Calendar of Physics Talks Vienna

CoQuS Colloquium Seminar Talk by Sebastian Huber
Speaker:Sebastian Huber ((CoQuS))
Abstract:"A quantized quadrupole insulator in a mechanical metamaterial" - The elastic properties of materials are determined by a few material constants such as the Young’s modulus. Using super-structures one can effectively change these “constants”. In this way we obtain functionalities such as wave-guiding, acoustic lensing or programmable failure. I will show how topological band theory, known from the description of electrons in solids, provides us with a powerful design-principle for such mechanical metamaterials.
Date: Mon, 04.12.2017
Time: 16:30
Duration: 120 min
Location:Lise-Meitner Hörsaal, Strudelhofgasse 4, 1090 Vienna

Holographic Entanglement Density
Speaker:Nikola Gushterov (Oxford U.)
Abstract:We will study the way in which the entanglement entropy of a holographic quantum system becomes the thermodynamic entropy, at finite temperature, as we vary the size of the entangling region. For this purpose, we will concentrate on the holographic entanglement entropy using the Ryu-Takyanagi prescription. We will study the holographic entanglement per unit volume, to understand how the Infrared degrees of freedom can affect the way in which the entanglement entropy becomes extensive. In particular, we will show that the holographic entanglement density will become over-extensive and develop a peak, for intermediate scales.
Date: Tue, 05.12.2017
Time: 14:00
Duration: 60 min
Location:SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna)
Contact:Daniel Grumiller and Stefan Fredenhagen

Calculating ground and excited state properties of solids & surfaces using beyond-DFT ab-initio methods
Speaker:Andreas Grüneis (TU Wien, Institut für Theoretische Physik)
Abstract:This presentation will review recent progress in applying periodic coupled cluster theories to the study of surfaces and solids. We will briefly discuss methods that reduce the computational cost and accelerate convergence of calculated properties towards the complete basis set as well as thermodynamic limit [1-4]. These recent developments have enabled an increasing number of ab-initio studies and allowed for assessing the accuracy of coupled cluster theories by comparing to experimental findings as well as quantum Monte Carlo results. The presented applications will include phase transitions of solids [5], molecular adsorption energies [6-7], hydrogen dissociation on silicon surfaces as well as ground and excited state studies of defects in solids.
Date: Tue, 05.12.2017
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:Univ.Prof. Dr. Ulrike Diebold

Gravity, blackbody radiation and chameleons – Towards lattice atom interferometry
Speaker:Dr. Philipp Haslinger (Berkeley, Department of Physics, University of California)
Abstract:Within the last decades atom interferometry has proven its surprising versatility to sense with high precision tiniest forces. In this talk I will give an overview of our recent work using an optical cavity enhanced atom interferometer to sense with gravitational strength for fifths forces and for an on the first-place counterintuitive inertial property of blackbody radiation. I will conclude with perspectives on the next generations of optically levitated atom interferometric sensors. If dark energy, which drives the accelerated expansion of the universe, consists of a light scalar field it might be detectable as a “fifth force” between normal-matter objects. In order to... [for full abstract please visit: https://indico.smi.oeaw.ac.at/event/253/ ]
Date: Wed, 06.12.2017
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

Nonvacuum stability of the Milne universe
Speaker:David Fajman (Vienna)
Abstract:The Milne model is the only cosmological vacuum solution to Einstein’s equations (with vanishing cosmological constant) that is known to be nonlinearly (future-) stable due to the work of Andersson-Moncrief. We present a first generalisation of this result to the nonvacuum case, namely to the Einstein-Vlasov system. In particular, we introduce a new idea to combine earlier approaches to control massive collisionless matter in cosmological spacetimes with a physically motivated estimate that is necessary to establish sufficient decay properties of the matter field. This is joint work with Lars Andersson (Golm).
Date: Thu, 07.12.2017
Time: 14:00
Duration: 60 min
Location:Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien
Contact:P.T. Chrusciel

Inflationary cosmology from quantum Conformal Gravity
Speaker:Petr Jizba (FNSPE, Czech Technical University in Prague & ITP, Freie Universitaet in Berlin)
Abstract:In my talk I will set up the functional integral for quantum Conformal Gravity and show that with the help of a Hubbard-Stratonovich transformation, the action can be broken into a local quadratic-curvature theory coupled to a scalar field. A one-loop effective action calculation reveals that strong fluctuations of the metric field are capable of spontaneously generating a dimensionally transmuted parameter which, in the weak-field sector of the broken phase, induces a Starobinsky-type f(R)-model with a gravi-cosmological constant. I will highlight a non-trivial relation between Starobinsky's parameter and the gravi-cosmological constant that is obtained in the broken phase. Finally, implications for cosmic inflation will be briefly discussed and compared with the recent BICEP2/Keck Array data. Ref.: P.Jizba, H.Kleinert and F.Scardigli, Eur. Phys. J. C (2015) 75:245
Date: Thu, 07.12.2017
Time: 16:00
Duration: 60 min
Location:SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna)
Contact:Daniel Grumiller