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Calendar of Physics Talks Vienna
| The anti-Unruh effect in black hole spacetimes |
| Speaker: | Aindriu Conroy (Charles University, Prague) |
| Abstract: | There is no well-defined notion of a particle in quantum field theory in curved spacetime due to the lack of global symmetries.The standard procedure in quantum field theory is to treat fields rather than particles as the fundamental object of interest.Nevertheless in a seminal 1976 paper by W.G. Unruh,an operational meaning was given to the particle concept by examining the absorption and emission of field quanta by a two-level atom.This is the so-called Unruh-DeWitt detector and, in this operational sense,we say a particle is what a particle detector detects!Computing the response of an Unruh-DeWitt detector in black hole spacetimes is technically challenging â a fact which has largely limited the literature to stationary detectors.In this talk we consider the response of an Unruh-DeWitt detector near an extremal charged black hole,modelling the near-horizon region of this extremal ... |
| Date: | Tue, 10.01.2023 |
| Time: | 14:00 |
| Duration: | 60 min |
| Location: | Fakultaet fuer Physik, Erwin Schroedinger-HS, Boltzmanngasse 5, 5. Stock |
| Contact: | S. Fredenhagen, D. Grumiller, E. Battista, R. Ruzziconi |
| Speaker: | Electrons meet light (TU Wien, Institut für Angewandte Physik) |
| Abstract: | The precise transverse control of electrons is at the heart of any high-resolution electron microscope where electron lenses and multipole aberration correctors have enabled sub-Angström spatial resolution.
This work describes a novel way of achieving transverse control over the electrons [1]. In the specimen chamber of a modified ultrafast scanning electron microscope, the electron pulse interacts in free space with a shaped counterpropagating laser pulse, inducing on-demand phase shifts to the electron wave. We demonstrate convex and concave light-based electron lensing, whereas concave lensing is impossible with traditional magnetostatic lenses. Furthermore, we show that we can create arbitrary electron intensity patterns. In contrast to other competing electron-shaping technologies, the light-based method is programmable and avoids losses, inelastic scattering, and instabilities due |
| Date: | Tue, 10.01.2023 |
| Time: | 16:00 |
| Location: | TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner HauptstraÃe 8-10 Yellow Tower âBâ, 5th floor, SEM.R. DB gelb 05 B |
| Contact: | Dr. Richard Wilhelm |
| The cosmological constant, anomalies and an emergent Standard Model |
| Speaker: | Steven Bass (Jagiellonian University, Krakow) |
| Abstract: | We discuss the Higgs mass and cosmological constant hierarchy puzzles with emphasis on the
interplay of Poincare invariance, mass generation and renormalization group invariance.
A plausible explanation involves an emergent Standard Model with the cosmological constant scale
suppressed by power of the large scale of emergence. In this scenario the cosmological constant scale
0.002 eV and (Majorana) neutrino masses should be of similar size. |
| Date: | Tue, 10.01.2023 |
| Time: | 16:15 |
| Duration: | 60 min |
| Location: | Fakultaet fuer Physik, Erwin Schroedinger-HS, Boltzmanngasse 5, 5. Stock |
| Contact: | A. Hoang, M. Procura |
| The Impact of Imperfect Timekeeping on Quantum Computation |
| Speaker: | Jake Xuereb (TU Wien) |
| Abstract: | In order to unitarily evolve a quantum system, an agent requires knowledge of time, a parameter which no physical clock can ever perfectly characterise. In this talk, I will communicate how limitations on acquiring knowledge of time impact quantum computation. The quality of timekeeping an agent has access to impacts the gate complexity they are able to achieve within a computation. Although some tasks such as cooling a qubit can be achieved using a timer of arbitrary quality for control.
To carry out these investigations, I will introduce tick distributions, a tool developed in the field of autonomous quantum clocks [1,2] which allows us to understand the operational performance of a clock and the average gate fidelity of a noisy channel introduced by the randomized benchmarking [3,4] community which allows one to investigate the quality of a quantum computation. Putting these techniqu |
| Date: | Wed, 11.01.2023 |
| Time: | 16:15 |
| Duration: | 45 min |
| Location: | Hörsaal/https://tuwien.zoom.us/j/99712909944?pwd=dmlybGJYa2tTUWdFQlNNRmJ6YWx3dz09 |
| Contact: | Maximilian Prüfer |
| Obstruction-free gluing for the Einstein equations |
| Speaker: | Stefan Czimek, Leipzig |
| Abstract: | We present a new approach to the gluing problem in General Relativity, that is, the problem of matching two solutions of the Einstein equations along a spacelike or characteristic (null) hypersurface.
In contrast to previous constructions, the new perspective actively utilizes the nonlinearity of the constraint equations. As a result, we are able to remove the 10-dimensional spaces of obstructions to
gluing present in the literature. As application, we show that any asymptotically flat spacelike initial data set can be glued to Schwarzschild initial data of sufficiently large mass. This is joint work with I. Rodnianski. |
| Date: | Thu, 12.01.2023 |
| Time: | 15:15 |
| Duration: | 60 min |
| Location: | Seminarraum A, Währinger Strasse 17, 2. Stock |
| Contact: | P. Chrusciel, D. Fajman |
| Strange metal heavy fermion compounds A testbed for quantum simulators and entanglement meters? |
| Speaker: | Silke Paschen (Institute of Solid State Physics, TU Wien) |
| Abstract: | Strange metals are best known for their linear-in-temperature electrical resistivity at low temperatures â a state out of which new phases such as unconventional superconductivity may nucleate. They can neither be described by the standard theory of metals, Fermi liquid theory, nor by the standard theory of quantum phase transitions, which is based on order parameter fluctuations. As they are ubiquitous in various classes of strongly correlated electron systems, a unified theoretical description is in high demand. Heavy fermion compounds are particularly versatile model materials for studying this physics: they are comparatively simple, clean, and highly tunable, and a number of unique characteristics have already been identified. After providing the necessary background and reviewing recent developments, I will discuss how insights gained from these studies may guide the development of |
| Date: | Fri, 13.01.2023 |
| Time: | 10:00 |
| Duration: | 45 min |
| Location: | Hörsaal/https://tuwien.zoom.us/j/99712909944?pwd=dmlybGJYa2tTUWdFQlNNRmJ6YWx3dz09 |
| Contact: | Jörg Schmiedmayer |
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