Calendar of Physics Talks Vienna

A Large Effective χ(2) Nonlinearity on a Si3N4-Chip
Speaker:Sven Ramelow (CoQuS)
Abstract:It is believed in nonlinear optics that intrinsic material nonlinearities would be far too weak to allow for efficient nonlinear interactions of single photons. This has been challenged by the coherent photon conversion (CPC) scheme [1]: strongly pumping one of the modes in a four-wave mixing(FWM) process one can generate an effective χ(2) nonlinearity for the remaining three fields which in principle can be made arbitrarily large by increasing the pump power. This theoretically allows for efficient single photon level χ(2) nonlinearities [1]. Here, I will present an overview and new results on efforts to implement CPC.I will explain how CPC can realize any effective 2nd order nonlinear process.
Date: Mon, 06.03.2017
Time: 17:00
Duration: 90 min
Location:Freihaus, Hörsaal 5, Wiedner Hauptstraße 8-10, 1040 Wien
Contact:CoQuS Team

Introduction to Topological Insulators and Superconductors (Part 1)
Speaker:Prof. Benoit Doucot (LPTHE, Paris-6)
Abstract:In these lectures, I will present some of the important concepts in this field, starting from the Quantum Hall effect, and several of its two-dimensional extensions by Haldane and Kane and Mele. Then, I will discuss the "bulk-edge correspondence" which plays a crucial role for the possible applications of these topological systems. Finally, I will present the key ideas behing the ten-fold classification. These lectures will be self-contained, and mostly with a pedagogical goal.
Date: Wed, 08.03.2017
Time: 16:00
Duration: 90 min
Location:10th floor seminar room in yellow tower of TU Wien Freihaus (Wiedner Hauptstrasse 8-10, A-1040 Vienna)
Contact:Ayan Mukhopadhyay

On the smoothness of the cylinder at spatial infinity in vacuum spacetimes
Speaker:Tim Paetz (Univ. Vienna)
Abstract:It is well-known that spatial infinity cannot be represented as a regular point due to blow-ups of the Weyl tensor whenever the ADM mass is non-zero. Because of this, the construction of vacuum spacetimes which admit a smooth past and future null infinity turns out to be a rather intricate problem. An approach which avoids these blow-ups is a cylinder representation of spatial infinity. However, for generic initial data the solutions will pick up log-terms at the critical sets where the cylinder "touches" null infinity. The goal of this talk is to set up an asymptotic initial value problem with data at past null infinity and to derive necessary conditions for the smoothness of these critical sets.
Date: Thu, 09.03.2017
Time: 14:00
Location:Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien
Contact:P.T. Chrusciel

Calabi-Yau fourfolds with non-trivial three-form cohomology
Speaker:Sebastian Greiner (MPP Munich & Utrecht)
Abstract:In this seminar, we will discuss various aspects of Calabi-Yau fourfolds, relevant for M- and F-theory effective actions in three and four dimensions. First, we perform a dimensional reduction of type IIA supergravity on a general Calabi-Yau fourfold and then apply mirror symmetry at the large volume/large complex structure point to gain information about the non-trivial three-form cohomology of the fourfold. In the second part, we discuss an explicit construction of Calabi-Yau fourfolds as toric hypersurfaces. In course of this discussion we develop tools to compute the metric on the three-form cohomology that arises in the effective action of type IIA supergravity on the fourfold.
Date: Thu, 09.03.2017
Time: 16:00
Location:TU Wien, seminar room, 10 Floor E136 (Yellow tower), Wiedner Hauptstr. 8-10, 1040 Wien
Contact:Abhiram M Kidambi (TU Wien, ITP)

Characterization of electron transport in azurin at the single molecule level
Speaker:MSc Montse López (Materials Science and Physical Chemistry Department, University of Barcelona, Spain Institute for Bioengineering of Catalonia (IBEC))
Abstract:Electron Transfer (ET) plays essential roles in crucial biological processes such as cell respiration and photosynthesis. It takes place between redox proteins and in protein complexes that display an outstanding efficiency and environmental adaptability. Although the fundamental aspects of ET processes are well understood, more experimental methods are needed to determine electronic pathways in these redox protein structures. Understanding how ET works is important not only for fundamental reasons, but also for the potential technological applications of these redox-active nanoscale systems. Electrochemical Scanning Tunneling Microscopy (ECSTM) is an excellent tool to study electronic materials and redox molecules including proteins. It offers atomic or single molecule resolution and allows working in aqueous solution, in nearly physiological conditions in the case of proteins, and unde
Date: Fri, 10.03.2017
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