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Calendar of Physics Talks Vienna
| The Golden Age of Neutron Stars |
| Speaker: | Gordon Baym (University of Illinois) |
| Abstract: | Neutron stars were first posited in the early thirties, and discovered as pulsars in the late sixties; however we are only recently beginning to understand the matter they contain. I will describe the ongoing development of a consistent picture of the liquid interiors of neutron stars, now driven by
ever increasing observations as well as theoretical advances. These include in particular observations of at least three heavy neutron stars of about 2.0 solar masses and higher; ongoing simultaneous inferences of masses and radii of neutron stars by the NICER telescope; and past and future observations of binary neutron star mergers, through gravitational waves as well as across the electromagnetic spectrum. Theoretically an understanding is emerging in QCD of how nuclear matter can turn into deconfined quark matter in the interior, and be capable of supporting heavy neutron stars, which |
| Date: | Mon, 29.09.2025 |
| Time: | 14:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Jörg Schmiedmayer |
| Entanglement in time and holography |
| Speaker: | Michal P. Heller (Ghent University and Jagiellonian University) |
| Abstract: | I will describe why it is interesting to think about entanglement in time in quantum field theory and propose how to compute such a notion in holography. Based on 2408.15752 (PRL) and 2507.17847 with Fabio Ori and
Alexandre Serantes. |
| Date: | Wed, 01.10.2025 |
| Time: | 09:00 |
| Duration: | 60 min |
| Location: | Sem.R. DA grün 05, Freihaus, TU Wien, Wiedner Hauptstrasse 8-10, 1020 Vienna |
| Contact: | Daniel Grumiller |
| A unified entropy for statistical mechanics: observational entropy meets maximum entropy principles |
| Speaker: | Joseph Schindler (Universitat Autònoma de Barcelona, Spain) |
| Abstract: | We introduce a definition of coarse-grained entropy that unifies measurement-based (observational entropy) and max-entropy-based (Jaynes) approaches to coarse-graining, by identifying physical constraints with information theoretic priors. The definition is shown to include as special cases most other entropies of interest in physics. We then consider second laws, showing that the definition admits new entropy increase theorems and connections to thermodynamics. We survey mathematical properties of the definition, and show it resolves some pathologies of the traditional observational entropy in infinite dimensions. Finally, we study the dynamics of this entropy in a quantum random matrix model and a classical hard sphere gas. Together the results suggest that this generalized observational entropy can form the basis of a highly general approach to statistical mechanics.
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| Date: | Thu, 02.10.2025 |
| Time: | 11:00 |
| Duration: | 45 min |
| Location: | Seminar room ZE-EG New Building ZE |
| Contact: | Maximilian Lock |
| Polaritons in two-dimensional materials and hybrid systems probed by electron beams |
| Speaker: | Nahid Talebi (Universität Kiel) |
| Abstract: | Polaritonic quasiparticles in two-dimensional (2D) materials have emerged as a powerful platform for studying light–matter interactions and mediating novel photon- and phonon-driven correlations between electronic excitations. In this work, we employ electron beam-based techniques to probe exciton and plasmon polaritons across a diverse set of 2D materials, including transition metal dichalcogenides, perovskites, hexagonal boron nitride, borophene, and hybrid heterostructures.
By combining cathodoluminescence and photoluminescence spectroscopy, we investigate how electron and photon excitations differ in their ability to access polaritonic modes—shedding light on distinct selection rules and excitation pathways. Furthermore, we apply a recently developed technique that leverages electron-driven photon sources (EDPHS) inside a transmission electron microscope to perform Ramsey-type ultraf |
| Date: | Fri, 03.10.2025 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Philipp Haslinger |
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