-2-08 (2. Stock) |
| Contact: | Prof. Dr. Eberhard Widmann, Dr. Martin Simon |
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