Calendar of Physics Talks Vienna

Finite element methods for gauge theories (Vienna Theory Lunch Seminar)
Speaker: Srinath Bulusu (TU Wien)
Abstract: The variational principle lies in the heart of classical physics: given an action $S[\phi]$ which depends on degrees of freedom $\phi$ the evolution of the physical system follows the equations of motion which can be obtained by means of variation $\delta_{\phi} S = 0$. This in combination with the theory of Partial Differential Equations (PDEs) naturally leads to the so-called Finite Element Method (FEM) - a practial approach to numerical simulations that has established itself in the fields of structural mechanics, fluid mechanics and electrodynamics. [...] [[part of the "Vienna Theory Lunch Seminar, see https://lunch-seminar.univie.ac.at ]]
Date: Tue, 12.12.2023
Time: 12:30
Duration: 75 min
Location: TU Wien: Wiedner Hauptstr. 8-10, yellow area, 10th floor, seminar room DB10E11
Contact:Florian Lindenbauer

Preparation of Model-Catalysts for Fundamental Studies in UHV
Speaker:Stefan Wendt (Interdisciplinary Nanoscience Center (iNANO), Aarhus University, Aarhus/Denmark)
Abstract:In this seminar, I will summarize surface science studies addressing transition metal oxide surfaces that have been conducted at the iNANO center in Aarhus. Although we often start our studies with high-resolution scanning tunneling microscopy (STM), it is the combination of STM studies with various other techniques, such as X-ray photoelectron spectroscopy (XPS), and infrared reflection absorption spectroscopy (IRRAS), and density functional theory (DFT) calculations, which leads to a knowledge gain. Firstly, I will present examples found on the anatase TiO2(101) surface (a-TiO2). The interaction with vanadium, the preparation of V2O5/ a-TiO2 and WO3/ a-TiO2 model catalysts will be addressed, as well as the interaction of water with a-TiO2(101). If time permits, I will summarize our results addressing ultrathin FeO islands supported on Pt(111). After assigning of the islands edges at ox
Date: Tue, 12.12.2023
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

Electroweak input schemes in Standard Model effective field theory
Speaker: Anke Biekoetter (JGU Mainz)
Abstract:Standard Model effective field theory (SMEFT) enables us to universally describe the effects of heavy new physics at lower energy scales. Recently, there has been a lot of progress on calculating next-to-leading order (NLO) effects in SMEFT. In this talk, we will discuss how the choice of the electroweak input scheme influences the convergence at NLO and how universal, scheme-dependent corrections can be resummed.
Date: Tue, 12.12.2023
Time: 16:15
Duration: 60 min
Location:Fakultaet fuer Physik, Erwin Schroedinger-HS, Boltzmanngasse 5, 5. Stock
Contact:A. Hoang, M. Procura, T. Corbett

Symplectic Singularities in Physics: Their Origins and Significance
Speaker:Marcus Sperling (University of Vienna)
Abstract:Symplectic singularities, also known as hyper-Kahler singularities, encompass well-known geometric spaces such as the Kleinian surface singularities or the moduli space of instantons. Recently, a new class of symplectic singularities has emerged through the construction based on a physics model known as the 3d N=4 Coulomb branch. In this talk, I aim to provide an introduction and overview of symplectic singularities in general, with a particular focus on the 3d N=4 Coulomb branches. I will place special emphasis on the symplectic singularities that manifest as moduli spaces of vacua within supersymmetric field theories containing 8 supercharges in space-time dimensions ranging from 3 to 6. These instances showcase how geometric features offer elegant descriptions of strongly coupled phenomena.
Date: Wed, 13.12.2023
Time: 14:15
Location: Seminarraum A, Waehringer Strasse 17, 2nd Floor
Contact:Piotr T. Chrusciel

A scalable scanning transfer cavity laser stabilization scheme based on the Red Pitaya STEMlab platform
Speaker:Einius Pultinevicius (TU Wien, Atominstitut)
Abstract:Many experiments in atomic and molecular physics require simultaneous frequency stabilization of multiple lasers. In this talk, I present a stabilization scheme based on a scanning transfer cavity lock that is simple, stable, and easily scalable to many lasers at minimal cost. This scheme is based on the Red Pitaya STEMlab platform, with custom software developed and implemented to achieve up to 100 Hz bandwidth. As an example demonstration, we realize simultaneous stabilization of up to four lasers and a reduction of long-term drifts to well below 1 MHz/h . This meets typical requirements, e.g. for experiments on laser cooling of molecules.
Date: Wed, 13.12.2023
Time: 16:15
Duration: 45 min
Location:Helmut Rauch Hörsaal ATI
Contact:Maximilian Prüfer

Interaction of fast electrons with optical excitations: from spatially resolved optical spectroscopy to generation of entangled states
Speaker:Andrea Konecna (CEITEC BRNO)
Abstract:In the seminar, I will review the basics of the inelastic interaction between fast free electrons and optical excitations in nanostructures such as plasmons, phonons, and excitons [1]. I will show how the interaction can be probed in a scanning transmission electron microscope equipped with electron energy-loss spectroscopy (EELS) or cathodoluminescence (CL) setups, and I will discuss several examples of EELS and CL experiments [2-5]. Finally, I will introduce how to achieve well-defined entangled states of electrons and low-energy excitations in nanostructured matter by tailoring the incident electron wave function [6]. [1] F. J. García de Abajo, Optical excitations in electron microscopy. Reviews of Modern Physics 82, 209-275 (2010). [2] O. Krivanek et al., Vibrational spectroscopy in the electron microscope. Nature 514, 209-212 (2014). [3] A. Konečná et al., Revealing Nanoscale Confin
Date: Fri, 15.12.2023
Time: 10:00
Duration: 45 min
Location:Helmut Rauch Hörsaal ATI
Contact:Philipp Haslinger

Maurer-Cartan perturbation theory and scattering amplitudes in general relativity
Speaker:Andrea Nuetzi (Stanford)
Abstract:I will describe a differential graded Lie algebra tailored to study perturbations of Minkowski spacetime, including asymptotics. This differential graded Lie algebra is defined on the conformal compactification of Minkowski spacetime. Its Maurer-Cartan equation is equivalent to the vacuum Einstein equations, and is symmetric hyperbolic including across the boundary of Minkowski spacetime. I will compare this to Friedrich's conformal vacuum field equations, a key difference is that we do not use a conformal factor as an unknown, and null infinity is a fixed locus independent of the unknown. I will then introduce an iteration scheme that gives an order-by-order construction of formal power series solutions about Minkowski. This is based on standard Maurer-Cartan perturbation theory and renormalization of the mass and angular momentum charges.
Date: Fri, 15.12.2023
Time: 13:00
Location:library on Währingerstraße 17, 1st floor
Contact:P. Chrusciel