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Calendar of Physics Talks Vienna
| CoQuS colloquium with Cindy Regal, University of Colorado, Boulder |
| Speaker: | Cindy Regal (CoQuS) |
| Abstract: | Harnessing opto-mechanical correlations in electro-optic conversion and quantum-limited interferometry
I discuss our work in quantum cavity optomechanics, and some recent experiments harnessing correlations between multiple modes – like those behind ponderomotive squeezing. In experiments to create an quantum converter between microwave and optical fields, we reduce the impact of thermal noise using electro-optic correlations in a 50% efficient converter. In an interferometer limited by the tradeoff between shot noise and backaction, we use correlations to improve broadband displacement detection at the standard quantum limit. |
| Date: | Mon, 14.01.2019 |
| Time: | 17:00 |
| Location: | Lise-Meitner Lecture Hall, Boltzmanngasse 5, 1090 Vienna |
| Contact: | CoQuS office |
| Quantum Null Energy Condition – Analytic, Perturbative and Numerical Results |
| Speaker: | Philipp Stanzer (TU Wien) |
| Abstract: | The quantum null energy condition (QNEC) is the only known local energy condition
which holds in any quantum field theory in more than two dimensions (given some
assumptions like unitarity). The QNEC relates the null-projection of the energy momentum tensor to the second variation of the entanglement entropy with respect
to a deformation of the entangling region along the same null direction.
After studying QNEC in four dimensional holographic conformal field theories, we
consider similar setups in two spacetime dimensions, where the QNEC takes a sharper
form. We are especially interested in the saturation behavior of the QNEC inequality
and its relation to matter in the bulk of the dual theory as well as in the leading
corrections to the supergravity approximation from quantum backreactions for
finite Newton coupling.
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| Date: | Tue, 15.01.2019 |
| Time: | 13:45 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | S. Fredenhagen, D. Grumiller |
| Catching, interfering, and entangling single bosonic atoms |
| Speaker: | Cindy Regal (University of Colorado, Boulder) |
| Abstract: | I will discuss experiments on control and entanglement of individual neutral atoms in optical tweezers laser-cooled to their motional ground state. We interfere atoms in an atomic analog to the Hong-Ou-Mandel effect, and we create spin entangled states using both on-site exchange and a measurement-based technique. Discussing all of these experiments together is a cute exercise in what can be done with two identical particles. To create larger sets of atoms for future quantum physics with many particles, we image atoms and rearrange them to form ordered arrays; our atom assembly is aided by a new technique for catching single atoms – namely using grey molasses to control atomic collisions in the optical tweezers. |
| Date: | Tue, 15.01.2019 |
| Time: | 14:30 |
| Location: | Atominstitut, Seminarraum, Stadionallee 2, Wien 2 |
| Contact: | Arno Rauschenbeutel |
| Experiments, Finite-Element and Molecular Dynamic Calculations for LIPSS (Laser Induced Periodic Surface Structures) formation during ultra-short laser ablation |
| Speaker: | Prof. Dr. Wolfgang Husinsky (TU Wien, Institut für Angewandte Physik) |
| Abstract: | Irradiation of many surface materials by ultra-short laser radiation, typically with pulsewidths of 10-300fs, results in the development of Laser-induced self-organized periodic surface structures (ripples). The periodicity of these structures range from the wavelength λ of the laser to well below λ. Structures down to a few tens of nm can be observed. However, the existence and form of the LiPSS critically depends on the the intensity, fluence, wavelength and pulsewidth of the laser light as well as on the number of laser pulses and, not to forget, the material properties [1].
The development of the LIPSS structure can be regarded as a complex interplay between the electric field on the surfaces (including surface plasmon-polaritons) [2] and the ultra-short-laser-ablation dynamics [3]. Since the formation of LIPSS in most cases requires multiple laser pulses, the surface topography and |
| Date: | Tue, 15.01.2019 |
| 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. Friedrich Aumayr |
| Infrared analysis for perturbative amplitudes |
| Speaker: | George F. Sterman (SUNY, Stony Brook) |
| Abstract: | 3. Vorlesung im Rahmen der Schrödinger-Gastprofessur:
I'll review how infrared divergences arise in perturbative amplitudes with massless particles
For fixed-angle and forward scattering, introducing Landau equations, Coleman-Norton
Physical pictures and power counting as tools. In gauge theories, this analysis leads to
factorized expressions, closely related to effective theory descriptions of the amplitudes.
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| Date: | Tue, 15.01.2019 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultät für Physik, Erwin-Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, H. Neufeld |
| Strong Cosmic Censorship and Quasinormal Modes |
| Speaker: | Joao Costa (ISCTE Lisboa, Portugal) |
| Abstract: | I will present some recent results concerning the Strong Cosmic Censorship Conjecture (SCCC) in the presence of a positive cosmological constant. I will start by reviewing some of the progress made in the context of the Einstein-Maxwell-scalar field system in spherical symmetry and the linear wave equation in the black hole interior of Reissner-Nordström de Sitter. These results show that the validity of the SCCC hinges on the precise decay rates of perturbations along the event horizon which are known to be determined by the black hole´s quasinormal spectrum. I will also discuss recent numerical computations of quasinormal modes that suggest the failure of th SCCC in
a near extremal regime of charged de Sitter black holes.
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| Date: | Thu, 17.01.2019 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel, D. Fajman |
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