CPT

Calendar of Physics Talks Vienna

Topological insulators go elemental
Speaker:Ralph Claessen (University of Würzburg, Germany)
Abstract:Topological insulators (TIs) are a new class of materials which due to intricate spin-orbit coupling effects are perfect insulators (at T=0K) in the bulk, while their boundaries carry topologically protected metallic surface (in case of 3D TIs) or edge (for 2D TIs) states. These states are spin-polarized and helical in nature, i.e. the spin is intrinsically locked to the electron´s momentum. As a consequence, backscattering is largely impeded, thereby strongly reducing the ohmic losses of surface (or edge) transport in TIs, with obvious application potential in semiconductor electronics. Furthermore, it has been proposed that TI-superconductor interfaces may host Maiorana fermion-like zero-energy quantum states of extraordinary large lifetimes, which could serve as solid-state realization of a qubit, the basic element for quantum computing.
Date: Mon, 29.05.2017
Time: 17:30
Duration: 60 min
Location:TU Wien-Freihaus, Wiedner Hauptstrasse 8 – 10, Lecture hall 5, Second floor, green area
Contact:Andrei Pimenov

Gravitational anomalies (in) matter
Speaker:Karl Landsteiner (U. Autonoma Madrid)
Abstract:The concept of symmetry is one cornerstone of modern theoretical physics. Quantum mechanics is another. Sometimes they are incompatible with each other. These incompatibilities are called anomalies. They constrain possible fermion spectra of gauge theories and explain otherwise forbidden processes such as the decay of the neutral pion into two photons. In the recent years however anomalies play an ever bigger role in a totally different realm of physics: condensed matter. In particular anomalies induce exotic transport phenomena such as the chiral magnetic and the chiral vortical effects. I will review of chiral anomalies, anomaly induced transport phenomena and discuss some of its applications in a new exciting class of materials: the Weyl semimetals with particular emphasis on the role played by the gravitational anomaly.
Date: Tue, 30.05.2017
Time: 10:00
Duration: 60 min
Location:ESI, Boltzmann lecture hall
Contact:Daniel Grumiller

Black hole quasinormal modes in twisted models of matter minimally coupled to gravity
Speaker:Andjelo Samsarov (Ruder Boskovic Institute, Zagreb)
Abstract:Black hole perturbation is followed by a ringdown phase which is dominated by quasinormal modes (QNM). These modes may provide key signature of the gravitational waves. The presence of a deformed spacetime structure may distort this signal. In order to account for such effects, we consider a toy model consisting of a charged scalar field propagating in some realistic black hole background and, within the framework of Hopf algebra deformation by Drinfeld twist, we analyse the corresponding field dynamics.The latter framework is particularly well suited for incorporating deformed symmetries into analysis. As a result, we obtain the black hole quasinormal modes that, besides containing the intrinsic informations about a black hole that is being analysed, also carry the information about the underlying structure of spacetime. Bearing on the example with BTZ spacetime, where the ..
Date: Tue, 30.05.2017
Time: 14:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:S. Fredenhagen, H. Steinacker

Single Atom Alloys for Efficient and Cost-effective Catalysis
Speaker:Charles Sykes (Department of Chemistry, Tufts University Boston MA, USA)
Abstract:Catalytic hydrogenations are critical steps in many industries including agricultural chemicals, foods and pharmaceuticals. In the petroleum refining, for instance, catalytic hydrogenations are performed to produce light and hydrogen rich products like gasoline. Typical heterogeneous hydrogenation catalysts involve nanoparticles composed of expensive noble metals or alloys based on platinum, palladium, rhodium, and ruthenium. We demonstrated for the first time how single palladium atoms can convert the otherwise catalytically inert surface of an inexpensive metal into an ultraselective catalyst. High-resolution imaging allowed us to characterize the active sites in single atom alloy surfaces, and temperature programmed reaction spectroscopy to probe the chemistry. The mechanism involves facile dissociation of hydrogen at individual palladium atoms followed by spillover onto the copper su
Date: Tue, 30.05.2017
Time: 16:00
Location:Technische Universität Wien, Institut für Angewandte Physik, E134 yellow tower „B“, 5th floor, Sem.R. DB gelb 05 B (room number DB05L03), 1040 Wien, Wiedner Hauptstraße 8-10
Contact:Univ.Prof. Dr. Ulrike Diebold/Dr.Parkinson

Top production cross section: matching between relativistic and non-relativistic regimes
Speaker:Angelika Widl (Univ. Wien)
Abstract:im Rahmen des Teilchenphysikseminars
Date: Tue, 30.05.2017
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:A. Hoang, H. Neufeld

Dualities for Wilson loop form factors
Speaker:Emeri Sokatchev (Annecy, LAPTH & CERN)
Date: Wed, 31.05.2017
Time: 11:30
Duration: 60 min
Location:ESI, Boltzmann lecture hall
Contact:Daniel Grumiller

The MoEDAL Experiment at the LHC: searching for highly ionising avatars of new Physics
Speaker:Prof. Nicolaos Mavromatos (Theory Division, CERN & Theoretical Particle Physics and Cosmology Group, King's College London)
Abstract:In the talk I will review the current status of the MoEDAL experiment at the Large Hadron Collder (LHC) at CERN, which is the seventh (in order of approval) LHC experiment. The experiment is dedicated to searches for Highly Ionising (slow moving long-lived or stable) Particles (HIPs), that are predicted to appear in a plethora of new physics models, including the elusive magnetic monopole, slowly moving, long-lived, charged supersymmetric partners etc. The arrays of plastic nuclear-track detectors and aluminum trapping volumes of MoEDAL provide two independent and passive detection techniques. The experiment has been in full operation already during the RUN I (8 TeV pp collisions) of LHC and continue to do so in the current RUN II (13 TeV pp collisions). In the talk, I will review in detail... (full abstract available at: https://indico.smi.oeaw.ac.at/event/222/)
Date: Wed, 31.05.2017
Time: 17:00
Duration: 60 min
Location:Stefan-Meyer-Institut, Boltzmanngasse 3, 1090 Wien, Seminarraum 3-2-08 (2. Stock)
Contact:Prof. Dr. Eberhard Widmann, Dr. Martin Simon

Life is rough for proteins in cell adhesion - binding constants of membrane-anchored proteins in cell adhesion strongly depend on the nanoscale roughness of the membranes
Speaker:Thomas Weikl (Max Planck Institute of Colloids and Interfaces Potsdam, Germany)
Abstract:Cell adhesion and the adhesion of vesicles to the membranes of cells or organelles are pivotal for immune responses, tissue formation, and cell signaling. The adhesion processes depend sensitively on the binding constant of the membrane-anchored receptor and ligand proteins that mediate adhesion, but this constant is difficult to measure in experiments. We have investigated the binding of membrane-anchored receptor and ligand proteins with molecular dynamics and Monte Carlo simulations. Our simulations indicate that the binding constant of the anchored proteins strongly decreases with the membrane roughness caused by thermally excited membrane shape fluctuations on nanoscales. I will present a general theory that explains the roughness dependence of the binding constant for the anchored proteins, and that relates this constant to the binding constant of soluble proteins without membrane
Date: Thu, 01.06.2017
Time: 09:00
Location:TU Wien 1060 Wien, Getreidemarkt 9 Lehar 2 (BC 2nd floor)
Contact:Univ.Prof. Dr. G. Schütz