Jahresübersicht für das Jahr 2020
Seminar für Kern und Radiochemie
Institut für Kernchemie 16 Uhr c.t., Seminarraum Kernchemie 
Dr. Nadine Chiera, PSI, Schweiz  
Chemical investigation of exotic radionuclides  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum 
Niklas Schmitt, University of Mainz  
Suche nach dunkler Energie in MonojetEreignissen bei 13TeV mithilfe des ATLASDetektors am LHC  
Bachelorkolloqium 
Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16 Uhr c.t., HS KPH 
Professor Christian Enss , Kirchhoff Institute for Physics, Heidelberg  
Small, Cold and Universal: Cryogenic MicroCalorimeters a New Key Technology  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, Staudingerweg 7 
Cristina Lazzeroni, University Birmingham, UK  
The decay K+→π+vv ̅, with a very precisely predicted branching ratio of less than 1010, 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 decayinflight technique. NA62 took data so far in 20162018. Statistics collected in 2016 allowed NA62 to reach the Standard Model sensitivity for K+→π+vv ̅, entering the domain of 1010 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.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., LorentzRaum (05127), 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 nonequilibrium phase diagrams. The first part of the talk will discuss longrange 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 prethermalisation are required to stabilise a strongly interacting nonequilibrium steady state. Time permitting, I will advertise some novel results on a purely dissipative analogue of longrange interacting quantum simulators, which can be implemented in quantum optics or solid state platforms.  

Seminar für Kern und Radiochemie
Institut für Kernchemie 16 Uhr c.t., Seminarraum Kernchemie 
Dr. Marine Vandebrouck, CEA Saclay  
243Es, 249Md: from production crosssections measurement to spectroscopy  Perspectives at GANILSPIRAL2/S3  

Theoriekolloquium
Die Dozierenden der Theoretischen Physik Sonderseminar: 14 Uhr c.t., Medienraum, Staudinger Weg 7, 03431 
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 highenergy 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 operatorbased 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, 03431 
Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum 
Julian Fischer, Institut für Physik  
Development of an EM trigger algorithm in the ATLAS forward region  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 10:00 Uhr s.t., MEDIENRaum, Staudingerweg 7, 3. Stock, Raum 03431 
Abhishek Erram , Indian Institute of Technology Kharagpur  
In this work, we have made a polycrystalline sample of Dy2BaNiO5 by a standard solidstate reaction route. The formation of the compound was ascertained by xray 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 zerofieldcooled (zfc) and fieldcooled (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 Xray diffraction (XRD). Magnetic behavior was also studied. Results show that of formation of thin film. Signs of magnetic behavior was also evident.  
Sonderseminar  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, 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 DysonSchwinger and BetheSalpeter 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 fourquark systems I will summarize results for light quarks and discuss recent progress on discriminating between tetraquark, molecule or hadroquarkonium configurations in heavylight systems.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 10:30 Uhr s.t., QUANTUM Seminarraum (02427), 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 drivendissipative 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 tightbinding dissipativedriven 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 dissipativedriven finite size system, i.e. a threesite Hubbard model with onsite 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 
SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 11:30 Uhr s.t., MAINZSeminarraum, Staudinger Weg 9, 03122 
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 spinorbitronics. Current scheme relies on electrical generation of the spin current/density by utilizing the spinorbit 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 RashbaEdelstein effect at the NM/FM interface, respectively. However, there has been a missing piece in spinorbitronics 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 RashbaEdelstein 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 RashbaEdelstein effect. Since both OT and ST contribute to magnetic dynamics, it opens a route to enhancing the torque efficiency in spinorbitronic 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 Physik 14 Uhr c.t., LorentzRaum (05127), 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 semiclassical 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 nonlinear hamiltonian.
Using semiclassical 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.
 

Institutsseminar Kern und Hadronenphysik
Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 
Christoph Matejcek, Mainz  
Lowenergy beam transport system for MESA  

Seminar für Kern und Radiochemie
Institut für Kernchemie 16 Uhr c.t., Seminarraum Kernchemie 
Dr. Zsolt Baranyi, Universität BRACCO  
Thema folgt  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 16:15 Uhr s.t., QUANTUM Seminarraum (02427), 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 crosslinking 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 tripletquadrupole 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 
Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16 Uhr c.t., HS KPH 
Professor Victorino Franco, Condensed Matter Physics, Universidad de Sevilla  
Phase Transitions and Critical Phenomena  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik 12:00 Uhr s.t., NewtonRaum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) 
Olga Lozhkina, Inst. f. Physik  
tba  

Theory of Condensed Matter: Hard Condensed Matter
Institut für Physik, SPICE 14:00 Uhr s.t., Galilei Room, 01128 (Staudinger Weg 9) 
Souvik Paul, ChristianAlbrechtsUniversität 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 transitionmetal interfaces (TMI) and multilayers are a very promising class of systems to realize nanometersized 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 firstprinciples 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 higherorder exchange interactions (HOI) on the stability of skyrmions. HOI are shown to stabilize magnetic ground states in transitionmetal 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  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, Staudingerweg 7 
Assumpta Parreno, Universitad de Barcelona  
A central goal of Nuclear Physics is to obtain a firstprinciples 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 quarkgluon 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 spacetime. I will present the results of our study in the twobaryon sector for different values of the light quark masses, as well as for the very light A=3,4 nuclei.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., LorentzRaum (05127), Staudingerweg 7 
Dr. Maria Chekhova, Institut für Optik, Information und Photonik, Universität Erlangen  
Spontaneous parametric downconversion is the workhorse of quantum optics. This process is used to generate entangled photon pairs and heralded single photons. When strongly pumped, spontaneous parametric downconversion 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, photonnumber 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 photonnumber 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 downconversion. 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 frequencyangular spectrum is extremely broad and as such it promises subwavelength and subcycle twophoton 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+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., MAINZSeminarraum, Staudinger Weg 9, 03122 
Stéphane Mangin, Institut Jean Lamour, UMR CNRS 7198, Université de Lorraine, Nancy, France  
During the last decade alloptical 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 femtosecond 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 femtosecond optical pulse. We will present the singlepulse switching of various magnetic material (ferrimagnetic, ferromagnetic) within a magnetic spinvalve structure and further show that the four possible magnetic configurations of the spin valve can be accessed using a sequence of single femtosecond light pulses. Our experimental study reveals that the magnetization states are determined by spinpolarized currents generated by the light pulse interactions with the GdFeCo layer [5]. A detail study showing how spinpolarized currents are generated and how they interact with magnetic layers (Ferromagnetic or Ferrimagnetic) to lead to magnetization switching will be presented.  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik 13:30 Uhr s.t., MEDIENRaum, Staudingerweg 7, 3. Stock, Raum 03431 
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 (= 16) 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 exchangecoupled bilayer 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 DzyaloshinskiiMoriya 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.  

Institutsseminar Kern und Hadronenphysik
Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 
Alexey Tyukin, Mainz  
Momentum transfer reconstruction for the P2 Experiment  

Seminar für Kern und Radiochemie
Institut für Kernchemie 16 Uhr c.t., Seminarraum Kernchemie 
Dr. Christian Smorra, Institut für Physik, JGU Mainz  
Precision measurements with antiprotons and transportable traps  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum 
Michael Wurm, Institut für Physik  
THEIA: Chertons, scintons and other new discoveries in lowenergy neutrino physics  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16 Uhr c.t., HS KPH 
Professor Manfred Popp, Karlsruher Institut für Technologie  
Was Hitlers Atombombe verhinderte  Kernphysik während des 2. Weltkrieges  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik 12:00 Uhr s.t., NewtonRaum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) 
Stanislav Bodnar, Inst. f. Physik  
Manipulation of Néel vector in antiferromagnetic Mn2Au by current and magnetic field pulses  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., MITP Seminar Room 
Fabian Lange, RWTH Aachen  
The GradientFlow 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 crossfertilization between perturbative and lattice calculations.
In my talk I will introduce the GradientFlow 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 energymomentum tensor of QCD on the lattice.  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, Staudingerweg 7 
Jonathan Butterworth, UCL London  
Particlelevel, differential measurements made in fiducial regions of phasespace at colliders have a high degree of modelindependence 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 longterm impact of precision LHC data. I present a method of exploiting this, with examples.
 

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., LorentzRaum (05127), Staudingerweg 7 
Prof. Dr. Philipp Haslinger, Atominstitut, TU Wien, Österreich  
Atom interferometry has proven within the last decades its surprising versatility to sense with high precision tiniest forces. In this talk I will give an overview of our recent work using an optical cavity enhanced atom interferometer to sense with gravitational strength for fifths forces [1,2] and for an on the firstplace counterintuitive inertial property of blackbody radiation [3].
Blackbody (thermal) radiation is emitted by objects at finite temperature with an outward energymomentum flow, which exerts an outward radiation pressure. At room temperature e. g. a cesium atom scatters on average less than one of these blackbody radiation photons every 10^8 years. Thus, it is generally assumed that any scattering force exerted on atoms by such radiation is negligible. However, particles also interact coherently with the thermal electromagnetic field [4] and this leads to a surprisingly strong force acting in the opposite direction of the radiation pressure [3].
If dark energy, which drives the accelerated expansion of the universe, consists of a light scalar field it might be detectable as a “fifth force” between normalmatter objects. In order to be consistent with cosmological observations and laboratory experiments, some leading theories use a screening mechanism to suppress this interaction. However, atominterferometry presents a tool to reduce this screening [5] on socalled chameleon models [6]. By sensing the gravitational acceleration of a 0.19 kg in vacuum source mass which is 10^8 times weaker than Earth´s gravity, we reach a natural bound for cosmological motivated scalar field theories and were able to place tight constraints [1,2].
[1] P. Hamilton, M. Jaffe, P. Haslinger, Q. Simmons, H. Müller, J. Khoury, Atominterferometry constraints on dark energy, Science. 349 (2015) 849–851.
[2] M. Jaffe, P. Haslinger, V. Xu, P. Hamilton, A. Upadhye, B. Elder, J. Khoury, H. Müller, Testing subgravitational forces on atoms from a miniature, invacuum source mass, Nat. Phys. 13 (2017) 938–942.
[3] P. Haslinger, M. Jaffe, V. Xu, O. Schwartz, M. Sonnleitner, M. RitschMarte, H. Ritsch, H. Müller, Attractive force on atoms due to blackbody radiation, Nat. Phys. 14 (2018) 257–260.
[4] M. Sonnleitner, M. RitschMarte, H. Ritsch, Attractive Optical Forces from Blackbody Radiation, Phys. Rev. Lett. 111 (2013) 23601.
[5] C. Burrage, E.J. Copeland, E.A. Hinds, Probing dark energy with atom interferometry, J. Cosmol. Astropart. Phys. 2015 (2015) 042–042. doi:10.1088/14757516/2015/03/042.
[6] B. Elder, J. Khoury, P. Haslinger, M. Jaffe, H. Müller, P. Hamilton, Chameleon dark energy and atom interferometry, Phys. Rev. D. 94 (2016) 44051.
 

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., MAINZSeminarraum, Staudinger Weg 9, 03122 
Prof. Matthias Wuttig, RWTH Aachen University of Technology, Germany  
It has been a longtime 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 welldefined 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’.  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau Sonderseminar: 10:30 Uhr s.t., Newtonraum, 01122, Staudingerweg 9 
Philipp Arras, MPI Astrophysics, Garching  
Information field theory and applications in calibration and imaging algorithms  
Sonderseminar  

Seminar für Kern und Radiochemie
Institut für Kernchemie 16 Uhr c.t., Seminarraum Kernchemie 
Prof. Dr. Bernd Krause, Universität Rostock  
Thema folgt  

Institutsseminar Kern und Hadronenphysik
Institut für Kernphysik 14 Uhr c.t., HS Kernphysik, Becherweg 45 
Oliver Noll, Mainz  
Digital signal processing for the PANDA electromagnetic calorimeter  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum 
Christopher Hils, Insitut für Physik  
Ultralow energy calibration of the XENON1T detector with an internal 37Ar source  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16 Uhr c.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 Physik 12:00 Uhr s.t., NewtonRaum, Staudingerweg 9, 1. Stock, Raum 122 (Nebengebäude) 
Amrit R. Pokharel, Inst. f. Physik  
Carrier relaxation dynamics in Kondo insulator YbB12  

TheoriePalaver
Institut für Physik 14:30 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.  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Markus Garst, KIT Karlsruhe, Germany  
The weak DzyaloshinskiiMoriya 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 fieldpolarized phase of chiral magnets, the DMI results in a pronounced nonreciprocity 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 nonreciprocal as confirmed by inelastic neutron scattering [1,2]. For wavevector with a finite perpendicular component of the wavevector, dipolar interactions induce a nonreciprocity which was detected by Brillouin light scattering [3]. We also discuss the spin wave spectrum of the skyrmion crystal phase where the nontrivial 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 nonreciprocity as confirmed by spin wave spectroscopy [4]. Finally, we discuss the nonlinear dynamics of a single skyrmion string [5].  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 15:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Kelvin van Hoorn, Technical University of Eindhoven, The Netherlands  
Magnetic field sensors based on deflection of membranes  
Sonderseminar  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 15:00 Uhr s.t., MEDIENRaum, Staudinger Weg 7, 3. Stock, Raum 03431 
Chi Fang, University of Chinese Academy of Sciences, Beijing, China  
The application potential of spinorbittorques in magnetic random access memory attracts great attention and research interest in spinorbit 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 threeterminal 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 spininjectioninduced 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. Threeterminal 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  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 14:30 Uhr s.t., MEDIENRaum, Staudinger Weg 7, 3. Stock, Raum 03431 
Dr. Kunie Ishioka, National Institute for Materials Science, Tsukuba, Japan  
Mittwoch, den 19. Februar 2020 um 14:30
im MEDIENRaum, Staudinger Weg 7, 03431
Ultrafast Carrier and Phonon Dynamics of Hybrid Lead Halide Perovskite
Kunie Ishioka
National Institute for Materials Science, Tsukuba, Japan
Inorganicorganic 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 anticorrelation 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 
SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Shefali Vaidya, IRCELYON, Lyon, France  
Molecular magnets to phase changing coordination polymers: criteria an challenges for molecules for their potential application in memory storage  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 3. Stock, 03122 
Thomas Allison, Stony Brook University, NY, USA  
Timeresolved ARPES at 88 MHz repetition rate with full 2π collection  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01122, Staudingerweg 9 
Fabian Kössel, Institut für Physik  
Emerging patterns from the collective dynamics of microswimmers in an external field  
Trial PhD defense talk 
SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., Galilei seminar room (Staudinger Weg 9, room 01128) 
Mehrdad Elyasi, Tohoku University, Sendai, Japan  
Magnons for Quantum Information  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 14:00 Uhr s.t., MAINZ seminar room (Staudinger Weg 9, 3rd floor, room 03122) 
Dr. Aga Shahee, Seoul University  
Doping tunable multiferroicity in PbCu3TeO7 and magnetoelectric coupling in Van der Waal CuCrP2S6  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01122, Staudingerweg 9 
Jan Rothörl, Institut fuer Physik  
Creating 3D structures of diploid cells from HiC data using a Molecular Dynamics approach  
Master Colloquium 
Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 11:00 Uhr s.t., MEDIENRaum, 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 highenergy electron di ffraction (RHEED) is used to control the growth process.  
Sonderseminar  

Seminar Festkörper und Grenzflächenphysik KOMET  experimentell
Institut für Physik Sonderseminar: 14:00 Uhr s.t., MEDIENRaum, 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 twodimensional systems called MXenes [1]. Mo4Ce4Al7C3 is affiliated with the MAX phase and in a family of REbased nanolaminates with a chemical formula of Mo4RE4Al7C3. From magnetization measurements, xray absorption nearedge structure (XANES), and xray magnetic circular dichroism (XMCD), a ferromagnetism below a Curie temperature of TC ~ 10.5 K and a mixedvalence states of the Ce 4f electrons have been reported [2].
To understand the origin of electronic/magnetic properties of Mo4Ce4Al7C3, we have performed angleresolved photoemission spectroscopy (ARPES) on Mo4Ce4Al7C3 singlecrystals. 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 4d4f 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  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Newtonraum, 01122, Staudingerweg 9 
Bing Li, Postdoctoral researcher, Institute of physics, JGU Mainz  
Shaping membrane vesicles by adsorption of a semiflexible polymer  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 10:30 Uhr s.t., online lecture series  streaming link: https://conference.unimainz.de/meet/dion/JBQR5429 
Merlin Pohlit, Uppsala University, Department of Physics and Astronomy  
Mesoscopic Spin Systems & Local Magnetic Sensing  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 15:00 Uhr s.t., online lecture series  streaming link: https://conference.unimainz.de/meet/dion/8VBKC6N9 
Simon Moser, Uni Würzburg  
ARPES on complex materials: A story told by electrons  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Michele Redi, Florence U. and INFN  
I will describe the conditions under which the PecceiQuinn 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  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 10:30 Uhr s.t., None 
Nadejda Bouldi, Heidelberg University  
Core level spectroscopies to study magnetic materials  
at Skype for Business  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 15:00 Uhr s.t., None 
Angela Wittmann, Massachusetts Institute of Technology  
Spintronic phenomena at interfaces  
at Skype for Business  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.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, socalled 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 LaueLangevin 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  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., None 
Bernard Brickwedde/Jan Lommler, Institut für Physik  
Deep Learning  
at Zoom  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16 Uhr c.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 nonconservation 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 betaNMR) to determine the magnetic dipole moments and electric quadrupole moments of shortlived nuclei. Recently, we have started applying betaNMR 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 betaNMR 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 GQuadruplex structures .  
at Recording of the presentation  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 10:30 Uhr s.t., None 
Michael Slota, Department of Materials, University of Oxford, OX1 3PH, UK  
Molecular Spin Nanostructures  
at Skype for Business  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 15:00 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.  
Spin Dynamics: from Microstructures to Individual Atoms  
at Skype for Business  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.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. GammaMRI
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
abovementioned techniques. Our team is at present working on a proofofconcept experiment.
GammaMRI is based on the detection of asymmetric γray emission of longlived polarized
nuclear states in the presence of magnetic fields [2]. The nuclei used in our study are longlived
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 laserpolarized rubidium vapor (Spin Exchange
Optical Pumping) [4]. Once polarized and placed inside a magnetic field, they emit γrays 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 countrates. 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 pickup 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, CERNINTC2017092 / INTCI205 (2017).
[4] T. G. Walker and W. Happer, Rev. Mod. Phys. 69, 629 (1997).  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 10:30 Uhr s.t., None 
Naëmi Leo, CIC nanoGUNE, Donostia, San Sebastian, Spain  
Artificial Spin Ice: From Frustration to Computation  
at Skype for Business  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 15:00 Uhr s.t., None 
Alan Farhan, Department of Applied Physics, Aalto University School of Science, P.O. Box 15100, FI00076 Aalto, Finland  
Frustrated spin architecture: from macroscopically degenerate artificial spin ice to artificial spin glasses  
at Skype for Business  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., None 
Ralf Gugel, Institut für Physik  
Measurement of Higgs boson production via gluon fusion and vectorboson fusion in the H → WW* decay mode with the ATLAS experiment at the LHC at √s = 13 TeV  
at Zoom  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Filippo Sala, CNRS Paris Jussieu  
SubGeV 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 SuperKamiokande and MiniBooNE data already exclude previously allowed regions of both DMelectron and DMnucleon interactions. I will then discuss search strategies and prospects at existing and planned neutrino facilities, such as HyperK, DUNE, IceCube and KM3NeT.  
at Zoom  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 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  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 17 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.de") 
Prof. Dr. Monika SchleierSmith, 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 longrange interactions among cold atoms. Our lab is exploring two approaches: photonmediated and Rydbergmediated interactions. By coupling atoms to light in an optical resonator, we generate tunable nonlocal Heisenberg interactions, characterizing the resulting phases and dynamics by realspace imaging. Notable observations include photonmediated spinmixing—a new mechanism for generating correlated atom pairs—and interactionbased 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 transversefield Ising model. I will discuss prospects in quantum simulation and quantum metrology promised by the versatility of optical control.  
Achtung: Uhrzeit geändert! 
Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., None 
Simone Schuchmann, Institut für Physik  
NA62: The Kaon Factory @ CERN  
at Zoom  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., online (zoom oder BigBlueButton) 
Jeff Hangst, Aarhus University  
COLLOQUIUM CANCELLED!  
COLLOQUIUM CANCELLED! 
Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 17 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.de") 
Prof. Dr. KaiMei 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 semiconductorondiamond 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. Virnau 10:30 Uhr s.t., Newtonraum, 01122, Staudingerweg 9 
Maike Jung, Institut für Physik  
Modeling Membrane Dynamics on the Level of Organelles  
at Zoom  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., None 
Antoine Laudrain, Institut für Physik  
Calibration of the ATLAS electromagnetic calorimeter  
at Zoom  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Alexander Ochirov, ETH Zurich  
In view of the recent observations of gravitationalwave signals from blackhole mergers, classical blackhole scattering has received considerable interest due to its relation to the classical boundstate 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 spins particles. Starting at first postMinkowskian (PM) order, I will explain how the spinexponentiated structure of the relevant treelevel amplitude follows from minimal coupling to Einstein's gravity and in the \(s \rightarrow \infty \) limit generates the black holes' complete series of spininduced multipoles. The resulting scattering function will be shown to encode in a simple way the known net changes in the blackhole 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 blackhole scattering.  
at Zoom  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 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 resolution. 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 flyby using image charge detection and to deliver the ion with nanometer precision employing 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 nanoimplantation methods as well as new developments in material science to overcome the limitations encountered in the creation of NV centers so far.  
at Recording of the presentation  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., None 
Alexander Fritz/Seva Orekhov, Institut für Physik  
Supernova  
at Zoom  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Achim Rosch, Universität Köln  
Magnetic skyrmions are tiny, topologically quantized magnetic whirls stabilized by relativistic spinorbit 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 Recording of the presentation  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.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 nonequilibrium dynamics of manybody quantum systems under almost ideal conditions. Introducing a controlled coupling to the environment “opens” the quantum system and nonunitary dynamics can be investigated. Such an approach provides new opportunities to study fundamental quantum phenomena and to engineer robust manybody 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 BoseEinstein 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 steadystates in a drivendissipative Josephson array [4]. For small dissipation, the steadystates 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. Virnau 10:30 Uhr s.t., Newtonraum, 01122, Staudingerweg 9 
Prof. Dr. Hossein Eslami, Chemistry Dept. TU Darmstadt  
Selfassembly of Janus particles  
at Zoom, email settanni@unimainz.de  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 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 Recording of the presentation  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.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 rfdressed 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.  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Martin Fertl, JGU Mainz  
Muon g2: Comparing the Muon’s Clocks to Test the Standard Model of Particle Physics  
at Recording of the presentation  

TheoriePalaver
Institut für Physik 15:00 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 dimensionsix 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  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 16:00 Uhr s.t., None 
Prof. Dr. Oliver Gutfleisch, Material Science, Technical University Darmstadt, D64287 Darmstadt, Germany  
Hysteresis design of magnetic materials for efficient energy conversion and the goals of CRC/TRR 270  
at Zoom  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Joachim Mnich, DESY  
Over the last years, intense discussions on the international level have started on the future perspectives of particle physics after the LHC era. In Europe, CERN Council has initiated an update of the European Strategy, supposed to conclude in spring 2020. This schedule might slip because of the current Covid19 pandemic, but some possible directions for the field have been identified in the community discussions. These include plans for Higgs factories to study this very peculiar particle to highest precision as well as ideas for future hadron colliders with a significantly higher energy reach than the LHC.
All of these projects will require large resources and can only be realized through global collaboration. It is therefore important to formulate a global strategy for particle physics, including for instance the USA in which the community discussions (Snowmass process) are starting now – with results expected in about a year. The International Committee for Future Accelerators (ICFA), which includes members from all world, regions will provide a forum for discussions towards a global strategy.
The talk will summarize the status of these discussions and try to provide an outlook into the future.  
at Recording of the presentation  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Gustavo Marques Tavares, Johns Hopkins U.  
In this talk I will discuss the effects of single derivative mixing in massive bosonic fields. In the regime of large mixing this leads to striking changes of the field dynamics, delaying the onset of classical oscillations and decreasing the effects of friction due to Hubble expansion. I will discuss how this can change the cosmological evolution of the axion field in the presence of primordial magnetic fields, and show that this increases the axion abundance allowing heavier axions to make up all of dark matter.  
at Zoom  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.de") 
Dr. Angela Papa, PSI, Villigen, Switzerland and University of Pisa/INFN, Italy  
Lepton flavor violation (LFV) research is currently one of the most exciting branches of particle physics due to its high sensitivity to new physics. The observation of neutrino oscillations has clearly demonstrated that neutral lepton flavor is not conserved. This implies that charged LFV (cLFV) processes, such as the µ⁺ > e⁺γ decay or the µ⁺ > e⁺ e⁺ e⁻ decay, can also occur in simple extended Standard Model (SM) versions (i.e. including Dirac neutrinos) which takes into account for neutrino oscillations, although strongly suppressed. On the other hand, Beyond SM (BSM) extensions strongly enhance the predictions for cLFV branching ratios. Therefore such decays are ideal probes for new physics.
In this talk the current status of the MEGII and the Mu3e experiments will be given. The first will aim at searching for the µ⁺ > e⁺γ decay with a sensitivity of approx. 6 x10⁻¹⁴ while the second will pursue the µ⁺ > e⁺ e⁺ e⁻ − decay search with an ultimate sensitivity of 10⁻¹⁶. Both experiments will be hosted at the Paul Scherrer Institut (Villigen, Switzerland) which delivers the most intense low energy continuous muon beam in the world (up to few x10⁸ µ/s), the optimal choice for such a kind of search. It will be also discussed the potentialities of these apparatuses to search for more exotics processes.  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Kristof Schmieden, Institut für Physik  
LightbyLight scattering & ALPs at the LHC  
at Zoom for now  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Rafael Lang, Purdue University, Indiana, USA  
I will review the science case for dark matter, presenting the evidence from cosmology and astrophysics. As will thus become clear, dark matter
has already been discovered  we just don't know yet what it is made of. The socalled direct detection of dark matter is a very promising
approach to tackle this question. I will present the status of this field, including the recently announced results from XENON1T.  
at Recording of the presentation  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., LorentzRaum 05127, Staudingerweg 7 
Dieter Riess, Institute of Nuclear Chemistry  
A nonzero electric dipole moment of the neutron (nEDM) would violate CP symmetry, and thus would be an indication for a new source of CP violation, which might help to explain the matter to antimatter asymmetry in our universe.
The nEDM collaboration has taken data at the Paul Scherrer Institute in 2015 and 2016 in order to improve on the previous limit
dn < 3×10−26 ecm at 90% C.L. [1].
In total more than 54000 individual measurement cycles were recorded using Ramsey’s method of separated oscillating fields to measure the precession frequency of ultracold neutrons in electric and magnetic fields. The analysis of this dataset has been carried out in a blind fashion.
The collaboration has unblinded their result at the end of November 2019.
The new result will be presented together with a detailed description of the experiment.
[1]: J.M. Pendlebury et al. PRD 92, 092003 (2015)  
at Panopto Recording  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.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 wellcontrolled manyparticle system. In ensembles
of atoms, ions and many other quantum emitters, such correlations can
be generated with a highfinesse optical cavity. This approach is
particularly promising for quantum metrology. I will present an
experiment combining a compact trappedatom clock on an atom chip and
a fiber FabryPerot microcavity. This first "metrologygrade" 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
manyparticle entangled states with the exchange interaction that
occurs in the trapped lowtemperature gas.  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 16:00 Uhr s.t., der Raum wird separat angekündigt 
Prof. Dr. Uwe Bovensiepen, CRC 1242 NonEquilibrium Dynamics of Condensed Matter in the Time Domain  
tba  
at Zoom  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Daniele Guffanti, Institut für Physik  
First detection of CNOcycle neutrinos with the Borexino experiment  
at Zoom for now  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Jo van den Brand, Nikhef  
The LIGO Virgo Consortium achieved the first detection of gravitational waves. A century after the fundamental predictions of Einstein, we report the first direct observations of binary black hole systems merging to form single black holes. The detected waveforms match the predictions of general relativity for the inspiral and merger of a pair of black holes and the ringdown of the resulting single black hole. Our observations provide unique access to the properties of spacetime at extreme curvatures: the strongfield, and high velocity regime. It allows unprecedented tests of general relativity for the nonlinear dynamics of highly disturbed black holes. In 2017 the gravitational waves from the merger of a binary neutron star was observed. This discovery marks the start of multimessenger astronomy and the aftermath of this merger was studied by using 70 observatories on seven continents and in space, across the electromagnetic spectrum.
The scientific impact of the recent detections on nuclear physics will be explained. In addition key technological aspects will be addressed, such as the interferometric detection principle, optics, and sensors and actuators. Attention is paid to Advanced Virgo, the European detector near Pisa that recently came online. The presentation will close with a discussion of the largest challenges in the field, including plans for a detector in space (LISA), and Einstein Telescope, an underground observatory for gravitational waves science.  
at Recording of the presentation  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Matheus Hostert, University of Minnesota  
In light of the recent experimental progress in the study of neutral and charged kaon decays, I will discuss how $K_L$ decays can offer a strong probe of dark sectors, independently from the decays of their charged partner. This is motivated by a recent excess in $K_L \to \pi^0 \nu\overline{\nu}$ reported by the KOTO experiment, which, if confirmed, would indicate the existence of light or new exotic particles. The models I discuss can easily accommodate such signatures, with some examples containing a dark matter candidate.  
at Zoom  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., None 
Ashreya Jayaram, Institut für Physik, JGU, PhD student  
Collective Behaviour of Anisotropic Active Particles  
at Zoom  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.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.  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., None 
Elisa RuizChóliz/Phi Chau, Institut für Physik  
Axions and ALPs searches  cancelled  
at Zoom  
This talk has been cancelled 
Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Paul Dodds, University College London  
Hydrogen caused an energy revolution when it was introduced from the early 1810s. Might we return to using hydrogen again in the future? Paul will examine the potential future roles of hydrogen and fuel cells across the economy, including for vehicles, heating your home and office, powering industry, and integrating renewable electricity generation. He will examine the innovation challenges and opportunities for hydrogen and fuel cells, from both engineering and economic perspectives. Finally he will compare them with alternative lowcarbon technologies to try to understand which of these roles are most likely to be realised.  
at Zoom (for more details see below)  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Yann Gouttenoire, DESY  
Cosmic strings (CS) are topological defects formed after spontaneous breaking of a U(1) symmetry. Remarkably, thanks to the scaling regime, CS loops constitute a longstanding source of Gravitational Waves (GW) and produce a flat GW spectrum during radiation domination, spanning many orders of magnitude in frequency.
I will discuss reasons to be excited about the possible future detection of GW from CS by the next generation of GW interferometers, in order to bring light on the existence of nonstandard cosmology before BigBang Nucleosynthesis starts and the related BeyondStandardModel physics. I will discuss the possibility to probe superstring theories with moduli scale up to 10^{10} GeV, heavy dark photon with kinetic mixing as low as 10^{18}, heavy ALPs with masses between 1 GeV and 10^{10} GeV or PBHs below 10^9 grams.  
at Zoom  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., https://zoom.us/j/94520261050 (PasswortAnfrage an "stuckker@unimainz.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 frequencydependent reflectors, Phys. Rev. Lett. 122, 243601 (2019).
[3] C. Sommer and C. Genes, Partial optomechanical refrigeration via multimode cold damping feedback, Phys. Rev. Lett. 123, 203605 (2019).  

SFB/TR49/SFB TRR 173 Spin+XKolloquium/TopDyn  Seminar experimentelle Physik der kondensierten Materie
SFB/TR49  Prof. Dr. Elmers 16:00 Uhr s.t., der Raum wird separat angekündigt 
Prof. Dr. Martin Weinelt, CRC/TRR 227 Ultrafast Spin Dynamics  
tba  
at Zoom  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Prof. Dr. Simon Stellmer, Rheinische FriedrichWilhelmsUniversität Bonn  
Our quantum metrology research group has recently been established at the University of Bonn. The overarching goal of our various projects is the improvement of precision measurements in an interdisciplinary context. In my talk, I will present two of our projects.
In the first project, we address one of the most pressing fundamental questions in contemporary physics: Why does the Universe contain matter, but almost no antimatter? This mattertoantimatter asymmetry is understood as massive CP violation, which in turn would show up as a permanent electric dipole moment (EDM) in fundamental particles. I will show how ultracold and even quantumdegenerate Fermi gases of mercury can be used to measure the neutron EDM with a sensitivity that might exceed stateoftheart limits.
The second project is related to geodesy: the rotation of Earth is not as constant as it may seem. On the contrary, it is an amazingly sensitive probe of all kinds of phenomena, ranging from rotational coupling to other celestial objects all the way to mantle/crust coupling and the anthropogenic climate change. We have started to develop novel gyroscopes to measure, via the Sagnac effect, variations in the Earth rotation rate at an unprecedented sensitivity.  
at Zoom  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Prof. William D. Phillips (Nobel Prize in Physics), National Institute of Standards and Technology (NIST), USA  
On 20 May 2019 the International System of Units (the SI) experienced its most revolutionary change since the French revolution produced the metric system. Today, all of the base units of the SI are defined by fixing the values of constants of nature, resulting in a fundamentally quantum system of measurement units. This talk will discuss why such a reform was needed and how it is implemented.  
at Zoom  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Digital meeting 
Lukas Stelzl, Institute of Physics  
From atomicresolution ensembles of disordered proteins to simulations of their biomolecular condensates  
at Zoom  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Daniel Wenz/Johannes Balz, Institut für Physik  
Dark Matter  
at Zoom for now  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Prof. Dr. Arno Rauschenbeutel, HumboldtUniversität zu Berlin  
Correlating photons using the collective nonlinear response of atoms weakly coupled to an optical mode
Typical schemes for generating correlated states of light require a highly nonlinear medium that is strongly coupled to an optical mode. However, unavoidable dissipative processes, which cause photon loss and blur nonlinear quantum effects, often impede such methods. In this talk, I will report on our recent experimental demonstration of a proposal that takes the opposite approach [1]. Using a strongly dissipative, weakly coupled medium, we generate and study strongly correlated states of light [2]. Specifically, we study the transmission of resonant light through an ensemble of noninteracting atoms that weakly couple to a guided optical mode. Dissipation removes uncorrelated photons while preferentially transmitting highly correlated photons created through collectively enhanced nonlinear interactions. As a result, the transmitted light constitutes a strongly correlated manybody state of light, revealed in the secondorder correlation function. The latter exhibits strong antibunching or bunching, depending on the optical depth of the atomic ensemble. The demonstrated mechanism opens a new avenue for generating nonclassical states of light and for exploring correlations of photons in nonequilibrium systems using a mix of nonlinear and dissipative processes. Furthermore, our scheme may turn out useful in quantum information science. For example, it offers a fundamentally new approach to realizing single photon sources, which may outperform sources based on single quantum emitters with comparable coupling strength [3].
[1] S. Mahmoodian, M. Čepulkovskis, S. Das, P. Lodahl, K. Hammerer, A. S. Sørensen, Phys. Rev. Lett. 121, 143601 (2018).
[2] A. Prasad, J. Hinney, S. Mahmoodian, K. Hammerer, S. Rind, P. Schneeweiss, A. S. Sørensen, J. Volz, A. Rauschenbeutel, Nat. Photonics (2020). https://doi.org/10.1038/s415660200692z
[3] European patent pending (PCT/EP2019/075386)  
at Zoom  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Digital event 
Jan Rothörl, Institute of Physics, JGU  
Coarsegrained Computer Simulations of Skyrmions  
at Zoom  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Elisa RuizChóliz/Phi Chau, Institut für Physik  
Axions and ALPs searches  
at Zoom for now  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Javier FuentesMartin, JGU Mainz  
In this talk, I will present a model for thirdfamily quarklepton unification at the TeV scale featuring a composite Higgs sector. The model is based on a variant of the PatiSalam model, the socalled 4321 model. The spontaneous symmetry breaking to the SM gauge group is triggered dynamically by a QCDlike confining sector. The same strong dynamics also produces a pseudo NambuGoldstone boson Higgs, connecting the energy scales of both sectors. The model predicts a massive U1 vector leptoquark coupled dominantly to the third generation, recently put forward as a possible solution to the Bmeson anomalies.  
at Zoom  

Theoriekolloquium
Die Dozierenden der Theoretischen Physik 16:00 Uhr s.t., usually NewtonRaum, Staudinger Weg 9, 01122 
Markus Heyl & Nicola Pancotti, MPKS, Dresden & Amazon Quantum  
We restart our series of theory colloquiums with a 90 minutes event on applications of machine learning to manybody physics. We will have two Zoom talks of 35 minutes+10 minutes of questions, each.
Talk 1 (M. Heyl): Quantum manybody dynamics in two dimensions with artificial neural networks
In the last two decades the field of nonequilibrium quantum manybody physics has seen a rapid development driven, in particular, by the remarkable progress in quantum simulators, which today provide access to dynamics in quantum matter with an unprecedented control. However, the efficient numerical simulation of nonequilibrium realtime evolution in isolated quantum matter still remains a key challenge for current computational methods especially beyond one spatial dimension. In this talk I will present a versatile and efficient machine learning inspired approach. I will first introduce the general idea of encoding quantum manybody wave functions into artificial neural networks. I will then identify and resolve key challenges for the simulation of realtime evolution, which previously imposed significant limitations on the accurate description of large systems and longtime dynamics. As a concrete example, I will consider the dynamics of the paradigmatic twodimensional transverse field Ising model, where we observe collapse and revival oscillations of ferromagnetic order and demonstrate that the reached time scales are comparable to or exceed the capabilities of stateoftheart tensor network methods.
Talk 2 (N. Pancotti): Neural Networks Quantum States, Tensor Networks and Machine Learning
Neural Networks Quantum States have been recently introduced as an Ansatz for describing the wave function of quantum manybody systems. In this talk I will give an overview of recent works on Neural Networks Quantum States taking the form of Boltzmann machines. I will explain the motivation for considering Boltzmann machines in machine learning and explain how they can be used to study ground state properties of quantum systems. I will then focus on the expressive power of this class of states and discuss their relationship to Tensor Networks. In particular I will show that restricted Boltzmann machines belong to an exotic class of tensor networks known as String Bond States. This mapping enables us to define generalizations of restricted Boltzmann machines that combine the entanglement structure of tensor networks with the efficiency of Neural Networks Quantum States. This connection sheds light on possible application of tensor networks in machine learning. I will discuss the tight relationship between tensornetwork techniques and probabilistic graphical models, an established class of models broadly used in computer science. I finally conclude by presenting possible advantages of using tensor network to tackle machine learning problems.  
at Zoom  
double seminar 
Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Univ.Prof. Dr. Tracy E. Northup, Universität Innsbruck  
Future quantum networks offer a route to quantumsecure communication, distributed quantum computing, and quantumenhanced sensing. A current challenge across all experimental platforms is how to move beyond proofofprinciple realizations to the efficient, faithful distribution of quantum states over scalable networks. I will present ongoing work on nodes for quantum networks based on trapped ions in optical cavities, focusing in particular on a connection between remote trappedion systems in Innsbruck and the development of fibercavitybased interfaces.
To conclude, we will consider another role for ions coupled to optical cavities, namely, how they may enable the preparation of macroscopic quantum states of motion, in this case, of levitated nanoparticles. A common theme in this talk will be how an optical cavity can serve as an interface between quantum states encoded in light, in motion, and in the electronic states of an ion.  
at Zoom  

GRK 2516 Soft Matter Seminar
Uni Mainz 10:30 Uhr s.t., via Zoom 
C. Patrick Royall, University of Bristol  
Gels are an everyday material, from foods to cosmetics to structures in living organisms. Yet gelation is among the most challenging phenomena in soft condensed matter to understand. Gels are nonequilibrium materials, which already puts them right at the limit of our understanding. As if the were not enough, gels sit at the intersection of the glass transition and failure in amorphous materials. The glass transition has been described as “the deepest problem in condensed matter physics” and failure of amorphous materials continues to evade a meaningful theoretical description [1,2].
Here we describe recent development in our understanding of the nature of colloidal gels [3,4] and explore mechanisms by which gels acquire their unusual “soft” solidity [3,4,6]. In particular, we elucidate the perceived wisdom of materials science that the microscopic structure determines the dynamics and macroscopic behaviour of the material. We develop an intuitive approach based on the local structure of constituent colloidal particles which provides a basic mechanism for local rigidity in the system. We show how this leads to a long—lived yet metastable solid material and provide approaches to understand the mechanisms of failure, which are key to applications in these complex yet everyday materials.
[1] Royall CP & Williams SR “The role of local structure in dynamical arrest”, Phys. Rep. 560 175 (2015).
[2] Royall CP, “Hunting Mermaids in Real Space: Known Knowns, Known Unknowns and Unknown
Unknowns” Soft Matter 14 40094016 (2018).
[3] Royall CP, Williams SR, Ohtsuka, T and Tanaka H, “Direct observation of a local structural mechanism for
dynamic arrest”, Nature Materials 7 556561, (2008).
[4] Royall CP, Williams SR and Tanaka H “Vitrification and gelation in sticky spheres”, J. Chem. Phys. 148
044501 (2018).
[5] Richard D, Hallett JE, Speck T and Royall CP, “Coupling between criticality and gelation in “sticky”
spheres: A structural analysis”, Soft Matter 14 55545564 (2018).
[6] Royall CP, Eggers J, Furukawa A and Tanaka H, “Probing Colloidal Gels at Multiple Length Scales: the Role of Hydrodynamics”, Phys. Rev. Lett. 114 258302 (2015).  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Martin Rongen, Institut für Physik  
The IceCube Upgrade Project  
at Zoom for now  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Dieter Ries, University of Mainz  
Ultracold Neutrons (UCN) provide a unique tool for fundamental neutron research with long observation times. Once produced e.g. in one of the UCN sources at the TRIGA Mainz research reactor, they can be confined by suitable materials, gravity or strong magnetic fields ultimately only limited by the beta decay lifetime of the free neutron.
The τSPECT experiment, which is close to being fully commissioned onsite at JGU, aims for a precision determination of the neutron lifetime, which is currently under scrutiny because different measurement techniques yield incompatible results.
Another precision measurement with UCN is the search for a nonvanishing electric dipole moment of the neutron, which would violate CP symmetry.
Together with the international nEDM collaboration we have recently published a new upper limit on the neutron EDM and are currently commissioning the next generation experiment "n2EDM" at PSI, Switzerland, which aims to push down the limit by an order of magnitude in the coming years. The current state of and results from the τSPECT, nEDM and n2EDM experiment will be presented.  
at Recording of the presentation  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Ana Peñuelas, JGU Mainz  
We perform a general modelindependent analysis of \(b \to c \tau \bar{\nu}_\tau\) transitions, including measurements of \(\mathcal{R}_D\), \(\mathcal{R}_{D^*}\), their \(q^2\) differential distributions, the longitudinal \(D^*\) polarization \(F_L^{D^*}\), and constraints from the \(B_c \to \tau \bar{\nu}_\tau\) lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective lowenergy Hamiltonian is presented working with a minimal set of assumptions: new physics is present only in the third generation of leptons, there are not light righthanded neutrinos, the electroweak symmetry breaking is linearly realized and the CPconserving limit is taken. The solutions of the fit are interpreted in terms of hypothetical newphysics mediators.
The impact of \(F_L^{D^*}\), measured by Belle last year is studied in detail. The difficulty to accommodate this measurement motivates the relaxation of some of our assumptions so the impact of a nonlinear electroweak symmetry breaking and the addition of light righthanded neutrinos is studied.
From the obtained results we predict selected \(b \to c\tau\bar\nu_\tau\) observables, such as the baryonic transition \(\Lambda_b \to \Lambda_c \tau \bar{\nu}_\tau\), the forwardbackward asymmetries \(\mathcal{A}_\text{FB}^{D^{(*)}}\), the \(\tau\) polarization asymmetries \(\mathcal{P}_\tau^{D^{(*)}}\), the longitudinal \(D^*\) polarization fraction \(F_L^{D^*}\) and several additional differential observables.  
at Zoom  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., only via ZOOM 
Prof. Dr. Anastasia Borschevsky, University of Groningen, NL  
The Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Nijenborgh 4, 9747 AG Groningen, The Netherlands Search for variation of fundamental constants and for violation of fundamental symmetries provides a unique opportunity for observing new physics and for testing various extensions of the Standard Model. Atomic and molecular experiments offer a low energy and comparatively inexpensive alternative to high energy accelerator research in this field. As the observable effects are expected to be very small, highly sensitive systems and extremely precise measurements are required in order to detect any manifestations of the physical phenomena beyond the Standard Model. An important task of theoretical research is to identify optimal molecular and atomic systems for measurements and to understand the mechanisms behind the enhanced sensitivity, which is strongly dependent on the electronic structure. Thus, accurate computational methods are needed in order to provide reliable predictions rather than estimates, and to obtain the various parameters that are required for the interpretation of the experiments.
I will present the results of our recent investigations of atoms and molecules in the context of search for variation of fundamental constants and for parity violating effects. A short overview of the theoretical methods will be provided, but the talk will focus on showcasing the different types of systems (highlycharged ions, diatomic and chiral molecules) that are promising candidates for experiments that aim to detect new physical phenomena.  

Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 10:30 Uhr s.t., Digital event 
William Janke, Institute of Physics  
Structure formation of C60 on CaF2 Substrates: Multiscale Modelling  
at Zoom  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Viacheslav Filimonov, Institut für Physik  
Global Demonstrator and PFM module  
at Zoom for now  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Bert Koopmans, Eindhoven University of Technology, The Netherlands  
Femtomagnetism meets spintronics: Towards integrated magnetophotonics  
at Recording of the presentation  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Davide Racco, Perimeter Institute  
The low frequency part of the gravitational wave spectrum generated by local physics, such as a phase transition, is largely fixed by causality, offering a clean window into the early Universe. Due to the difference between subhorizon and superhorizon physics, it is inevitable that there will be a distinct spectral feature that could allow for the direct measurement of the conformal Hubble rate at which the phase transition occurred.
As an example, freestreaming particles present during the phase transition affect the production of superhorizon modes. This leads to a steeper decrease in the spectrum at low frequencies as compared to the wellknown causal \(k^3\) superhorizon scaling of stochastic gravity waves. If a sizeable fraction of the energy density is in freestreaming particles, they even lead to the appearance of oscillatory features in the spectrum.
If the universe was not radiation dominated when the waves were generated, a similar feature also occurs at the transition between subhorizon to superhorizon causality. These features can be used to show surprising consequences, such as the fact that a period of matter domination following the production of gravity waves actually increases their power spectrum at low frequencies.  
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PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., None 
Matteo Alfonsi, Institut für Physik, ETAP  
The XENON1T experiment has recently reported new results from the analysis of low energy electronic recoils data, characterized by the lowest background rate ever achieved in the energy range between 1 and 30 keV. An excess over known background has been observed around 23 keV, and this observation has been interpreted in terms of the existence of solar axions, or as an enhancement of the neutrino magnetic moment observed in solar neutrinos, or as an additional background initially not considered. In the latter hypothesis, among the various possibilities considered such as traces of 127Xe or 37Ar or tritium diluted into the active volume, only the tritium hypothesis cannot be confirmed or excluded with the current knowledge of the production and reduction mechanism. In this seminar I will describe the detector operation, the analysis approach and the arguments that allowed us to arrive to such conclusions, trying to address also the additional questions that has been posed by the community.  
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Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Dr. James Millen, King's College London, UK  
Nanoparticles suspended and cooled in vacuum are seen as ideal candidates for testing the limits of quantum mechanics, beyond stateoftheart sensing, and tabletop detection of gravitational waves and dark matter. The standard technology involves optical trapping and levitation, though this comes with issues of optical absorption and photon scattering.
Away from the optical regime, electromechanics concerns the control of mechanical motion via its coupling to an electrical circuit. Chipbased electromechanical systems are leading quantum technologies, allowing entanglement between different circuitsignals, quantum squeezing, and the coherent conversion of signals between different frequency regimes.
I will present our preliminary results in the field of Levitated Electromechanics, where particles are levitated, detected and controlled allelectrically. I will introduce the concept of bath engineering in this system with a preliminary study of nonequilibrium dynamics, and our work towards miniaturization.
For more information see www.levinano.com  
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Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
All ETAP members, ETAP  
Dear all,
as announced yesterday in the ETAP seminar, we will take the opportunity next week in the seminar to have a special roundtable. Under normal circumstances, you would meet and see old and new faces during the the summer or Christmas party, or the ETAP seminar.
Under the current circumstances, we should have a virtual get together, so I would like to invite as many of you to join the meeting, from student to staff member and even if you normally do not join the seminar. Everyone should give a short introduction to yourself. You can let everyone know, who you are, in which group you are working in, what are you working on and everything else you can fill in one minute. If you can, please use your camera or at least share a picture of you. Maybe we can even make a zoom group picture!
Looking forward to seeing many of you next week!
Cheers
Duc  
at Zoom for now  

Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Eli Zeldov, Department of Condensed Matter Physics, Weizmann Institute of Science, Israel  
Energy dissipation is a fundamental process governing the dynamics of classical and quantum systems. Despite its vital importance, direct imaging and microscopy of dissipation in quantum systems is currently mostly inaccessible because the existing thermal imaging methods lack the necessary sensitivity and are unsuitable for low temperature operation. We developed a scanning nanoSQUID that resides at the apex of a sharp pipette acting simultaneously as nanomagnetometer with single spin sensitivity and as nanothermometer providing cryogenic thermal imaging with four orders of magnitude improved thermal sensitivity of below 1 µK [1]. The noncontact noninvasive thermometry enables direct visualization and control of the minute heat generated by electrons scattering off a single atomic defect in graphene [2]. By further combining the scanning nanothermometry with simultaneous scanning gate microscopy we demonstrate independent imaging of work and dissipation and reveal the microscopic mechanisms that conceal the true topological protection in the quantum Hall state in graphene [3].
[1] D. Halbertal, J. Cuppens, M. Ben Shalom, L. Embon, N. Shadmi, Y. Anahory, H. R. Naren, J. Sarkar, A. Uri, Y. Ronen, Y. Myasoedov, L. S. Levitov, E. Joselevich, A. K. Geim, and E. Zeldov, Nature 539, 407 (2016).
[2] D. Halbertal, M. Ben Shalom, A. Uri, K. Bagani, A.Y. Meltzer, I. Marcus, Y. Myasoedov, J. Birkbeck, L.S. Levitov, A.K. Geim, and E. Zeldov, Science 358, 1303 (2017).
[3] A. Marguerite, J. Birkbeck, A. AharonSteinberg, D. Halbertal, K. Bagani, I. Marcus, Y. Myasoedov, A.K. Geim, D.J. Perello, and E. Zeldov, Nature 575, 628 (2019).  
at Recording of the presentation  

TheoriePalaver
Institut für Physik 14:30 Uhr s.t., None 
Saereh Najjari, JGU Mainz  
I will introduce a scenario where both the Higgs and a complex scalar dark matter candidate arise as the pNGB of breaking a global \(SO(7)\) symmetry to \(SO(6)\). In our construction the symmetry partners of the Standard Model topquark are charged under a hidden \(SU(3)_c\) color group. We show how the Large Hadron Collider along with current and next generation dark matter experiments will explore this framework.  
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Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Prof. Dr. Andrey Surzhykov, PhysikalischTechnische Bundesanstalt Braunschweig  
The Gamma Factory (GF) is a novel research tool, currently considered by CERN as part of its Physics Beyond Colliders initiative. While the main goal of the GF is the generation of highintensity beams of gamma rays, it will also open up many opportunities in atomic, nuclear and particle physics. In my presentation, I will focus especially on the planned atomic physics activities. In particular, we will discuss how the GF can enable a wide range of groundbreaking studies, from the highprecision spectroscopy of partially stripped ions to testing Special Relativity and fundamental symmetries of Nature.
Joint seminar with the MITP workshop on Physics Opportunities with the Gamma Factory:
https://www.himainz.de/de/newsevents/detail/news/physicsopportunitieswiththegammafactory/
Prof. Dr. Andrey Surzhykov, PhysikalischTechnische Bundesanstalt Braunschweig  
at Zoom  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Rainer Wanke, Institut für Physik  
New results from NA62  
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Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Sherry Suyu, TU München  
Strong gravitational lenses with measured time delays between the multiple images can be used to determine the Hubble constant (H0) that sets the expansion rate of the Universe. An independent determination of H0 is important to ascertain the possible need of new physics beyond the standard cosmological model, given the tension in current H0 measurements. I will describe techniques for measuring H0 from lensing with a realistic account of systematicuncertainties, and present the latest resultsfrom a program aimed to measure H0 from lensing. Search is underway to find new lenses in imaging surveys. An exciting discovery of the first strongly lensed supernova offered a rare opportunity to perform a true blind test of our modeling techniques. I will show the bright prospects of gravitational lens time delays as an independent and competitive cosmological probe.  
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TheoriePalaver
Institut für Physik 14:30 Uhr s.t., MITP seminar room 
Aldo Cotrone, Florence U. and INFN  
I will first review the basics of holography and some properties of the SakaiSugimoto model, the topdown holographic theory closest to QCD. Then, in this model I will describe the process of nucleation of bubbles of true vacua in the case of two firstorder transitions: the confinement/deconfinement and chiral symmetry breaking/restoration ones. Finally, using these information, I will present the calculation of the gravitational wave spectra generated in these transitions, when the SakaiSugimoto model is employed as a dark sector. Prospects of detection will be discussed.  
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Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Dr. Lars von der Wense, JILA, University of Colorado, Boulder, USA  
A nuclear optical clock based on ^229Th ions is expected to achieve a higher accuracy than the best atomic clocks operational today [1]. Although proposed back in 2003 [2], such a nuclear frequency standard has not yet become reality. The main obstacle that has so far hindered the development of a nuclear clock was an imprecise knowledge of the energy value of a nuclear excited state of the ^229Th nucleus, generally known as the ^229Th isomer. This metastable nuclear excited state is the one of lowest energy in the whole nuclear landscape and  with an energy of less than 10 eV  offers the potential for nuclear laser spectroscopy, which poses a central requirement for the development of a nuclear clock [3].
Recently, a couple of new experiments have led to an improved knowledge about the isomer’s excitation energy [4, 5, 6], thereby constraining the isomeric energy to a value of 8.12 0.11 eV. This new knowledge offers great potential for future laser spectroscopy experiments and the development of a nuclear optical clock. With a wavelength equivalent of 152.7 2.1 nm, the energy is very well accessible by the 7th harmonic of a highpower Yb:dopedfiber frequencycomb [7] and a corresponding spectroscopy experiment is already in preparation [8]. If successful, the experiment would provide the first laser spectroscopy of a nuclear transition, thereby improving our current constraints of the isomer’s energy by six orders of magnitude. In addition, the stabilization of an individual combmode to the nuclear transition would result in the immediate development of a nuclear frequency standard. In this presentation I will give an overview over the current status of the nuclear clock development, with a particular focus on the most recent progress. Also the next required steps will be detailed and future perspectives will be given.
References
[1] C.J. Campbell et al., Phys. Rev. Lett. 108, 120802 (2012).
[2] E. Peik and C. Tamm, Eur. Phys. Lett. 61, 181 (2003).
[3] L. von der Wense and B. Seiferle, arXiv:2009.13633 (2020).
[4] B. Seiferle et al., Nature 573, 243 (2019).
[5] A. Yamaguchi et al., Phys. Rev. Lett. 123, 222501 (2019).
[6] T. Sikorsky et al., Phys. Rev. Lett. 125, 142503 (2020).
[7] C. Zhang et al., Phys. Rev. Lett. 125, 093902 (2020).
[8] L. von der Wense and C. Zhang, Eur. Phys. J D 74, 126 (2020).  
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Seminar über Theorie der kondensierten Materie / TRR146 Seminar
K. Binder/ A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau 18:00 Uhr s.t., Digital event 
AnChang Shi, MacMaster University, Hamilton, Canada  
Selfconsistent field theory  
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TheoriePalaver
Institut für Physik 15:30 Uhr s.t., MITP seminar room 
Alexandros Papageorgiou, University of Minnesota  
Motivated by some of the recent swampland conjectures, we study a model of dark energy in which a quintessence axion slowly rolls in a steep potential due to its interactions with a U(1) or an SU(2) gauge field. We compare the differences between the U(1) and SU(2) cases and specify the parameter space for which the model is compatible with observations. We also apply our methodology to studying the transition between a preinflationary era and inflation and note some interesting oscillatory effects in the particle production parameter which could lead to interesting phenomenology. Finally we analyze the potential of the "Warm Dark Energy" model to produce gravitational waves observable by PTA, CMB polarization or spectral distortion experiments and find a negative result.  
at Zoom  

Seminar about Experimental Particle and Astroparticle Physics (ETAP)
Institut für Physik 12:30 Uhr s.t., usually Staudingerweg 7, Minkowskiraum 
Hans Steiger, Institut für Physik  
The Taishan Antineutrino Observatory  TAO  
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Physikalisches Kolloquium
Institut für Kernphysik, Remote Seminar 16:15 Uhr s.t., None 
Baha Balantekin, University of Wisconsin, Madison, USA  
Earlier theoretical work on neutrino propagation in dense media, in particular the MikheyevSmirnovWolfenstein effect describing phase changes in neutrino wave functions resulting from their interaction with the background particles, provided an explanation of the measured distortions of the solar neutrinos. A more complex effect takes place in the denser media inside supernovae and neutronstar mergers, where neutrinos interact not only with the background particles but also among themselves. After reviewing key roles neutrinos play in such environments, this manyneutrino problem and resulting collective neutrino oscillations will be discussed. Implications of correlations between neutrinos in this manyneutrino system for nucleosynthesis and terrestrial detection of supernova neutrinos will be explored.  
at Recording of the presentation  

PRISMA Colloquium
Institut für Physik 13:00 Uhr s.t., None 
Marina Marinkovic, LMU München  
Simulating strong interaction at scale  
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Theoriekolloquium
Die Dozierenden der Theoretischen Physik 16:00 Uhr s.t., usually NewtonRaum, Staudinger Weg 9, 01122 
Matthew P. A. Fisher, UC Santa Barbara  
The inexorable growth of nonlocal quantum entanglement is the key feature that distinguishes quantum from classical systems. Monitoring an open system (by making projective measurements) can compete against entanglement growth, leading to a manybody quantum Zeno effect. A hybrid quantum circuit model consisting of both unitary gates and projective measurements exhibits a quantum dynamical phase transition between a weak measurement phase and a quantum Zeno phase. Detailed properties of the weak measurement phase  including relations to quantum error correcting codes  and of the critical properties of this novel quantum entanglement transition will be described.  
at Zoom  

Seminar über Quanten, Atom und Neutronenphysik (QUANTUM)
Institut für Physik 14 Uhr c.t., None 
Univ.Prof. Dr. Markus Arndt, Universität Wien  
Physics is currently in a state where many would say, the essential laws of nature are well understood. And it is true that quantum physics has matured for more than a century and has become the basis of a stunning range of modern technologies. And yet, fundamental questions of quantum physics have remained unsolved until today such as its transition into classical phenomenology or its relation to gravity theory. More recently a growing evidence has also suggested that we may actually know only a few percent of the world, missing the entire dark sector in matter and energy.
Here I will focus on how to set up universal matter  wave interferometers that can demonstrate and utilize the quantum wave nature of matter. I will present experiments to explore the interface between quantum physics and classical phenomena and shine light on the question of objective wave function collapse. I will discuss how gravity influences all matterwave interferometry, and many conceivable ways for it may to modify the dynamics of very massive superpositions. Finally, matterwave interferometers built for that purpose will also mature into sensors for dark matter in a specific energy range. Ideas and prospects are briefly discussed.  
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Emergent AI Center Seminars
JGU Research Center for Algorithmic Emergent Intelligence 14:00 Uhr s.t., Online 
Dr. Jean Anne Incorvia, The University of Texas at Austin  
There are pressing problems with traditional computing, especially for accomplishing dataintensive and realtime tasks, that motivate the development of computing devices to both store information and perform computation (inmemory) as well as efficiently implement neuromorphic computing architectures. Magnetic tunnel junction memory elements can be used for computation by introducing a third terminal and manipulating a domain wall, a transition region between magnetic domains, below the junction, called a domain wallmagnetic tunnel junction (DWMTJ). I will present results on building DWMTJ devices and circuits with high on/off ratio, as well as modeling their behavior for bioinspired energyefficient computing, including spiketiming dependent plasticity, winnertakeall, and leaky, integrate, and fire properties.  
at Zoom  

GRK 2516 Soft Matter Seminar
Uni Mainz 10:30 Uhr s.t., via Zoom 
Thomas Hermans, University of Strasbourg, CNRS  
Looking at nature, we see that living materials with biological functionality, such as the actin or microtubule (MT) cytoskeletal network, achieve dynamics as well as supramolecular structures with the same protein building blocks. In other words, the components can assemble, but also react (i.e., tubulin is also an enzyme that hydrolyses guanosine triphosphate GTP), which in turn affects the assemblies. In this way, living systems use chemical fuels (e.g., GTP) and selfassembly to create a builtin chemomechanical interaction. Moreover, such networks operate in sustained outofequilibrium states at the onset of oscillations,1–3 which results in rapid response and adaptivity. Here, we present our recent4–6 reaction cycles in solution and gels, where interesting new behaviors were found, such as supramolecular size oscillations, traveling polymerization, or transient disassembly. We hope such reaction cycles form the basis of new lifelike materials where material properties are fuel (and waste) dependent.
1. Obermann, H., Mandelkow, E. M., Lange, G. & Mandelkow, E. Microtubule oscillations. Role of nucleation and microtubule number concentration. J. Biol. Chem. 265, 4382–4388 (1990).
2. Valiron, O., Caudron, N. & Job, D. Microtubule dynamics. Cell. Mol. Life Sci. CMLS 58, 2069–2084 (2001).
3. Westendorf, C. et al. Actin cytoskeleton of chemotactic amoebae operates close to the onset of oscillations. Proc. Natl. Acad. Sci. 110, 3853–3858 (2013).
4. Singh, N., Lainer, B., Formon, G. J. M., De Piccoli, S. & Hermans, T. M. Reprogramming Hydrogel Properties Using a FuelDriven Reaction Cycle. J. Am. Chem. Soc. 142, 4083–4087 (2020).
5. LeiraIglesias, J., Tassoni, A., Adachi, T., Stich, M. & Hermans, T. M. Oscillations, travelling fronts and patterns in a supramolecular system. Nat. Nanotechnol. 13, 1021 (2018).
6. Unpublished. (2020).  
