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Calendar of Physics Talks Vienna
| Speaker: | Sang-Wook Cheong (Rutgers University ) |
| Abstract: | Chirality with all broken mirror symmetries, combined with spatial rotations, matters ubiquitously from DNA functionality, vine climbing, to the piezoelectricity of quartz crystals. Chirality does not necessarily involve the presence of screw-like twisting, and magnetic chirality means chirality in spin ordered states or mesoscopic spin textures. Magnetic chirality does not change with time reversal operation, and chirality prime means that time reversal symmetry in addition to all mirror symmetries, combined with any spatial rotations, are broken.
Four examples of magnetic chirality will be discussed: helical spin state, magnetic toroidal moment combined with canted moment, magnetic quadruple moment combined with alternating canted moments, and Bloch-type skyrmions. Some of these exotic phenomena have been recently observed, and many of them steel need to be experimentally confirmed |
| Date: | Mon, 14.11.2022 |
| Time: | 11:00 |
| Duration: | 45 min |
| Location: | Fachgruppenraum Physics, yellow area, 1st floor |
| Contact: | Andrei Pimenov |
| Speaker: | Joerg Frauendiener (Otago, New Zealand) |
| Abstract: | It is well known that gravitational waves interact in a non-linear way. This makes it difficult to describe them rigorously. The cleanest description is based on a certain conformal invariance of the Einstein equations â a fact which was established by R. Penrose and was used by H. Friedrich to prove several important global results for general relativistic space-times. The so-called conformal field equations implement this conformal invariance on the level of partial differential equations. They provide various well-posed initial (boundary) value problems for use in different situations. The talk will give a computational perspective on the non-linear interaction of gravitational waves with an initially static (and spherically symmetric) black hole. We will show how to kick it and possibly how to spin it up. Time permitting, we will also discuss the emergence of quasi-normal modes. |
| Date: | Mon, 14.11.2022 |
| Time: | 14:10 |
| Duration: | 60 min |
| Location: | Gravitationsphysik, Seminarraum A, Waehringer Strasse 17, 2. Stock |
| Contact: | P. Chrusciel, D. Fajman |
| Power corrections in Drell-Yan processes |
| Speaker: | Sergio Leal Gomez (Universität Wien) |
| Abstract: | Factorization theorems are known to be extremely powerful tools in high-energy particle physics. Processes like SIDIS, Drell-Yan vector-boson production,Higgs-boson production through gluon fusion and electron-positron annihilation to jets and/or hadrons are just some examples of processes that have been thoroughly investigated by applying rigorous factorization formulae. Furthermore, if in these processes the transverse momentum qT of the vector boson or final-state hadrons is measured, then in the limit of small qT,leading-power transverse-momentum-dependent (TMD) factorization is an established tool to obtain further insight into the internal structure of the hadrons involved (like spin and helicity distributions, sea quark contributions).However, in order to properly exploit increasingly precise experimental data, it is important to investigate sub-leading contributions. |
| Date: | Tue, 15.11.2022 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Erwin-Schrödinger-Hörsaal, Fakultät für Physik, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, M. Procura |
| The Quantum Wigner-Smith Operator: Optimal Micromanipulation, Metrology and Vacuum Forces |
| Speaker: | Lukas Rachbauer (TU Wien Atominstitut) |
| Abstract: | We introduce the quantum Wigner-Smith (QWS) operator, a Hermitian operator describing the interaction between the spatial as well as the quantum degrees of freedom of light and a local classical parameter of a linear, but otherwise arbitrarily complex scattering medium through which the light propagates. The QWS operator builds a bridge between quantum micromanipulation, vacuum forces and quantum metrology on the one side, and the formalism of classical scattering matrices, which are experimentally measurable in a noninvasive manner, on the other side. We show how to design protocols for optimal micromanipulation as well as for optimal parameter estimation by shaping both the spatial and the quantum degrees of freedom of light. Also, the forces of the quantum vacuum naturally emerge from the formalism. |
| Date: | Wed, 16.11.2022 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Hörsaal ATI |
| Contact: | Maximilian Prüfer |
| Strong Cosmic Censorship near FLRW spacetimes with negative spatial curvature |
| Speaker: | Liam Urban (Vienna) |
| Abstract: | To understand to which extent cosmological models make sense as an approximation of our universe,it is of particular interest to study their stability within the Einstein equations.In this talk,I will present a recent result based on joint work with David Fajman,in which we prove that FLRW spacetimes with negative spatial sectional curvature and(non-trivial)spatially homogeneous scalar field are nonlinearly stable within the Einstein scalar-field system.This also verifies the Strong Cosmic Censorship conjecture(in a C^2-sense)near these FLRW spacetimes in both the collapsing and the expanding direction,which we analyse separately:Toward the Big Bang,one observes stable curvature blow-up that drives geodesic incompleteness.Crucially,this is shown with a covariant approach using Bel-Robinson variables that is largely independent of spatial geometry and may prove to be very robust . . |
| Date: | Thu, 17.11.2022 |
| Time: | 15:15 |
| Duration: | 60 min |
| Location: | Gravitationsphysik, Seminarraum A, Waehringer Strasse 17, 2. Stock |
| Contact: | P. Chrusciel, D. Fajman |
| Quantum Photonics using Structured Photons |
| Speaker: | Robert Fickler (Tampere University) |
| Abstract: | Shaping the transverse structure of quantum light has attracted a lot of attention in quantum photonics ranging from fundamental studies to quantum information applications. A powerful way to describe any spatial structure in the paraxial limit are orthogonal transverse spatial modes e.g. Laguerre-Gauss modes. Amongst many other things, such modes show interesting features like a theoretically unbound quanta of orbital angular momentum (OAM) per single photon. Moreover, such spatial structures serve as a versatile testbed for novel complex quantum states.
In this seminar, I will introduce the concept of spatial structures and show some of the key areas of their application in quantum optics and quantum information. I will present advanced schemes of spatial-mode modulation and how they can be used to generate spatial-mode N00N states. The latter describes states where N photons are in a |
| Date: | Fri, 18.11.2022 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | ATI Hörsaal/https://tuwien.zoom.us/j/93672218922?pwd=dEZNQ2liVzRNNURvNmVWVE5KUWRiQT09 |
| Contact: | Marcus Huber |
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