CPT

Calendar of Physics Talks Vienna

Intensity correlations: imaging and quantum optics in astrophysics
Speaker:Robin Kaiser (Université Côte d'Azur)
Abstract:In this talk, I will give an introduction to intensity correlations for astrophysical imaging, as pioneered by Hanbury Brown and Twiss. This triggered a wider effort for the field of quantum optics, which I will put into a larger context beyond astrophysical imaging. I will also give an overview of the past results on intensity correlations for astrophysical imaging by our group in Nice and present the ongoing effort towards resolving a white dwarf and to search for signatures of random lasing in space.
Date: Tue, 28.01.2025
Time: 11:00
Duration: 45 min
Location:Ernst Mach Hörsaal, Boltzmanngasse 5, 2nd floor, University of Vienna
Contact:Uros Delic

Exploring atom-ion Feshbach resonances below the s-wave limit
Speaker:Fabian Thielemann (Universität Freiburg)
Abstract:Collisions between particles are at the heart of many physical and chemical processes. The ability to control them down to the single quantum level is crucial to understanding the constituents and their interaction. We use our hybrid setup to combine a single 138Ba+ ion with a cloud of ultra-cold, spin-polarized 6Li near degeneracy. By tuning the collision energy of the system, we observe the transition from the classical to the quantum regime of collisions. Applying this technique to investigate individual atom-ion Feshbach resonances, we identify two resonances that obey qualitatively different scaling laws. By comparison with a beyond-threshold resonant recombination model, we associate this with different orbital-angular-momentum scattering channels
Date: Tue, 28.01.2025
Time: 13:30
Duration: 45 min
Location:Helmut Rauch Hörsaal ATI
Contact:Tim Langen

Competing ferroelectric and incommensurate states in DyFeO3
Speaker:Maxim Mostovoy (Zernike Institute for Advanced Materials, University of Groningen)
Abstract:Rare earth orthoferrites exhibit a variety of interesting physical phenomena in magnetically ordered states, such as the anomaly of the speed of sound and the magnetically-induced ferroelectricity. The frustrated magnet, Dy orthoferrite, hosts competing states with very different physical properties. I will show that the coupling between Dy and Fe spins makes the uniform state unstable against formation of a periodic array of domain walls. The interaction between the Dy domain walls is mediated by magnons propagating through the Fe magnetic subsystem, similar to the Yukawa interactions between protons and neutrons resulting from the pion exchange. The magnetic domain walls are electrically charged and the competition between the incommensurate and uniform phases leads to high sensitivity of the spin state to applied electric and magnetic fields.
Date: Wed, 29.01.2025
Time: 16:00
Duration: 45 min
Location:Freihaus, Seminarraum DC rot 07 (roter Bereich, 7. OG)
Contact:Andrei Pimenov

Glueball phenomenology in the eLSM and the rho-pi puzzle
Speaker:Arthur Vereijken (Jan Kochanowski U., Kielce)
Abstract:QCD predicts bound states of its force carrier particles, the gluons, called glueballs. They are not yet discovered by experiment although there is a lot of theoretical models for them. I will give a brief overview of the status of glueballs and results on glueballs in an effective chiral model called the extended Linear Sigma Model (eLSM). Afterwards I will focus on the "rho-pi" puzzle, an unexplained phenomena in the decay of bound charm-anticharm states, and show some preliminary results on how mixing with a vector glueball might resolve this issue.
Date: Thu, 30.01.2025
Time: 14:00
Duration: 60 min
Location:TU Wien, Wiedner Hauptstr. 8-10, seminar room, 10th floor (yellow) and https://tuwien.zoom.us/j/61583396074?pwd=SXYspHPbbj6CaypsbTC2MV0BDD2bx3.1
Contact:Anton Rebhan