## Jahresübersicht für das Jahr 2020

06 Jan 2020

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

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Niklas Schmitt, University of Mainz
##### Suche nach dunkler Energie in Monojet-Ereignissen bei 13TeV mithilfe des ATLAS-Detektors am LHC

Bachelorkolloqium

07 Jan 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:00 Uhr s.t., HS KPH
Professor Christian Enss , Kirchhoff Institute for Physics, Heidelberg

08 Jan 2020

### PRISMA Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7
 Cristina Lazzeroni, University Birmingham, UK The decay K+→π+vv ̅, with a very precisely predicted branching ratio of less than 10-10, is one of the best candidates to reveal indirect effects of new physics at the highest mass scales. The NA62 experiment at the CERN SPS is designed to measure the branching ratio of the K+→π+vv ̅ with a decay-in-flight technique. NA62 took data so far in 2016-2018. Statistics collected in 2016 allowed NA62 to reach the Standard Model sensitivity for K+→π+vv ̅, entering the domain of 10-10 single event sensitivity and showing the proof of principle of the experiment. Thanks to the statistics collected in 2017, NA62 surpasses the present best sensitivity. The preliminary result from the 2017 data set is presented. The general status of the experiment, including other recent measurements, are presented. Plans for the next data taking and for a longer term future are also discussed.
09 Jan 2020

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

###### Institut für Physik14:00 Uhr s.t., Lorentz-Raum (05-127), Staudingerweg 7
 Jun.-Prof. Dr. Jamir Marino, Institut für Physik, Universität Mainz The talk will discuss instances of dynamical phases of interacting quantum many body models where coherent and dissipative dynamics occur on equal footing, shaping novel non-equilibrium phase diagrams. The first part of the talk will discuss long-range interacting quantum simulators where an external periodically driven field can stabilise phases without equilibrium counterpart against instabilities triggered by many body quantum fluctuations. In the second part, I will present an instance of ‘cold' time crystal occurring in open quantum systems, where neither MBL or pre-thermalisation are required to stabilise a strongly interacting non-equilibrium steady state. Time permitting, I will advertise some novel results on a purely dissipative analogue of long-range interacting quantum simulators, which can be implemented in quantum optics or solid state platforms.
13 Jan 2020

### Seminar für Kern- und Radiochemie

###### Institut für Kernchemie16:00 Uhr s.t., Seminarraum Kernchemie
Dr. Marine Vandebrouck, CEA Saclay

### Theoriekolloquium

###### Die Dozierenden der Theoretischen PhysikSonderseminar: 14:00 Uhr s.t., Medienraum, Staudinger Weg 7, 03-431
 Prof. James Freericks, Georgetown University, USA Quantum mechanics was created with the matrix mechanics of Heisenberg, Born, and Jordan. Schroedingers wave mechanics shortly followed and allowed for simpler and more powerful calculations. Both Pauli and Dirac introduced a formulation of quantum mechanics based on operators and commutation relations, but it was never fully developed in the 1920s. Instead, Schroedinger formulated the operator approach with his factorization method, which later was adopted by the high-energy community as supersymmetric quantum mechanics. In this talk, I will explain how one can formulate all of quantum mechanics algebraically by a proper use of the translation operator on top of Schroedingers factorization method. I will give examples of how one can compute spherical harmonics algebraically, how one can find harmonic oscillator wavefunctions, and will even describe an operator-based derivation of the wavefunctions of Hydrogen. I will end with a proposal for a novel way to teach quantum mechanics, focusing first on conceptual ideas related to superposition, projective measurements, and entanglement. Then developing more conventional topics like spin, harmonic oscillator, angular momentum, interacting spin models, central potentials, particles in a box and so on. This is the subject of a book in progress entitled Quantum Mechanics without Calculus. Sonderseminar Sondertermin/-raum Montag, 14:15 h im Medienraum, Staudinger Weg 7, 03-431

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

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Julian Fischer, Institut für Physik

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für PhysikSonderseminar: 10:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 03-431
 Abhishek Erram , Indian Institute of Technology Kharagpur In this work, we have made a polycrystalline sample of Dy2BaNiO5 by a standard solid-state reaction route. The formation of the compound was ascertained by x-ray powder diffraction pattern. The dc χ measurements were carried out in the temperature interval 5–300 K in the presence of magnetic fields of 100 Oe and 5 kOe for zero-field-cooled (zfc) and field-cooled (fc) conditions using (SQUID) and isothermal magnetization (M) behavior was studied at a certain selected low temperature. Then, Thin film of Dy2BaNiO5 certain thickness were deposited on Mgo , Al203 ,STO and LAO substrate by Pulsed Layer Deposition method these films were annealed at temperature 650 oC. Some of the samples were Characterized by X-ray diffraction (XRD). Magnetic behavior was also studied. Results show that of formation of thin film. Signs of magnetic behavior was also evident. Sonderseminar
15 Jan 2020

### PRISMA Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7
 Christian Fischer, Universität Gießen In this talk I will give an overview on recent results on the spectrum and properties of conventional baryons and 'exotic' tetraquarks as obtained in the framework of Dyson-Schwinger and Bethe-Salpeter equations. I will discuss the spectrum of light baryons with focus on the comparison with quark model expectations, the impact of dynamical mass generation and the importance of relativistic components in the wave functions of baryons. I will also discuss extensions to SU(3). For four-quark systems I will summarize results for light quarks and discuss recent progress on discriminating between tetraquark, molecule or hadro-quarkonium configurations in heavy-light systems.

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

###### Institut für Physik10:30 Uhr s.t., QUANTUM Seminarraum (02-427), Institut für Physik, Staudingerweg 7
 Brian Rost and Lorenzo Del Re , Georgetown, USA The driven dissipative many body problem is one of the longest standing unsolved problems in physics and it has experienced a renewed interest in the last decade. In fact, dissipation has been theoretically proposed as a resource for quantum computation and experimentally has been demonstrated that it can be employed to prepare maximally entangled states. Thus, quantum computers could shed some light on the unsolved problem of driven-dissipative quantum systems but there are many choices for how one engineers the reservoir. An attractive approach is to integrate the bath degrees of freedom out via a master equation. Here we show how accurate this approach is by comparing it to an exact solution in the case of a tight-binding dissipative-driven model of fermions coupled to an external fermionic bath, and how to actually simulate it on a currently available IBM quantum computer. We also address the case of an interacting dissipative-driven finite size system, i.e. a three-site Hubbard model with on-site interaction driven by an external field and coupled to a bath. Here, we obtain many of the qualitative features already displayed in the thermodynamic limit. The biggest challenge in implementing these ideas on current quantum computers lies with the need for partial resetting of qubits. We discuss strategies to implement on commercially available hardware and what might be possible with academic machines (such as those available at Mainz). Sondertermin und -ort
16 Jan 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers11:30 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122
 Dr. Dongwook Go, Peter Grünberg Institut and Institute for Advanced Simulation, Forschungszentrum Jülich Electrical control of magnetism is a central theme in the field of spin-orbitronics. Current scheme relies on electrical generation of the spin current/density by utilizing the spin-orbit coupling (SOC) instead of using an extra ferromagnet (FM) as a spin polarizer. For example, in a bilayer structure consisting of a FM layer and a nonmagnet (NM) layer, spin current and density can be induced by the spin Hall effect in the NM and Rashba-Edelstein effect at the NM/FM interface, respectively. However, there has been a missing piece in spin-orbitronics so far: electrons carry angular momentum in the orbital wave function as well as in the spin. In this seminar, I demonstrate that the orbital degree of freedom exhibits rich dynamical phenomena, which is in contrast to a common expectation that the orbital is quenched in solids. In the first part, I explain how to electrically generate the orbital angular momentum. Here, I introduce concepts of the orbital Rashba-Edelstein effect [1] and the orbital Hall effect [2], which are orbital analogs of the Rashba effect and the spin Hall effect, respectively. These are not only parental effects for their spin analogs, such that the spin phenomena follow the orbital phenomena by the SOC, but also present even in the absence of the SOC. In the second part, I focus on the consequence of the injection of the orbital angular momentum into the FM. As the spin injection gives rise to the spin torque (ST), the orbital injection results in torque on the magnetic moment, which we call orbital torque (OT) [3]. In the mechanism of the OT, it is not necessary to prepare the spin current or density beforehand as in the conventional mechanisms such as the spin Hall effect and Rashba-Edelstein effect. Since both OT and ST contribute to magnetic dynamics, it opens a route to enhancing the torque efficiency in spin-orbitronic devices. Interestingly, we notice that the sign of the torque efficiency in the NM/FM bilayer can be opposite to the sign of the spin Hall effect in the NM if the sign of the OT differs from that of the ST. As a prototypical example, I compare Fe/W(110) and Ni/W(110) bilayers from first principles calculation and discuss qualitatively distinct features of the OT for the experimental detection [4]. As the study on the orbital dynamics has started very recently, I briefly discuss future directions for consistent understanding of entangled dynamics of the spin and orbital degrees of freedom in solids.

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

###### Institut für Physik14:00 Uhr s.t., Lorentz-Raum (05-127), Staudingerweg 7
 Shane P. Kelly, Theoretical Division, LANL, Los Alamos, USA In recent years, many experimental platforms have succeeded in producing quantumsystems that, on relevant time scales, are completely isolated from an environment. This opens the possibility of observing equilibrium states that are not described by standard thermal ensembles and long time dynamics that indefinitely maintain memory of initial states. In this talk, I discuss two mechanisms for this to occur: many body localization (MBL) and a novel mechanism which occurs in the semi-classical limit of a large spin. In the first part of my talk, I will discuss the phenomenon of MBL in a disordered spin chain and its effects when coupled to a small environment. We model this small environment as a clean spin chain and find that, under sufficient coupling and disorder, the dirty chain can induce an MBL effect in the clean chain. In the second part of my talk, I will discuss the dynamics of a large spin evolving with a non-linear hamiltonian. Using semi-classical techniques, we identify when the spin does and does not thermalize. In doing so, we find a novel mechanism for the breakdown of thermalization based on the slow dynamics of an unstable fixed point.
20 Jan 2020

###### Institut für Kernphysik14:00 Uhr s.t., HS Kernphysik, Becherweg 45
Christoph Matejcek, Mainz

### Seminar für Kern- und Radiochemie

###### Institut für Kernchemie16:00 Uhr s.t., Seminarraum Kernchemie
Dr. Zsolt Baranyi, Universität BRACCO

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

###### Institut für Physik16:15 Uhr s.t., QUANTUM Seminarraum (02-427), Institut für Physik, Staudingerweg 7
 Dr. Guanghua Du, Institute of Modern Physics, Chinese Academy of Sciences, Lanzhou, China When heavy ion beam with energy from MeV to GeV is incident on the target material, the target material distributed along the ion trajectory will be excited or ionized, which will cause lattice damage, polymer chain break or cross-linking in the material and then result in nanoscale latent track, cluster damage and single event effect. The high energy microbeam facility of Lanzhou National Laboratory of Heavy Ion Accelerator is the highest energy microbeam system in the world which uses triplet-quadrupole magnets to produce micron sized high energy ion beams of up to several GeVs. This talk first introduces the accelerator complex and nuclear physics activity at Lanzhou National Lab, and then focuses on the interdisciplinary application of the high energy microbeam facility, including single event effect studies, single ion hitting, nanomaterials, and biomedical studies. Sondertermin und -ort
21 Jan 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:00 Uhr s.t., HS KPH
Professor Victorino Franco, Condensed Matter Physics, Universidad de Sevilla

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für Physik12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude)
Olga Lozhkina, Inst. f. Physik

### Theory of Condensed Matter: Hard Condensed Matter

###### Institut für Physik, SPICE14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9)
 Souvik Paul, Christian-Albrechts-Universität zu Kiel Magnetic skyrmions, localized spin structure with topological protection, have become a research hotspot as they show promise for future memory and logic devices. The key challenges for applications are to achieve small bits and stability of those skyrmionic bits. Research shows that transition-metal interfaces (TMI) and multilayers are a very promising class of systems to realize nanometer-sized and stable magnetic skyrmions. Therefore, a lot of effort has been put to tailor the properties of these systems for application. In this direction, using first-principles methods, we have proposed ultrathin films, Fe/Rh and Rh/Fe bilayers on Re(0001) substrate, which show various spin structures at the interface including isolated skyrmions, depending on the stacking order of Fe/Rh and Rh/Fe bilayers. This study would encourage the experimentalist to check our predictions and would generate more investigations on other bilayers on Re(0001). The other topic I would focus on is the effect of higher-order exchange interactions (HOI) on the stability of skyrmions. HOI are shown to stabilize magnetic ground states in transition-metal ultrathin films, however, their role on the stability of metastable skyrmions has note been investigated yet. We showed that the HOI increase the stability of skyrmions by a large amount at TMI. This study opens up a route to tune skyrmions stability and lifetime in ultrathin films. [1] Nat. Nanotechnol. 8, 899–911 (2013) [2] Sci. Rep. 4, 6784 (2014) [3] Nat. Commun. 5, 4652 (2014) [4] arXiv:1912.03465 [5] Nat. Phys. 7, 713 (2011) [6] Phys. Rev. Lett. 120, 207201 (2018) [7] Phys. Rev. Lett. 120, 207202 (2018) [8] arXiv:1912.03474
22 Jan 2020

### PRISMA Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7
 Assumpta Parreno, Universitad de Barcelona A central goal of Nuclear Physics is to obtain a first-principles description of the properties and interactions of nuclei from the underlying theory of the strong interaction, Quantum Chromodynamics (QCD). Being the theory that governs the interactions between the basic building blocks of matter, quarks and gluons, it is also responsible for confining those primary pieces into hadronic states, binding neutrons and protons through the nuclear force to give the different elements in the periodic table. Nevertheless, due to the large complexity of the quark-gluon dynamics, one cannot obtain analytical solutions of QCD in the energy regime relevant to nuclear physics. In order to address this problem, numerical solutions of QCD can be obtained in a finite volume through its formulation in a Euclidean discretized space-time. I will present the results of our study in the two-baryon sector for different values of the light quark masses, as well as for the very light A=3,4 nuclei.
23 Jan 2020

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

###### Institut für Physik14:00 Uhr s.t., Lorentz-Raum (05-127), Staudingerweg 7
 Dr. Maria Chekhova, Institut für Optik, Information und Photonik, Universität Erlangen Spontaneous parametric down-conversion is the workhorse of quantum optics. This process is used to generate entangled photon pairs and heralded single photons. When strongly pumped, spontaneous parametric down-conversion generates so many photon pairs that they overlap and form radiation with almost laser brightness. Despite being bright, this radiation manifests nonclassical effects: quadrature squeezing, photon-number correlations, and macroscopic entanglement. It has no coherent component and can be considered as amplified vacuum noise; it is therefore often called bright squeezed vacuum. In addition, strong photon-number fluctuations of bright squeezed vacuum make it extremely efficient for pumping multiphoton effects. My talk will cover this and other applications of strongly pumped parametric down-conversion. In addition, I will talk about the other extreme case of this process. Namely, if photon pairs are generated in a very thin nonlinear layer, the process does not require phase matching – in other words, the momentum of the pump photon is not conserved by the daughter photons. To demonstrate this, I will show the results of generating photon pairs from a 300 nm layer. This nanoscale generation of entangled photons offers unique radiative characteristics: the frequency-angular spectrum is extremely broad and as such it promises subwavelength and subcycle two-photon correlation widths in position and time, respectively. Additionally, it gives an insight into the subwavelength resonances for vacuum fluctuations.

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers14:00 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122
 Stéphane Mangin, Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, France During the last decade all-optical ultrafast magnetization switching in magnetic material thin film without the assistance of an applied external magnetic field has been explored [1,2]. It has been shown that femto-second light pulses can induce magnetization reversal in a large variety of magnetic materials [3,4]. However, so far, only certain particular ferrimagnetic thin films exhibit magnetization switching via a single femto-second optical pulse. We will present the single-pulse switching of various magnetic material (ferrimagnetic, ferromagnetic) within a magnetic spin-valve structure and further show that the four possible magnetic configurations of the spin valve can be accessed using a sequence of single femto-second light pulses. Our experimental study reveals that the magnetization states are determined by spin-polarized currents generated by the light pulse interactions with the GdFeCo layer [5]. A detail study showing how spin-polarized currents are generated and how they interact with magnetic layers (Ferromagnetic or Ferrimagnetic) to lead to magnetization switching will be presented.
24 Jan 2020

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für Physik13:30 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 03-431
 Mona Minakshee Manjaree Bhukta , National Institute of science education and research, Bhubaneswar, India 1.Thermal diffusion of nπ Skyrmion and Skyrmion bags Skyrmionics have recently emerged as active field of research because of their potential applications in high density data storage technology and logic gate computing. Magnetic skyrmions correspond to localized whirling spin configurations, which are characterized by a topological charger (Q). Recent atomistic simulations and experimental finding ensure the diffusive behaviour of skyrmion at finite temperatures in ultrathin model, which open up the possibility of application thermal induced skyrmion dynamics in probabilistic computing. In this work we studied the thermal diffusion of nπ skyrmion up to n= 5 and N skyrmion bag (N (= 1-6) skyrmion surrounded by a bigger skyrmion with opposite chirality) using atomistic spin simulation on Pt_{0.95}/Ir_{0.05} on Pd (111) bilayer by statistically averaging out 100s of these spin texture. Further the SkHE of all these structures has been calculated using both simulation and analytics. 2.Frustrated Skyrmionic States in synthetic Antiferromagnet The spherical topology of a skyrmion leads to an extra force, that acts on moving skyrmion, pointing perpendicular to its velocity. This deviates the path of the skyrmion towards the edge of the nanotrack and this phenomenon is referred as the Skyrmion Hall effect (SkHE). In an antiferromagnetically exchange-coupled bi-layer nanotrack, this SkHE could be suppressed without affecting the topological protection of the skyrmion. Recently it is shown that skyrmion in frustrated ferromagnets have more helicity and vorticity degrees of freedom in compared with the skyrmion stabilized by Dzyaloshinskii-Moriya Interaction (DMI). In this work, we attempted to model a system using micromagnetic simulation to induce frustration by taking RKKY interaction as perturbation in a Synthetic antiferromagnet (SAF). The frustration in the system could be due to the equivocation of DMI between two antiferromagnetically coupled layer. We not only found the existence of Q = 0 skyrmion, but also able to stabilize the skyrmion and antiskyrmion in the same layer. Later we deposited Ta/(Pt/Co)_2/Ir(x)/Co/Pt (x= 0.5 and 1.0 nm) on Silicon substrate using DC magnetron sputtering to optimize the SAF nature of the thin films and to observe the domain images using Kerr Microscope.
27 Jan 2020

###### Institut für Kernphysik14:00 Uhr s.t., HS Kernphysik, Becherweg 45
Alexey Tyukin, Mainz

### Seminar für Kern- und Radiochemie

###### Institut für Kernchemie16:00 Uhr s.t., Seminarraum Kernchemie
Dr. Christian Smorra, Institut für Physik, JGU Mainz

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

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Michael Wurm, Institut für Physik

28 Jan 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:00 Uhr s.t., HS KPH
Professor Manfred Popp, Karlsruher Institut für Technologie

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für Physik12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude)
Stanislav Bodnar, Inst. f. Physik

### Theorie-Palaver

###### Institut für Physik14:30 Uhr s.t., MITP Seminar Room
 Fabian Lange, RWTH Aachen The Gradient-Flow formalism was primarily introduced for simulations of Quantum Chromodynamics (QCD) on the lattice and has now found widespread use in this field. In addition, it offers the potential for cross-fertilization between perturbative and lattice calculations. In my talk I will introduce the Gradient-Flow formalism and outline the perturbative approach. Afterwards, I will present two examples of its applications. First, I will show how it could be used to extract the strong coupling constant from lattice simulations. As second application, I will illustrate how it helps to define the energy-momentum tensor of QCD on the lattice.
29 Jan 2020

### PRISMA Colloquium

###### Institut für Physik13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7
 Jonathan Butterworth, UCL London Particle-level, differential measurements made in fiducial regions of phase-space at colliders have a high degree of model-independence and can therefore be compared in a very generic way not only to precision Standard Model predictions, but to beyond the Standar Model physics implemented in Monte Carlo generators. This allows a wider array of final states to be considered than is typically the case, as well as a wider array of specific models, and optimises the long-term impact of precision LHC data. I present a method of exploiting this, with examples.
30 Jan 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers14:00 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122
 Prof. Matthias Wuttig, RWTH Aachen University of Technology, Germany It has been a long-time dream of mankind to design materials with tailored properties. In recent years, the focus of our work has been the design of phase change materials for applications in data storage. In this application, a remarkable property portfolio of phase change materials (PCMs) is employed, which includes the ability to rapidly switch between the amorphous and crystalline state. Surprisingly, in PCMs both states differ significantly in their properties. This material combination makes them very attractive for data storage applications in rewriteable optical data storage, where the pronounced difference of optical properties between the amorphous and crystalline state is employed. This unconventional class of materials is also the basis of a storage concept to replace flash memory. This talk will discuss the unique material properties, which characterize phase change materials. In particular, it will be shown that only a well-defined group of materials utilizes a unique bonding mechanism (‘Bond No. 6’), which can explain many of the characteristic features of crystalline phase change materials. Different pieces of evidence for the existence of this novel bonding mechanism, which we have coined metavalent bonding, will be presented. In particular, we will present a novel map, which separates the known strong bonding mechanisms of metallic, ionic and covalent bonding, which provides further evidence that metavalent bonding is a novel and fundamental bonding mechanism. This insight is subsequently employed to design phase change materials as well as thermoelectric materials. Yet, the discoveries presented here also force us to revisit the concept of chemical bonds and bring back a history of vivid scientific disputes about ‘the nature of the chemical bond’.
31 Jan 2020

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

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. VirnauSonderseminar: 10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Philipp Arras, MPI Astrophysics, Garching

Sonderseminar

03 Feb 2020

### Seminar für Kern- und Radiochemie

###### Institut für Kernchemie16:00 Uhr s.t., Seminarraum Kernchemie
Prof. Dr. Bernd Krause, Universität Rostock
##### Thema folgt

###### Institut für Kernphysik14:00 Uhr s.t., HS Kernphysik, Becherweg 45
Oliver Noll, Mainz

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

###### Institut für Physik12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum
Christopher Hils, Insitut für Physik

04 Feb 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:00 Uhr s.t., HS KPH
Dr. Friederike Otto, ECI, University of Oxford
##### COLLOQUIUM CANCELLED! Angry Weather How Climate Change is affecting extreme Weather around the World

COLLOQUIUM CANCELLED!

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für Physik12:00 Uhr s.t., Newton-Raum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude)
Amrit R. Pokharel, Inst. f. Physik

### Theorie-Palaver

###### Institut für Physik14:30 Uhr s.t., MITP seminar room
 Avirup Ghosh, Harish Chandra Research Institute The existence of Dark Matter (DM) as one of the major component of our universe is inevitable today. Though there are several evidences of DM, all of them are gravitational in nature. The particle nature of DM is yet unknown. The most popular theory of particle DM is Weakly Interacting Massive Particles(WIMP) which though very interesting from the point of view of naturalness, is not yet tested in experiments. On the other hand, Feebly Interacting Massive Particles (FIMP) as an alternative scenario is gaining attention in recent times which due to their feeble interaction can not be observed in current generation of experiments. I shall discuss in my talk how in some FIMP scenarios the tiny coupling of FIMP DM give rise to interesting signals.
06 Feb 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122
 Markus Garst, KIT Karlsruhe, Germany The weak Dzyaloshinskii-Moriya interaction (DMI) in chiral magnets stabilizes spatially modulated magnetic textures like helices and skyrmion crystals. In this talk we focus on the dynamical properties of such textures. In the field-polarized phase of chiral magnets, the DMI results in a pronounced non-reciprocity of the magnon spectrum, i.e. the excitation energy is not symmetric with respect to an inversion of the wavevector. In the conical helix phase, the spin waves experience Bragg scattering off the periodic magnetic texture that leads to a backfolding of the magnon spectrum. As a result, the spectrum becomes reciprocal for wavevectors along the helix axes. However, the distribution of spectral weight in the spin structure factor remains non-reciprocal as confirmed by inelastic neutron scattering [1,2]. For wavevector with a finite perpendicular component of the wavevector, dipolar interactions induce a non-reciprocity which was detected by Brillouin light scattering [3]. We also discuss the spin wave spectrum of the skyrmion crystal phase where the non-trivial topology leads to an emergent electrodynamics for magnons. As a result the spectral weight of the spin structure factor is widely distributed at high energies. The spin wave excitations propagating along the skyrmion strings also exhibit a non-reciprocity as confirmed by spin wave spectroscopy [4]. Finally, we discuss the non-linear dynamics of a single skyrmion string [5].

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für PhysikSonderseminar: 15:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122
Kelvin van Hoorn, Technical University of Eindhoven, The Netherlands

Sonderseminar

07 Feb 2020

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für PhysikSonderseminar: 15:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 3. Stock, Raum 03-431
 Chi Fang, University of Chinese Academy of Sciences, Beijing, China The application potential of spin-orbit-torques in magnetic random access memory attracts great attention and research interest in spin-orbit coupling in heavy metals like Platinum and Tantalum. Thus the spin relaxation time τ_s, as a crucial parameter to investigate spin relaxation mechanism in the heavy metals, requires accurate and effective estimation. A traditional three-terminal method is also widely utilized to estimating τ_s of semiconductors and light metals. Its reliability, however, has recently been challenged by some experiments in which tunneling anisotropic magnetoresistance (MR) or spin blockage MR rather than the MR induced by spin injection and subsequent Hanle effect is more appropriate to explain the data. In this talk, I will introduce the spin-injection-induced magnetoresistance of which the magnitude is comparable with other MR phenomena originating from the tunnel barrier is observable at room temperature as well as low temperatures in the second harmonic signals. Three-terminal and second harmonic method are combined in our measurement in Pt and Ta systems. Furthermore, we could estimate τ_s of heavy metals through fitting the signal with Lorentz function. This experimental approach make it possible to directly acquire τ_s of heavy metals with electrical method. Sonderseminar
19 Feb 2020

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für PhysikSonderseminar: 14:30 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 3. Stock, Raum 03-431
 Dr. Kunie Ishioka, National Institute for Materials Science, Tsukuba, Japan Mittwoch, den 19. Februar 2020 um 14:30 im MEDIEN-Raum, Staudinger Weg 7, 03-431 Ultrafast Carrier and Phonon Dynamics of Hybrid Lead Halide Perovskite Kunie Ishioka National Institute for Materials Science, Tsukuba, Japan Inorganic-organic hybrid lead halide perovskites, consisting of the soft lead halide octahedral framework and the organic molecular cations, are among the key materials for the next generation photovoltaics. In the first half of my talk I present on the charge separation dynamics at the interfaces of methylammonium lead iodide MAPbI3 with three different hole transport materials (HTMs) [1]. Here, the differential transmission signals revealed the hole injection from the perovskite to organic HTMs to occur on the time scale of 1 ps, whereas that to inorganic NiOx on an order of magnitude longer timescale. The anti-correlation with the fill factor of the solar cells suggests that the interfacial quality was responsible. In the second half I present our recent results on the coherent phonons of MAPbI3 [2]. We observe periodic modulations in the transient transmissivity due to the photoinduced libration and torsion of the methylammonium cations and the deformation of the PbI6 octahedral framework. The frequencies of the cation torsion and the octahedral deformations exhibited downchirps, in agreement with theoretically predicted strong anharmonicities of their vibrational potentials. Sonderseminar Sondertermin
27 Feb 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122
Shefali Vaidya, IRCELYON, Lyon, France

05 Mar 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03-122
Thomas Allison, Stony Brook University, NY, USA

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

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Fabian Kössel, Institut für Physik
##### Emerging patterns from the collective dynamics of microswimmers in an external field

Trial PhD defense talk

10 Mar 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers14:00 Uhr s.t., Galilei seminar room (Staudinger Weg 9, room 01-128)
Mehrdad Elyasi, Tohoku University, Sendai, Japan

12 Mar 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers14:00 Uhr s.t., MAINZ seminar room (Staudinger Weg 9, 3rd floor, room 03-122)
Dr. Aga Shahee, Seoul University

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

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Jan Rothörl, Institut fuer Physik
##### Creating 3D structures of diploid cells from Hi-C data using a Molecular Dynamics approach

Master Colloquium

13 Mar 2020

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für PhysikSonderseminar: 11:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 431
 Jonas Knobel, Universität Würzburg New directions in spintronics heading towards devices based on antiferromagnetic materials require a fundamental understanding of the underlying physics. CuMnSb grown by molecular beam epitaxy (MBE) on GaSb substrates can provide a model system of a thin film antiferromagnet. I will report on the growth of virtually unstrained pseudomorphic single crystals showing clear antiferromagnetic behavior. The ordering temperature of CuMnSb between 50K and 62K lies well within the reach of standard cryostats. This allows to diff erentiate thermal from magnetic properties in transport devices. I will first discuss the epitaxial growth of a GaSb buff er layer needed for a sharp interface. Subsequent CuMnSb growth is highly dependent on the flux ratios of the respective elements. I will explain their influence on crystal properties and how reflection high-energy electron di ffraction (RHEED) is used to control the growth process. Sonderseminar

### Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

###### Institut für PhysikSonderseminar: 14:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 431
 Kanji Furuta, Department of Materials Science and Engineering, Nagoya University, Japan. MAX phase compounds have recently attracted much attention due to their possible application to the production of a new class of two-dimensional systems called MXenes [1]. Mo4Ce4Al7C3 is affiliated with the MAX phase and in a family of RE-based nanolaminates with a chemical formula of Mo4RE4Al7C3. From magnetization measurements, x-ray absorption near-edge structure (XANES), and x-ray magnetic circular dichroism (XMCD), a ferromagnetism below a Curie temperature of TC ~ 10.5 K and a mixed-valence states of the Ce 4f electrons have been reported [2]. To understand the origin of electronic/magnetic properties of Mo4Ce4Al7C3, we have performed angle-resolved photoemission spectroscopy (ARPES) on Mo4Ce4Al7C3 single-crystals. As a result, we have succeeded to obtain the electronic band structure as well as Fermi surface of this system. From the comparison between Ce 4d-4f on and off resonant ARPES, strong Ce 4f character at the electron pocket around the G point has been elucidated. Furthermore, we have found a clear increase of the Ce 4f spectral weight below TC. The results suggest that itinerant Ce 4f electrons may play an important role in the magnetic properties of Mo4Ce4Al7C3. REFERENCES [1] M. Barsoum, MAX phases (Wiley, Weinheim, 2013). [2] Q. Tao et al., Phys. Rev. Mat. 2, 114401 (2018). Sonderseminar
02 Apr 2020

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

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Bing Li, Postdoctoral researcher, Institute of physics, JGU Mainz

17 Apr 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers10:30 Uhr s.t., online lecture series - streaming link: https://conference.uni-mainz.de/meet/dion/JBQR5429
Merlin Pohlit, Uppsala University, Department of Physics and Astronomy

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers15:00 Uhr s.t., online lecture series - streaming link: https://conference.uni-mainz.de/meet/dion/8VBKC6N9
Simon Moser, Uni Würzburg

21 Apr 2020

### Theorie-Palaver

###### Institut für Physik14:30 Uhr s.t., None
 Michele Redi, Florence U. and INFN I will describe the conditions under which the Peccei-Quinn phase transition of the QCD axion is first order. I will then show that in approximately conformal scenarios, both at weak and strong coupling, the PQ phase transition can lead to a gravity wave background that is within the reach of Ligo or future ground based experiments. at Zoom
22 Apr 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers15:00 Uhr s.t., None
Angela Wittmann, Massachusetts Institute of Technology

23 Apr 2020

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

###### Institut für Physik14:00 Uhr s.t., None
 Dr. Tobias Jenke, ILL Grenoble Neutrons are excellent probes to test gravity at short distances – electrically neutral and only hardly polarizable. Very slow, so-called ultracold neutrons form bound quantum states in the gravity potential of the Earth. This allows combining gravity experiments at short distances with powerful resonance spectroscopy techniques, as well as tests of the interplay between gravity and quantum mechanics. In the last decade, the qBounce collaboration has been performing several measurement campaigns at the ultracold and very cold neutron facility PF2 at the Institut Laue-Langevin in Grenoble/France. A new spectroscopy technique, Gravity Resonance Spectroscopy, was developed and realized, and snapshots of falling wavepackets of these gravitationally bound quantum states were recorded. The results were applied to test gravity at micron distances as well as various Dark Energy and Dark Matter scenarios in the lab, like Axions, Chameleons and Symmetrons. In my talk, I will review the experiments, explain key technologies and summarize the results obtained. at Zoom Meeting ID: 236 122 4872
27 Apr 2020

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

###### Institut für Physik12:30 Uhr s.t., None
Bernard Brickwedde/Jan Lommler, Institut für Physik
at Zoom

28 Apr 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., None
 Magdalena Kowalska, CERN/ U Genf When we polarise the spins of unstable nuclei, their beta emission will be asymmetric, due to the parity non-conservation of the weak interaction. This feature has been used by our team in a variety of fields. It is a way to look for New Physics through the determination of the Vud matrix element of the CKM quark mixing matrix in nuclear mirror decays. In nuclear physics, in allows to apply an ultrasensitive type of NMR (called beta-NMR) to determine the magnetic dipole moments and electric quadrupole moments of short-lived nuclei. Recently, we have started applying beta-NMR to chemistry and biology, since its sensitivity is up to a billion times higher than in conventional NMR. In this talk I will introduce spin polarisation via optical pumping and beta-NMR principles. I will present our experimental setup located at CERN/ISOLDE. Finally, I will discuss the three scientific topics: Vud from 35Ar decay, magnetic moment of 26Na with ppm accuracy, and the interaction of Na with DNA G-Quadruplex structures . at Recording of the presentation
29 Apr 2020

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers10:30 Uhr s.t., None
Michael Slota, Department of Materials, University of Oxford, OX1 3PH, UK

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers15:00 Uhr s.t., None
Max Hänze, 1. University of Stuttgart, Institute for Functional Matter and Quantum Technologies, Stuttgart, Germany. 2. Max Planck Institute for Solid State Research, Stuttgart, Germany.

30 Apr 2020

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

###### Institut für Physik14:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Dr. Karolina Kulesz, CERN, Geneve GammaMRI project aims to develop a new medical imaging modality able to overcome the limitations of existing imaging techniques and to combines their advantages. Gamma-MRI introduces the spatial resolution of MRI, the sensitivity of nuclear medicine (PET and SPECT) and possible clinical benefits of xenon isotopes [1,2]. At the same time, it eliminates drawbacks of the above-mentioned techniques. Our team is at present working on a proof-of-concept experiment. Gamma-MRI is based on the detection of asymmetric γ-ray emission of long-lived polarized nuclear states in the presence of magnetic fields [2]. The nuclei used in our study are long-lived nuclear isomers of Xe isotopes: 129mXe (T1/2 = 9 d),131mXe (T1/2 = 12 d) and 133mXe (T1/2 = 2 d) produced at the ILL high flux reactor in Grenoble or at ISOLDE facility at CERN [3]. The isomers of Xe are then hyperpolarized via collisions with laser-polarized rubidium vapor (Spin Exchange Optical Pumping) [4]. Once polarized and placed inside a magnetic field, they emit γ-rays whose direction of emission depends on the degree of spin polarization. Emitted radiation is acquired with CeGAAG crystals coupled to Si photodetectors and readout electronics compatible with strong magnetic fields, which are able to support very high count-rates. Once high polarization is successfully acquired, similar procedure can be used to record the spins’ response to rf pulses in gradient magnetic field, which is up to 105 more sensitive than usual signal pick-up in rf coils. References: [1] R. Engel, Master thesis 2018, https://cds.cern.ch/record/2638538. [2] Y. Zheng et al., Nature 537, 652 (2016). [3] M. Kowalska et al., Letter of Intent, CERN-INTC-2017-092 / INTC-I-205 (2017). [4] T. G. Walker and W. Happer, Rev. Mod. Phys. 69, 629 (1997).

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers10:30 Uhr s.t., None
Naëmi Leo, CIC nanoGUNE, Donostia, San Sebastian, Spain

### SFB/TR49/SFB TRR 173 Spin+X-Kolloquium/TopDyn - Seminar experimentelle Physik der kondensierten Materie

###### SFB/TR49 - Prof. Dr. Elmers15:00 Uhr s.t., None
Alan Farhan, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI-00076 Aalto, Finland

04 May 2020

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

###### Institut für Physik12:30 Uhr s.t., None
Ralf Gugel, Institut für Physik
at Zoom

05 May 2020

### Theorie-Palaver

###### Institut für Physik14:30 Uhr s.t., None
 Filippo Sala, CNRS Paris Jussieu Sub-GeV Dark Matter particles upscattered by cosmic rays gain enough kinetic energy to pass the thresholds of large volume detectors on Earth. I will show how public Super-Kamiokande and MiniBooNE data already exclude previously allowed regions of both DM-electron and DM-nucleon interactions. I will then discuss search strategies and prospects at existing and planned neutrino facilities, such as Hyper-K, DUNE, IceCube and KM3NeT. at Zoom

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., None
 Joachim Peinke, Universität Oldenburg The current development of wind energy is summarised, and it is shown that wind energy has become one of the cheapest ways to produce electrical energy. From the perspective of a physicist there are several challenging research questions which arise, although wind energy systems have been used already over several centuries. A central point of this talk will be to show how fundamental research in physics can contribute to the modern development of wind energy systems. at Recording of the presentation
07 May 2020

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

###### Institut für Physik17:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Prof. Dr. Monika Schleier-Smith, Stanford University, USA The dream of the quantum engineer is to have an “arbitrary waveform generator” for designing quantum states and Hamiltonians. Motivated by this vision, I will report on advances in optical control of long-range interactions among cold atoms. Our lab is exploring two approaches: photon-mediated and Rydberg-mediated interactions. By coupling atoms to light in an optical resonator, we generate tunable non-local Heisenberg interactions, characterizing the resulting phases and dynamics by real-space imaging. Notable observations include photon-mediated spin-mixing—a new mechanism for generating correlated atom pairs—and interaction-based protection of spin coherence. In a separate platform, we employ Rydberg dressing to induce Ising interactions in a gas of cesium atoms in their hyperfine clock states, enabling the realization of a Floquet transverse-field Ising model. I will discuss prospects in quantum simulation and quantum metrology promised by the versatility of optical control. Achtung: Uhrzeit geändert!
11 May 2020

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

###### Institut für Physik12:30 Uhr s.t., None
Simone Schuchmann, Institut für Physik
at Zoom

12 May 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., online (zoom oder BigBlueButton)
Jeff Hangst, Aarhus University
##### COLLOQUIUM CANCELLED!

COLLOQUIUM CANCELLED!

14 May 2020

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

###### Institut für Physik17:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Prof. Dr. Kai-Mei Fu, Depts of Physics and Electrical and Computer Engineering, University of Washington, Seattle, USA Single defects in crystals, often termed “quantum defects”, are promising qubit candidates for quantum network applications. I will first provide an overview of the types of properties we seek in single defects, how we create these defects and how we measure them, illustrated with examples from my group’s research. I will then present the semiconductor-on-diamond integrated photonics platform my group is developing to scale networks of many entangled quantum defects. Achtung: Uhrzeit geändert!

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

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Maike Jung, Institut für Physik
at Zoom

18 May 2020

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

###### Institut für Physik12:30 Uhr s.t., None
Antoine Laudrain, Institut für Physik
at Zoom

19 May 2020

### Theorie-Palaver

###### Institut für Physik14:30 Uhr s.t., None
 Alexander Ochirov, ETH Zurich In view of the recent observations of gravitational-wave signals from black-hole mergers, classical black-hole scattering has received considerable interest due to its relation to the classical bound-state problem of two black holes inspiraling onto each other. In this talk I will discuss the link between classical scattering of spinning black holes and quantum scattering amplitudes for massive spin-s particles. Starting at first post-Minkowskian (PM) order, I will explain how the spin-exponentiated structure of the relevant tree-level amplitude follows from minimal coupling to Einstein's gravity and in the $$s \rightarrow \infty$$ limit generates the black holes' complete series of spin-induced multipoles. The resulting scattering function will be shown to encode in a simple way the known net changes in the black-hole momenta and spins at 1PM order and to all orders in spins. Then I will move on to the new results at 2PM order for the case of aligned black holes' spins and discuss the current state of the art for classical black-hole scattering. at Zoom

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., None
 Jan Meijer, Universität Leipzig The key technology to fabricate quantum devices, i.e. devices that employ single atoms or defects as functional unit is the addressing of single atoms in a solid with high lateral resolu-tion. Whereas the manipulation of single atoms at the surface has been possible since several years, the three dimensional addressing in the bulk requires more effort. The combination of surface manipulation and overgrowth is one possibility but technologically very challenging. Ion beam implantation allows addressing single countable atoms inside a given solid with nanometer precision. To meet this goal we firstly need to focus or collimate the ion beam and to count the ions delivered to the sample. Our approach is to detect a single ion during fly-by using image charge detection and to deliver the ion with nanometer precision employ-ing a modified commercial FIB system. However, to create a deterministic quantum register based on NV centers a third requirement has to be considered: The implanted nitrogen atom has to be converted into an NV center with nearly 100% efficiency. Unfortunately, the creation of vacancies by ion impact is a statistical process and therefore not predictable. Additionally, the charge state of the NV center has to be converted into the negative state to make it functional. The talk will discuss the state of the art of single ion nano-implantation methods as well as new developments in material science to overcome the limitations encountered in the crea-tion of NV centers so far. at Recording of the presentation
25 May 2020

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

###### Institut für Physik12:30 Uhr s.t., None
Alexander Fritz/Seva Orekhov, Institut für Physik
at Zoom

26 May 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., None
 Achim Rosch, Universität Köln Magnetic skyrmions are tiny, topologically quantized magnetic whirls stabilized by relativistic spin-orbit interactions. They couple extremely efficiently to charge-, spin- and heat currents and can be manipulated by ultra small forces. They are therefore promising candidates for, e.g., future magnetic memories. The coupling of skyrmions to electrons can efficiently be described by artifical electromagnetic fields. We explore how these fields can be measured. Phase transitions in and out of the skyrmion phase are driven by topological point defects which can be identified as emergent magnetic monopoles. at Zoom
28 May 2020

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

###### Institut für Physik14:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Prof. Dr. Herwig Ott, Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Germany Ultracold quantum gases are usually well isolated from the environment. This allows for the study of ground state properties and non-equilibrium dynamics of many-body quantum systems under almost ideal conditions. Introducing a controlled coupling to the environment “opens” the quantum system and non-unitary dynamics can be investigated. Such an approach provides new opportunities to study fundamental quantum phenomena and to engineer robust many-body quantum states. I will present an experimental platform [1,2] that allows for the controlled engineering of dissipation in ultracold quantum gases by means of localized particle losses. This is exploited to study quantum Zeno dynamics in a Bose-Einstein condensate [3], where we find that the particle losses are well described by an imaginary potential in the system’s Hamiltonian. We also investigate the steady-states in a driven-dissipative Josephson array [4]. For small dissipation, the steady-states are characterized by balanced loss and gain and the eigenvalues are real. This situation corresponds to coherent perfect absorption [5], a phenomenon known from linear optics. Above a critical dissipation strength, the system decays exponentially, indicating the existence of purely imaginary eigenvalues. We discuss our results in the context of dissipative phase transitions. References [1] T. Gericke et al., Nature Physics 4, 949 (2008). [2] P. Würtz et al., Phys. Rev. Lett. 103, 080404 (2009). [3] G. Barontini et al., Phys. Rev. Lett. 110, 035302 (2013). [4] R. Labouvie et al. Phys. Rev. Lett. 116, 235302 (2016). [5] A. Müllers et al. Science Advances 4, eaat6539 (2018).

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

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Prof. Dr. Hossein Eslami, Chemistry Dept. TU Darmstadt
##### Self-assembly of Janus particles
at Zoom, email settanni@uni-mainz.de

02 Jun 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., None
 Laura Baudis, University of Zurich Neutrinos are the only known elementary particles that are Majorana fermion candidates, implying that they would be their own antiparticles. The most sensitive and perhaps only practical probe of the Majorana nature of neutrinos is an extremely rare nuclear decay process, the double beta decay without the emission of neutrinos. After an introduction to the physics of neutrinoless double beta decay, I will present the experimental techniques to search for this exceedingly rare process. I will show the latest results from leading experiments in the field, then discuss future projects and their prospects to probe the inverted neutrino mass ordering scenario. at Zoom (for more details see below)
04 Jun 2020

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

###### Institut für Physik14:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Dr. Hélène Perrin, Université de Paris 13, Sorbonne, Paris Cite, France In this talk, I will discuss the dynamics of a superfluid quantum Bose gas confined at the bottom of a shell rf-dressed trap. Weakly interacting quantum degenerate atoms present a superfluid behavior, characterized by several properties including the emergence of specific collective modes at low energy or the apparition of quantum vortices when the fluid is set into rotation. In the talk I will describe the collective dynamical behavior of the atoms confined in this very smooth potential, from the low excitation regime where the first collective modes are observed to the fast rotation limit where the bubble shape of the trap plays an essential role.
zukünftige Termine
09 Jun 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., online (zoom oder BigBlueButton)
Martin Fertl, JGU Mainz

### Theorie-Palaver

###### Institut für Physik16:00 Uhr s.t., None
 Elina Fuchs, Chicago U. & Fermilab Complex Yukawa couplings of the Higgs boson have interesting implications for Higgs production and decay rates, EDMs and CP violation for electroweak baryogenesis. I will present if there are viable regions fulfilling all of these three complementary constraints, for real and imaginary dimension-six terms of the tau, muon, top and bottom. After considering each flavor separately, I will show that combinations of several sources allow for cancellations in the EDM and an enhancement of the baryon asymmetry. at Zoom
11 Jun 2020

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

###### K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9
Ashreya Jayaram, Institut für Physik, JGU, PhD student

15 Jun 2020

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

###### Institut für Physik12:30 Uhr s.t., None
Daniel Wenz/Johannes Balz, Institut für Physik
at Zoom

16 Jun 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., online (zoom oder BigBlueButton)
Joachim Mnich, DESY

### Theorie-Palaver

###### Institut für Physik14:30 Uhr s.t., Zoom
 Gustavo Marques Tavares, Johns Hopkins U. TBA
18 Jun 2020

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

###### Institut für Physik14:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
Dr. Angela Papa, PSI Villigen

23 Jun 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., online (zoom oder BigBlueButton)
Elena Aprile, Columbia University

25 Jun 2020

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

###### Institut für Physik14:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Prof. Dr. Jakob Reichel, Laboratoire Kastler Brossel, ENS Paris, France Many if not all future quantum technologies are enabled by quantum correlations in a well-controlled many-particle system. In ensembles of atoms, ions and many other quantum emitters, such correlations can be generated with a high-finesse optical cavity. This approach is particularly promising for quantum metrology. I will present an experiment combining a compact trapped-atom clock on an atom chip and a fiber Fabry-Perot microcavity. This first "metrology-grade" spin squeezing experiment enabled us to produce spin squeezed states with unprecedented lifetime up to a second, and to observe a "quantum phase magnification" effect due to the subtle interplay of these many-particle entangled states with the exchange interaction that occurs in the trapped low-temperature gas.
29 Jun 2020

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

###### Institut für Physik12:30 Uhr s.t., None
Elisa Ruiz-Chóliz/Phi Chau, Institut für Physik
at Zoom

30 Jun 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., online (zoom oder BigBlueButton)
Jo van den Brand, Nikhef

02 Jul 2020

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

###### Institut für Physik14:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Dr. Philipp Schindler, Institut für Experimentalphysik, Uni Innsbruck, Österreich I will review our effort to build scalable quantum information processors with trapped atomic ions. In particular, I will focus on experiments to benchmark quantum operations that allow to predict the performance of quantum error correction. I will then discuss how to adapt these operations and benchmarking techniques to characterize ultrafast dynamics in single molecular ions.
07 Jul 2020

### Physikalisches Kolloquium

###### Institut für Kernphysik, Remote Seminar16:15 Uhr s.t., online (zoom oder BigBlueButton)
Paul Dodds, University College London

09 Jul 2020

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

###### Institut für Physik14:00 Uhr s.t., https://zoom.us/j/94520261050 (Passwort-Anfrage an "stuckker@uni-mainz.de")
 Dr. Claudiu Genes, MPI for the Science of Light, Erlangen Optical photons typically carry very little energy and momentum. Despite this, they can still be successfully employed to control the motion of various objects ranging from small molecules to macroscopic vibrating mirrors or membranes. We theoretically employ stochastic methods to show how light can be used to read out vibrations of nuclei in molecules [1] or to cool down the motion of photonic crystal mirrors [2] or membranes [3], close to their quantum ground state. [1] M. Reitz, C. Sommer and C. Genes, Langevin approach to quantum optics with molecules, Phys. Rev. Lett. 122, 203602 (2019). [2] O. Cernotik, A. Dantan and C. Genes, Cavity quantum electrodynamics with frequency-dependent reflectors, Phys. Rev. Lett. 122, 243601 (2019). [3] C. Sommer and C. Genes, Partial optomechanical refrigeration via multi-mode cold damping feedback, Phys. Rev. Lett. 123, 203605 (2019).