ERIK MCLEAN / UNSPLASH

Physikalisches Kolloquium

Freitag, 8. Mai 2026 17:00 Uhr  Polymers - Soft Matter as Model Systems for Physics

Prof. Dr. Kurt Kremer, Max-Planck-Institut für Polymerforschung, Mainz Polymers / Soft Matter as Model Systems for Physics Kurt Kremer; Max Planck Institute for Polymer Research, Mainz, Germany Polymers, long chain molecules, comprise important materials of our daily life, being it simple commodities with all their advantages and disadvantages or high-tech materials in electronics or medicine, to give just two examples. Furthermore, biopolymers such as cellulose or proteins are central functional constituents of living organisms. Not surprisingly, they have been subject of applied physics research since their discovery/invention. This application focused view, however, changed with de Gennes’ discovery of the n→0 theorem, showing that the inverse chain length 1/N, N being the number of chain repeat units, can be mapped onto the distance |T-Tc|/Tc from the critical point in a n-vector spin model. At about the same time computer simulations became powerful tools to study critical phenomena in spin systems, complemented by experiment, most notably neutron scattering for the case of polymers. At that point polymers became important and versatile systems to study general questions of critical phenomena. Polymers/Soft Matter display slow dynamics and are susceptible to small molecular stimuli. Thus, local chemistry specific aspects like minute changes in local interactions easily turn into macroscopic property changes. At that point generic physical concepts meet the consequences of chemically detailed interactions. This interplay makes soft matter so versatile and so interesting. The talk will review a few characteristic examples, where such effects lead to physically interesting phenomena, which apply to modern statistical physics (active systems, glass transition) as well as soft matter materials science (nanoporous materials). Finally, challenges and perspectives for physics of soft matter but also for new physics studied by soft matter will be shortly discussed.

Teilchenkolloquium

Muonic Atoms

Andreas Abeln, Kirchhoff-Institut für Physik Universität Heidelberg Muonic Atoms Andreas Abeln Kirchhoff-Institut, Universität Heidelberg The QUARTET collaboration aims to improve the accuracy of absolute nuclear charge radii of light nuclei from Li to Ne by about one order of magnitude using high-precision X-ray spectroscopy of muonic atoms. Metallic Magnetic Calorimeters (MMC) operated at temperature around 20 mK are used because of the demonstrated high energy resolution and large dynamic range, as well as a reliable and stable energy calibration. After the first experiment at the PiE3 beamline at the Paul Scherrer Institute (PSI) in 2023, which showed the suitability of MMCs for the high-precision X-ray spectroscopy of muonic atoms, two data taking campaigns have been performed in 2024 and 2025 for the measurement of different stable Li-, Be-, B-, O-isotopes as well as proof-of-principle measurements of C-isotopes. In addition, a short measurement for the determination of the chemical composition of a prehistoric human tooth was carried out, showing the outstanding performance of MMCs with respect to conventional detectors. While for the first experiments an already available detector system could be used, a new MMC array had to be developed for achieving high quantum efficiency for x-rays emitted in muonic oxygen and heavier elements, covering the energy range up to 200 keV. This new detector system will be also used for the three weeks beamtime in 2026. The optimization of the MMC array as well as the non-trivial integration of the detector system at the PiE3 beamline will be discussed. The data acquisition system will be shortly introduced in order to discuss the data reduction and, in particular, the suppression of background events. The importance of the energy calibration will be discussed, before presenting the spectra obtained for muonic Li, with a precise isotope shift determination, and Be. As special highlight, the chemical composition of the prehistoric human tooth will be shown.

Astronomisches Kolloquium

Dienstag, 5. Mai 2026 16:30 Uhr  Solar models and their uncertainties: the current state and the impact for PLATO

Gaël Buldgen, University of Liege Solar evolutionary models are key calibrators of stellar evolution theory. The high quality of observational constraints and the fact that the solar mass, radius and age are known with high accuracy and precision allows to use the Sun as a true laboratory of fundamental physics. Over the last decades, most solar modellers relied on a simplified framework to model the evolution of the Sun, called the Standard Solar Model framework, neglecting dynamical processes and designed for large-scale computations. These models encountered widespread success (see e.g. Model S from Christensen-Dalsgaard et al. 1996), but both helioseismic and asteroseismic data have shown the limitations of standard models. In the last months of the preparation of the PLATO mission (to be launched in early 2027), the accuracy of stellar models comes as a crucial question that actually links all our recent progress in asteroseismology back to one burning question: how well do we know our Sun? To arrange a visit with the speaker during the visit, please contact their host: Maria Bergemann

Zentrum für Quantendynamik Kolloquium

Mittwoch, 6. Mai 2026 16:30 Uhr  Analog gravity in atomic condensates: a fruitful bidirectional synergy of gravity and quantum optics

Dr. Iacopo Carusotto, INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento Analog gravity in atomic condensates: a fruitful bidirectional synergy of gravity and quantum optics Prof. Dr. Iacopo Carusotto INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento In this talk I will review recent advances in the theoretical and experimental study of ultracold atomic gases as a platform for analog models of gravity, aka the quantum simulation of gravitational and quantum field problems using atomic systems. Beyond analog Hawking emission from black holes and super-radiance from rotating objects, special attention will be paid to back-reaction effects in cosmological particle generation and false vacuum decay phenomena. Avenues for application of these effects to new quantum technologies will be finally outlined.