|
Calendar of Physics Talks Vienna
| Successful training of a triangular swimmer: a genetic algorithm approach (Vienna Theory Lunch Seminar) |
| Speaker: | Ruma Maity |
| Abstract: | Natural microswimmers use various swimming gaits to propel under low Reynolds number conditions in their fluid surrounding for various reasons: search for nutrition, escape from predators or search for prey. A very common strategy for propulsion is the non-reciprocal deformation of the shape of the swimmer in an effort to realize its motion through the medium. In recent times efforts have been made to design artificial swimmers that can successfully mimic their natural counterparts and are thus able to perform specific tasks, such as targeted drug delivery in the case of nanomedical applications. In this work, we train a two-dimensional, triangular swimmer to move in a desired direction and to detect in an efficient manner nutrition sources. [ part of https://lunch-seminar.univie.ac.at ] |
| Date: | Tue, 19.11.2024 |
| Time: | 12:15 |
| Duration: | 75 min |
| Location: | TU Wien, Wiedner Hauptstr. 8-10, yellow area, 10th floor, seminar room DB10E11 |
| Contact: | Luciano Montecchio |
| Aspects of generalized symmetries from string theory: symmetry theories and generalized charges |
| Speaker: | Fabio Apruzzi (University of Padova) |
| Abstract: | Symmetries are crucial in any physical system, as they define the theoretical model that describes it. For instance, symmetries play a fundamental role in quantum field theory (QFT), both in defining the QFT and in constraining its dynamics. The full power of symmetries has only been exploited very recently through the introduction of a generalized notion of symmetry. For example, generalized symmetries have been used to theoretically describe many phases of QFT in terms of symmetry realization, such as confinement. This generalization hinges on recognizing that the notion of conservation extends to the topological nature of the symmetry operator. It leads to higher-form symmetries, higher groups, and non-invertible symmetries.In my talk, I will first introduce how these symmetry structures are conveniently described by a (d+1)-dimensional topological field theory, whose topological defe |
| Date: | Tue, 19.11.2024 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | online on Zoom |
| Contact: | S. Fredenhagen, M. Sperling |
| Entanglement and Bell non-locality in high-energy collision |
| Speaker: | Marco Fabbrichesi (INFN Trieste) |
| Abstract: | Quantum tomography, the study of quantum states and their properties, has increasingly been used in high-energy physics as a tool for testing Bell inequalities and constrain new physics. I will describe some recent results in B-meson and charmonium decays and the ongoing work on top-quark, tau-lepton and gauge boson production. |
| Date: | Tue, 19.11.2024 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-Hoersaal, 1090 Vienna, Boltzmanngasse 5, 5th floor |
| Contact: | A. Hoang, M. Procura |
| NEC angle in critical collapse |
| Speaker: | Daniel Grumiller (TU Wien) |
| Abstract: | We identify a new critical parameter in Choptuik's gravitational collapse: the angle at which null energy condition (NEC) saturation lines intersect at the center of the critical spacetime. These NEC lines coincide with regions of vanishing curvature, dividing spacetime into stripes of positive and negative curvature. By numerically solving Choptuik's original system we find the NEC angle to be \alpha=0.64 (about 37 degrees) and analytically derive \alpha=2\arccot(D-1) for any spacetime dimension D>3. |
| Date: | Wed, 20.11.2024 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Waehringer Strasse 17, 2nd Floor |
| Contact: | Piotr T. Chrusciel, David Fajman |
| New approach to conserved charges of generic gravity in AdS |
| Speaker: | Emel Altas (Karamanoglu Mehmetbey University, Turkey) |
| Abstract: | Starting from a divergence-free, rank-4 tensor, which yields the cosmological Einstein tensor after contracting its indices and which has the symmetries of the Riemann tensor, we give a construction of conserved charges in Einstein's gravity and its higher derivative extensions for asymptotically anti-de Sitter spacetimes. In this construction, not only the conserved charges but also the current four vector yielding the charge are explicitly gauge-invariant, and the charge expression involves the linearized Riemann tensor.
Also, constructing an identity using the same divergence free tensor, we provide two ways to compute the surface gravity and Hawking temperature of a stationary black hole. In one of these methods we gave the Hawking temperature in terms of three volume integral of Gauss-Bonnet invariant in the total region outside the event horizon. |
| Date: | Thu, 21.11.2024 |
| Time: | 17:00 |
| Duration: | 60 min |
| Location: | TU Wien, Freihaus, Seminar room on the 10th floor |
| Contact: | Daniel Grumiller, Iva Lovrekovic |
| Speaker: | Simone Felicetti (Institute for Complex Systems, Italian National Research Council) |
| Abstract: | Critical quantum sensing (CQS) is by now a well-established approach, based on the exploitation of quantum properties spontaneously developed in proximity of phase transitions. Numerous theoretical studies and first experimental demonstrations show that a quantum-enhanced sensing precision can be achieved by exploiting static or dynamical properties of many-body systems in proximity of the critical point [1]. It has been recently shown [2] that CQS protocols can also be implemented using finite-component phase transitions (FCPTs), where the thermodynamic limit is replaced with a rescaling of the system parameters. This class of phase transitions emerges in quantum resonators with atomic or Kerr-like nonlinearities, and it is of high theoretical and experimental relevance.
Here, we show [3,4] that optimal quantum sensing protocols can be implemented using FCPTs taking place in... |
| Date: | Fri, 22.11.2024 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | IQOQI Seminar room, 2nd floor |
| Contact: | Uros Delic |
| The Dark Universe: from Cosmology to the Laboratory |
| Speaker: | Clare Burrage (University of Nottingham) |
| Abstract: | We do not understand 95% of our Universe. 63% of this unknown is dark energy (or a cosmological constant), which drives the accelerated expansion of the universe and 27% is dark matter, an additional matter component which clumps together to form large halos around visible galaxies. These two dominating components of the universe have only been observed through their gravitational effects, and both represent the failure of our standard models of particle physics and gravity to explain cosmology from a fundamental physics standpoint.
In this talk I will focus on the introduction of new light scalar fields which have been suggested as possible explanations for dark matter and the accelerated expansion of the universe. I will show examples of the unusual phenomenology that can arise in such theories, and explain why properties of macroscopic objects, such as density and compactness, are im |
| Date: | Fri, 22.11.2024 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Lecture Hall |
| Contact: | Mario Pitschmann |
|