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Calendar of Physics Talks Vienna
| Spatial entanglement patterns and Einstein-Podolsky-Rosen steering in a Bose-Einstein condensate |
| Speaker: | Matteo Fadel (Universität Basel) |
| Abstract: | Atomic Bose-Einstein condensates (BECs) are highly controllable isolated quantum systems with long coherence times, and offer applications in metrology and quantum information processing. We experimentally prepare two-component Rubidium-87 BECs, consisting of a few hundred atoms, on an atom-chip. Using state-selective potentials to tune the collisional interactions (one-axis twisting dynamics); we prepare many-particle non-classical states. After a time-of-flight expansion, high-resolution images allow us to access sub-regions of the atomic density distribution of various shapes and measure the spin correlations between them.
We observe that bi-partitions violate a separability criterion, indicating the presence of entanglement between different spatial regions of our many-body system. In one of such partitions, entanglement is strong enough for Einstein-Podolsky-Rosen steering: measurement outcomes for non-commuting observables in one spatial region can be predicted based on a corresponding measurement in the other region with an inferred uncertainty product below the Heisenberg relation. This feature could be exploited for imaging of electromagnetic and other field distributions with an uncertainty beyond the standard quantum limit.
Reference: https://arxiv.org/pdf/1708.02534.pdf
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| Date: | Mon, 05.03.2018 |
| Time: | 11:00 |
| Location: | Atominstitut, Seminarraum, Stadionallee 2, Wien 2 |
| Contact: | M. Bonneau |
| CoQuS Colloquium Seminar Talk by Jeff Steinhauer |
| Speaker: | Jeff Steinhauer (CoQuS) |
| Abstract: | "Obervation of quantum Hawking radiation and its enganglement in an analogue black hole" - for further information please access: www.coqus.at
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| Date: | Mon, 05.03.2018 |
| Time: | 16:30 |
| Duration: | 120 min |
| Location: | TU Wien, Gußhausstraße 27-29, HS9 |
| Contact: | CoQuS-Team |
| Cold highly charged ions as spectroscopic probes of fundamental interactions |
| Speaker: | José R. Crespo López-Urrutia (Max-Planck-Institut für Kernphysik Heidelberg, Germany) |
| Abstract: | Forbidden optical transitions within the ground state configurations of highly charged ions (HCI) are laseraccessible
and extremely impervious to perturbations and systematics that limit optical clock performance.
Due to these advantages, they have been proposed for novel optical frequency standards. Moreover,
extremely large relativistic, QED, and nuclear size contributions to their wavelengths make them ideal tools
for fundamental studies, and several recent proposals call for their use in sensitive searches of a time
variation of the fine-structure constant. Since HCI withstand photoionization by vacuum-ultraviolet
photons, they could also provide frequency standards for future lasers in that spectral range. We have
demonstrated sympathetic cooling by more than seven orders of magnitude down to mK temperatures for
HCI with lasers, and are carrying out a variety of experiments explorin |
| Date: | Tue, 06.03.2018 |
| 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 |
| “α_s from non-strange hadronic tau decays“ |
| Speaker: | Santiago Peris (IFAE, Barcelona) |
| Date: | Tue, 06.03.2018 |
| Time: | 16:15 |
| Location: | Erwin Schrödinger-Hörsaal, Boltzmanngasse 5, 5. Stock |
| Contact: | G. Ecker, H. Neufeld |
| Low regularity Lorentzian metrics and the causal character of maximizers |
| Speaker: | Melanie Graf (Vienna) |
| Abstract: | For metrics that are at least C1,1 maximizing curves must be solutions of the geodesic equation and hence cannot change causal character: they must remain either timelike or null. This is no longer obvious for metrics of lower regularity and once the regularity drops below Lipschitz there are examples of "bubbling" metrics, for which maximizing causal curves may contain both timelike and null segments. We will present a recent result stating that Lipschitz regularity of the metric is sufficient for maximizing curves to have fixed causal character
and show how this almost immediately gives a Lipschitz inextendibility result for timelike geodesically complete spacteimes. This is joint work with E. Ling.
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| Date: | Thu, 08.03.2018 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Arbeitsgruppe Gravitation, Währinger Strasse 17, Raum 218, 2. Stock, 1090 Wien |
| Contact: | P.T. Chrusciel |
| BLACK HOLE DEGENERACIES & GOPAKUMAR-VAFA INVARIANTS FROM MATHIEU MOONSHINE |
| Speaker: | Aradhita Chattopadhyaya (Indian Institute of Science) |
| Abstract: | The talk is based to 2 papers and is divided into two parts based on the papers: arxiv 1704.00434 & arxiv 1712.08791 respectively.
Part-I:
We study Siegel modular forms associated with the theta lift of twisted elliptic genera of K3 orbifolded with g' corresponding to the conjugacy classes of the Mathieu group M_{24}. We show that the Siegel modular forms satisfy the required properties for them to be generating functions of 1/4 BPS dyons of type II string theories compactified on K3xT^2 and orbifolded by g'.
Part-II:
We evaluate the low energy gravitational couplings, F_g in the heterotic E_8xE_8 string theory compactified on orbifolds of K3xT^2 by g'. The holomorphic piece of F_g is given in terms of a polylogarithim with index 3-2g and predicts the Gopakumar-Vafa
invariants in the corresponding dual type II Calabi-Yau compactifications. |
| Date: | Thu, 08.03.2018 |
| Time: | 16:00 |
| Duration: | 60 min |
| Location: | SEM 136, TU Wien, Freihaus, 10th floor (Wiedner Hauptstr. 8-10, A-1040 Vienna) |
| Contact: | Timm Wrase |
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