Calendar of Physics Talks Vienna

Space-time curvature-induced corrections to Rytov's law in optical fibers (Vienna Theory Lunch Seminar)
Speaker: Mario Hudelist (Universität Wien)
Abstract: According to Rytov's law, the polarization vector of light follows a Fermi-Walker transport equation in optical fibers. Recent advancements in theory propose a modification to Rytov's law due to fiber bending. The aim of this talk is to further extend these predictions from flat to curved space-time. This involves perturbatively solving Maxwell's equations under the assumption that the wavelength is significantly shorter than the fiber radius, as well as the characteristic length-scales of the ambient space-time. This results in a coupling of the polarization vector to the Riemann curvature tensor. [[part of the "Vienna Theory Lunch Seminar, see https://lunch-seminar.univie.ac.at ]]
Date: Tue, 19.03.2024
Time: 12:30
Duration: 75 min
Location:University of Vienna, Boltzmanngasse 5, 5th floor, Schrödinger Lecture Hall
Contact:Florian Lindenbauer

Covariant charges and fluxes at null infinity.
Speaker:Antoine Rignon-Bret (Universite d'Aix-Marseille)
Abstract:In this talk, I will review the application of Noether theorem to general relativity and the covariant phase space techniques to construct Noether charges and fluxes on spacetime boundaries. In particular, I will detail the Wald-Zoupas procedure and focus on the physical interpretation. I will show that the implementation of the procedure implies that the algebra of local Noether currents is free of cocycle. Then, I will focus on non-trivial examples at null infinity. I will implement the Wald-Zoupas procedure for BMS and eBMS boundary conditions, and argue that it cannot be implemented successfully for generalized BMS fall-off conditions but for a symmetry group preserving different fall off conditions isomorphic to gBMS with a different algebra. [[NB. The seminar will also be streamed in the Schroedinger-Hoersaal. For ZOOM attendees: Meeting ID: 420 707 3557, Password: Q4Tfue5N]]
Date: Tue, 19.03.2024
Time: 14:00
Duration: 60 min
Location:Online (ZOOM). Link : https://tuwien.zoom.us/j/4207073557?pwd=YVhUSVpZRnRMR3p0aXdsb1BmaXFwUT09&omn=64465475582
Contact:Adrien Fiorucci, Daniel Grumiller

Exploring the influence of plasma triangularity on pedestal stability and structure in ASDEX Upgrade
Speaker:Lidija Radovanovic (TU Wien, Institut für Angewandte Physik)
Abstract:The confinement and the performance of a tokamak plasma in the high confinement regime are closely related to the structure of the plasma edge region, the so-called pedestal. In this region, density and temperature of the plasma drastically drop, acting as an insulator for the core of a fusion plasma. One possible factor limiting the pedestal width is the onset of instabilities, kinetic ballooning modes, at the top of the pedestal which we approximate by local ideal ballooning modes. The stability of these modes can be altered by varying the plasma shape. The results show that different physical mechanisms influence the pedestal width of electrons and ions with respect to their density and temperature. These individual effects are nevertheless conditioned by the overall limit on the total pressure, set by the ideal magnetohydrodynamic (MHD) stability.
Date: Tue, 19.03.2024
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:Prof. Richard Wilhelm

Hollow atoms: A simulation approach to describe the formation and de-excitation of multiply excited atoms
Speaker:Matthias Werl (TU Wien, Institut für Angewandte Physik)
Abstract:Hollow atoms are formed when (highly) charged ions approach a surface: Here, electrons are (resonantly) captured from the surface, populating states in the projectiles with very high principal quantum numbers. Studying exotic hollow atoms is challenging, because they de-excite quickly, typically via radiative and auto-ionisation pathways. The exact lifetime is, however, not easily estimated. A code to simulate both the formation and the subsequent de-excitation of the HA is presented here. Using coupled rate equations with rates computed using atomic structure codes, it is possible to resolve the dynamics of the de-excitation cascade, giving access to the spectra of emitted photons and electrons as well as being able to determine the life-time of freely decaying hollow atoms.
Date: Tue, 19.03.2024
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:Prof. Richard Wilhelm

"EW corrections in SMEFT"
Speaker:Benjamin Pecjak (University of Durham)
Abstract:Standard Model Effective Field Theory (SMEFT) is not only a practical tool for searching for small deviations from SM expectations in data, but is also a well-defined quantum field theory. In this talk I focus on interesting field-theoretical features involved in calculations of EW corrections in SMEFT. Compared to the SM, these include subtleties in Higgs-Z mixing, electric charge renormalisation,gauge fixing, and the treatment of tadpoles when using hybrid renormalisation schemes where some parameters are renormalised in the MS-bar scheme and some in the on-shell scheme.
Date: Tue, 19.03.2024
Time: 16:15
Duration: 60 min
Location:Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:A. Broggio

Gravitational memory effects for particles and wave packets
Speaker:Marius Oancea ((U of Vienna))
Abstract: Gravitational waves can generally influence the dynamics of test objects with which they interact. Changes in the relative dynamics of test objects can persist even after the gravitational wave has passed and spacetime is again flat. These are generally referred to as gravitational memory effects, since the properties of the passing gravitational wave remain encoded in the relative dynamics of test objects. In this talk, I will discuss gravitational memory effects in plane wave spacetimes for different classes of test objects: particles following geodesics, spinning particles with non-geodesic motion, and test scalar fields. For all these objects, memory effects are encoded into a set of four memory tensors that depend on the gravitational wave profile. Joint work with Abraham Harte, Thomas Mieling, and Florian Steininger.
Date: Wed, 20.03.2024
Time: 14:15
Duration: 60 min
Location:Seminarraum A, Waehringer Strasse 17, 2nd Floor
Contact:Piotr T. Chrusciel

Toward quantum-logic control of homonuclear molecules
Speaker:Ziv Meir (Weizmann Institute)
Abstract:In the last two decades, we have witnessed tremendous advancements in the control of quantum systems, leading to what is known as “the 2nd quantum revolution”. For a long time, molecules were considered too complicated for coherent and quantum control. The Nobel laureate Arthur Schawlow illustrated this concept in his famous quote, “A diatomic molecule is a molecule with one atom too many.” Nowadays, molecules are headed to the forefront of quantum research. The increasing interest in molecules stems from their additional degrees of freedom, i.e., rotations, vibrations, and different isomers. These extra degrees of freedom open up opportunities that are exclusive to molecular systems. In this talk, I will describe the latest results in high-fidelity quantum-non-demolition state detection of trapped homonuclear molecular ions using quantum-logic protocols [1]. In addition, I will discuss
Date: Fri, 22.03.2024
Time: 10:00
Duration: 45 min
Location:Helmut Rauch Hörsaal ATI
Contact:Tomas Sikorsky