Programm für das Sommersemester 2024
Tuesdays, 16 Uhr c.t.
Institut für Physik
HS KPH
16.04.24  Prof. Dr. Ulrich Stroth, Max Planck Institute for Plasma Physics, Garching  
In times of a shift towards a low CO2 energy supply and boosted by the recent success of laser fusion, the advantages of nuclear fusion in general have come into the focus of politics and private investors as an attractive energy source. This talk introduces the concept of magnetic fusion and outlines the path to a fusion reactor. The perspectives of magnetic fusion will be compared with those of laser fusion and the concepts of startups. The role of plasmas, in which energy is obtained from the fusion of hydrogen isotopes, and their physical properties are explained. Slides here...  
16:15 Uhr s.t., HS KPH  

30.04.24  Prof. Dr. Joacim Rocklöv, Heidelberg University  
In this talk I will introduce infectious diseases and their sensitivity to climate variability and change. I will describe and contrast experimental evidence with empirical observations and data. In the talk I will discuss systems and interactions enabling introduction and transmission of emergent vectors, hosts, and pathogens. I will further give examples of how mathematical processbased models and machine learning approaches are used and how they can be applied to study patterns and responses to these changes. Finally, I will talk about novel applications of machine learning in surveillance and early warnings, as well as the evaluation of interventions to guide effective responses. Slides here...  
16:15 Uhr s.t., HS KPH  

07.05.24  Prof. Dr. Michael Kramer, Max Planck Institute for Radio Astronomy, Bonn  
Pulsars, the natural beacons of the universe, put physics to extreme test. As neutron stars, they are not only the densest objects in the observable universe, but they also serve as highprecision laboratories for testing the general theory of relativity. Pulsars not only allow the observation of predicted effects that cannot be observed by other methods, but they provide also extremely precise tests of the properties of gravitational waves. The latest results even use pulsars as galactic gravitational wave detectors, which detect a continuous "hum" of spacetime. This buzz is, most likely, caused by the merging of supermassive black holes in the early universe. The talk gives an overview of the latest results and an outlook into the future. Slides here...  
16:15 Uhr s.t., HS KPH  

14.05.24  Prof. Dr. Jochem Marotzke, Max Planck Institute for Meteorology, Hamburg  
I will first illustrate two key conclusions from the latest report of the Intergovernmental Panel on Climate Change, IPCC, from 2021. The first states that “it is unequivocal that human influence has warmed the atmosphere, ocean and land”. The second states that “global warming of 1.5°C and 2°C will be exceeded during the 21st century unless deep reductions in CO2 and other greenhouse gas emissions occur in the coming decades.” I will then explain how these results built on the work of Klaus Hasselmann and Syukuro Manabe, respectively, who shared the Nobel Prize in physics in 2021. The second of the statements was made possible through remarkable research progress during the past decade, and I will demonstrate how the scientific process within the IPCC turned a seeming scientific crisis into substantial progress. Finally, I will look at the still unsolved problem of understanding the future of the Atlantic Ocean circulation and how we tackle this problem in current research. Slides here...  
16:15 Uhr s.t., HS KPH  

21.05.24  Prof. Dr. Cristian Micheletti, SISSA, Trieste, Italy  
Sampling equilibrium ensembles of dense polymer mixtures is a paradigmatically hard problem in computational physics, even in latticebased models. For instance, using realspace Monte Carlo to sample polymer systems becomes impractical for increasing size, rigidity, and density of the chains. In response to these challenges, we introduce and apply a formalism to recast polymer sampling as a quadratic unconstrained binary optimization (QUBO) problem [1].
Thanks to this mapping, dense systems of stiff polymers on a lattice can be efficiently sampled with classical QUBO solvers, resulting in more favourable performance scaling compared to realspace Monte Carlo [2]. Tackling the same problems with the DWave quantum annealer leads to further performance improvements [2]. As an application, we discuss the use of the quantuminspired encoding on a hitherto untackled problem, namely the linking probability of equilibrated melts of ring polymers, for which we unveil counterintuitive topological effects.
References
[1] C.Micheletti, P. Hauke and P. Faccioli, "Polymer physics by quantum computing", Phys. Rev. Lett. 127, 080501 (2021)
[2] F. Slongo, P. Hauke, P. Faccioli and C. Micheletti "Quantuminspired encoding enhances stochastic sampling of soft matter systems", Sci. Adv. 9, art. no adi0204 (2023) Slides here...  
16:15 Uhr s.t., HS KPH  

28.05.24  Prof. Dr. Ingo Rehberg, University of Bayreuth  
Spherical magnets are an invaluable but affordable physics toy! While vividly demonstrating chemical, physical and mathematical problems, they can also greatly inspire creativity: Questions concerning the favoured state of dipole cluster configurations lead – via an encounter with tipping points – to the invention of magnetic gears based on degenerate continua. Open source animations and patentfree hardware to play with shall garnish this triptychon. Slides here...  
16:15 Uhr s.t., HS KPH  

04.06.24  Prof. Dr. Claudia Felser, Max Planck Institute for Chemical Physics of Solids, Dresden  
Topology, a wellestablished concept in mathematics, has nowadays become essential to describe condensed matter. At its core are chiral electron states on the bulk, surfaces and edges of the condensed matter systems, in which spin and momentum of the electrons are locked parallel or antiparallel to each other. Magnetic and nonmagnetic Weyl semimetals, for example, exhibit chiral bulk states that have enabled the realization of predictions from high energy and astrophysics involving the chiral quantum number, such as the chiral anomaly, the mixed axialgravitational anomaly and axions. The potential for connecting chirality as a quantum number to other chiral phenomena across different areas of science, including the asymmetry of matter and antimatter and the homochirality of life, brings topological materials to the fore. Slides here...  
16:15 Uhr s.t., HS KPH  

11.06.24  Dr. Karen Alim, TU München  
Propagating, storing and processing information is key to take smart decisions – for organisms as well as for autonomous devices. In search for the minimal units that allow for complex behaviour, the slime mould Physarum polycephalum stands out by solving complex optimization problems despite its simple makeup. Physarum’s body is an interlaced network of fluidfilled tubes lacking any nervous system, in fact being a single gigantic cell. Yet, Physarum finds the shortest path through a maze. We unravel that Physarum’s complex behaviour emerges from the physics of active flows shuffling through its tubular networks. Flows transport information, information that is stored in the architecture of the network. Thus, tubular adaptation drives processing of information into complex behaviour. Taking inspiration from the mechanisms in Physarum we outline how to embed complex behaviour in active microfluidic devices and how to program human vasculature. Slides here...  
16:15 Uhr s.t., HS KPH  

18.06.24  Dr. Thomas Cocolios, KU Leuven, Belgium  
Nuclear medicine is currently experiencing some major changes and developments: Lu177 has become a standard radionuclide for patient care, in particular with Lutathera® and Pluvito®, two recently marketed drug for endocrine and prostate cancers, respectively. Those successes are but the tip of the iceberg of possibilities: with 3000 radionuclides synthesized in the laboratory, it seems unbelievable that only a handful are actually used in medical applications. This is mostly due to the absence of a supply pipeline to support research until their production is picked up by the industry. To break that paradigm, CERN has established the MEDICIS facility (MEDical Isotopes Collected from ISolde), where the techniques developed for the last 50 years on radioactive ion beams are now applied to produce medical radionuclides for research. The success of the development of noncarrieradded Sm153 has led it to first clinical trials in 2024. At the European level, this has triggered a new consortium, federated around MEDICIS but with a larger reach, as PRISMAP, the European medical radionuclide programme. Slides here...  
16:15 Uhr s.t., HS KPH  

25.06.24  Prof. Dr. Klaus Blaum, MaxPlanck Institute for Nuclear Physics, Heidelberg  
The four fundamental interactions and their symmetries, the fundamental constants as well as the properties of elementary particles like masses and moments, determine the basic structure of the universe and are the basis for our so well tested Standard Model (SM) of physics. Performing stringent tests on these interactions and symmetries in extreme conditions at lowest energies and with highest precision by comparing, e.g., the properties of particles and their counterpart, the antiparticles, will allow us to search for physics beyond the SM. Any improvement of these tests beyond their present limits requires novel experimental techniques.
An overview is given on recent mass and gfactor measurements with extreme precision on single or few cooled ions stored in Penning traps. Among others the most stringent test of boundstate quantum electrodynamics could be performed. Here, the development of a novel technique, based upon the coupling of two ions as an ion crystal, enabled the most precise determination of a gfactor difference to date. This difference, determined for the isotopes 20,22Ne9+ with a relative precision of 5 × 10−13, improved the precision for isotopic shifts of g factors by about two orders of magnitude. Our latest results on precision measurements with exotic ions in Penning traps will be presented. Slides here...  
16:15 Uhr s.t., HS KPH  

02.07.24  Prof. Dr. Laura Kreidberg, Max Planck Institute for Astronomy, Heidelberg  
The recent launch of the James Webb Space Telescope (JWST) has revolutionized the field of exoplanet atmosphere characterization, thanks to its unprecedented sensitivity and broad wavelength coverage. In this talk, I will give a tour of the latest JWST results for transiting exoplanets, from gas giants down to rocky worlds. For the largest planets, I'll focus on the complex physical processes recently revealed in their atmospheres, including photochemistry, 3D effects, and cloud formation. Pushing down to smaller worlds, I'll share the first measurements of chemical composition for the elusive subNeptune population; and finally give an update on which (if any) rocky planets have atmospheres at all. Slides here...  
16:15 Uhr s.t., HS KPH  

09.07.24   canceled  Dr. Kerem Çamsarı, University of California, Santa Barbara  
tba  
16:15 Uhr s.t., HS KPH  

16.07.24  Prof. Dr. Frank Saueressig, Radboud University, NL  
Fusing the principles of general relativity and quantum mechanics in a consistent theoretical framework still constitutes one of the main open challenges in theoretical physics today. Over the last decades, the gravitational asymptotic safety program has taken significant steps towards achieving this goal. A central virtue, driving the success of the approach, is its conservative nature: the program builds on wellestablished principles of quantum field theory and extends them in a rather minimalistic way. In this talk, we will review the key developments in the program, building up to its present status. I will also attempt to give an outlook on the challenges that need to still be addressed in the future. Slides here...  
16:15 Uhr s.t., HS KPH  

16.07.24  Prof. Dr. Reinhard Noack, Philipps University Marburg  
Correlated Electrons from Zero to Infinite Dimensions: Early Days of KOMET 7 in Mainz.
I will talk about the problems in correlated electron systems that occupied us in the early days of the KOMET 7 research group headed by Peter van Dongen. These problems include quantum impurity problems as well as the dynamical mean field theory (DMFT), i.e., correlated electrons in the infinitedimensional limit. At first glance, these two problems are very different because the impurity problem is in a sense zerodimensional, whereas the DMFT is formally infinitedimensional. However, the effective problems and solution methods of these two problems are losely related, and both approaches can be used to describe the behavior of real threedimensional materials. In addition, a major activity of group members has been to develop and use matrixproductstate and tensornetwork methods, especially the density matrix renormalization group.
These methods are ideally suited to study quasionedimensional and twodimensional strongly correlated systems. They can be applied to a variety of
systems ranging from transitionmetal coumpounds such as the cuprates to organometallic materials such as Bechgaard salts as well as to quantum simulators formed from cold atomic gases on optical lattices. Slides here...  
16:15 Uhr s.t., HS KPH  

Koordination:  Kontakt: 
Prof. Dr. Hans Jockers Prof. Dr. Concettina Sfienti  Caroline Hoffmann Sibylle Wittek 