Calendar of Physics Talks Vienna

Towards full quantum-coherent control of coupled electron spins on a surface
Speaker:Christoph Wolf (Center for Quantum Nanoscience, Institute for Basic Science and Ewha Womans University, Seoul/Korea)
Abstract:In less than a decade since the first measurement of electron spin resonance (ESR) in a scanning tunneling microscope (STM) we have now achieved quantum-coherent control of individual electron spins on a surface.[1,2] In this talk, I first want to highlight a few aspects of the ESR-STM technique, such as the ability to distinguish different isotopes by identifying the nuclear spin, the high-precision determination of the electron ground state and the measurement of exchange-coupling constants between individual molecular dimers. [3-5]. In the second part of my talk, I will introduce a new paradigm in ESR-STM that has only emerged in the past two years: quantum coherent control. By utilizing the sub-atomic spatial precision of the STM, we are able to build structures of only a few atoms. Using the high energy resolution we can then determine the interaction Hamiltonian and design quantu
Date: Tue, 30.05.2023
Time: 16:00
Location:TU Wien, Institut für Angewandte Physik, E134 1040 Wien, Wiedner Hauptstraße 8-10 Yellow Tower „B“, 5th floor, SEM.R. DB gelb 05 B
Contact:Univ.Prof. Dr. Ulrike Diebold

Setup of an atom array with cavity-mediated interactions
Speaker:Johannes Schabbauer (TU Wien, Atominstitut)
Abstract:Achieving non-local interactions and multiparticle entanglement are essential goals for quantum simulation and quantum information processing. I will report on the construction of a new platform with neutral atoms trapped in an array of optical tweezers with photon-mediated interactions. A strong coupling of the single atoms to the photon field is implemented by a fiber cavity with high finesse . The atoms are individually addressable by using a high resolution microscope, which is also used for imaging. In addition, site-resolved non-destructive readout can be achieved via dispersive coupling to the cavity field. Our approach provides a scalable platform to study many-body physics and entanglement with programmable connectivity.
Date: Wed, 31.05.2023
Time: 16:15
Duration: 15 min
Location:Helmut Rauch Hörsaal ATI
Contact:Maximilian Prüfer

A topological path to the Hawking temperature: astrophysical black holes and analogues
Speaker:Charles Robson (Tampere University)
Abstract:In this talk, a topological approach to determining the Hawking temperature of black holes is presented, embodied in a powerful, covariant formula involving the Euler characteristic of a (Euclideanized) spacetime manifold. This method has the advantage of allowing thermodynamical calculations to be simply carried out on spacetimes of complicated metrical form, as well as shining a light on the little-known but deep links between lower-dimensional topology and black hole thermodynamics. The method's efficacy for quantum soliton thermodynamics is also illustrated. Based on Phys. Rev. D 99, 044042 (2019) and New J. Phys. 21 (2019) 053042.
Date: Thu, 01.06.2023
Time: 15:00
Duration: 60 min
Location:TU Wien, Freihaus, Seminar room 10th floor
Contact:Daniel Grumiller, Iva Lovrekovic

Large-scale structure cosmology at the interface of numerical and analytical techniques
Speaker:Oliver Hahn (Astrophysics, Vienna)
Abstract:The quest for physics beyond the standard models of cosmology and particle physics is the primary motivation for upcoming observatories in space and on earth.The cosmic large-scale structure provides a unique testing ground for connecting fundamental physics to astronomical observations.A detection of the signature of massive neutrinos,deviations from Einstein’s theory of gravity,physical insights into the earliest inflationary phase of the Universe and the microphysical nature of dark matter and dark energy are all within the potential reach of these experiments in the next decade.In order to accurately link observations to fundamental physics,analytical,numerical, and data-driven techniques will be used.I will give a general introduction and discuss recent progress at the interface between numerical simulations and analytical calculations that enable faster and more robust predictions
Date: Thu, 01.06.2023
Time: 15:30
Duration: 60 min
Location:Seminarraum A, Waehringer Straße 17, 2. Stock
Contact:P. Chrusciel, D. Fajman

Coherent perfect absorption and transmission of light with arbitrary wavefronts
Speaker:Stefan Rotter (TU Wien)
Abstract:In my talk I will present two recent works focused on the perfect absorption and transmission of waves through interferometric cancellation of backscattering. In the first case [1], we demonstrate that even a weakly absorbing film can be turned into a “coherent perfect absorber” by building a degenerate cavity around it. This special cavity perfectly couples incoming light fields with arbitrary wavefronts into the absorber – even for the case that light is a dynamically varying speckle pattern. In the second case [2], we demonstrate how to construct an anti-reflection structure for a complex scattering system like a disordered medium. Similar to an anti-reflection coating for conventional eye-glasses, this structure leads to perfect transmission across the scattering system by suppressing back-scattering for any incoming wavefront. Successful experimental implementations will be discusse
Date: Fri, 02.06.2023
Time: 10:00
Duration: 45 min
Location:ATI Hörsaal/https://tuwien.zoom.us/j/93672218922?pwd=dEZNQ2liVzRNNURvNmVWVE5KUWRiQT09
Contact:Jörg Schmiedmayer