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Calendar of Physics Talks Vienna
| Learning Order: Can Neural Networks Discover Phase Transitions Without Symmetry Functions |
| Speaker: | Carina Karner (TU Wien) |
| Abstract: | Phase transitions in soft matter systems — from crystallization to gelation — arise from collective particle rearrangements that are challenging to capture in full microscopic detail. Conventional approaches rely on physically inspired order parameters or symmetry functions to characterize emerging structures, but such descriptors may overlook crucial features in the often complex organisation of biolgical materials or synthetic super-structures. Here we investigate whether machine learning can uncover these hidden features directly from raw particle configurations. |
| Date: | Tue, 02.12.2025 |
| Time: | 12:15 |
| Duration: | 75 min |
| Location: | TU Wien: Wiedner Hauptstr. 8-10, green area, 5th floor, seminar room DA05E10 |
| Contact: | Luciano Montecchio |
| Conformally Symmetric Views from a Fuzzy Sphere: Generalizing deconfined criticality to 3d N-flavor SU(2) quantum chromodynamics |
| Speaker: | Emilie HUFFMANN (Wake Forest University) |
| Abstract: | We present an innovative way to study quantum phase transitions on spherical geometry, using a fuzzy sphere regularization derived from the quantum hall effect. We have accurately calculated and analyzed the energy spectra at the (2+1)-d Ising transition, and explicitly demonstrated the state-operator correspondence (i.e., radial quantization), a fingerprint of conformal field theory. Since then we have computed many more quantities of interest to conformal field theory, such as the F-function, OPE coefficients, and observables for defect models. After reviewing the method and its applications generally, we specifically look at an application to an N-flavor candidate theory for QCD which exhibits a deconfined quantum critical point (DQCP), which is a mechanism for phase transitions beyond the Landau paradigm. The fuzzy sphere formalism offers a powerful lens to probe the modelâÂÂs... |
| Date: | Tue, 02.12.2025 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | -> ONLINE - Erwin-Schroedinger-Lecture Hall, 1090 Vienna, Boltzmanngasse 5, 5th floor |
| Contact: | S. Fredenhagen, M. Sperling |
| Spin textures and spin waves as seen by x-ray imaging |
| Speaker: | Sebastian Wintz (Institute for Nanospectroscopy, Helmholtz-Zentrum Berlin, Germany) |
| Abstract: | The investigation of spin-wave phenomena—magnonics—plays an increasingly central role in modern condensed-matter research [1]. Spin waves are considered promising signal carriers for next-generation spintronic information-processing devices, with the potential to surpass charge-based technologies in both energy efficiency and device miniaturization. A key challenge on this path is the generation, control, and detection of spin waves with nanoscale wavelengths.
In this talk, I will show how time-resolved x-ray microscopy enables direct imaging of nanoscale spin dynamics. Using this technique, it has been demonstrated that ferromagnetic spin textures—particularly vortex cores and domain walls—can act as nanoscale spin-wave emitters and waveguides [2–5]. I will further discuss recent advances in x-ray imaging of spin-wave dynamics in ferrimagnetic and antiferromagnetic materials, as well a |
| Date: | Tue, 02.12.2025 |
| 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. A. Fernández-Pacheco |
| Non-leptonic B Decays with Multi Hadron Final States |
| Speaker: | Thomas Mannel (University of Siegen) |
| Abstract: | Non-leptonic B decays are notoriously difficult to describe, on the other hand, most data on CP violation is from non-leptonic decays. In this talk I will discuss the status and the prospects of non-leptonic B Decays with multi hadron final states, in particular for decays like B → π π π and B → K π π, for which now first measurements of the Dalitz distribution of CP asymmetries exist. |
| Date: | Tue, 02.12.2025 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-HS, Boltzmanngasse 5, 1090 Wien, 5.Stock |
| Contact: | A. Hoang, M. Procura, J. Pradler, H. Neufeld |
| Finitely correlated states: virtual systems beyond quantum theory |
| Speaker: | Andreas Winter (Universität Köln) |
| Abstract: | A fundamental problem of inference comes from the observation of a
long (ideally infinite) stationary time series of events, generated by a hidden Markov chain. What can we say about the internal structure of the hidden Markov model, aka the latent, or virtual, variables? If the system generating the observations is classical, we are looking to reconstruct the "hidden" Markov chain from its "visible" image. If the hidden system is quantum mechanical, this gives rise to a special class of finitely correlated states, which we call quantum hidden Markov models. However, the most general finitely correlated process is generated by a so-called "general probabilistic theory" (GPT). The latter case is entirely described by a certain canonical (real) vector space with associated positive cone preserved under the hidden dynamics of the model. It was known since the late 1960s that there exist su |
| Date: | Fri, 05.12.2025 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Marcus Huber |
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