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Calendar of Physics Talks Vienna
| Reconstructing complexity and effective Hamiltonians |
| Speaker: | Zala Lenarcic (Jozef Stefan Institute, Slovenia) |
| Abstract: | The vast complexity is a daunting property of generic quantum states that poses a significant challenge for theoretical treatments, especially in non-equilibrium setups. Therefore, it is vital to recognize states which are locally less complex and thus describable with (classical) effective theories. I will discuss how unsupervised learning can detect the local complexity of states. This approach can be used as a probe of scrambling, hydrodynamics, and thermalization in chaotic quantum systems, as well as for the reconstruction of the Hamiltonians from local measurements.
Reconstructing Hamiltonians from local measurements is key to enabling reliable quantum simulations: both validating the implemented model, and identifying any left-over terms with sufficient precision is a problem of increasing importance. Our deep-learning-assisted variational algorithm can reconstruct Hamiltonian usi |
| Date: | Mon, 14.10.2024 |
| Time: | 11:00 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Maximilian Prüfer |
| Conformal Renormalization of anti-de Sitter gravity |
| Speaker: | Rodrigo Olea (Universidad Andrés Bello, Chile) |
| Abstract: | Boundary counterterms are required to cancel the divergences in the bulk action of asymptotically AdS gravity. These boundary terms are prescribed by a systematic procedure known as Holographic Renormalization, developed in the context of AdS/CFT correspondence. In this seminar, we show that, in four and six bulk dimensions, these counterterms can also be obtained from a proper embedding of Einstein in Conformal gravity (Conformal Renormalization). |
| Date: | Tue, 15.10.2024 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Sem.R. DC rot 07 (7th floor, red sector) |
| Contact: | Daniel Grumiller, Ankit Aggarwal |
| Non-regular spacetime geometry via metric geometry and optimal transport |
| Speaker: | Clemens Sämann (University of Vienna) |
| Abstract: | I present an approach to Lorentzian geometry and General Relativity that does neither rely on smoothness nor on manifolds, thereby leaving the framework of classical differential geometry. This opens up the possibility to study curvature (bounds) for spacetimes of low regularity or even more general spaces.
An analogous shift in perspective proved extremely fruitful in the Riemannian case (Alexandrov-, CAT(k)- and CD-spaces). Using strategies from metric geometry and tools from optimal transport this approach to non-regular spacetime geometry has given rise to a fresh and very active line of research. I will report on its progress and, if time permits, give an outlook on future directions.
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| Date: | Tue, 15.10.2024 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-HS, Boltzmanngasse 5, 1090 Wien, 5.Stock |
| Contact: | S. Fredenhagen, M. Sperling |
| Turbulent Cascades and condensation in Hamiltonian systems |
| Speaker: | Anxo Biasi (Ecole Normale Superieure-PSL) |
| Abstract: | This talk concerns the problems of energy concentration and structure formation in Hamiltonian systems. I will present a novel mechanism for the dynamical formation of condensates, which markedly differs from that predicted by the wave turbulence theory. I will also show that the process is accompanied by a deterministic turbulent cascade that concentrates energy at arbitrarily small scales in finite time. The result is fully analytic, based on explicit solutions representing all the aforementioned phenomena. This talk is based on my recent work: Phys. Rev. E 110, 034107 (2024). |
| Date: | Wed, 16.10.2024 |
| Time: | 14:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Waehringer Strasse 17, 2nd Floor |
| Contact: | Piotr T. Chrusciel, David Fajman |
| Entanglement quantification with collective measurements in many-body systems |
| Speaker: | Giuseppe Vitagliano (TU Wien, Atominstitut) |
| Abstract: | I will present some recent results on entanglement detection and quantification with collective measurements in many-body ensembles. First I will give an introduction into entanglement and the idea of 'spin squeezing', which was introduced in the context of metrology, and explain the relation between the two concepts. I will show how the original spin squeezing approach can be generalized in several respects and how it allows to quantify multipartite entanglement in different types of experimentally-controlled many-body systems, such as cold atomic clouds or solid-state magnetic materials. These entanglement witnesses are based on variances of collective operators, which can be extracted from simple averaged two-body correlation functions, which is the reason why they find widespread application in many-body systems, where higher-order correlation functions of more complex measurements |
| Date: | Wed, 16.10.2024 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Helmut Rauch Hörsaal ATI |
| Contact: | Maximilian Prüfer |
| Synchrotron Light for Catalysis and Corrosion Research |
| Speaker: | Andreas Stierle (Deutsches Elektronen-Synchrotron DESY, Hamburg/Germany) |
| Abstract: | Synchrotron light has become an important tool in materials, nanomaterials, and surface analysis. For in-operando insights in processes such as heterogeneous catalysis, electrocatalysis, or corrosion often unique experiments are possible. In this talk I will present examples from present research. |
| Date: | Fri, 18.10.2024 |
| Time: | 15:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Green Tower âAâ, 3rd floor, SEM.R. DA grün 03 B |
| Contact: | Univ.Prof. Markus Valtiner |
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