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Calendar of Physics Talks Vienna
| Mechanochemical and Mechanocatalytic Reactions in Ball Mills -- from Voodoo to Science |
| Speaker: | Ferdi Schüth (SFB TACO) |
| Abstract: | Mechanochemical synthesis allows in various cases the synthesis of materials that are otherwise difficult to access or complex to synthesize, such as rare earth metal hydrides, corundum with high surface areas, or supported metal catalysts. For such studies, milling vessels were equipped with various additional features, such as cryo-capabilities and remote sensors for pressure and temperature to follow the processes in the mill in more detail. Mechanochemistry can also be used for catalytic reactions, such as the depolymerization of cellulose and lignocellulose, which proceeds fast and with high yield in ball mills. Moreover, running catalytic gas phase reactions under milling can lead to reactivity increases by several orders of magnitude, as proven for several cases. The presentation will highlight the synthesis of interesting materials by milling and the opportunities in carrying out |
| Date: | Mon, 07.11.2022 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Josef-Loschmidt-Saal, WähringerstraÃe 42, 1090 Wien |
| Contact: | Stefan Uttenthaler |
| String integrability of defect CFT and dynamical reflection matrices |
| Speaker: | Georgios Linardopoulos (Wigner Research Centre for Physics, Budapest) |
| Abstract: | The D3-D5 and D2-D4 probe-brane systems with nonzero worldvolume flux are holographically dual to N=4 super Yang-Mills and ABJM theoryin the presence of half-BPS domain walls. The two domain wallsystems are thought to be integrable; the evidence comes mainly from the studyof correlation functionsat weak coupling. In the present talk we show that the string theory duals of these systems are classically integrable.
In other words, the string boundary conditions on the probe branes preserve the integrability of the corresponding Green-Schwarz sigma models. This finding suggests that the dual domain wall systems
are integrable to all loop orders and for any value of the bond dimension. |
| Date: | Tue, 08.11.2022 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Seminarraum DB gelb 03 Freihaus, TU Wien, Wiedner Hauptstrasse 8 |
| Contact: | S. Fredenhagen, D. Grumiller, E. Battista, R. Ruzziconi |
| Experiences and experiments with single crystals with focus on a-Al2O3 |
| Speaker: | Johannes Luetzenkirchen (Institut für Nukleare Entsorgung, Karlsruhe Institut für Technologie, Karlsruhe/Germany) |
| Abstract: | Work on single crystals at INE was initiated to better understand the interaction of radionuclides with mineral surfaces. Compared to particles, single crystals have the advantage that surface structure and site densities are known. First steps included elaborating a cleaning procedure for a range of a-Al2O3 faces and subsequent uptake and spectroscopic experiments with trivalent actinides. Surprisingly, uptake was strongest on the face that was expected to be the least reactive, i.e., the (0001) face. On this face, the spectroscopy also showed different patterns than on the other faces studied. Subsequently, additional effort was made to gain more understanding of the (0001) face which exposes only doubly-co-ordinated oxygens. Literature suggested an unexpectedly low isoelectric point, which was confirmed by own experiments. The interpretation of a set of published data was possible by |
| Date: | Tue, 08.11.2022 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Yellow Tower âBâ, 5th floor, SEM.R. DB gelb 05 B |
| Contact: | Univ.Prof. Dr. Ulrike Diebold |
| Energy Correlators for collider QCD |
| Speaker: | Jack Holguin (Ecole Polytechnique, Paris) |
| Abstract: | The ability to measure detailed aspects of the substructure of high energy jets passing through the quark-gluon plasma(QGP)has provided a completely new probe of its internal dynamics and of QCD. However
drawing robust conclusions from traditional jet substructure observables has been difficult.This is for two main reasons, one practical and one theoretical. The environment of a heavy ion collision is messy and traditional approaches to jet substructure often find that the backgrounds are largest in the regions of phase-space most sensitive to the QGP dynamics.Compounding this problem, the QGP has complicated multi-scale dynamics.Disentangling these scales has proved difficult for theorists, indeed debate still persists over the most basic mechanisms through which a jet interacts with the QGP. |
| Date: | Tue, 08.11.2022 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schroedinger-Hoersaal, Fakultaet für Physik, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, M. Procura |
| The bosonic skin effect in asymmetric thermal transport |
| Speaker: | Louis Garbe (TU Wien Atominstitut) |
| Abstract: | We ask the following question: what is the effect of asymmetry in thermal transport? We consider a minimal model of bosons hopping through a one-dimensional lattice connected to heat baths on both ends. The hopping process is non-reciprocal ie, the probability of hopping towards the left and the right is different. Although for reciprocal hopping we recover the usual diffusive behavior and Fourier law, the non-reciprocity results in a ballistic current. We observe the appearance of a region near the boundary in which the density profile shows a zig-zag configuration, alternating between bose-condensed states and thermal states. We dub this process the bosonic skin effect. We show that the onset of this phase at the boundary can be described by an effective non-Hermitian Hamiltonian, and signified by a so-called exceptional point, akin to a lasing transition. Such unusual transport eff |
| Date: | Wed, 09.11.2022 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Hörsaal ATI |
| Contact: | Peter Rabl |
| Precise and Parsimonious Computational Quantum Physics: from Electrons in Materials to Quantum Circuits |
| Speaker: | Marco Bernardi (California Institute of Technology) |
| Abstract: | Computational physics plays a central role in studies of many-body quantum systems, which suffer from an intrinsic exponential complexity due to the curse of dimensionality. Notable examples include the many-electron problem in condensed matter physics and the simulation of quantum circuits in quantum information.
In this talk, I will show precise but practical computational methods to tackle these challenges. First, I will discuss ab initio calculations of electron interactions and dynamics in materials, focusing on the interactions between electrons, spin, and atomic vibrations (phonons) and the associated transport and nonequilibrium phenomena. After introducing relevant theory and computational workflows, I will highlight three emerging frontiers: (i) The transition from weak to strong interactions, including novel methods to study polarons and strongly correlated materials; |
| Date: | Thu, 10.11.2022 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | ATI Library/https://tuwien.zoom.us/j/93672218922?pwd=dEZNQ2liVzRNNURvNmVWVE5KUWRiQT09 |
| Contact: | Sarah Bayer-Skoff |
| Direct detection of dark matter and the COSINUS experiment |
| Speaker: | Florian Reindl (OEAW, TU Wien, Hephy) |
| Abstract: | The quest for dark matter is one of the most pressing questions of modern physics. We know that it exists, but its(particle)nature remains in the dark. Direct dark matter detection experiments aim to detect interactions of dark matter particles in earth-bound detectors. Despite tremendous improvement in sensitivity over the last decades, all experiments report null results except for the DAMA experiment. DAMA has observed since the 1990s an annually modulating event rate in their NaI detectors compatible with dark matter particles in the milky way. To resolve the contradicting results in direct detection, experiments with the same target material -- NaI -- are needed to be immune against material and model dependencies. COSINUS is one of these experiments,
albeit the only one operating NaI as a cryogenic detector. |
| Date: | Thu, 10.11.2022 |
| Time: | 15:15 |
| Duration: | 60 min |
| Location: | Gravitationsphysik, Seminarraum A, Waehringerstrasse 17, 2nd floor |
| Contact: | P. Chrusciel, D. Fajman |
| Flat JT Gravity and the Schwarzian of BMS2 |
| Speaker: | Blagoje Oblak (Ecole Polytechnique) |
| Abstract: | This talk is devoted to Jackiw-Teitelboim (JT) gravity in Bondi gauge, with a vanishing cosmological constant. The asymptotic symmetries of the theory span an infinite-dimensional group commonly dubbed `BMS2' (for Bondi-Metzner-Sachs in two dimensions), but most of the existing literature reduces this group to its warped Virasoro subgroup. I shall argue that one can avoid this reduction and use the BMS2 group throughout. In particular, the boundary action of the system is a BMS-Schwarzian with an extra zero-mode, and its partition function is one-loop exact with respect to the Haar measure on (centrally extended) BMS2. The peculiarities of BMS2 are pointed out, including the fact that it has a single coadjoint orbit at fixed (real) central charges. [Based on arXiv:2112.14609.] |
| Date: | Thu, 10.11.2022 |
| Time: | 16:30 |
| Duration: | 60 min |
| Location: | Freihaus, Sem.R. DB gelb 10 |
| Contact: | Iva Lovrekovic, Romain Ruzziconi, Daniel Grumiller |
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