## Semesterübersicht Wintersemester 2022/2023

24 Oct 2022

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Olivera Vujinovic, Institut für Physik
at Zoom

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t., Munich
 Albrecht Klemm, Bonn U. Recently it has been realized that the parameter dependence of Feynman integrals in dimensional regularisation can be calculated explicitly using period-- and chain integrals of suitably chosen Calabi-Yau motives, where the transcendentality weight of the motive is proportional to the dimension of the Calabi Yau geometry and the loop order of the Feynman graphs. We exemplify this for the Banana graphs, the Ice Cone graphs and the Train Track graphs in two dimensions. In the latter case there is a calculational very useful relation between the differential realisation of the Yangian symmetries and the Picard-Fuchs system of compact Calabi-Yau spaces M as well as between the physical correlations functions and the quantum volume of the manifolds W that are the mirrors to M. at Zoom
25 Oct 2022

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr hab. Wojciech Gawlik, JU Krakow, PL I will begin with a historical introduction starting from Michael Faraday’s discovery of the magneto-optical phenomena and the basic physics behind it. Next, I will present the revolution caused by the advent of lasers in magneto-optics studies and the developments which made the nonlinear magneto-optics one of the most precise measurement techniques. While focusing on hot atomic-vapor samples, I will also present some magneto-optic studies with cold, trapped atoms and colour centers in diamonds and their applications to magnetometry.
26 Oct 2022

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Dr. Chien-Yeah Seng, Univ. Bonn The precision measurement of the top-row Cabibbo-Kobayashi-Maskawa (CKM) matrix element $V_{ud}$ from beta decays of pion, neutron and nuclei plays an important role in low-energy precision tests of Standard Model (SM) predictions. The recent observation of an apparent deficit of the top-row CKM unitarity has attracted wide attentions and provided hints for physics beyond the Standard Model (BSM). Higher precision for the $V_{ud}$ extraction is needed to confirm (or reject) such an observation; in this talk the referent will discuss some ongoing efforts from the theory and experimental side to achieve this goal.Slides here...

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t.
James McIver, MPSD and Columbia University
##### Ultrafast optoelectronic probes of quantum materials
at Zoom and SPICE YouTube Channel

27 Oct 2022

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Prof. Dr. hab. Wojciech Gawlik, Jagiellonian University, Poland By simultaneous application of a laser and two microwave fields upon a spin system (e.g. NV centers in diamond) one can observe magnetic resonance structures with two-component, composite shapes of nested Lorentzians with different widths. One component is regularly power-broadened, whereas the linewidth of the other one undergoes field-induced stabilization and becomes power-independent. The observed stabilization appears to be a general phenomenon that occurs in open systems. It is caused by the competition between coherent driving and non-conservation of populations and can be interpreted in terms of specific bright and dark combinations of state populations. Bio: Studied physics at the Jagiellonian University in Kraków (MSc in 1970), 1972-74 worked in the Physikalisches Inst. der Uni Heidelberg (with G. zu Putlitz), PhD in 1975 (Uni Kraków). Longer research stays: Reading (GB) with G.W. Series, Munich with H. Walther, Paris with S. Haroche, Boulder with A. Gallagher, Berkeley with D. Budker. Head of the Atomic Optics Dept. (1990-94) and Photonic Dept. (2003-2017) in Jagiellonian Univ. (Kraków), since 2018 Professor Emeritus at the Institute of Physics Jagiellonian University.
31 Oct 2022

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Liam O'Sullivan, Institut für Physik
at Zoom

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t.
 Lorenz Eberhardt, IAS I will revisit string one-loop amplitudes in this talk. After reviewing the basics, I will explain how Witten’s iepsilon prescription gives a manifestly convergent representation of the amplitude. I will then consider the imaginary part of the amplitude and show directly that it satisfies the standard field theory cutting rules. This leads to an exact representation of the imaginary part of the amplitude. I will also discuss physical properties of the imaginary part such as the singularity structure of the amplitude, its Regge and high energy fixed-angle behaviour and low-spin dominance. Finally, I will tease how Rademacher’s contour can be used to evaluate the full one-loop open string amplitude exactly in terms of a convergent infinite sum. at Zoom
02 Nov 2022

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t.
Eric Fullerton, UC San Diego
##### Stripe domain phases in chiral magnetic systems with perpendicular anisotropy
at Zoom and SPICE YouTube Channel

03 Nov 2022

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Dr. Benjamin Stickler, Imperial College London, Dept. of Physics Controlling the quantum dynamics of massive and complex objects, such as large molecules and nanoparticles, requires a detailed understanding of the interaction between their many interacting degrees of freedom and control fields. In this talk, I will discuss how light scattering induces non-reciprocal interactions between co-levitated objects [1], how the rotational quantum interference of nanoparticles with embedded nitrogen-vacancy centres gives rise to novel quantum phenomena [2,3], and how diffraction of chiral molecules can prepare superpositions of molecular configurations [4]. These examples illustrate the potential of macro-mechanical quantum systems for novel force and torque sensing schemes and for high-mass tests of quantum physics. [1] Rieser, Ciampini, Rudolph, Kiesel, Hornberger, Stickler, Aspelmeyer, and Delić, Tunable light-induced dipole-dipole interaction between optically levitated nanoparticles, Science 377, 987 (2022). [2] Stickler, Hornberger, and Kim, Quantum rotations of nanoparticles, Nat. Rev. Phys. 3, 589 (2021). [3] Rusconi, Perdriat, Hétet, Romero-Isart, and Stickler, Phys. Rev. Lett. 129, 093605 (2022). [4] Stickler, Diekmann, Berger, Wang, Phys. Rev. X 11, 031056 (2021). Short Bio: I studied Chemistry and Physics at TU Graz, and received my PhD in Physics form the University of Graz in 2013. I held postdoc positions at the University of Duisburg-Essen and at Imperial College London (as a Marie Sklodowska Curie Fellow). I obtained my Habilitation at the University of Duisburg Essen in 2022, where I now work on the theory of macroscopic quantum physics and levitated nanomechanics.. In 2022, I was elected into the NRW Academy of Sciences and Arts as a Young Fellow and I was recently admitted to the prestigious Heisenberg Programme by the DFG.
07 Nov 2022

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Ioana Caracas, Institut für Physik
at Zoom

08 Nov 2022

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Horst Schmidt-Böcking, University of Frankfurt In der Nacht vom 7. auf den 8. Februar 1922 gelang es Walther Gerlach und Otto Stern im sogenannten Stern-Gerlach-Experiment SGE, zum ersten Male das magnetische Moment eines Atoms, des Silberatoms, zu messen und den Beweis zu erbringen, dass Arnold Sommerfelds und Pieter Debyes Postulat der Richtungsquantelung von atomaren magnetischen Momenten in einem äußeren Magnetfeld der Wahrheit entsprach. Das Messprinzip des Experimentes als hochauflösendes Impulsspektrometer für einzelne Atome im Vakuum und der historische Weg der Durchführung dieses Experimentes werden dargestellt. Das Ergebnis des SGE zeigte damit auch erstmals, dass auch die inneratomaren Drehimpulse gequantelt sind. Die Bedeutung des SGE für die Entwicklung der Quantenphysik besprochen.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Cem Eröncel, DESY Axion-like-particle (ALP) is a well-motivated candidate for dark matter, and it has been subject to extensive theoretical and experimental research in recent years. The most popular ALP production mechanism studied in the literature is the misalignment mechanism, where the ALP field initially has negligible kinetic energy and starts oscillating when its mass becomes comparable to the Hubble scale. Recently, a new mechanism called Kinetic Misalignment has been proposed where the ALP field receives large kinetic energy at early times due to the explicit breaking of the Peccei-Quinn symmetry. This causes a delay in the onset of oscillations so that the ALP dark matter parameter space can be expanded to lower values of the axion decay constant. At the same time, the ALP fluctuations grow exponentially via parametric resonance in this setup, and most of the energy in the homogeneous mode is converted to ALP particles. This process is known as fragmentation. In this talk, I will discuss the observational consequences of fragmentation for the axion mini-clusters and show that a sizable region of the ALP parameter space can be tested by future experiments that probe the small-scale structure. at Zoom
09 Nov 2022

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Prof. Dr. Alessandro Roggero, Univ.Trento, Italy In extreme astrophysical environments like supernova explosions, the large neutrino density can lead to collective flavor oscillations driven by neutrino-neutrino interactions. These phenomena are important to describe flavor transport and have potentially important consequences for both the explosion mechanism and nucleosynthesis in the ejected material. Even simple models of neutrino-neutrino interactions require the solution of a challenging many-body problem whose exact solution requires exponential resources in general. In this talk the referent will describe the physics of collective flavor oscillations and present the recent efforts to simulate the real-time flavor dynamics of two-flavor neutrinos using current generation quantum computers based on both superconducting qubits as well as trapped ions.
10 Nov 2022

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Dr. Anna Ermakova, MPI Mainz Color centers in diamonds offer wonderful sensing possibilities in the case of the detection of magnetic or electric fields or temperature. Color centers in nanodiamonds can be incorporated into the biological systems to investigate them. One of the biggest advantages of quantum sensors based on nanodiamonds is that they operate at room temperature or higher. Therefore, they can be used to study living systems. We investigate how nanodiamonds can be brought into the living system in the most efficient way and what information we can get from them. Bio: Studied physics in Belarusian State University (MSc in 2011), PhD in physics (magna cum laude) with Fedor Jelezko at Ulm University, Institute for Quantum Optics (2011-2016). From 2017 to 2021 she held positions as a postdoc at Ulm University, researcher at Silicon Austria Lab GmbH, and a senior scientist at MPIP (Mainz). Since 2022 – Anna is Independent Group Leader at Max-Planck-Institute for Polymer Research, Mainz, Germany supported by Carl-Zeiss Foundation, her group works on investigating potential of Nanodiamonds for intracellular magnetometry and thermometry, novel all-optical sensing methods, and cell metabolism processes.

### GRK 2516 Soft Matter Seminar

###### Uni Mainz14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Gokul Govind, JGU, Physics Sequence controlled polymerization is an inevitable process in natural systems. The amino acid sequence arrangement is the vital part in determining the structure function of proteins. This process of selection and formation of sequence interests scientists to build polymers that are made of self-assembled monomers that interact through Van der Waals interactions such as hydrogen bonds and hydrophobic interactions. In this talk I will be discussing the copolymerization of two monomers that are having hydrophobic and hydrophilic domains whose interplay induces a supramolecular polymerization in water. We discuss the concentration factors that can contribute to the formation of homopolymers and copolymers with different sequences. References : Macromol. Rapid Commun. 2021, 2100473 Macromolecules 2019, 52, 7661−7667 J. Am. Chem. Soc. 2020, 142, 16, 7606–7617 at Zoom

### GRK 2516 Soft Matter Seminar

###### Uni Mainz15:00 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Bhuwan Poudel, MPI-Polymer Research It is crucial to understand how stimuli-responsive polymer surfaces, such as polymer brushes, accommodate nanoparticles and how the presence of nanoparticles alters the structural and dynamical properties of the brushes in order to use the brush/NPs hybrid in optimal applications. We plan on answering this question by carrying out detailed molecular dynamics simulations. As a first step toward the project's goal, we investigated the properties of brushes and studied how a nanoparticle interacts with them. at Zoom
11 Nov 2022

### Theorie-Palaver

###### Institut für Physik15:00 Uhr s.t., HIM building, room 02.111
Pere Masjuan, Universitat Autonoma de Barcelona
##### The role of Pade approximants as fitting functions

Note the special time and room.

14 Nov 2022

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Martin Rongen, Institut für Physik
at Zoom

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t.
 Raghu Mahajan, Stanford U. We use insights from string field theory to analyze and cure the divergences in the cylinder diagram in minimal string theory, with both boundaries lying on a ZZ brane. Minimal string theory refers to the theory of two-dimensional gravity coupled to a minimal model CFT that serves as the matter sector; it includes JT gravity as a limiting case. ZZ branes are akin to D-instantons, and give rise to features that reflect the underlying discreteness of the dual theory. The exponential of the cylinder diagram represents the one-loop determinant around the instanton saddle. The finite result for this one-loop constant computed using the string field theory procedure agrees precisely with independent calculations in the dual double-scaled matrix integrals performed by several authors many years ago. at Zoom
15 Nov 2022

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Peter Spichtinger, JGU Institute for Atmospheric Physics Ice clouds constitute an important component in the Earth-atmosphere system. Like all clouds, they influence the hydrological cycle and the energy budget of the system. Thereby, the partial reflection of incident radiation results into a cooling effect (albedo effect), and the absorption and re-emission of thermal radiation results into a warming effect (greenhouse effect). However, for ice clouds in the tropopause region the net effect (warming or cooling) is unclear, because both opposite effects are of the same order of magnitude. Thus, the net effect depends on further properties of the multiscale system of ice clouds, such as the size and shape of the crystals, as well as the formation of structures within clouds resulting into heterogeneous media. In particular, the formation of structures in (ice) clouds is relatively poorly known so far and requires further investigation. In this talk we investigate processes and phenomena on different scales of ice clouds. We start with single crystals and their properties, as well as methods to measure these particles. To represent the ensemble ice cloud, models have to be developed and further investigated. The formulation of reduced order models leads us to ice clouds as nonlinear oscillators. The interaction on different scales and of different processes finally leads to the formation of characteristic structures. These investigations are current research and are carried out in interdisciplinary collaboration.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Mathias Becker, JGU Mainz A non-minimal dark sector could explain why WIMP dark matter has evaded detection so far. Based on the extensively studied example of a simplified t-channel dark matter model involving a colored mediator, we demonstrate that the Sommerfeld effect and bound state formation must be considered for an accurate prediction of the relic density and thus also when inferring the experimental constraints on the model. We find that parameter space thought to be excluded by LHC searches and direct detection experiments still remains viable. Moreover, we point out that the search for bound state resonances at the LHC offers a unique opportunity to constrain a wide range of dark matter couplings inaccessible to prompt and long-lived particle searches.
16 Nov 2022

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Dr. Graziano Venanzoni, Frascati, Italy The latest measurement of the muon g-2 announced at Fermilab exhibits a 4.2$\sigma$ discrepancy from the currently accepted Standard Model prediction. The main source of uncertainty on the theoretical value is represented by the leading order hadronic contribution $a_{\mu}^{HLO}$, which is traditionally determined through a data-driven dispersive approach. A recent calculation of $a_{\mu}^{HLO}$ based on lattice QCD is in tension with the dispersive evaluation, and reduces the discrepancy between theory and experiment to 1.5$\sigma$. An independent evaluation of $a_{\mu}^{HLO}$ is therefore required to solve this tension and consolidate the theoretical prediction. The MUonE experiment proposes a novel approach to determine $a_{\mu}^{HLO}$ by measuring the running of the electromagnetic coupling constant in the space-like region, via $\mu-e$ elastic scattering. The measurement will be performed by scattering a 160 GeV muon beam, currently available at CERN's North Area, on the atomic electrons of a low-Z target. A Test Run on a reduced detector is planned to validate this proposal. The status of the experiment in view of the Test Run and the future plans will be presented.Slides here...

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t.
Yoav William Windsor, FH Institute of the MPS and TU Berlin
##### Towards a "complete" picture of ultrafast dynamics in the 2D ferromagnet FGT
at Zoom and SPICE YouTube Channel

21 Nov 2022

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Patrycja Potepa, Institut für Physik
at Zoom

22 Nov 2022

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Erwin Frey, University of Munich Protein pattern formation is essential for the spatial organization of intracellular processes like cell division, and flagellum positioning. A prominent example of intracellular patterns is the oscillatory pole-to-pole oscillations of Min proteins in E. coli whose function is to ensure precise cell division. Cell polarization, a prerequisite for processes such as stem cell differentiation and cell polarity in yeast, is also mediated by a diffusion-reaction process. More generally, these functional modules of cells serve as model systems for self-organization, one of the core principles of life. Under which conditions spatio-temporal patterns emerge, and how these patterns are regulated by biochemical and geometrical factors are major aspects of current research. In this talk I will review recent theoretical and experimental advances in the field of intracellular pattern formation, focusing on general design principles and fundamental physical mechanisms.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Alfredo Guerrera, Padua U. and INFN Axion--Like--Particles are among the most economical and well motivated extensions of the Standard Model. In this talk ALP production from hadronic and leptonic meson decays are studied. The hadronization part of these decay amplitudes has been obtained using Brodsky--Lepage method or LQCD, at needs. In particular, the general expressions for ALP emission in mesonic s-- and t--channel tree--level processes are thoroughly discussed, for pseudoscalar and vector mesons. Accordingly, exact results as well as some useful approximation for meson-to-meson and meson leptonic decay amplitudes are presented. I will the discuss the phenomenology of various decays and highlight the most robust in terms of experimental searches and theoretical predictions. Finally, bounds on the (low--energy effective Lagrangian) ALP--fermion couplings are derived, from present and future flavour experiments. If I have time left I'll also cover some of the new form factors calculations in B mesogenesis. at Zoom
23 Nov 2022

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Francesca Carlin, Berlin (Please note: Event will take 2 hours) Evaluations and selections determine scientific careers possibly like no other factor. Knowing that they are also susceptible to bias and preconceptions, how can we ensure a fair recruitment process and assure to pick the best candidate? Together, we want to reflect how we hold discussions in selection committees (on all career levels!) and learn what practices prove helpful in guaranteeing more equitable opportunities for all applicants. Please register through prisma@uni-mainz.de to receive preparatory material.Slides here...
24 Nov 2022

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Dr. Lars von der Wense, LMU München Optical atomic clocks are today’s most accurate time-keeping devices. They achieve stunning relative accuracies in the range of 10-18, corresponding to an error of 1 second in 30 billion years. An even improved accuracy is expected to be achieved by a nuclear optical clock, since the nucleus is significantly less sensitive to external influences than the atomic shell. Developing a nuclear optical clock requires laser spectroscopy of a nuclear transition, an objective which has so far not been achieved, but which has come into reach due to recent gain of knowledge. In this talk I will give an overview over the recent progress that has been made toward the development of a nuclear optical clock. I will introduce several experiments that are currently in preparation aiming toward first-time laser spectroscopy of a nuclear transition. Finally, I will introduce the investigations planned within the framework of the newly funded BMBF project “NuQuant”.

### GRK 2516 Soft Matter Seminar

###### Uni Mainz14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Seraphine Wegner, WWU Münster Bottom-up synthetic biology aims to construct cell-like systems starting from molecular building blocks. These synthetic cells give insight into the molecular details and principles that give rise to cell function. Many functions in cells arise directly from the spatial and temporal regulation of cell-matrix and cell-cell interactions. In this talk, I will present strategies of how such spatiotemporal control over adhesions of synthetic and natural cells can be achieved with visible light and functions that arise from these. The photoswitchable adhesions allow us recapitulate cell migration, to self-assemble and self-sort cells into multicellular functional architectures with high precision, regulate their interactions with synthetic materials, program cell to cell communication and to study the underlying biology. Synthetic minimal cells, which reduce complexity and yet capture key features of natural cells, allow us to quantify and correlate cell behavior with molecular information. Further, complementary approaches pursued with synthetic minimal cells as well as bacterial and mammalian cells allow translating concepts between different systems and integration into hybrid structures. Overall, our work on one hand provides insight into underlying design principles of life and on the other hand engineer new synthetic cell biology. at Zoom
28 Nov 2022

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t.
 Enno Keßler, MPI-M Bonn J-holomorphic curves or pseudoholomorphic curves are maps from Riemann surfaces to symplectic manifolds satisfying the Cauchy-Riemann equations. J-holomorphic curves are of great interest because they allow to construct invariants of symplectic manifolds and those invariants are deeply related to topological superstring theory. A crucial step towards Gromov–Witten invariants is the compactification of the moduli space of J-holomorphic curves via stable maps which was first proposed by Kontsevich and Manin. In this talk, I want to report on a supergeometric generalization of J- holomorphic curves and stable maps where the domain is a super Riemann surface. Super Riemann surfaces have first appeared as generalizations of Riemann surfaces with anti-commutative variables in superstring theory. Super J-holomorphic curves couple the equations of classical J-holomorphic curves with a Dirac equation for spinors and are critical points of the superconformal action. The compactification of the moduli space of super J- holomorphic curves via super stable maps might, in the future, lead to a supergeometric generalization of Gromov-Witten invariants. Based on arXiv:2010.15634 [math.DG] and arXiv:1911.05607 [math.DG], joint with Artan Sheshmani and Shing-Tung Yau. at Zoom
29 Nov 2022

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Markus Fröb, U. Leipzig Perturbative Quantum Gravity (pQG), the effective quantum field theory of gravitational fluctuations around a given background, is currently the only experimentally accessible theory of quantum gravity. Its tree-level predictions, in the form of temperature fluctuations of the Cosmic Microwave Background, have been experimentally confirmed, and it is possible that loop corrections are accessible to future experiments. However, while the tree-level results are well understood also from a theoretical point of view, the diffeomorphism symmetry of gravity makes the construction of invariant observables very difficult beyond this. Only recently, this issue has been overcome, and a class of causal invariant observables has been constructed. I will discuss this construction and how it can be related to observations, and present some predictions of pQG for graviton loop corrections to the Newtonian gravitational potential and the Hubble rate, the local expansion rate of the universe. Lastly, I show that pQG also predicts that spacetime becomes non-commutative at the Planck scale, but in a different way from previous approaches. The talk is based (in particular) on the recent papers arXiv:1806.11124, 2108.11960, 2109.09753 and 2207.03345. at Zoom

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Katrin Amann-Winkel, MPI für Polymerforschung Mainz Water is ubiquitous and the most important liquid for life on earth. Although the water molecule is seemingly simple, various macroscopic properties of water are most anomalous, such as the density maximum at 4°C or the divergence of the heat capacity upon cooling. Computer-simulations suggest that the anomalous behaviour of ambient and supercooled water could be explained by a two state model of water. An important role in this ongoing debate plays the amorphous forms of water. Since the discovery of two distinct amorphous states of ice with different density (high- and low density amorphous ice, HDA and LDA) it has been discussed whether and how this phenomenon of polyamorphism at high pressures is connected to the occurrence of two distinct liquid phases (HDL and LDL). X-ray free electron laser allow us to investigate metastable states of supercooled water within nano- to microseconds. In my talk I will give an overview on our recent X-ray experiments on supercooled water and amorphous ices.
30 Nov 2022

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Prof. Dr. Tetyana Galatyuk, GSI Darmstadt What happens when gold nuclei, accelerated to about 90% of the speed of light, strike gold nuclei at rest? For an extremely short time, t~10^-23 seconds, states of matter at extreme temperatures (10^12 K) and densities (>280 Mt/cm^3) are produced. The microscopic properties of the strong-interaction matter under extreme conditions of temperature and density is a topic of great current interest. Despite 18 orders of magnitude difference in system size and time, the conditions present in heavy-ion collisions share great overlap with the conditions of the strong-interaction matter in neutron-star mergers. The possibility to form and explore in the laboratory strong-interaction matter under extreme conditions is truly fascinating. The Compressed Baryonic Matter (CBM) experiment at FAIR has the potential to discover the most prominent landmarks of the QCD phase diagram expected to exist at high net baryon densities. The measurement of comprehensive set of diagnostic probes offers the possibility to find signatures of exotic phases, and to discover the conjectured first order deconfinement phase transition and its critical endpoint. In this talk the referent will focus on relevant observables to study criticality, emissivity, vorticity and equation-of-state of baryon rich matter. Particular emphasis is put on rare probes which are not accessible by other experiments in this energy range.

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t., Zoom
Alice Mizrahi, CNRS-Thales
##### Multilayer spintronic neural networks with radio-frequency connections
at Zoom and SPICE YouTube Channel

### Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

###### JGU10:00 Uhr s.t., TUK, Building 76, Room 276 (LASE)
Prof. Victor L’vov, Dept. of Chemical and Biological Physics, Weizmann Institute of Science
at Zoom

01 Dec 2022

### Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

###### JGU16:15 Uhr s.t., 01-122 Newton Raum
 Martin Beye, DESY Resonant inleastic X-ray scattering (RIXS) especially in the soft X-ray region has seen a tremendous increase in applicability and scientific insight over the recent years. This was largely enabled by progress in instrumentation and theoretical description. Now the time is ripe to apply RIXS to pressing problems and develop the technique further making full use of the capabilities of novel X-ray sources. In my talk, I will address three main themes from my research: 1. Time-resolved RIXS at free-electron lasers applied to relevant dynamic processes in chemistry (on surfaces, in liquids and in solid catalysts) 2. RIXS with micrometer spatial resolution to resolve domain dynamics in complex materials and on devices in-operando 3. Non-linear spectroscopies in the soft X-ray range to enhance information content and signal levels I will show and discuss experimental results from all research themes and point to future development directions.

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau15:00 Uhr s.t., Remote
Oliver Beckstein, Arizona State University

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Dr. Masaki Hori, MPI für Quantenoptik, Garching/Institut für Physik, Uni Mainz A Metastable antiprotonic helium is a Rydberg exotic atom composed of a helium nucleus, electron, and an antiproton. It is among the hadron-anti- hadron bound systems with the longest known lifetimes. Intense beams of laser light can be used to excite atomic transitions involving the anti- proton orbital. By utilizing sub-Doppler two-photon laser spectroscopy or buffer gas cooling, its atomic transition frequencies were measured to ppb-scale precision. Comparisons with the results of QED calculations allowed the antiproton-to-electron mass ratio to be determined as 1836.1526734(15). The results were used to set upper limits on fifth forces between antiprotons and nucleons at atomic length scales, and on forces that may arise between an electron and antiproton mediated by hypothetical bosons by Mainz theoretical groups. Efforts are currently underway to improve the experimental precision using CERN’s ELENA facility. We also observed narrow spectral lines of these atoms formed in super fluid helium with asurprisingly high spectral resolution of 2 parts per million. This revealed the hyperfinestructure arising from the spin-spin interaction between the antiproton and electron,despite the fact that the atom was surrounded by a dense matrix of normal atoms. Thisphenomenon may imply future possibilities in condensed matter or astrophysical fields. Metastable pionic helium (πHe+) contains a negative pion occupying a state of n≈l-1≈17, and retains a 7 ns average lifetime. We recently used the 590 MeV ringcyclotron facility of Paul Scherrer Institute near Zurich to synthesize the atoms, and irradiated them with resonant infrared laser pulses. This induced a pionic transition within the atom and triggered an electromagnetic cascade that resulted in the π- being absorbed into the helium nucleus. This constitutes the first laser excitation and spectroscopy of an atom containing a meson. By improving the experimental precision, the pion mass may bedetermined to a high precision as in the antiproton case. We wish to extend these studies to other atoms containing kaons or hyperons that includes the strange quark. Bio: Masaki Hori obtained his PhD in 2000 at the University of Tokyo in the field ofnuclear physics. After CERN and JSPS fellowships in Geneva involving antiprotonexperiments and building LHC injector parts, he became group leader at the Max Planck Institute of Quantum Optics in 2008. He obtained a Habilitation and became Privatdozent in 2020 at the Ludwig Maximillians University, while working in a commercial company that develops optical frequency combs. He joined the Institute of Physics of Mainz today as a Heisenberg position. He is spokesperson of the laser spectroscopy experiments of exotic helium atoms at CERN and PSI.
05 Dec 2022

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Rainer Wanke, Institut für Physik
at Zoom

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t.
 Nikita Nekrasov, Stony Brook U. Calogero-Moser-Sutherland system of particles is a prototypical example of a system with fractional statistics. I review the old and new connections of this system to (super) Yang-Mills theory in various dimensions. at Zoom
06 Dec 2022

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Peter Hommelhoff, University of Erlangen Optical fields can now be controlled with similar degrees of freedom as microwave fields for many decades already: we can now control not just the pulse envelope but also the optical carrier field. With few cycle laser pulses, this allows steering of electrons in unprecedented ways. I will give an overview over recent experiments we performed mainly with the atomically thin material graphene. Here we can drive the intraband motion of electrons but also interband transitions. For the intense ultrashort fields we employ, these processes become intricately coupled - a hallmark of strongfield physics. In particular, we could observe subsequent coherent Landau-Zener transitions, leading to Landau-Zener-Stückelberg-Majorana interferometry, representing fully coherent electron dynamics in a room-temperature material. In the second part of the talk, we will shine light on the graphene-gold interface and how it will add to the currents we can excite. Because of the different symmetries involved, we can disentangle virtual and real carrier excitations. With these insights, we have recently demonstrated a first Boolean logic gate based on two laser pulses carrying the logic information in the carrier envelope phase, which might bring lightwave or petahertz electronics closer to reality.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Johanna Erdmenger, Würzburg U. Within the AdS/CFT correspondence, the entanglement properties of the CFT are related to wormholes in the dual gravity theory. This gives rise to questions about the factorisation properties of the Hilbert spaces on both sides of the correspondence. We show how the Berry phase, a geometrical phase encoding information about topology, may be used to reveal the Hilbert space structure. Wormholes are characterized by a non-exact symplectic form that gives rise to the Berry phase. For a wormholes connecting two spacelike regions in AdS3 spacetimes, we find that the non-exactness gives rise to one phase space variable appearing in each of the two boundary CFTs located at each end of the wormhole. The two CFTs are thus coupled, reflecting non-factorization. Mathematical concepts such as coadjoint orbits and geometric actions play an important role in this analysis. In addition to its relevance for quantum gravity, the approach presented also suggests how to experimentally realize the Berry phase and its relation to entanglement in table-top experiments involving photons or electrons. This provides a new example for relations between very different branches of physics that follow from the AdS/CFT correspondence and its generalizations. Based on 2202.11717 and 2109.06190. at Zoom
07 Dec 2022

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Prof. Dr. Tim Cohen, CERN, Switzerland The referent will describe some recent work on applying Effective Field Theory (EFT) methodology to three different physically interesting systems. First he will explain the philosophy and general methodology of EFT. He will then present three short vignettes. The first has to do with techniques for systematically computing the EFT parameters from a given more fundamental description. The second will show how EFT can be used to understand the behavior of quantum fields in an inflationary background, with applications to light scalar fields and the inflaton itself. And in the third, the referent will show how EFT ideas can be applied to systematically improve a numerical technique for quantum field theory known as Hamiltonian truncation.Slides here...

### SPICE-Spin+X Seminar

##### Light-driven phonomagnetism
at Zoom and SPICE YouTube Channel

08 Dec 2022

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Dr. Nikita Kavokine, MPI for Polymer Research, Mainz Liquids are usually described within classical physics, whereas solids require the tools of quantum mechanics. I will show how in nanoscale systems this distinction no longer holds. At these scales, liquid flows may in fact exhibit quantum effects as they interact with electrons in the solid walls. I will first discuss the quantum friction phenomenon, where charge fluctuations in the liquid interact with electronic excitations in the solid to produce a hydrodynamic friction force. Using many-body quantum theory, we predict that this effect is particularly important for water flowing on carbon-based materials, and we obtain experimental evidence of the underlying mechanism from pump-probe terahertz spectroscopy. I will then show how the theory can be pushed one step further to describe hydrodynamic Coulomb drag – the generation of electric current by a liquid in the solid along which it flows. This phenomenon involves a subtle interplay of electrostatic and electron-phonon interactions, and suggests strategies for designing materials with low hydrodynamic friction. Bio: Nikita Kavokine obtained a Bachelor in Chemistry and a Master in Theoretical Physics from Ecole Normale Supérieure (ENS) in Paris. He continued at ENS for his PhD, in the group of Prof. Lydéric Bocquet, working on both theory and experiments in nanoscale fluid dynamics. He then obtained a Flatiron Research Fellowship and spent a year in New York, learning advanced numerical methods for condensed matter systems. He is now a postdoctoral fellow at the Max Planck Institute for Polymer Research. His research is at the interface between ‘hard’ and ’soft’ condensed matter, focussing on the quantum behavior of liquids near solid surfaces.

### GRK 2516 Soft Matter Seminar

###### Uni Mainz14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Leila Saheb Mohamadi, TU Darmstadt, Physics In nature, many biological systems self-assemble into structures such as peptides, proteins, or DNA. The molecule's self-assembly arose from noncovalent interaction, steric limitations and excluded volume effects. In this project, we used thermosensitive amphiphilic dendritic C3-symmetric peptides containing either glutamic acid or lysin groups. In situ QCM-D reveal a layer-by-layer absorption of the oppositely charged peptides, forming a multilayer. The total amount of adsorbing peptides is derived by the adsorbed temperature and increases with increasing temperature. Exposure to high or low pH (12 or 2) removes the peptide stacks apparently due to reduced electrostatic interaction. AFM result shows the distribution pattern is nanorod-like. These experiments prove stable switchable blocks on the surface that can carry biological and colloidal materials. at Zoom

### GRK 2516 Soft Matter Seminar

###### Uni Mainz15:00 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Janka Bauer, JGU, Physics Intrinsically disordered proteins (IDPs) are essential components for the formation of membraneless organelles, which play key functional and regulatory roles within biological systems. These complex assemblies form and dissolve spontaneously over time via liquid-liquid phase separation of IDPs. Mutations in their amino acid sequence can alter their phase behavior, which has been linked to the emergence of severe diseases such as cancer and neurodegenerative diseases including amyotrophic lateral sclerosis. In this work, we study the conformation and phase behavior of a low-complexity domain of heterogeneous nuclear ribonucleoprotein A1 (hnRNPA1), using coarse-grained implicit solvent molecular dynamics simulations [1]. We systematically analyze how these properties are affected by the number of aromatic residues within the examined sequences. We find a significant compaction of the chains and an increase in the critical temperature with increasing number of aromatic residues within the IDPs. Comparing single-chain and condensed state simulations, we find much more collapsed polymer conformations in the dilute systems, even at temperatures near the estimated θ-temperature of the solution. These observations strongly support the hypothesis that aromatic residues play a dominant role for condensation, which is further corroborated by a detailed analysis of the intermolecular contacts, and conversely that important properties of condensates are captured in coarse-grained simulations. Interestingly, we observe density inhomogeneities within the condensates near criticality, which are driven by electrostatic interactions. Finally, we find that the relatively small fraction of hydrophobic residues in the IDPs results in interfacial tensions which are significantly lower compared to typical combinations of immiscible simple liquids. [1] Dignon et al., PLOS Comput. Biol. 14, e1005941 (2018) at Zoom
12 Dec 2022

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Uwe Oberlack, Institut für Physik
at Zoom

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t.
 Ida Zadeh, JGU Mainz I will discuss compactification of the heterotic string on the smooth, flat 3-manifold T3/Z2, without supersymmetry. The low energy dynamics of the corresponding ten dimensional heterotic supergravity will be described. The semi-classical theory has both Coulomb and Higgs branches of non-supersymmetric vacua. An exact worldsheet description of the compactification will then be presented using the framework of asymmetric orbifolds of T3, where the orbifold generator involves a Nikulin non-symplectic involution of the even self-dual lattice of signature (19,3). This construction gives a novel conformal field theory description of the semi-classical field theory moduli space and reveals a rich pattern of transitions amongst Higgs and Coulomb branches. at Zoom

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau15:30 Uhr s.t.
Wanda Niemyska, University of Warsaw

13 Dec 2022

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Michael E. Flatté, University of Iowa Electric manipulation of magnetization is essential for the integration of magnetic functionalities in integrated circuits. Spin-orbit torque (SOT), originating from the coupling of electron spin and orbital motion through spin-orbital interaction, can effectively manipulate magnetization. Symmetry breaking plays an important role in spintronics based on SOT. SOT requires inversion asymmetry in order to have a net effect on magnetic materials, which is commonly realized by spatial asymmetry: a thin magnetic layer sandwiched between two dissimilar layers. This kind of structure restricts the SOT by mirror and rotational symmetries to have a particular form: an “antidamping-like” component oriented in the film plane even upon reversal of the magnetization direction. Consequently, magnetization perpendicular to the film plane cannot be deterministically switched with pure electric current. To achieve all-electric switching of perpendicular magnetization, it is necessary to break the mirror and rotational symmetries of the sandwiched structure.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Ricardo Cepedello, U. Würzburg While the matching of specific new physics scenarios onto the SMEFT framework is a well-understood procedure, the inverse problem, going from the SMEFT to UV scenarios, is more involved and requires the development of new methods to perform a systematic exploration of models. In this talk, I will discuss a diagrammatic approach to construct in an automated way a complete set of possible BSM models, given a certain set of well specified assumptions, that can reproduce specific patterns of SMEFT operators, and illustrate its use by generating models with no tree-level contributions to four-fermion operators. These class of models, which on the SMEFT only contribute to four-fermion operators at one-loop order, can contain relatively light particles that could be discovered at the LHC in direct searches, and even accommodate a dark matter candidate. In these scenarios, there is an interesting interplay between indirect SMEFT and direct searches, combining low-energy observables with the SMEFT Higgs-fermion analyses and searches for resonances at the LHC.
14 Dec 2022

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Dr. Gaia Lanfranchi, Frascati, Italy With the establishment and maturation of the experimental programs searching for New Physics with sizeable couplings at the LHC, there is an increasing interest in the broader particle and astroparticle community for exploring the physics of light and feebly-interacting particles (FIPs) as a paradigm complementary to a New Physics sector at the TeV scale and beyond. SHADOWS is a new experiment proposed at the CERN North Area to search for a large variety of FIPs produced in the interactions of a proton beam with a dump. It will use the 400 GeV primary proton beam extracted from the CERN SPS currently serving the NA62 experiment. SHADOWS can expand the exploration for a large variety of FIPs well beyond the state of the art in the MeV-GeV mass range which is allowed by cosmological and astrophysical observations and become one of the main players in the search for FIPs at accelerators in the next decade. After an introduction about the current plans for searching for FIPs at CERN within the Physics Beyond Colliders activity the referent will present the status of the SHADOWS project.Slides here...

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t.
Christopher Marrows, University of Leeds
##### Skyrmions in chiral magnetic multilayers
at Zoom and SPICE YouTube Channel

15 Dec 2022

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Dr. Boris Naydenov, Helmholtz Zentrum Berlin Electron Paramagnetic Resonance (EPR) is a well established technique with wide applications in various scientific fields, but with limited spin sensitivity. Here two approaches for measuring small ensembles of electron spins will be presented. In the first part of the talk a miniaturized EPR spectrometer based on a single chip (EPRoC) will be introduced, where the sample volume can be reduced down to few nanolitres. Recent results using rapid frequency sweeps for detection will be shown, which improve the signal to noise for samples with long relaxation times. In the second part of the talk Optically Detected Magnetic Resonance (ODMR) on Nitrogen-Vacancy centers (NVs) in diamond nano-structures will be shown. The NVs can be detected and controlled at the single spin level and they are well studied physical systems as they are very promising quantum sensors and qubits. The presented experiments with NV ensembles are the first steps towards the realization of a unforgeable quantum token, which is protected by the quantum non-cloning theorem.
19 Dec 2022

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t., LMU Munich (Room A348)
 Niccolo Cribiori & Ralph Blumenhagen, Max Planck Institut for Physics, Munich The absence of global symmetries is widely believed to be a principle of quantum gravity. Recently, it has been generalised to the statement that the cobordism group of quantum gravity must be trivial. Indeed, a non-trivial group detects a higher-form global symmetry, which has then to either be gauged or broken. In the case in which it is broken, defects have to be introduced into the setup. These can be end-of-the-world branes furnishing a dynamical realization of cobordism, of which we will provide a new concrete example. In the case in which the symmetry is gauged, we will argue that there is a non-trivial interplay between cobordism and K-theory, leading to the construction of type IIB/F-theory tadpoles from a bottom-up perspective. This interpretation of cobordism and K-theory as charges in quantum gravity can be given further support when passing from groups of the point to groups of a generic manifold X. We will argue that these more general groups have a natural interpretation in terms of the dimensional reduction of the theory on X. A systematic analysis can possibly lead to the prediction of new contributions to string theory tadpoles. at Zoom
20 Dec 2022

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Sarah Köster, Uni Göttingen We have about 200 different types of cell in our body, and each of them has very special mechanical properties. Illustrative examples are contracting muscle cells, migrating immune cells or elastic red blood cells. There intriguing mechanical properties are to a great part determined by the so-called cytoskeleton (the “skeleton of the cell”), a composite biopolymer network composed of three filament systems – intermediate filaments, actin filaments and microtubules – along with cross-linkers and molecular motors. In my talk, I will focus on intermediate filaments, the most flexible and the most extensible ones among the different types of filament, with an intriguing non-linear behavior. It has been shown previously that the presence of intermediate filaments in a cell has an influence on its mechanics. Here we unravel different contributions to network properties and cell mechanics, such as the assembly kinetics and mechanical properties of the individual filaments, filament-filament interactions, and network rheology. To explain our experimental results on molecular grounds, we design models that include the strictly hierarchical build-up of the filaments and non-equilibrium transitions between folded and un-folded states. Taken together, the experiments and the modelling indicate that intermediate filaments serve as “safety belts” and shock absorbers” for the cell, thus avoiding damage at strong and fast impact, while maintaining flexibility (e.g., during cell motility).
22 Dec 2022

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Dr. Sven Sturm, MPI für Kernphysik, Heidelberg Experiments with single ions confined in a Penning trap enable access to a broad range of observables that are of fundamental importance for our understanding of fundamental physics. In the magnetic field of the trap, the cyclotron frequency of an ion can be determined with unique precision and gives direct access to the charge-to-mass ratio. Furthermore, we have access to the gyromagnetic g-factor via a measurement of the (Larmor) spin precession frequency. This way, we have determined a number of fundamental parameters, such as the electron, proton, neutron and deuteron atomic masses with leading precision. This way, in our new generation experiment ALPHATRAP we have recently measured the g-factor of highly charged, hydrogenlike 118Sn. A comparison to a precise prediction by quantum electrodynamics (QED) allows probing the validity of QED in extreme electric fields, in the order of 1015 V/cm. Furthermore, by crystallizing two ions simultaneously in one trap we have achieved a leap of two orders of magnitude on the precision frontier. With this new technique, we have recently determined the isotopic effect of the g-factor in hydrogenlike neon ions, at 13 digits precision with respect to g and are consequently sensitive to previously invisible contributions, such as the QED recoil, and can set limits on hypothetical new physics such as dark matter mediated couplings. Finally, the possibility to determine the internal state of a single ion gives us access to systems that were previously difficult to handle, such as the molecular hydrogen ions. Currently, we are performing spectroscopy on HD+ and soon H2+. The development of the necessary toolbox will be a seminal step towards a possible future spectroscopy of the antimatter equivalent, anti-H2-, which will enable a unique test of charge-parity-time (CPT) reversal symmetry.

### GRK 2516 Soft Matter Seminar

###### Uni Mainz14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Nicolas Vogel, Friedrich-Alexander University Erlangen-Nürnberg The spontaneous organization of individual building blocks into ordered structures is extensively used in nature and found at all length scales, from crystallization processes, via composite materials, to living cells constituting complex tissue. Understanding the relationship between building blocks, environmental conditions, and resulting structure is of fundamental importance for controlling materials properties. Confining elements imposed upon the self-organizing particles can significantly alter the assembly process and may lead to entirely different colloidal crystals. Especially interesting confinements are emulsion droplets that prevent the formation of periodic structures by introducing boundaries and curvature. Here, we explore the surprising diversity of crystal structures and symmetries that can form in this confining element. We create a phase diagram of observed crystal phases in dependence of the number of colloidal particles within the confinement and support our model by event-driven molecular dynamics simulations of hard-spheres in a spherical confinement. A closer look at the thermodynamics in such systems shows that certain configurations exist as minimum energy structures, a signature associated with magic number clusters which are well known in the atomic world, but have not been observed in the colloidal realm. Importantly, and differing from their atomic analogues, the occurrence of such magic number states is not driven by the mutual attraction of the individual building blocks. Instead, the thermodynamics in our colloidal system is entirely governed by entropy maximisation. In this presentation, I introduce synthetic requirements that are necessary for the self-assembly of magic colloidal clusters and present a detailed study on the structures, thermodynamics and formation kinetics of this confined self-assembly process.Slides here... at Zoom

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau18:00 Uhr s.t., Minkowski-Raum 05-119, Staudingerweg 7
 Thomas Mehren, Physiker https://gemeinschaft-der-physik.fb08.uni-mainz.de/2022/12/02/thomas-mehren-physicist-in-hardware-software/
05 Jan 2023

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14 Uhr c.t., IPH Lorentzraum 05-127
 Prof. Dr. Nir Bar-Gill, Hebrew University, Jerusalem, Israel The study of open quantum systems, quantum thermodynamics and quantum many-body spin physics in realistic solid-state platforms, has been a long-standing goal in quantum and condensed-matter physics. In this talk I will address these topics through the platform of nitrogen-vacancy (NV) spins in diamond, in the context of purification (or cooling) of a spin bath as a quantum resource and for enhanced metrology and sensing. I will first describe our work on characterizing noise using robust techniques for quantum control ([1], in collaboration with Ra’am Uzdin). Suppression of such noise can be related to control and cooling of the spin-bath surrounding the NV, using a single optically pumped NV quantum central spin as a refrigerator [2]. I will then present a general theoretical framework we developed for Hamiltonian engineering in an interacting spin system [3]. This framework is applied to the coupling of the spin ensemble to a spin bath, including both coherent and dissipative dynamics [4]. Using these tools I will present a scheme for efficient purification of the spin bath, surpassing the current state-of-the-art and providing a path toward applications in quantum technologies, such as enhanced MRI sensing. Finally, if time permits, I will describe our work in using NV-based magnetic microscopy to implement quantum sensing in various modalities. I will present measurements of 2D vdW magnetic materials, and specifically the phase transition of FGT through local imaging of magnetic domains in flakes of varying thicknesses [5], as well as a technique for sensing radical concentrations through the change in the charge state of shallow NVs ([6], in collaboration with Uri Banin). 1. T. Zabelotsky et. al., in preparation. 2. P. Penshin et. al., in preparation. 3. K. I. O. Ben’Attar, D. Farfurnik and N. Bar-Gill, Phys. Rev. Research 2, 013061 (2020). 4. K. I. O. Ben’Attar et. al., in preparation. 5. G. Haim et. al., in preparation. 6. Y. Ninio et. al., ACS Photonics 8, 7, 1917-1921 (2021).
09 Jan 2023

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t., Munich
 Nicolo Piazzalunga, Uppsala U. I'll introduce the higher-rank Donaldson-Thomas theory for toric Calabi-Yau three-folds, within the setting of equivariant K-theory. I'll present a factorization conjecture motivated by Physics. As a byproduct, I'll discuss some novel properties of equivariant volumes, as well as their generalizations to genus-zero Gromov-Witten theory of non-compact toric varieties. at Zoom
10 Jan 2023

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Dr. Nico Döttling, Helmholzt Center for Information Security (CISPA) in Saarbrücken In the early 1990s cryptography went into a foundational crisis when efficient quantum algorithms were discovered which could break almost all public key encryption schemes known at the time. Since then, an enormous research effort has been invested into basing public key cryptography, and secure computation in general, on problems which are conjectured to be hard even for quantum computers. This research program has been resoundingly successful, leading to unexpected developments, such as the discovery of fully homomorphic encryption schemes. Furthermore, cryptography research has now moved beyond just "post-quantum security”, i.e. security against quantum adversaries, and investigates cryptographic protocols for a (still hypothetical) quantum world, where not just adversaries, but also honest users have access to scalable quantum computers and quantum communication channels. This enables applications such as quantum money, which are impossible using purely classical information. In this talk I will give an overview of the field and some of the (in my opinion) most challenging open problems.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Tim Höhne, TU Dortmund We address the notorious metastability of the standard model (SM) Higgs potential and promote it to a model building task: What are the new ingredients required to stabilize the SM up to the Planck scale without encountering subplanckian Landau poles? Using the SM extended by vector-like fermions, we chart out the corresponding landscape of Higgs vacuum stability. We find that the gauge portal mechanism, triggered by new SM charge carriers, opens up sizeable room for stability in a minimally invasive manner. We also find models with Yukawa portals into Higgs stability opening up at stronger coupling. Several models allow for vector-like fermions in the TeV-range, which can be searched for at the LHC. For nontrivial flavor structure of Yukawa couplings severe FCNC constraints arise which complement those from stability, and push lower fermion masses up to a few hundred TeV.
11 Jan 2023

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Dr. Valentina Santoro, ESS, Lund, Sweden The European Spallation Source, ESS, currently under construction in Lund, will be the world’s most powerful facility for research using neutrons. Supported by 3MEuro Research and Innovation Action within the EU Horizon 2020 program, a design study (HighNESS) is now underway to develop a second neutron source below the spallation target. Compared to the first source, located above the spallation target and designed for high cold and thermal brightness, the new source will provide a higher intensity (the total number of neutrons from the moderator), and a shift to longer wavelengths in the spectral regions of Cold (4-10 ˚A), Very Cold (10-100 ˚A), and Ultra Cold (> 500 ˚A) neutrons. The core of the second source will consist of a large liquid deuterium moderator to deliver a high flux of cold neutrons and to serve secondary VCN and UCN sources, for which different options are under study. The features of this new source will boost several areas of condensed matter research and will also provide unique opportunities in fundamental physics with the neutron antineutron oscillations experiment NNBAR. This experiment will search for the baryon number violating process of n → ¯n oscillation with a sensitivity of three orders of magnitude over the previously attained limit obtained at the Institut Laue-Langevin ILL. As a part of the HighNESS project work is ongoing to deliver the Conceptual Design Report of the experiment. Concerning the design of the Ultra Cold Neutron and Very cold neutron source for the ESS, a digital workshop has been held from February 2nd to February 4th, 2022 where experts from various laboratories and Universities have gathered to propose and discuss ideas and challenges for the development of these sources. During the course of the workshop, several possibilities have been identified on where to locate the VCN and UCN sources. The UCN source could be placed in close vicinity or at some distance from the primary cold source. Regarding the VCN source, we have identified two possibilities. In the first option, the VCNs are extracted from the main CN source using advanced reflectors. While in the other case we make use of a dedicated VCN converter, for which a material capable of delivering a high flux of VCNs is needed. From the point of view of neutronic performance, two promising materials, which are under study in the HighNESS project, are solid deuterium at about 5 K and deuterated clathrate hydrates at around 2 K. In summary in the the talk, the referent will discuss the HighNESS project, the status of the NNBAR experiment and all the possibilities for a dedicated UCN and VCN source at the ESS.Slides here...
12 Jan 2023

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14 Uhr c.t., IPH Lorentzraum 05-127
 Dr. Andreas Mooser, MPI für Kernphysik, Heidelberg The hyperfine structure of hydrogen like ions are a unique probe to access nuclear magnetic moments and nuclear structure. Thus, while eliminating the ignorance of essential links in metrology due to insufficiently known magnetic moment, at the same time these ions provide complementary insight into the inner nucleus. The very recently started ³He experiment exploits these characteristics to provide a new standard for absolute precision magnetometry and determine the nuclear charge and current distribution of ³He. To this end, a novel four Penning trap experiment was designed and built. Using novel techniques, this system enables non demolition measurements of the nuclear quantum state and allows sympathetic laser cooling of single, spatially separated ions to sub-thermal energies [1]. In the first measurement campaign, ³He was investigated by exciting microwave transitions between the ground state hyperfine states. This enabled us to determine the nuclear g-factor, the electronic g-factor and the zero field ground state hyperfine splitting of ³He with a precision of 5*10 -10, 3*10 -10 and 2*10 -11, respectively [2]. Our measurement constitutes the first direct and most precise determination of the ³He nuclear magnetic moment. The result is of utmost relevance for absolute precision magnetometry, as it allows the use of He NMR probes as an independent new standard with much higher accuracy. In addition, the comparison to advanced theoretical calculations enables us to determine the size of the ³He nucleus with a precision of 2.4*10 -17 m. In future, we aim at a direct determination of the bare nuclear magnetic moment of ³He to be compared to the bound state result. For this measurement, it is essential to implement new methods and technology such as sympathetic laser cooling and a high precision voltage source based on Josephson junctions [3]. The latest results, status and the future prospect of the experiment will be presented. References [1] A Mooser et al., J. Phys.: Conf. Ser. 1138, 012004 (2018) [2] A. Schneider et al., Nature 606, 878 (2022) [3] A. Schneider et al., Ann. Phys. 531, 1800485 ( 2019)
16 Jan 2023

at Zoom

17 Jan 2023

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Georg von Freymann, TU Kaiserslautern Photonic quantum simulation and sensing Georg von Freymann1,2 1Physics Department and Research Center OPTIMAS, Rheinland-Pfälzische Technische Universität Kaiserslautern Landau RPTU, 67663 Kaiserslautern, Germany 2Fraunhofer Institute for Industrial Mathematics ITWM, 67663 Kaiserslautern, Germany Applications of quantum technology are highly sought-after and thus supported by public funding agencies. However, the meaning of application varies depending on who you talk to: In the physics community application often means a useful laboratory implementation, while from an industrial perspective, application means solving a measurement problem in production or even creating a saleable product. To address the physics perspective, I will discuss 3D µ-printed photonic quantum simulators based on coupled waveguide system, focusing on topological protection and Floquet (time-periodic) driving. Such experimental model systems allow for studying these phenomena under very well controlled conditions. Examples are periodic driving of topologically protected edge modes in the one-dimensional Su-Schrieffer-Heeger-chain leading to depopulation of the edge mode despite topological protection [1], periodic driving of two-dimensional honey-comb-lattices establishes topological protection in an otherwise topologically trivial model system [2], switching of topological protection via excitation with and without orbital angular momentum of light [3], and establishing higher-order topological insulators using p-orbitals of the waveguides [4]. From the industry perspective I discuss recent results for terahertz quantum-sensing with undetected photons [5] allowing to measure terahertz spectral properties with visible light only, enabling both single-shot layer thickness measurements as well as spectroscopy. [1] Z. Cherpakova, C. Jörg, et al., Limits of topological protection under local periodic driving, Light: Science&Applications 8, 63 (2019). [2] C. Jörg, et al., Dynamic defects in photonic Floquet topological insulators, New J. Phys. 19, 083003 (2017). [3] C. Jörg, et al., Artificial gauge field switching using orbital angular momentum modes in optical waveguides, Light: Science&Applications 9, 150 (2020). [4] J. Schulz, J. Noh, et al., Photonic quadrupole topological insulator using orbital-induced synthetic flux, Nature Communications 13, 6597 (2022) [5] M. Kutas et al, Terahertz Quantum Sensing, Science Advances 6, eaaz8065 (2020)

### Theorie-Palaver

###### Institut für Physik14:15 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Carlos Tamarit, JGU Mainz The characteristics of the cosmic microwave background provide circumstantial evidence that the hot radiation-dominated epoch in the early universe was preceded by a period of inflationary expansion. Here, it will be shown how a measurement of the stochastic gravitational wave background can reveal the cosmic history and the physical conditions during inflation, subsequent pre- and reheating, and the beginning of the hot big bang era. This will be exemplified with a particularly well-motivated and predictive minimal extension of the Standard Model which is known to provide a complete model for particle physics -- up to the Planck scale, and for cosmology -- back to inflation. Please note the unusual time (we start 15min later than usual)
18 Jan 2023

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Dr. Anatael Cabrera, Paris, France The neutrino discovery (1956), by Reines & Cowan, paved the technical ground behind the establishment of much of today’s neutrino detection. Large instrumented volumes have been achieved via a key (implicit) principle: the impeccable transparency of detector, almost regardless of detection technique.Much of that technology has yielded historical success, including several discoveries and Nobel prizes, such as that of 2015 for the discovery of the Neutrino Oscillation phenomenon leading to an important modification of the Standard Model of Particle Physics. Despite their remarkable success, much of the transparent-based technology is also known to suffer from some key limitations, even after 70 years of maturity towards perfection. The pending challenge is to be to endow detectors with powerful active background rejection while allowing large volume articulation. Indeed, poor particle identification is a long standing issue. This forces experiments to rely on expensive and cumbersome external shield (active or passive), including major overburden in underground laboratories, as the only mean to mitigate otherwise overwhelming backgrounds. In this seminar, the referent shall introduce the LiquidO technology — in final stages of demonstration — relying, for the first time, heavily on detection medium opacity. The goal is enable sub-atomic particle event-wise imaging, so event topology may be use for particle ID purposes, even in the low MeV region. The development is led by the homonymous LiquidO international academic consortium with institutions over 10 countries. While not perfect, LiquidO appears to be capable to offer several detection features that might lead to breakthrough potential in the context of both neutrino and rare decay physics. The physics potential will be briefly highlighted. Beyond its most basic demonstration, LiquidO remains a testbed context for further detection R&D, where much innovation is expected and ongoing.
19 Jan 2023

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14:00 Uhr s.t., IPH Lorentzraum 05-127
 Prof. Giuseppe Vallone, University of Padova, Italy Within the last two decades, Quantum Technologies have made tremendous progress, from proof of principle demonstrations to real life applications, such as Quantum Key Distribution (QKD) and Quantum Random Number Generators (QRNGs). Here, we first briefly review the basic principles of QKD and QRNGs. We then discuss the results that we have recently obtained in our group at the University of Padova towards the realization of ultra-fast and secure QRNGs and mature and efficient QKD systems. Prof. Giuseppe Vallone is an Associate Professor at University of Padua since 2019 (www.dei.unipd.it/~vallone) and co-founder and CTO of ThinkQuantum (www.thinkquantum.com), a spin-off of the Univeristy of Padua pioneering a new generation of secure communication systems based on quantum technology. His research is focused on quantum information, photonic states, quantum communication, quantum random number generators and Orbital Angular Momentum states. He has three patents and more than 130 publications in the area of quantum optics and quantum information. He is currently the coordinator of the European Project QUANGO (www.quango.eu) and the Italian Project QUASAR (quasar.dei.unipd.it).

### GRK 2516 Soft Matter Seminar

###### Uni Mainz14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Weixiang Chen, JGU, Chemistry Liquid-liquid phase separation (LLPS) has been identified as a key mechanism regulating the formation of membraneless organelles inside cells. These membraneless organelles, typically composed of DNA, RNA, protein, etc., are involved in many cellular reaction networks by forming micro-sized reactors to locally concentrate specific species or signal molecules, facilitating metabolic reactions, and thus maintaining the functionality of cells. Herein, building on an established model DNA-condensate system, we report an anomalous diffusion process of short oligonucleotide during their uptake by large DNA-condensates driven by specific binding interaction. We show that the interior dynamics of DNA-condensates can be tuned by orders of magnitude at varied salinity, while the diffusional mechanism of signal uptake simultaneously adapts from non-Fickian to Fickian type diffusion. With systematical study on such anomalous diffusion process, we have found pathway to control the velocity of the diffusional process and established a generic mechanism explaining it based on an old polymer physics concept. at Zoom

### GRK 2516 Soft Matter Seminar

###### Uni Mainz15:00 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Lorena Baranda, JGU, Chemistry DNA nanotechnology employs synthetic nucleic acid strands to design and engineer nanoscale structural and functional systems of increasing complexity that may find applications in sensing, computing, molecular transport, information processing, and catalysis. Several features make synthetic DNA a particularly appealing and advantageous biomaterial for all the applications mentioned above but more specifically for sensing. First, synthetic DNA sequences, especially if of limited length (<100 nucleotides), have highly predictable interactions and thermodynamics. Second, DNA recently became quite easy and inexpensive to synthesize. Third, DNA contains several functional groups that make it quite straightforward to modify a synthetic nucleotide sequence at both ends or internally. A variety of additional reactive groups can be introduced into DNA sequences. For sensing applications, these functional groups can be used to conjugate signaling moieties (for example, fluorophore/quencher pairs). Importantly, it is also possible to conjugate different recognition elements such as antigens to a synthetic DNA sequence, thus allowing the use of antibodies as targets to be detected with DNA-based sensors. Over my introductory talk, I will present the developed work during my PhD on DNA-based sensors and how I am applying the acquired knowledge in the field of soft colloids and synthetic cells during my postdoctoral research at Prof. Andreas Walther group. at Zoom
20 Jan 2023

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:00 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Roland Netz, Freie Universität Berlin

23 Jan 2023

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Johannes Balz, Institut für Physik
at Zoom

24 Jan 2023

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Markus Klute, KIT „I think we have it“ – with these words, the then Director General of CERN, Rolf-Dieter Heuer, commented on July 4th, 2012 the detection of a new elementary particle at the Large Hadron Collider (LHC). The search for the Higgs boson, which had lasted almost 50 years, had reached its goal. With the discovery of the Higgs boson, a new era began at the LHC, the precise measurement of the particle's properties. With the help of these properties, conclusions can be drawn about the fundamental structure of the universe and matter. In this colloquium, I will discuss the latest result and prospects in the quest to decipher the Higgs boson.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Quentin Decant, Brussels U. Dark matter (DM) from freeze-in or superWIMP production is well known to imprint non-cold DM signatures on cosmological observables. It will be discussed how to derive constraints from Lyman-α forest observations for both cases, based on a reinterpretation of the existing Lyman-α limits on thermal warm DM. Special emphasis is placed on the mixed scenario, where contributions from both freeze-in and superWIMP are similarly important. In this case, the imprint on cosmological observables can deviate significantly from thermal warm DM. The above will be illustrated by studying a coloured t-channel mediator DM model, in which case contributions from both freeze-in through scatterings and decays, as well as superWIMP production can be important. The entire cosmologically viable parameter space, cornered by bounds from Lyman-α observations, the LHC, and Big Bang Nucleosynthesis, will be mapped.
25 Jan 2023

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Prof. Dr. Peter von Ballmoos, IRAP, Toulouse, France The tentative detection of a few anti-Helium nuclei [1] is presently revitalising the discussion on the existence of baryonic antimatter in the Universe. As ”the discovery of a single anti-helium nucleus in the cosmic ray flux would definitely point toward the existence of stars and even of entire galaxies made of anti-matter” [2] it has been proposed that the anti-Helium nuclei could originate from anti-clouds or anti-stars in the solar vicinity [3]. We discuss possible entities of antimatter in the Universe that would be probed through ordinary matter, with annihilation-radiation providing indirect evidence for their presence [4]. The observations of high energy (∼ 100 MeV) gamma-rays sets limits on the fraction of nuclear antimatter contained in our local and Galactic neighbourhood. We review recent gamma-ray [5] observations that set upper limits on such emissions. [1] S. Ting, https://indico.cern.ch/event/729900, (2018) [2] P.Salati, et al., Nuclear Physics B, 70, 1-3, 492, (1999) [3] V. Poulin, et al., Phs. Rev. D 99, 023016, (2019) [4] P. von Ballmoos, Hyperfine Interact. 228, 91,, (2014) [5] S. Dupourque, et al., Phs. Rev. D 103, 083016, (2021)

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t.
Claus Ropers, MPI for Biophysical Chemistry and University of Göttingen
##### Developments in ultrafast electron microscopy
at Zoom and SPICE YouTube Channel

26 Jan 2023

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14 Uhr c.t., IPH Lorentzraum 05-127
 Prof. Vahid Sandoghdar, Max-Planck-Institut für die Physik des Lichts, Erlangen Laboratory manipulation of single quantum emitters and single photons has matured to a routine procedure over the past two decades. These activities have led to new emerging topics such as optomechanical functionalities and coherent cooperative interactions among several quantum emitters. In this presentation, I discuss our efforts of the last decade in coupling molecules to high-finesse Fabry-Perot cavities and nanoscopic waveguides on a chip, demonstrating dipole-induced transparency, strong coupling and single-photon nonlinearity. Moreover, I present data on precision spectroscopy of the vibronic transitions in single molecules as well as theoretical conception of hybrid optomechanical platforms for achieving long coherence and storage times. I will also present the latest results on the coupling of two or molecules to each other via a common mode of a micro-resonator.

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau11:30 Uhr s.t., Hörsaal Kernphysik
Andrey Milchev, Institute of Physical Chemistry, Bulgarian Academy of Sciences

### Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

###### JGU14:00 Uhr s.t., 01-122 Newton Raum
 Vincent Cros, Unité Mixte de Physique CNRS, Thales, Univ. Paris-Saclay From 2D skyrmions to 3D cocoons : nucleation, motion and electrical detection of non collinear topogical spin textures Vincent Cros Unité Mixte de Physique, CNRS, Thales, Université Paris-Saclay, 91767, Palaiseau, France. In the last decade, magnetic multilayers have proven to be essential structures for creating and investigating complex, topologically non-trivial spin textures through the ability to tune their composition and properties [1-2]. Two-dimensional magnetic textures such as skyrmions (or chiral domain walls) were mostly under focus. First, I will share some of our recent results showing the skyrmion nucleation can be precisely controlled using injection of current pulses through artificial notches and show how the spin-orbit torques, responsible for the skyrmion motion, can be optimized in multilayers. More specifically, I will explain how, in atomically thin Co, the SOTs amplitudes, both for damping and field-like symmetries, varies significantly when a light element, such as Al is deposited on top of Co, surpassing the values existing in literature [3]. Then I will describe how the presence and the displacement of skyrmions can be precisely followed through a simple electrical detection. By relying on our ability to perform fully-electrical manipulation and detection of magnetic skyrmions in multilayers, I will present some recent device developments for performing a basic unconventional computation operation in hardware. Beyond the 2D skyrmions, a strong interest has emerged for more complex magnetic objects which display a non-homogeneous behavior over the vertical dimension, giving them a 3D character e.g. magnetic bobbers [4] or the recently observed hopfions [5]. In the second part of my talk, I will present our recent results on 3D spin textures, called skyrmionic cocoons [6], that have a typical ellipsoidal shape and that can be stabilized in aperiodic magnetic multilayers with a variable thickness for the ferromagnetic elements. Interestingly, these skyrmionics cocoons can coexist with more standard tubular skyrmions going through all the multilayer as evidenced by the existence of two very different contrasts in room temperature magnetic force microscopy. They can also be electrically detected using magneto-transport measurements, an interesting feature for potential applications. The presence of these novel skyrmionic textures as well as the understanding of their layer resolved chiral and topological properties have been investigated by micromagnetic simulations. Finally, I will describe how the use of x-ray holography and x-ray laminography gives a precise insight into the 3D distribution of the magnetization which demonstrate the 3D nature of skyrmionic cocoons. Financial supports from FLAG-ERA SographMEM (ANR-15-GRFL-0005), from ANR MEDYNA (ANR-20-CE42-0012), from “Investissements d’Avenir" program SPiCY (ANR-10-LABX-0035), from France 2030 government grant (ANR-22-PEPR-Electronique-EMCOM and ANR-23-PEPR-Spin) and the EU Horizon2020 Programme under FET-Proactive Grant agreement No. 824123 (SKYTOP) are acknowledged. [1] A. Fert, N. Reyren and V. Cros, Nat. Rev. Materials 2, 17031 (2017) [2] K. Everschor-Sitte et al, J. Appl. Phys. 124, 240901 (2018) [3] S. Krishnia, VC et al, arXiv:2205.08486 (2022) [4] F. Zheng et al. Nat. Nanotech., 13, 451 (2018) [5] N. Kent et al. Nat. Comm. 12, 1 (2021) [6] M. Grelier, VC et al. Nature Comm, 13, 6843 (2022)
30 Jan 2023

### Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

###### JGU16:00 Uhr s.t., Medien-Raum (03-431)
Joo-Von Kim, CNRS, Université Paris-Saclay
at Zoom

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t.
 Konstantin Wernli, University of Southern Denmark In the Batalin-Vilkovisky (BV) formalism, one can define a perturbative (i.e. given by Feynman graphs and rules) partition function $Z(x_0)$ for any choice of classical background (solution to Euler-Lagrange (EL) equations) $x_0$. In some examples one can extract from $Z$ a volume form on the smooth part of the moduli space of solutions to EL equations, and compare its integral with non-perturbative approaches to quantization. I will review this construction, some results from examples in the literature and ongoing joint work with P. Mnev about the behaviour at singular points $x_0$. at Zoom

### Seminar about Experimental Particle and Astroparticle Physics (ETAP)

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Peter Krämer, Institut für Physik
at Zoom

### Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

###### JGU16:00 Uhr s.t., Medien-Raum (03-431)
 Joo-Von Kim, Centre for Nanoscience and Nanotechnology, CNRS, Université Paris-Saclay Magnetic skyrmions are nanoscale, chiral topological solitons which exhibit a wide variety of interesting dynamical phenomena that have solicited much interest for fundamental reasons and technological applications alike. In this talk, I will discuss some recent experimental and theoretical results on two aspects of skyrmion dynamics in ferromagnetic thin film systems. The first involves the resonant dynamics in multilayered films of [Pt/FeCoB/AlOx]20, which are found to host dense robust skyrmion lattices at room temperature with a relatively low Gilbert damping of ∼0.02 [1]. Broadband ferromagnetic resonance measurements, combined with micromagnetic simulations, reveal distinct resonant modes detected in the skyrmion lattice phase. These are found to involve localised excitations, along with skyrmion core precession emitting spin waves into uniform background with wavelengths in the 50–80 nm range. The second aspect involves thermal diffusion of skyrmions in frustrated systems under spin-orbit torques, where the helicity dynamics leads to an anomalous drift that strongly depends on the strength of the Dzyaloshinskii-Moriya interaction. Such drift processes suggest the importance of helicity coupling to spin-orbit torques and may have bearing on dipole-stabilized bubbles for which drive-dependent skyrmion Hall angles and low drift velocities have been reported. [1] T. Srivastava et al, arXiv:2111.11797 [cond-mat.mes-hall].
31 Jan 2023

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Dr. Philipp Schmidt-Wellenburg, PSI Switzerland An electric dipole moment (EDM) of a fundamental particle would violate time and parity symmetry and by the virtue of the CPT theorem also the combined symmetry of charge conjugation and parity inversion. Searches for EDM are generally considered highly sensitive probes for new physics and might shed light on still unresolved questions in particle physics and cosmology like the origins of matter, dark matter, and dark energy. At the Paul Scherrer Institute in Switzerland, we are setting up an experiment searching for a muon EDM with a sensitivity of 3E-21 ecm using, for the first time, the frozen-spin technique~\cite{Farley2004PRL} in a compact storage ring. This will lay the ground work for a second phase with a final precision of better than 6e-23 ecm. This staged approach to search for a non-zero muon EDM probes previously uncharted territory and tests theories of BSM physics by: i) improving the current direct experimental limit of d < 1.5E-19 ecm (CL 90%) by roughly three orders of magnitude; ii) being a complementary search for an EDM of a bare lepton; iii) being a unique test of lepton-flavor symmetries; and iv) in the case of a null result, will be a stringent limit on an otherwise very poorly constrained Wilson coefficient.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Felix Kahlhöfer, KIT Given our detailed knowledge of the dark matter energy density in the present universe, it is of great interest to study its evolution at early times in order to understand the mechanism of dark matter production. A particularly intriguing scenario, known as freeze-in, is that dark matter particles have tiny couplings and never enter into equilibrium with the thermal bath of Standard Model particles. In this talk, I will discuss various technical challenges that arise in this scenario as a result of the high temperatures and densities in the early universe. Specifically, I will show how to consistently treat the spin statistics of relativistic quantum gases and how to accurately calculate dark matter production via the Higgs resonance. Finally, I will discuss the case of freeze-in with low reheating temperature, which may be testable through cosmological, astrophysical and laboratory observations.
01 Feb 2023

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
CANCELED: Prof. Dr. Steen Hannestad, Univ. Aarhus, Denmark

02 Feb 2023

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14 Uhr c.t., IPH Lorentzraum 05-127
 Prof. Stephan Schiller, Heinrich-Heine-Universität Düsseldorf, Institut für Experimentalphysik Molecular hydrogen ions (MHI), the simplest molecules, are three-body quantum systems composed of two simple nuclei and one electron. They are of high interest for fundamental physics and metrology because they provide the missing link between the fields of mass and g-factor measurements with Penning traps and spectroscopy of hydrogen-like atoms. Basically, the new ingredients introduced by the MHI are the long-range nucleus-nucleus interaction, absent in the hydrogen atom, and the quantized motion of the nuclei. Precision spectroscopy of the MHI can thus furnish novel results: (1) on the masses of proton and deuteron (in the future, also of tritium), (2) set limits for beyond-Standard-Model (BSM) forces, (3) verify the wave character of matter, and (4) test alternative theories of quantum mechanics. This is performed by comparing or matching experimental and theoretical rotational and/or vibrational frequencies. The comparison is enhanced by the availability of several recently measured transition frequencies and recent advances in ab initio theory. An additional opportunity for probing the interactions between the particles within the MHI is the precision measurement of its hyperfine structure (HFS). Only the synthesis of the HFS of the hydrogen atom, of the deuterium atom and of the molecular hydrogen ion allows probing the physics of HFS at the finest level, resolving the issue of the uncalculable nuclear contributions. We present recent results of our spectroscopy of sympathetically cooled MHI, its results and interpretation. An outlook on near-future studies is also given.

### GRK 2516 Soft Matter Seminar

###### Uni Mainz14:30 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7
 Swapnasopan Datta, JGU, Chemistry Conventional chemistry deals with reactants that lead to stable molecules following a classical equilibration pathway. The same holds for classical self-assembly processes, in which non-covalent interactions lead to assembly according to thermal equilibration. There are also a number of systems that reach a metastable state momentarily, and subsequently jump to another lower energy state. In supramolecular systems, this is called pathway complexity. The propensity to transition from a metastable state to an equilibrium state is a function of the energy barrier with respect to thermal energy. This is fundamentally different from the far-from-equilibrium way living systems work, which can be achieved by employing a ‘fuel’ which drives a system to a high energy state and coupling it with an environment which can bring the system back to the original state. Keys to non-equilibrium behaviour are the mechanisms through which systems are able to extract energy from the chemical reactants (‘fuel’) that drive such processes. In our group, a fuel driven enzyme mediated reaction network was established where a ligation reaction occurs followed by a dynamic steady state, whose lifetime depends on the fuel concentration and dynamics is decided by the ratio of the ligation and restriction enzymes, and finally the restriction process dominates giving back the monomers. This is achieved in our case by using ATP as a fuel which activates a ligation enzyme leading to formation of DNA polymers which get cleaved by the restriction enzyme giving back the monomers. By tuning the interactions between these polymers, one can give rise to multivalent DNA coacervates which phase separate as a function of time and eventually vanish when the restriction step dominates. This liquid liquid phase separation (LLPS) process is fundamentally different from conventional coacervation in that it occurs as a result of interaction between polymers which are at a very high energy as opposed to thermodynamically stable phase separation. In this talk I will talk about trapping such a reaction module inside a ‘protocell’ which is a simple mimic of a real cell and explore the possibility of making a synthetic cell bottom up inside which transient LLPS might occur. For this project, we are using liposomes as cell mimics as the phospholipid bilayer which they contain closely resembles a cell. at Zoom
03 Feb 2023

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:00 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Jeetain Mittal, Texas A&M

06 Feb 2023

### RIND seminar on Mathematical Physics and String Theory

###### U. Mainz, LMU Munich, U. Heidelberg, U. Vienna16 Uhr c.t., Munich, Theresienstr. 37A, R. 348
 Renann Lipinski Jusinskas, Prague In this talk I will present a worldsheet model obtained from "twisting" the target space CFT of conventional string theory. The physical spectrum becomes finite and corresponds to the massless spectrum of closed strings plus a single massive level of the open string. The underlying idea is to explore the field/string theory interface in both directions. On one hand, the goal is to generate effective field theories describing massive higher spins using worldsheet methods. Conversely, we may try to use field theory methods to obtain a systematic description of string scattering amplitudes using field theory methods. at Zoom
07 Feb 2023

### Physikalisches Kolloquium

###### Institut für Kernphysik16:15 Uhr s.t., HS KPH
 Prof. Dr. Tom Aumann, TU Darmstadt & GSI Darmstadt Reactions with short-lived nuclei are key to understand the properties of neutron-rich nuclei and neutron-rich nuclear matter. In recent years, quasi-free scattering experiments have been developed and established for experiments with radioactive beams at GSI and RIKEN. The inverse kinematics of the reaction opens thereby the possibility for a complete characterisation of the final state, which results in an almost background-free measurement. Recent results with stable and radioactive beams will be discussed including the first measurement of short-range correlations in inverse kinematics, the observation of alpha clusters at the surface of heavy nuclei, as well as the observation of a correlated four-neutron state. The perspective for a precise determination of the neutron-neutron scattering length using the 6He(p,p alpha)2n reaction will be discussed as well.

### Theorie-Palaver

###### Institut für Physik14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)
 Weiguang Jiang, JGU Mainz Nuclear saturation is a key property of low-energy nuclear physics that depends on the fine details of the nuclear interaction. We develop a unified statistical framework that uses realistic nuclear forces to link the theoretical modeling of finite nuclei and infinite nuclear matter. We also construct fast and accurate emulators for nuclear-matter observables and employ an iterative history-matching approach to explore and reduce the enormous parameter domain of Delta-full chiral interactions.
08 Feb 2023

### PRISMA+ Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum, 05-127, Staudingerweg 7
 Prof. Dr. Julien Lesgourgues, Aachen Cosmologists are puzzled by a tension between the results of two categories of observations, which has been growing over the past few years. This “Hubble tension” arises from contradictory indications concerning the current expansion rate of the universe. The referent will try to give a pedagogical overview of this problem, with a summary of the physical assumptions that go into the interpretation of each observation. Then, assuming that the tension persists with future data releases, he will give examples of the kind of new fundamental physics that could help solving it.Slides here...
09 Feb 2023

### Seminar über Quanten-, Atom- und Neutronenphysik (QUANTUM)

###### Institut für Physik14 Uhr c.t., IPH Lorentzraum 05-127
 Prof. Dr. Immanuel Bloch, Max-Planck-Institute of Quantum Physics, Garching Quantum Simulations using Ultracold Atoms in Optical Lattices 40 years ago, Richard Feynman outlined his vision of a quantum simulator for carrying out complex calculations of physical problems. Today, his dream has become a reality and a highly active field of resarch across different platforms ranging from ultracold atoms and ions, to superconducting qubits and photons. In my lecture, I will outline how ultracold atoms in optical lattices started this vibrant and interdisciplinary research field 20 years ago and now allow probing quantum phases in- and out-of-equilibrium with fundamentally new tools and single particle resolution. In addition, I will show how fundamentally new avenues of controlling light-matter interactions can be realized based on the rich interplay of photon-mediated dipole-dipole interactions in structured subwavelength arrays of quantum emitters. In the experiments, we directly observe the cooperative subradiant response of such an ordered array of ultracold atoms. Through spatially resolved spectroscopic measurements, our experiments show that the array acts as an efficient mirror formed by only a single monolayer of a few hundred atoms. Finally, I will discuss latest experiments, where the optical properties of the entire array can be switched via a single Rydberg impurity that is deterministically prepared in the center of the array. This opens the path towards novel structured quantum light matter interfaces with unique properties in free space.

### Seminar über Theorie der kondensierten Materie / TRR146 Seminar

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau15:00 Uhr s.t., Minkowski Room, 05-119, Staudingerweg 7,
 Roberto Covino, Frankfurt Institute for Advanced Studies Molecular self-organization driven by concerted many-body interactions produces the ordered structures that define both inanimate and living matter. Understanding the physical mechanisms that govern the formation of molecular complexes is key to controlling the assembly of nanomachines and new materials. Molecular dynamics simulations and single-molecule experiments offer the unprecedented possibility to reveal mechanisms of molecular self-organization in high resolution. However, outstanding limitations hinder their success. Machine learning and artificial intelligence promise to empower both approaches to overcome fundamental challenges. In the first part of my talk, I will present an autonomous AI that learns molecular mechanisms from computer simulations. The AI agent simulates infrequent and stochastic molecular reorganizations and progressively learns how to predict their outcome. Using symbolic regression, we distill simplified quantitative models that reveal mechanistic insight in a human-understandable form. Our innovative AI enables sampling rare events by autonomously driving many parallel simulations with minimal human intervention and aids their mechanistic interpretation. I will present applications on nucleation processes, the assembly of membrane proteins in lipid bilayers, and polymer and protein folding. In the second part of my talk, I will discuss how integrating physical modeling and AI helps extract mechanistic understanding from single-molecule force spectroscopy. While these experiments offer the possibility of measuring fundamental quantities like free energies, these measurements are often incomplete and indirect. In practice, we measure a few order parameters that are the outcome of the coupled dynamics of the molecule and the mesoscopic experimental apparatus, which could lead to estimation artifacts. I will discuss this problem as Bayesian inference and illustrate how simulation-based inference provides a powerful solution. Coupling a simulator that encodes the physics of the measuring process with density estimation using neural networks leads to accurate estimates of molecular free energies. In conclusion, integrating physics-based models and AI provides a powerful way to extract accurate quantitative information from simulations and biophysical experiments.
15 Feb 2023

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t.
Alberta Bonanni, Johannes Kepler University
##### A stride down the quantum materials roadmap
at Zoom and SPICE YouTube Channel

22 Feb 2023

### SPICE-Spin+X Seminar

###### TUK and JGU15:00 Uhr s.t.
Angela Wittmann, JGU
##### Exploring spintronics at unconventional hybrid interfaces
at Zoom and SPICE YouTube Channel

16 Mar 2023

### Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

###### JGU14:00 Uhr s.t., 01-122 Newton Raum
 Masahiro Yamashita, Department of Chemistry, Faculty of Science, Tohoku University, Sendai, Japan Spintronics, based on the freedoms of charge and spin of the electron, is a key technology in the 21st century. Magnetic random access memory (MRAM), which uses giant magnetoresistance (GMR), has several advantages compared with electronics. Although conventional magnets composed of transition metals are normally used, in our study, we use molecule-based nano-magnets and single-molecule magnets (SMMs) to overcome “Moore`s Limitation”. SMMs are also available for quantum computer. I will talk about the molecular spin qubits for quantum computer ([1]Crystal Engineering Method, [2]g-Tensor Engineering Method, [3]Orbital Engineering Method, and [4]Molecular Technology Method) as well as high-density memory devices such as single-molecule memory device, SMMs encapsulated into SWCNT, and metallic conducting SMMs with negative magnetoresistances.