
Calendar of Physics Talks Vienna
Quantum Theseus beats the Minotaur faster 
Speaker:  Yasser Omar (University of Lisbon) 
Abstract:  Quantum computers can offer a speedup for the spatial search problem, namely to find a marked vertex in a given graph. In particular, as defined by Childs and Goldstone, it is possible to perform quantum spatial search using a continuoustime quantum walk. Until recently, this approach was known to yield the optimal quadratic speedup only for a handful of graphs, where symmetry and regularity seemed to be key features. However, in a sequence of works together with A. Ambainis, M. Mohseni, H. Neven, L. Novo, and S. Chakraborty, we have shown that quantum spatial search by quantum walk is robust to the loss of edges in a graph, and is in fact optimal for almost all graphs. Furthermore, I will show how these results on search can be extended to establish high fidelity quantum communication between two arbitrary nodes of a random network of interacting qubits, namely to perform quantum sta 
Date:  Mon, 20.06.2016 
Time:  17:30 
Duration:  60 min 
Location:  ATI, Stadionallee 2, LectureHall, Vienna 
Contact:  www.coqus.at / Christina Becker 
Loop functions in thermal QCD 
Speaker:  Antonio Vairo (TU München) 
Abstract:  im Rahmen des Teilchenphysikseminars: We present recent computations of loop functions in thermal QCD like
the Polyakov loop, the Polyakov loop correlator and the cyclic Wilson loop.
We discuss divergences and how to renormalize them. Finally we compare
with lattice data.

Date:  Tue, 21.06.2016 
Time:  16:15 
Duration:  60 min 
Location:  Fakultät für Physik, ErwinSchrödingerHörsaal, Boltzmanngasse 5, 5. Stock 
Contact:  A. Hoang, Y. Wang 
Speaker:  Markus Aspelmeyer (Univ. Wien) 
Abstract:  This is an overview talk on the topic. It starts with the early pioneering experiments by Pound and Rebka and by Colella, Overhauser and Werner that demonstrate the effect of the gravitational potential on the frequency of a photon and on quantum interference fringes in a neutron interferometer, respectively.
The latter represents the first experiment that required the use of both Planck’s constant and Newton’s constant (via earth’s acceleration g) to describe the observed interference fringes. Over the following decades, modern quantum physics added new tools and allowed to significantly expand the available quantum experiments that test the effects of weak gravitational fields, including atomic fountains (pioneered by Kasevich and Chu), lab¬‐based atomic clock tests of the gravitational red shift or the demonstration of gravitationally bound states of cold neutrons. . . . . . 
Date:  Thu, 23.06.2016 
Time:  12:30 
Duration:  60 min 
Location:  Arbeitsgruppe Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock, 1090 Wien 
Contact:  P.T. Chrusciel 
Smooth conformal Einsteinlambdadust flows across timelike infinity 
Speaker:  Helmut Friedrich (MPI Golm) 
Abstract:  We consider the Einsteindust equations with positive cosmological constant $\lambda$ onmanifolds with time slices diffeomorphic to an orientable, compact 3manifold $S$.
It is shown that the set of standard Cauchy data for the Einstein$\lambda$dust equations
on $S$ contains an open (in terms of suitable Sobolev norms) subset of data which develop into solutions that admit at future timelike infinity a spacelike conformal boundary ${\cal J}^+$ that is $C^{\infty}$ if the data are of class $C^{\infty}$ and of correspondingly lower smoothness otherwise. The class of solutions considered here comprises nonlinear perturbations of FLRW solutions as very special cases. It can conveniently be characterized
in terms of asymptotic end data induced on ${\cal J}^+$. These data must only satisfy a linear differential equation. .... 
Date:  Thu, 23.06.2016 
Time:  14:00 
Duration:  60 min 
Location:  Arbeitsgruppe Gravitation, Währinger Strasse 17, Seminarraum A, 2. Stock, 1090 Wien 
Contact:  P.T. Chrusciel 
Nonrelativistic limits of relativistic (super)gravity 
Speaker:  Jan Rosseel (U. Bern) 
Date:  Thu, 23.06.2016 
Time:  14:15 
Duration:  60 min 
Location:  SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 810, A1040 Vienna) 
Contact:  Daniel Grumiller 
Mixed surface oxides on rutile TiO2(011) & Onedimensional electron systems in grain boundaries of MoSe2 
Speaker:  Matthias Batzill (Department of Physics, University of South Florida, Tampa, FL 33620, USA) 
Abstract:  Materials with reduced dimensions, i.e. two or onedimensional, often exhibit unique structural, chemical, and electronic properties compared to bulk (3D) materials. Here I will discuss two quite diverse systems. One system is the 2D mixed surface oxide on a bulk rutile TiO2(011) surface. In particular we investigate the formation of intermixed FeO/TiO2(011) and VOx/TiO2(011) surfaces. These surfaces form complex mixed oxides without bulk counterparts and may give insight on interfaces of oxide heterostructures or surface properties of mixed oxides. The other system is the twin grain boundary in MoSe2. These boundaries form during van der Waals epitaxy of MoSe2 on MoS2 or HOPG substrates. A high density and crystallographical alignment enables angle resolved photoemission (ARPES) electronic structure characterization on crystaldefects for the first time. We demonstrate that these line 
Date:  Thu, 23.06.2016 
Time:  16:00 
Location:  yellow tower „B“, 2th floor, lecture room FH Hörsaal 2 (room number DB02O23), 1040 Wien, Wiedner Hauptstraße 810 
Contact:  Univ.Prof. Dr. Ulrike Diebold 
Circuit NanoElectromechanics 
Speaker:  Hans Hübl (WaltherMeißnerInstitut , Garching, Deutschland) 
Abstract:  Micro and nanomechanical elements are extensively studied due to their importance in force and mass sensing applications. To access their mechanical response, these vibrating elements are typically integrated into an electronic, electromagnetic, or optical environment. In cavity optomechanics, the interaction of a light field in an optical resonator with the mechanical degree of freedom goes beyond the sole readout functionality. Here, the lightmatter interaction enables the manipulation of the mechanical state, manifesting itself e.g. in the form of a damped and amplified the mechanical motion [1]. This coupling concept can be straightforwardly transferred from the optical to the microwave (MW) regime defining the subfield of circuit nanoelectromechanics. Moreover, quantum information processing based on superconducting circuits is also at home in this frequency domain. Therefore, nanoelectromechanics and superconducting quantum circuits use compatible technologies. This paves the way for true hybrid quantum nanoelectromechanical systems that enable the investigation of quantum mechanics in the literal sense.
In my talk, I present a mechanical sensing approach for the investigation of solidstate properties in nanosized systems, show implementations and consequences of the lightmatter interaction in circuit nanoelectromechanical systems, and discuss the physics of a hybrid combining superconducting quantum circuits with nanomechanical elements.

Date:  Fri, 24.06.2016 
Time:  15:30 
Location:  Atominstitut, Hörsaal, Stadionallee 2, Wien 2 
Contact:  J. Majer 
How far we have advanced from the Abrikosov vortices 
Speaker:  Prof. Mikhail A. Shifman (Univ. of Minnesota) 
Abstract:  In the early 1950s, Alexei Abrikosov predicted superconductors of the second kind
and demonstrated that external magnetic fields should generate vortices (magnetic flux
tubes) in the bulk of the superconducting sample. This was the first example of
topological solitons in quantum field theory. In the mid1970s, Nambu, 't Hooft and
Mandelstam conjectured that the dual Meissner effect and formation of chromoelectric
vortex lines were resonsible for quark (color) confinement at strong coupling.
The second coming of the topological vortex strings occurred with the advancement
of supersymmetry.
In 1994 Seiberg and Witten analytically proved the dual Meissner effect in a
supersymmetric YangMills theory with parallels in QCD.
In 2003 the socalled nonAbelian vortex flux tubes were constructed, also in a
supersymmetric setting. . . . . . 
Date:  Fri, 24.06.2016 
Time:  16:15 
Duration:  90 min 
Location:  Fakultät für Physik, ErwinSchrödingerHörsaal, Boltzmanngasse 5, 5. Stock 
Contact:  G. Ecker, A. Hoang, H. Neufeld 
