Calendar of Physics Talks Vienna

CoQuS colloquium - Seminar Talk by Matthias Troyer (ETH Zurich)
Speaker:Matthias Troyer (ETH Zurich)
Abstract:-- Applications and validation of quantum devices -- About a century after the development of quantum mechanics we have now reached an exciting time where non-trivial devices that make use of quantum effects can be built. Already there are a number commercial and experimental devices making non-trivial use of quantum effects (including quantum random number generators, quantum encryption systems, analogue quantum simulators and quantum optimizers). In this colloquium I will present validation tests we performed on some of the early analogue quantum devices and will end with an outlook towards universal “digital” quantum computers and their applications
Date: Mon, 07.11.2016
Time: 16:30
Location:Lise Meitner Hörsaal, Strudlhofgasse 4, 1st floor, Vienna
Contact:CoQuS Team

Exact solution of quantum field theory toy models
Speaker:Prof. Raimar Wulkenhaar (Mathematisches Inst. der Westfälischen Wilhelms-Univ., Münster)
Abstract:Matrix models share all interesting features of quantum field theory: graphical description and Feynman rules, power counting dimension, regularisation and renormalisation, divergence of the perturbation series. The first half of the talk will discuss that analogy. In the second half we report on two matrix models where much more is possible: to give exact non-perturbative formulae for any renormalised correlation function, or at least their reduction to one new special function. We will also describe a map which projects these matrix correlation functions to Schwinger functions of an ordinary quantum field theory. We are optimistic that in one of the models the Schwinger 2-point functions satisfies the Osterwalder-Schrader axioms. These results were obtained in joint work with Harald Grosse and partly with Akifumi Sako.
Date: Tue, 08.11.2016
Time: 14:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:S. Fredenhagen, H. Grosse

Cyclotron resonance in Dirac-type materials
Speaker:Milan Orlita (Laboratoire National des Champs Magnétiques Intenses - Grenoble, CNRS)
Abstract:Cyclotron motion of electrons in a magnetic field, and the related resonant absorption of light at the cyclotron frequency, is probably the most representative magneto-optical effect, characteristic of any solid with non-zero free charge carrier density. In this talk, I will review selected results of cyclotron resonance measurements done on different materials which host conical (Dirac-type) features within their band structures (e.g., single and multilayer graphene, graphite, gapless HgCdTe, HgTe quantum wells). In contrast to conventional systems with parabolic bands, such materials imply fairly complex, in general multimode, cyclotron resonance response, which allows us get relevant insights into the electronic states of these materials, as well as into particular elastic and inelastic (e.g. Auger) scattering mechanisms.
Date: Tue, 08.11.2016
Time: 15:00
Duration: 45 min
Location:Seminarraum DC rot 07 (Freihaus, roter Bereich, 7. OG), Wiedner Hauptstraße 8-10, 1040 Wien
Contact:Andrei Pimenov

Discovery of emergent materials for spintronics applications
Speaker:Prof. Dr. Hugo Dil (Institute of Physics, Ecole Polytechnique Fédérale de Lausanne (EPFL) Switzerland)
Abstract:Spintronics, the use of the spin of the electron rather than its charge, bears significant promise to expand on current technology. Besides a reduced energy consumption and increased flexibility, spintronics also can function as the basis for quantum computing. To make true on this promise, materials with novel electronic and spin properties are required. In our research we primarily focus on how spin-­‐orbit interaction can be used as a powerful tool for creating novel properties, especially when combined with magnetism or correlation effects. Spin-­‐orbit interaction can also drive the system to new physical phases as exemplified by topological insulators and Weyl semimetals. Using various spectroscopic techniques we explored a wide variety of materials with different characteristics. After a brief introduction to the used techniques and the scientific background, I will give an overvi
Date: Tue, 08.11.2016
Time: 16:15
Location:TU Wien, Freihaus Zeichensaal 3, 7. Stock, Turm A
Contact:Univ.Prof.Dr. Friedrich Aumayr

Two puzzles in the beauty sector of QCD
Speaker:Dmitri Melikhov (Uni Wien)
Date: Tue, 08.11.2016
Time: 16:15
Duration: 60 min
Location:Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock
Contact:H. Neufeld

A "liquid-solid" phase transition in a simple model for swarming
Speaker:Prof Elliott Lieb (Princeton University)
Abstract:We consider a non-local shape optimization problem, which is motivated by a simple model for swarming and other self-assembly/aggregation models, and prove the existence of different phases. A technical key ingredient, which we establish, is that a strictly subharmonic function cannot be constant on a set of positive measure. (With Rupert Frank)
Date: Wed, 09.11.2016
Time: 14:00
Location:Erwin Schrödinger International Institute, Boltzmanngasse 9, 1090 Wien, Boltzmann lecture hall

Exotic Charged States of Charmonium and Bottomonium
Speaker:Prof. Dr. Simon Eidelman (Budker Institute of Nuclear Physics SB RAS and Novosibirsk State University)
Abstract:We discuss exotic charged states in heavy quarkonia based on recent experimental observations from Belle, BESIII and LHCb. For charmonium they include studies of Z(4430) at Belle and LHCb as well as studies of Z_c(3900) and Z_c(4020) at BESIII. For bottomonium a discovery of Z_b(10610) and Z_b(10650) at Belle is presented. We also briefly report on the observation of some other exotic states of charmonium. both charged, like X(4050) and X(4250), and neutral, like X(3872), whose nature is not yet completely understood.
Date: Wed, 09.11.2016
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

Decoherence due to time dilation
Speaker:Caslav Brukner (Univ. Vienna)
Abstract:im Rahmen des Literaturseminars der Gravitationsphysik
Date: Thu, 10.11.2016
Time: 14:00
Duration: 60 min
Location:Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien
Contact:P.T. Chrusciel

Time dependence of holographic spectral function
Speaker:Lata Joshi (IIT Bombay, India)
Abstract:Using state/geometry map, we have proposed a method to find retarded propagator in generic non-equilibrium states. We discuss the spectral function of a scalar in a class of non-equilibrium states. This class is given in terms of AdS-Vaidya geometry with an arbitrary parameter characterizing the dual state transition from one thermal state to another due to a homogenous quench. In this talk, I will discuss different routes and patterns of spectral function thermalization under various quench duration and scalar momenta.
Date: Thu, 10.11.2016
Time: 16:00
Location:SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna)
Contact:Ayan Mukhopadhyay

Exploring strong correlations in few-fermion
Speaker:Andrea Bergschneider (Universität Heidelber)
Abstract:Our experimental preparation of few-fermion systems give us full control on the many-body quantum state and allows us to explore few-particle physics in the limit of low entropy. By tailoring the trapping potential and tuning the inter-particle interaction strengths we study strongly correlationed systems with few particles. I will talk about two examples of strongly correlated systems that we have recently realized in our setup. In the first set of experiments, we prepared an anti-ferromagnetic Heisenberg spin chain consisting of up to four fermions in 1D potential. Our measurements represent the first observation of anti-ferromagnetic ordering without an underlying lattice potential. In another experiment, we prepared two interacting fermions in the ground state of a double-well potential. This system represents the fundamental building block of the Fermi-Hubbard model. Our current research interest is to increase the size of our systems while keeping the entropy low to study strong correlations in the cross-over to the many-body regime. For probing the system we detect single atoms with spin and spatial resolution. I will report on our progress on a simple detection method that will allow us to directly measure correlations in our systems with arbitrary atom numbers.
Date: Fri, 11.11.2016
Time: 11:00
Location:Atominstitut, Hörsaal, Stadionallee 2, Wien 2
Contact:J. Schmiedmayer

Structures, processes and interactions at solid/liquid interfaces
Speaker:Prof. Dr. Markus Valtiner (Max-­‐Planck-­‐Institut für Eisenforschung GmbH, Düsseldorf & Technische Universität Bergakademie Freiberg Germany)
Abstract:Structure and molecular dynamics at solid/liquid interfaces are central to many applications and processes in biological and technological areas. These range from specific surface/molecule interactions in biological signaling, adhesion and sensor applications, to energy storage and conversion, as well as materials degradation. Here, I will first provide a detailed overview on the chemical physics and our current understanding of solid/liquid interfaces and will discuss their technological importance. I will then specifically detail how force probe techniques allow us to study and understand processes at solid/liquid interfaces. Specific applications of force probe techniques in the field of corrosion, electrolyte structuring and the study of dynamic single molecule/surface interactions will be reviewed in detail. Finally, new ideas and perspectives for further unraveling structure and dy
Date: Fri, 11.11.2016
Time: 16:00
Location:Technische Universität Wien, TU-Bibliothek, Resselgasse 4, 5th floor, lecture hall
Contact:Univ.Prof.Dr. Friedrich Aumayr