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Calendar of Physics Talks Vienna
| A Difficult Game of Catch |
| Speaker: | Sarah Waddington (University of Southampton) |
| Abstract: | The talk will be on my part in the effort to elucidate the boundary between quantum and classical models â specifically on developing a method of ejecting and recapturing a nanoparticle in an optical trap. This constitutes part of a larger project to demonstrate matter wave interference using the near field Talbot effect.
Objective collapse models are one approach to resolving the measurement problem of quantum mechanics- demonstration of quantum effects on the larger scales provided by matter wave experiments puts further constraints on the parameters of these models.
Talbot Lau interferometry has been used to demonstrate quantum behaviour in molecules of up to 25000AMU, and its application to larger particles is in development.
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| Date: | Tue, 28.03.2023 |
| Time: | 11:00 |
| Location: | Atominstitut - Seminarraum |
| Contact: | Julian Léonard |
| Some approaches to superstring cosmology |
| Speaker: | Robert Brandenberger (McGill University Montreal) |
| Abstract: | I will review the criteria which a model of the early universe must satisfy in order to make successful contact with current observations.
I will then show that effective field theory inevitably breaks down in the early universe, and that tools from quantum gravity must be used if we are to understand the early stages of the universe. I will then discuss models of early universe cosmology arising from superstring theory, in particular "String Gas Cosmology".
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| Date: | Tue, 28.03.2023 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Fakultaet fuer Physik, Erwin Schroedinger-HS, Boltzmanngasse 5, 5. Stock |
| Contact: | S. Fredenhagen, D. Grumiller, H. Steinacker, R. Ruzziconi |
| Interpreting Top quark LHC data in the Standard Model Effective Field Theory |
| Speaker: | Ken Mimasu (Kingâs College London) |
| Abstract: | I will review the status and prospects for searching for new physics via the SMEFT, focusing on the importance and impact of top quark data.
I will discuss how top quark data directly and indirectly improves the global new physics reach, showing results from recent global analyses.
I will also highlight some avenues for future improvements in sensitivity, particularly on top quark electroweak interactions, that are currently relatively poorly known.
These include loop-induced effects and the search for high-energy and high-multiplicity processes that exploit the characteristic unitarity-violating behaviour of EFT amplitudes. |
| Date: | Tue, 28.03.2023 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger Lecture Hall, Faculty of Physics, Boltzmanngasse 5, 5th floor - zoom: https://univienna.zoom.us/j/93342693866?pwd=aUpTR0VJNUhJY2Q0ajdaKzI1YWVBQT09 |
| Contact: | A. Hoang, M. Procura, T. Corbett |
| Learning Hamiltonians in Quantum Simulation of Quantum Field Theories |
| Speaker: | Robert Ott (University of Innsbruck) |
| Abstract: | We present a new protocol to learn the microscopic description of quantum field theories for quan- tum simulation experiments. By integrating out the unobservable short-distance field fluctuations, we derive an effective field theory for the degrees of freedom of the measurement apparatus, from which measurable Schwinger-Dyson equations are derived to constrain the microscopic couplings. We demonstrate the approach for a Sine-Gordon field theory, as relevant e.g. for a system of two quasi one-dimensional tunnel-coupled superfluids, by simulating the observed system correlations in the classical thermal regime and learning the microscopic couplings from the field correlation func- tions across a broad range of values. Our approach provides a tool to probe the validity of quantum simulations for applications ranging from condensed matter physics, to high-energy physics and cosmology. |
| Date: | Wed, 29.03.2023 |
| Time: | 16:15 |
| Location: | Atominstitut - Hörsaal |
| Contact: | Maximilian Prüfer |
| Polarization transport in optical fibers beyond Rytovâs law |
| Speaker: | Thomas Mieling (Univ. Wien) |
| Abstract: | Within geometrical optics, Rytovâs law states that the polarization vector is FermiâWalker transported along light rays.
A transport law of this kind was experimentally observed in optical fibers â a regime in which ray optics does not suffice,
but wave optics is required. In this talk, I will present a perturbative solution to the full Maxwell equations in arbitrarily bent fibers,
under the sole assumption that the fiberâs radius of curvature is much larger than its diameter.
At leading order, this provides a rigorous derivation of Rytov's law. At next order, one obtains non-trivial dynamics of the electromagnetic
phase and polarization. We discuss potential experiments signatures of of these corrections and compare with similar results on this subject.
This is joint work with Marius Oancea. |
| Date: | Thu, 30.03.2023 |
| Time: | 15:30 |
| Duration: | 60 min |
| Location: | Gravitationsphysik, Seminarraum A, Waehringerstrasse 17, 2nd floor |
| Contact: | P. Chrusciel, D. Fajman |
| Challenging QED with atomic Hydrogen |
| Speaker: | Thomas Udem (MPQ) |
| Abstract: | Precise determination of transition frequencies of simple atomic systems are required for a number of fundamental applications such as tests of quantum electrodynamics (QED), the determination of fundamental constants and nuclear charge radii. The sharpest transition in atomic hydrogen occurs between the metastable 2S state and the 1S ground state with a natural line width of only 1.3 Hz. Its transition frequency has been measured with almost 15 digits accuracy using an optical frequency comb and a cesium atomic clock as a reference [1]. A measurement of the Lamb shift in muonic hydrogen is in significant contradiction to the hydrogen data if QED calculations are assumed to be correct [2]. In order to shed light on this discrepancy the transition frequency of one of the broader lines in atomic hydrogen has to be measured with very good accuracy [3,4]. |
| Date: | Fri, 31.03.2023 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | ATI Hörsaal/https://tuwien.zoom.us/j/93672218922?pwd=dEZNQ2liVzRNNURvNmVWVE5KUWRiQT09 |
| Contact: | Jörg Schmiedmayer |
| Building a realistic neutron star from holography |
| Speaker: | Andreas Schmitt (U. Southampton) |
| Abstract: | Matter in the interior of neutron stars is governed by the strong interaction and very difficult to understand from first principles. Holographic methods, i.e., employing the gauge/string duality to understand properties of strongly coupled matter, have been developed and improved in recent years in the context of dense baryonic and quark matter. I will present the latest results within the holographic Witten-Sakai-Sugimoto model, which has been used to construct the entire neutron star, including the crust, within a single framework. This construction is in accordance with all known astrophysical constraints and yields predictions for future gravitational wave observations. I will also discuss some more theoretical results concerning the phase structure of this model, in particular the quarkyonic phase and the behavior at large isospin chemical potentials.
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| Date: | Fri, 31.03.2023 |
| Time: | 13:15 |
| Duration: | 60 min |
| Location: | Wiedner Hauptstr. 8-10, 3rd floor, seminar room yellow tower (Sem.R. DB gelb 03) |
| Contact: | Anton Rebhan, TU Wien |
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