Semesterübersicht – letztes Semester

Semesterübersicht Sommersemester 2019

Sommersemester 2019 - Wintersemester 2019/2020 - Sommersemester 2020

Mittwoch, 10.04 2019

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

Sonderseminar: 14 Uhr c.t., HIM Konferenzraum I

Dr. Andreas Bick, COMSOL
https://indico.him.uni-mainz.de/event/31/

Sonderseminar

Donnerstag, 11.04 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Maike Jung, Institut für Physik
Modeling membrane dynamics on the level of organelles and tether induced organelle movement
Montag, 15.04 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Friedemann Neuhaus, ETAP
An introduction into light-by-light scattering and the FASER experiment

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

A. Brinkmann, ZDV, Universität Mainz
Herr Professor Brinkmann vom Zentrum für Datenverarbeitung wird in dieser Infoveranstaltung mit einigen Kollegen die Telefonmodelle vorstellen. Die Veranstaltung wird ca. eine Stunde dauern. Es werden für die Sekretariate etc. im Nachgang auch noch zusätzliche Schulungstermine angeboten.
Dienstag, 16.04 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP seminar room

Zoltan Trocsanyi, Eötvös Lorand University
We consider an anomaly free extension of the standard model gauge group G by an abelian group to GxU(1)Z. The condition of anomaly cancellation is known to fix the Z-charges of the particles, but two. We fix one remaining charge by allowing for all possible Yukawa interactions of the known left handed neutrinos and new right-handed ones that obtain their masses through interaction with a new scalar field with spontaneously broken vacuum. We discuss some of the possible consequences of the model. Assuming that the new interaction is responsible for the observed differences between the standard model prediction for the anomalous magnetic moment of the muon or anti-muon and their measured values, we predict the size of the vacuum expectation value of the new scalar field.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Diederik Wiersma, LENS, University of Florence, Italy
Nature provides a great source of inspiration for many fields in science. When looking at locomotion in the living world, for instance, amazing solutions can be found especially for tiny, sub-millimeter size creatures. On these length scales the laws of physics behave so differently from what we are used to in our meter scale world. In this contribution we will discuss how liquid crystalline elastomers can be used to create micro meter scale artificial creatures, taking inspiration from nature. We will show that it is possible to create microscopic robots with an overall size of hundreds of micrometers out of elastomers, that can walk on dry surfaces and swim in fluid environments and perform tasks like grabbing microscopic particles. The liquid crystalline elastomer constitutes the essential material in the realization of these microscopic robots, since it allows to use light as source of energy and control mechanism. We will give an overview of the recent progress that was made in this exciting adventure.
Mittwoch, 17.04 2019

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7

Chris Allton, Swansea University
Although the strong interaction of particle physics normally confines quarks inside hadrons (with a force equivalent to 15 tonnes of weight!), at very high temperatures the interaction changes nature and quarks become essentially free. These conditions existed for the first few microseconds after the Big Bang and can be recreated in heavy-ion collision experiments. Studying these conditions is problematic for both experimentalists and theorists. This talk discusses the lattice approach to simulating quarks and hadrons at these temperatures using Bayesian and other approaches.
Dienstag, 23.04 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP seminar room

Brian Henning, University of Geneve
Common to every theoryfundamental, phenomenological, or even toyis a notion of degrees of freedom living on some space(time). While at first glance such a statement may sound so broad as to render it meaningless, it actually imposes quite a strong structure. The basic point is that the degrees of freedom allow for certain types of measurements (scattering, correlation functions, etc.), and that these measurements can only take values consistent with the relevant spacetime symmetry. Turning this around, we can use spacetime symmetry to parameterize the kinematics of experiments, thereby allowing a clearer way to study the dynamics. In this talk I will show that this is precisely what effective field theory (EFT) does. Viewing EFT through the lens of spacetime symmetry unveils previously unnoticed structures. For example, in an N particle phase space of massless particles we will find a certain U(N) actiongeneralizing the U(1)N little group scaling of the particleswhose harmonic decomposition also gives a harmonic decomposition of the spacetime symmetry group (in this case, the conformal group). This provides a basis not only for an EFT, but also a basis for the Hilbert space of free theories. As I will explain, the latter is an essential ingredient in the recently revived technique of Hamiltonian truncation to numerically study quantum field theories.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Markus Valtiner, Vienna University of Technology, Institute for Applied Physics
Multiple beam interferometry (MBI) evolved as a powerful tool for the simultaneous evaluating of thin film thicknesses and refractive indices in Surface Forces Apparatus (SFA) measurements. However, analysis has relied on simplifications for providing fast or simplified analysis of recorded interference spectra. I will describe the implementation of new optics and a generalized fitting approach to 4x4 transfer matrix method simulations for the SFA and will describe a numerical approach for constructing transfer matrices for birefringent materials. This enables self-consistent fitting of thicknesses, birefringence and relative rotation of anisotropic layers, evaluation of reflection and transmission mode spectra, simultaneous fitting of thicknesses and refractive indices of ultrathin (molecular) layers confined between two transparent surfaces. I will showcase a variety of different topics including measuring refractive indices of confined fluids and organic thin films (e.g. lipid bilayers, liquid crystals and ionic liquids), the thickness of ultrathin films, the thickness of metal layers and the relative rotations of birefringent thin films during normal and shear load application.
Mittwoch, 24.04 2019

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

SFB/TR49 - Prof. Dr. Elmers

Sonderseminar: 11:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 03-431

Dr. Rair Macedo, School of Physics and Astronomy, University of Glasgow
Ordered magnetic 'meta'-materials such as ferromagnets and/or antiferromagnets can have remarkable changes in their electromagnetic properties at special frequencies, knows as resonances. For example, a small change in frequency, or a small change in an applied magnetic field, can change the material from blocking electromagnetic waves to transmitting said waves. Here, I will discuss both new bulk and surface waves may emerge leading to new optical effects. Negative refraction being an example. These system also have new surface waves and an external field can make these waves highly non-reciprocal i.e., the forward and reverse waves are very different from each other. These results could be important for signal processing and devices that work across a broad frequency range, as I will also discuss.

Sonderseminar

Donnerstag, 25.04 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Nawaz Qaisrani, ICTP/SISSA, Trieste, Italy
A computational study to investigate the structural and optical properties of self assembled protein aggregates

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

Institut für Physik

14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7

Prof. Dr. Charles Adams, Joint Quantum Centre (JQC), Durham University, Durham-Newcastle, UK
When there is more than one emitter (or scatterer), light couples predominantly to collective modes, however, often the interesting consequences of these collective-mode interactions are masked by other effects such as atomic motion. In this talk, I will review some topics where the collective-mode interactions dominate such as light-matter interactions in cold dense ensembles and in Rydberg quantum optics. Also I will discuss the potential for the applications of engineered collective light-matter interactions to high-fidelity quantum technologies.
Montag, 29.04 2019

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

Murray Moinester, Tel Aviv
The electric απ and magnetic βπ charged pion polarizabilities characterize the induced dipole moments of the pion during γπ Compton scattering. Pion polarizabilities affect the shape of the γπ Compton scattering angular distribution. By crossing symmetry, the γπ→γπ amplitudes are related to the γγ→ππ amplitudes. Dispersion relations (DR) describe how charged pion polarizabilities contribute to both γγ → π+π- and γγ → π0π0 reactions. A stringent test of chiral perturbation theory (ChPT) is possible by comparing the experimental polarizabilities with ChPT predictions. The combination (απ-βπ) has been measured by: (1) radiative pion Primakoff scattering πZ → πZγ at CERN COMPASS, (2) two-photon pion pair production γγ→ππ at SLAC PEP Mark-II, (3) radiative pion photoproduction γp→ γπn at Mainz MAMI. COMPASS and Mark-II (but not Mainz) polarizabilities are in good agreement with ChPT predictions; and by DRs, with DESY Crystal Ball γγ → π0π0 data. A pion polarizability status report is presented, following the review by S. Scherer and M. Moinester for IJMPA.
Dienstag, 30.04 2019

Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE

14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9)

Dr. Sayani Majumdar, Aalto University
Energy efficient ferroelectric tunnel junction memristors for neuromorphic computing

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP seminar room

Daniel G. Figueroa, EPFL, Switzerland
The inflationary sector might very well have no direct couplings to other species, apart from inevitable gravitational interactions. In the context of General Relativity, a thermal universe can still emerge after inflation if i) a radiation sector is excited towards the end of inflation, and ii) the equation of state after inflation becomes sufficiently stiff w >> 1/3. In such circumstances, the inflationary background of gravitational waves (GWs) is significantly enhanced, making this signal (potentially) observable by GW detectors. I will discuss first how LISA & LIGO could measure this signal, probing in this way the expansion rate of the early Universe. Secondly, I will show that the very same enhancement of the GW signal leads however to an inconsistency of the scenario, violating standard bounds on stochastic backgrounds of GWs. Finally, I will show that the very existence of the Standard Model Higgs can actually save the day, by simply demanding the Higgs to be non-minimally coupled to gravity.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Dr. Eva Benckiser, Max Planck Institute for Solid State Research, Stuttgart
Transition-metal oxides with strong electron-electron correlations show a variety of interesting properties including metal-insulator transitions, different magnetic orders, and superconductivity. These phases are of technological interest, but often difficult to access because they only occur at very low temperatures, high external fields, or high pressures. Heterostructures offer promising new research approaches. Targeted interfacial reconstructions in epitaxial multilayers can stabilize novel phases that are not present in the bulk phase diagrams of the individual components. This is particularly relevant for multilayers with nanometre thin layers in which the properties are essentially governed by the interfacial reconstructions. Our research focuses on the investigation of such electronic reconstructions in the two-dimensional limit by means of x-ray spectroscopy. As a model system we have investigated perovskite-type nickelate heterostructures with composition RNiO3 (R = rare-earth ion). In my talk, I will present results of our studies on multilayers and will address layer-resolved orbital occupations, the unusual antiferromagnetic order and its interplay with the bond-order instability, and the feasibility of digital charge carrier doping.
Donnerstag, 02.05 2019

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

SFB/TR49 - Prof. Dr. Elmers

14:00 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 03-122

Jan Minar, University of West Bohemia, Pilsen, CZ
Angle-resolved photoemission spectroscopy (ARPES) is a leading experimental probe for studying the electronic structure and complex phenomena in quantum materials. Modern experimental arrangements consisting of new photon sources, analyzers and detectors supply not only spin resolution but also extremely high angle and energy resolution. Furthermore, the use of photon energies from few eV up to several keV makes this experimental technique a rather unique tool to investigate the electronic properties of solids and surfaces. On the theoretical side, it is quite common to interpret measured ARPES data by simple comparison with calculated band structure. However, various important effects, like matrix elements, the photon momentum or phonon excitations, are in this way neglected. Here, we present a generalization of the state of the art description of the photoemisison process, the so called one-step model that describes excitation, transport to the surface and escape into the vacuum in a coherent way. Nowadays, the one-step model allows for photocurrent calculations for photon energies ranging from a few eV to more than 10 keV, for finite temperatures and for arbitrarily ordered and disordered systems, and considering in addition strong correlation effects within the dynamical mean-field theory. Application of this formalism in order to understand ARPES response of new materials like low-dimensional magnetic structures, Rashba systems, topological insulator materials or high TC materials will be shown. In this presentation I review some of the recent ARPES results and discuss the future perspective in this rapidly developing field.

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

Sonderseminar: 14 Uhr c.t., HIM Konferenzraum I

B.P. Otte, HIM
https://indico.him.uni-mainz.de/event/35/

Sonderseminar

Freitag, 03.05 2019

Theorie-Palaver

Institut für Physik

Sonderseminar: 13:30 Uhr s.t., Social Room

Fang Ye, Korean Advanced Institute of Science and Technology
Cosmological relaxation of the electroweak scale proposed by Graham, Kaplan and Rajendran (GKR) arises as a solution to the naturalness problem. However, certain downsides exist in the original GKR scenario which relies on the Hubble expansion to dissipate the relaxion energy, such as the extremely small parameters and large e-foldings. In order to avoid these issues, in this work, we investigate the plausibility of using fermion production as a dominant friction source to drain the relaxion energy, maintaining the slow-roll of the relaxion. Benchmark points will be given for successful relaxation, and some remaining issue and the phenomenology will also be discussed.

Sonderseminar

Montag, 06.05 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Rainer Wanke, ETAP
Search for Hidden Particles: The SHiP Experiment at CERN

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

Chloe Hebborn, Bruxelles
What nuclear-structure information can be inferred from inclusive measurements of breakup of halo nuclei?

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

Institut für Physik

16:00 Uhr s.t., Medienraum des Instituts für Physik (03-431), Staudingerweg 7

Dr. Rene Gerritsma, Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, The Netherlands
In recent years, a novel field of physics and chemistry has developed in which trapped ions and ultracold atomic gases are made to interact with each other. These systems find applications in studying quantum chemistry and collisions [1], and a number of quantum applications are envisioned such as ultracold buffergas cooling of the trapped ion quantum computer and quantum simulation of fermion-phonon coupling [2]. Up until now, however, the ultracold temperatures required for these applications have not been reached, because the electric traps used to hold the ions cause heating during atom-ion collisions [3]. In our experiment, we overlap a cloud of ultracold 6Li atoms in a dipole trap with a 171Yb+ ion in a Paul trap. The large mass ratio of this combination allows us to suppress trap-induced heating. For the very first time, we buffer gas-cooled a single Yb+ ion to temperatures close to the quantum (or s-wave) limit for 6Li-Yb+ collisions. We find significant deviations from classical predictions for the temperature dependence of the spin exchange rates in these collisions. Our results open up the possibility to study trapped atom-ion mixtures in the quantum regime for the first time. Finally, I will present a novel way to control interactions between atoms and ions, that employs Rydberg-coupling of the atoms to tune their polarizability [4,5]. [1] M Tomza et al., arXiv:1708.07832 (2017). [2] U. Bissbort et al., Phys. Rev. Lett. 111, 080501 (2013). [3] M. Cetina et al., Phys. Rev. Lett. 109, 253201 (2012). [4] T. Secker et al., Phys. Rev. Lett. 118, 263201 (2017). [5] N. Ewald et al., arXiv:1809.03987 (2018).

Sondertermin und -raum

Dienstag, 07.05 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., THEP Sozialraum

Claudius Krause, Fermilab
With no direct observation of physics beyond the Standard Model (SM) at the LHC, bottom-up Effective Field Theories (EFTs), especially in the newly-established Higgs sector, have become popular in the past years. Depending on the assumptions on the Higgs-like scalar, two different EFTs can be constructed: The Standard Model EFT (SMEFT) that assumes the Higgs is part of an SU(2) doublet; and the Electroweak Chiral Lagrangian (EWChL) that treats the Higgs scalar as independent singlet. In the first part of my talk, I will discuss the assumptions underlying these two EFTs and the different power counting schemes that arise within them. In the second part, I will derive a master formula for the complete one-loop renormalization of a generic Lagrangian employing background-field method and super-heat-kernel expansion. Then, I will apply the formula to the two Higgs EFTs and discuss the results.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Dr. Dr. Justin Shaw, National Institute of Standards and Technology, Boulder/CO, USA
Modern spin-based technologies rely on multiple, simultaneous phenomena that originate from the spin-orbit interaction in magnetic systems. These include damping, magnetic anisotropy, orbital moments, and spin-orbit torques that are manifested in the spin-Hall and Rashba-Edelstein effects. While cavity based ferromagnetic resonance (FMR) spectroscopy has been used to characterize magnetic materials for many decades, recent advances in broadband and phase-sensitive FMR techniques have allowed further refinement, improved accuracy, and new measurement capability. In fact, broadband FMR techniques can now precisely measure spin-orbit torques at the thin-film level without the requirement of device fabrication. Broadband FMR measurements have also improved our fundamental understanding of magnetic damping. Numerous extrinsic relaxation mechanisms can obscure the measurement of the intrinsic damping of a material. This created a challenge to our understanding of damping because experimental data were not always directly comparable to theory. As a result of the improved ability to quantify all of these relaxation mechanisms, many theoretical models have been refined. In fact, this has recently led to both the prediction and discovery of new materials with ultra-low magnetic damping that will be essential for future technologies based on spintronics, magnonics, spin-logic and high-frequency devices. I will begin this lecture with a basic introduction to spin-orbit phenomena, followed by an overview of modern broadband FMR techniques and analysis methods. I will then discuss some recent successes in applying broadband FMR to improve our ability to control damping in metals and half-metals, quantify spin-orbit torques and spin-diffusion lengths in multilayers, and determine the interrelationships among damping, orbital moments, and magnetic anisotropy. The impact of these result on specific technologies will also be discussed.

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

SFB/TR49 - Prof. Dr. Elmers

Sonderseminar: 14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 03-122

Alberta Bonanni, Johannes Kepler University Linz, Austria
Semiconductor nitride compounds own their relevance, not only to state-of-the-art applications in opto- and high-power-electronics, but also to a number of features particularly attractive for spintronics and spin-orbitronics, enabling, e.g ., spin-charge interconversion via spin-orbit coupling associated with inversion asymmetry and leading to a sizable Rashba field and piezoelectric properties. Through the addition of magnetic dopants fostering the formation of magnetic complexes or driving the system to the state of a condensed magnetic semiconductor, these materials open wide perspectives in both fundamental and applicationoriented research. An overview is provided here on how, by controlling the fabrication parameters and establishing a comprehensive protocol of characterization involving also synchrotronradiation- based methods, we have unraveled and can now control a number of relevant features of these systems. Particularly significant in this context is the generation of pure spin current at room temperature in nitride-based bilayers, pointing at these systems as efficient spin current generators. Besides controlling the self-aggregation and performance of embedded functional magnetic nanocrystals and of optically active complexes, we have proved that the magnetization of dilute III-nitrides doped with transition metals may be controlled electrically. In this way, the piezoelectricity of wurtzite semiconductors and electrical magnetization switching have been bridged. Prospects for proximity-induced topological superconductivity in heterostructures combining graded and Rashba III-nitrides with layered s -wave superconductors are also discussed.

Sonderseminar

Mittwoch, 08.05 2019

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7

Johannes Albrecht, TU Dortmund
Precision measurements of decays of heavy mesons offer a unique lab to test the Standard Model of particle physics. Heavy, virtual particles in loop processes lead to quantum corrections that are measurable in the precision tests of flavour physics. Using this strategy, hints for postulated new particles can be found. The energy range tested here extends the range reachable in direct searches by about one order of magnitude. Historically, many discoveries in particle physics have first been seen in precision measurements. The talk will give a status of the current measurements in flavour physics with a focus on the recent measurements of the LHCb collaboration. Recently observed tensions between LHCb data and the Standard Model prediction will be discussed and perspectives to clarify these in the near future are given.

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

Sonderseminar: 14 Uhr c.t., HIM Konferenzraum I

David Rodriguez Pieiro, HIM
Tools for Physicists: 3D Printing and Designing Basics

Sonderseminar

Donnerstag, 09.05 2019

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

Institut für Physik

14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7

Prof. Dr. Selim Jochim, Physikalisches Institut, Universität Heidelberg
While all matter is at a microscopic level governed by quantum physics, there are also materials that show quantum effects at a macroscopic scale. Such "quantum matter" exhibits for example superfluidity or superconductivity. Materials that exhibit such phenomena in a very robust way or at very high temperatures, are typically characterized by strong interactions and correlations. Therefore experimentally verifying the role of correlations and engtanglement is a promising route to gain a deeper understanding of such systems. Using spin resolved imaging of individual atoms in free space we measure both the position and momentum distributions of a system of two particles deterministically prepared in a double well. These measurements allow us to determine correlations and entanglement of the motional degree of freedom. We envisage to apply these newly acquired tools to our experiments with strongly correlated Fermi gases where we will use up to 100 particles, determining high-order correlation functions.

Vortrag im Rahmen des SFB/TR 49-Kolloquiums

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

SFB/TR49 - Prof. Dr. Elmers

14:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 03-431

Tomasz Dietl, International Centre for Interfacing Magnetism and Superconductivity with Topological Matter - MagTop, Institute of Physics, Polish Academy of Sciences, Warsaw
As an introduction, I will show how relativistic effects in quantum materials science lead to inverted band structures and topological phases in a broad classes of semiconductors. As a specific example of the fascinating new physics, I will discuss point-contact spectroscopy of several topological materials, which reveals a transition to a low temperature phase that is characterized by zero-energy modes superimposed on an energy gap showing a Bardeen-Cooper-Schrieffer-type of criticality. An experimental(1) and theoretical(2) search for the origin of this striking behavior in diamagnetic, paramagnetic, and ferromagnetic topological crystalline insulators will be presented. 1. G.P. Mazur, K. Dybko, A. Szczerbakow, A. Kazakov, M. Zgirski, E. Łusakowska, S. Kret, J. Korczak, T. Story, M. Sawicki, T. Dietl "Experimental search for the origin of zero-energy modes in topological materials", arXiv:1709.04000v2 (2018). 2. W. Brzezicki, M.M. Wysokiński, and T. Hyart, "Topological properties of multilayers and surface steps in the SnTe material class", arXiv:1812.02168 (2018).
Montag, 13.05 2019

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

Institut für Physik

11 Uhr c.t., Medienraum (03-431) des Instituts für Physik, Staudingerweg 7

Prof. Dr. Sebastian Wüster, Indian Institute of Science, Education and Research (IISER) Bhopal, India
Rydberg Atoms in highly excited electronic states with n=30-100 are recent additions to the versatile toolkit of ultracold atomic physics. At rest, treated as a "frozen gas", they hold promise for applications well beyond atomic physics and serve as experimentally accessible interacting many-body systems for quantum information and in condensed matter physics. While for those applications the residual atomic motion is usually an unavoidable perturbation and source of noise, we will make use of this motion for preserving coherent electron dynamics, very much like in molecules, but for transport instead of stationary states [1]. In Rydberg atoms, accelerated via dipole-dipole interactions, we find an intricate link between atomic motion and the transport of electronic excitation energy. This link allows one to realize adiabatic exciton transport schemes and system potential energy landscapes that mimick those of relevance for quantum chemistry [2]. The analogy between the chemical energy surfaces and those among Rydberg atoms will enable more detailed studies of quantum many-body dynamics on these surfaces. On shorter time scales where atomic motion is no longer crucial, a system of a few interacting Rydberg atoms shows parallels to energy transport in photosynthetic light harvesting complexes. Consequently, it provides a transparent analog for the quantum simulation of the latter [3]. In particular, by embedding the assembly of Rydberg atoms into a background atomic gas, crucial but complex features in light harvesting systems, such as disorder and decoherence can be introduced in a controlled manner. Finally the two features can be combined, to investigate the effect of controllable decoherence on Rydberg motion [4], or the effect of impurity motion onto a condensed environment [5]. [1] S. Wüster and J.M. Rost JPB 51, 032001 (2018). [2] S. Wüster, A. Eisfeld and J. M. Rost , PRL 106, 153002 (2011). [3] D. Schönleber et al. PRL 114 123005 (2015). [4] S. Wüster, PRL 119 013001 (2017). [5] S. Tiwari and S. Wüster, PRA 99 043616 (2019).

Sondertermin und -raum

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Matthias Schott, ETAP
Probing Quantum Chromo Dynamics at the LHC

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

Edoardo Mornacchi, Mainz
Nucleon polarizabilities
Dienstag, 14.05 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., THEP Sozialraum

Georgios Papathanasiou, DESY
Scattering amplitudes form a bridge connecting theoretical particle physics with the real world of collider experiments, yet their computation by means of Feynman diagrams quickly becomes prohibitive. Focusing on the simplest case of N=4 super Yang–Mills theory, in this talk I present recent progress in bypassing these limitations and directly constructing amplitudes, by exploiting their expected analytic structure. First, I describe the discovery of new, possibly universal analytic properties known as the extended Steinmann relations, or equivalently cluster adjacency, as well as the coaction principle. Then, I demonstrate their power in computing the six-particle amplitude up to seven loops, as well as the seven-particle amplitude up to four loops, and discuss further applications.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Univ.-Prof. Dr. Monika Ritsch-Marte, Medical University of Innsbruck, Dept. for Medical Physics
Optical wavefront shaping by means of spatial light modulators (SLMs) based on liquid crystal (LC) panels, has become a powerful tool in Biophotonics. “Holographic optical tweezers” are well-known and widespread, but an SLM can also be integrated into optical imaging systems. This makes the microscope programmable and adaptable with respect to the needs of a specific sample. A particular strength of the Synthetic Holography approach with programmable phase masks is the possibility to multiplex, which means that one can ‘pack’ several tasks into one computer-generated hologram. One can, for instance, create images which are composed of sub-images belonging to different microscopy modalities, to different depths inside the volumetric sample, or to different parameter settings. Moreover, if the phase modulation range is not restricted to 2π, the wealth of possibilities significantly increases: Several computer-generated holograms can be read out at different wavelengths from one and the same input pattern sent to the LC panel. In this way holographically modified imaging in the visible can be accommodated in the same phase mask that is used for holographically controlled trapping in the near-infrared.
Donnerstag, 16.05 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Raphael Kromin, Institut fr Physik
Vergrberte Simulationen von Schleifenbildungen in Chromosomen

Bachelorkolloquium

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

Institut für Physik

14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7

Prof. Dr. Thomas Pohl, Department of Physics and Astronomy, Aarhus University, Denmark
The combination of electromagnetically induced transparency (EIT) and strongly interacting atomic states in optical media has opened up new routes towards achieving few-photon optical nonlinearities. While EIT provides strong light-matter coupling under low-loss conditions, the interactions between such Rydberg states can be used to generate nonlinearities that are large enough to operate on the level of single photons. Such synthetic interactions promise few-photon applications and exotic many-body physics, emerging from the interplay of coherent driving, quantum light propagation, strong atomic interactions and dissipative photon scattering. This talk will present basic concepts underlying this approach and discuss simple examples that afford an intuitive understanding. Placing particular emphasis on many-body decoherence processes we will identify challenges but also new opportunities for generating and manipulating nonclassical states of light. Finally, we will consider new ideas beyond traditional Rydberg-EIT approaches as well as new platforms beyond ultracold atomic ensembles.
Montag, 20.05 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Jens Söngen, ETAP
Characterization of Low Gain Avalanche Detectors for the ATLAS High Granularity Timing Detector

Master Kolloquium

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

Andrea Mazzolari, Ferrara
Crystals as elements for particle beam steering and emission of radiation
Dienstag, 21.05 2019

Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE

14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9)

Boerge Goebel, Max Planck Institute of Microstructure Physics, Halle (Saale), Germany
Magnetic skyrmions are topologically non-trivial spin textures which are stable at small sizes and which exhibit emergent electrodynamic effects: they show a topological contribution to the Hall effect, and can be driven by currents. Skyrmions are considered as the bits in future data storage devices, where information can be stored very densely and accessed with an enormous energetic efficiency. One issue, which is hindering the realization of this application, is the so-called skyrmion Hall effect: A skyrmion does not move parallel to an applied spin-polarized current. Instead, the skyrmion is pushed towards the edge of the sample where it annihilates. In this talk, I will give an overview about the different observed or proposed magnetic quasiparticles. The stabilization, as well as the emergent electrodynamic effects will be discussed for the antiferromagnetic skyrmion [1], the skyrmionium [2], the bimeron [3], and the biskyrmion [4]. These magnetic objects are either remarkable from a fundamental point of view, or are advantageous application-wise. As an example, the antiferromagnetic skyrmion is understood as the combination of two skyrmions with mutually reversed magnetic moments. The compensation of topological charge leads to the suppression of the skyrmion Hall effect for these objects. Consequently, the resulting velocity is drastically increased when they are driven by currents. Included publications: [1] B. Gbel, A. Mook, J. Henk, I. Mertig. Phys. Rev. B. 96, 060406(R) (2017). [2] B. Gbel, A. Schffer, J. Berakdar, I. Mertig, S. Parkin. arXiv: 1902.06295 [3] B. Gbel, A. Mook, J. Henk, I. Mertig, O. Tretiakov. Phys. Rev. B. 99, 060407(R) (2019) [4] B. Gbel, J. Henk, I. Mertig. arXiv: 1902.10491

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Dr. Chiara Caprini, Laboratoire Astroparticule et Cosmologie, Paris
LIA (Laser Interferometer Space Antenna) is the space mission of the European Space Agency to observe gravitational waves. After an introduction to gravitational waves and to the recent direct detections made by Earth-based interferometers, we will describe the scientific potential of the LISA mission, in particular for what concerns cosmology and the physics of the very early universe.

Theorie-Palaver

Institut für Physik

Sonderseminar: 12:00 Uhr s.t., Social Room (05-427), Staudingerweg 7

Aleksandrs Aleksejevs, Memorial University of Newfoundland
As the new generation of precision experiments aims to search for physics beyond the Standard Model, it becomes increasingly important to evaluate the relevant higher-order corrections. In collaboration with MOLLER and P2, we work to address the full set of two-loop electroweak radiative corrections to electron-electron and electron-proton scattering cross sections and asymmetries. In this presentation, we will describe the recent developments in dispersive sub-loop insertion approach in two-loop calculations, which would allow partial automatization.

Sonderseminar

Mittwoch, 22.05 2019

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7

Francesca Bellini, CERN
The observation of anti-deuteron and anti-helium in cosmic rays has been suggested as a smoking gun in indirect searches for Dark Matter in the Galaxy, under the hypothesis that the background from secondary astrophysical production is negligible. Constraining predictions for the secondary cosmic-ray flux of anti-helium and anti-deuteron with data is therefore crucial to searches with space-based or balloon-based experiments such as AMS-02 and GAPS. To this end, the LHC can be used as “anti-matter factory” to measure the production of d, 3He and 4He in the laboratory. In proton-proton, proton-nucleus and nucleus-nucleus collisions at the TeV collision-energy scale, light nuclei and their anti-matter counterparts are produced in equal amounts for a given species. Not only accelerator data on light (anti-)nuclei provide unique information to characterise the system produced in high-energy collisions, but they can also be used to test and constrain coalescence production models widely employed in astrophysics. In this Seminar, I will present the most recent results on anti-nuclei production at the LHC and discuss their implications for cosmic ray physics and indirect dark matter searches. Finally, I will present perspectives for future precision measurements with the increased integrated luminosity foreseen for the upcoming High-Luminosity phase of the LHC in years 2021-2029. 1
Donnerstag, 23.05 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Jiarul Midya, Institut für Physik
Disentangling the mechanical properties of polymer grafted nanoparticles
Freitag, 24.05 2019

THEP Internal Seminar / Exp. Theory Crosstalk

Institut für Physik

13:00 Uhr s.t., Minkowski Raum, Staudinger Weg 7, 05-119

Katsuki Hiraide, ICRR and U. of Tokyo
Although there are substantial astronomical observations which support the existence of dark matter in the Universe, its identity is still unknown. The most plausible candidate of dark matter is thought to be weakly interacting massive particles (WIMPs). Therefore, direct detection of dark matter would be of importance in both astrophysics and particle physics. XMASS is a large-volume single-phase liquid xenon scintillation detector located in the Kamioka underground laboratory in Japan and has stably taken data for more than five years. With these long-term data, we have conducted a search for annual modulation caused by dark matter as well as searches for various types of dark matter particles and interactions. XMASS has also challenged various research topics in particle and astroparticle physics. In this talk, recent results from XMASS will be presented.
Montag, 27.05 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Michael Nieslony, ETAP
The Accelerator Neutrino Neutron Interaction Experiment (ANNIE)

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

Victoria Durant, Mainz
From chiral EFT interactions to nucleus-nucleus optical potentials
Dienstag, 28.05 2019

Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE

14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9)

Calum Ross, Heriot-Watt University, Edinburgh, UK
In a recent mathematical study of a family of models for magnetic skyrmions in the plane a critical choice of couplings was found where the models admit infinitely many explicit solutions [1]. These solutions satisfy first order Bogomol'nyi solutions and their energy is given in terms of their degree. The explicit solutions are given in terms of an arbitrary holomorphic function. The simplest solutions are the basic Bloch and Nel skyrmions, but we also exhibit distorted and rotated single skyrmions as well as line defects, and configurations consisting of skyrmions and anti-skyrmions. Away from critical coupling I will give some examples of explicit axially symmetric solutions and an expression for their energy. [1] Bruno Barton-Singer, Calum Ross, Bernd J Schroers, https://arxiv.org/abs/1812.07268 All interested are cordially welcome!

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Thomas Birner, LMU München, Meteorologisches Institut
Earth’s tropical belt can be defined by the band of rainy equatorial regions bordered by the arid subtropics to the north and the south. Because of the strong latitudinal gradients in temperature and precipitation at the edges of the tropical belt, any shift in its edges could drive major local changes in surface climate. Theoretical arguments and experiments with climate models suggest that increasing greenhouse gas concentrations should lead to a widening of the tropical belt alongside a poleward shift of the mid-latitude jet stream. However, observationally-based estimates of changes in tropical width have resulted in disparate rates of expansion, some of which much higher than those expected based on experiments with climate models. In this talk, I will first discuss the morphology of the tropical belt in terms of its thermodynamic and circulation characteristics, and the resulting metrics that can be used to define its edges. By studying the interrelationships across different metrics and accounting for methodological differences, the tropics are found to have widened by about 2 degrees of latitude over the last four decades. However, it is too early to detect robust anthropogenically induced widening imprints due to large unforced variability. I will then discuss the coupling between large-scale atmospheric disturbances originating along the mid-latitude jet and the tropical overturning circulation (the Hadley cell), which gives rise to year-to-year variability in tropical edge latitudes and is fundamental for the tropical width response to increased greenhouse gas concentrations.
Mittwoch, 29.05 2019

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7

Adriana Palffy, MPI Heidelberg
More than fifty years ago, it was the invention of the laser that revolutionized atomic physics and laid the foundations for quantum optics and coherent control. With only optical frequencies available, the interaction of coherent light with matter was for a long time mainly restricted to atomic transitions. Only recently have novel high-frequency light sources rendered possible the photo-excitation of low-lying nuclear states opening the new field of nuclear quantum optics and promising substantial progress in the field of metrology. These developments aim to exploit the fact that nuclei are very clean quantum systems, well isolated from the environment and benefiting from long coherence times. The lecture will follow these perspectives at the borderline between nuclear and atomic physics on the one hand side and metrology and quantum optics on the other hand side. First, the present status of the efforts to use the 229Th isomer at approx. 8 eV for a nuclear frequency standard will be discussed. Second, the lecture will follow the developments on the emerging field of x-ray quantum optics and focus on the mutual control of coherent x-ray radiation and nuclear transitions in this new regime of laser-matter interactions.

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

Sonderseminar: 10:30 Uhr s.t., Medienraum, 3rd floor, Staudingerweg 7

Prof. Subir K. Das, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, India
Diversity in Dynamics of Phase Transitions: Some recent examples

Sonderseminar

Montag, 03.06 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Jan Lommler, ETAP
Event Processing in Compton-Pair-Telecopes
Dienstag, 04.06 2019

Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE

13:30 Uhr s.t., MAINZ Seminarraum (Staudingerweg 9, 03-122)

Dr. Herbert Jaeger, Jacobs University, Bremen, Germany
Recurrent neural networks (RNNs) are general approximators for nonlinear dynamical systems and have recently become widely used in the "deep learning" field of machine learning, especially for speech and language processing tasks. For instance, Google's speech recognition and language translation services are based on RNNs. However, the deep learning set-ups for RNN training are computationally expensive, require very large volumes of training data, and need high-precision numerical processing. For such reasons, deep-learning variants of RNNs are problematic in fields where training data are scarce, where fast and cheap algorithms are desired, or where noisy or low-precision hardware is to be used. This is often the case in domains of nonlinear signal processing, control, brain-machine interfacing, biomedical signal processing, or unconventional (non-digital) computing hardware. Reservoir Computing (RC) is an alternative machine learning approach for RNNs which is in many ways complementary to deep learning. In RC, a large, random, possibly low-precision and noisy RNN is used as a nonlinear excitable medium - called the "reservoir" - which is driven by an input signal. The reservoir itself is not adapted or trained. Instead, only a "readout" mechanism is trained, which assembles the desired output signal from the large variety of random, excited signals within the reservoir. This readout training is cheap - typically just a linear regression. RC has become a popular approach in research that aims at useful computations on the basis on unconventional hardware (non-digital, noisy, low-precision). The talk gives an introduction to the basic principles and variants of RC. Illustrative examples will be selected according to wishes from the audience All interested are cordially welcome!

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Ulrich Heinz, Ohio State University, Columbus/Ohio, USA
The Little Bangs created in ultra-relativistic heavy-ion collisions share many characteristic features with the cosmological evolution after the Big Bang. They create a quark-gluon plasma - an extremely dense state of strongly interacting matter that flows like an almost perfect fluid. This allows to describe such heavy-ion collisions with dissipative relativistic fluid dynamics, supplemented by an early pre-hydrodynamic and a late kinetic freeze-out stage. Similar to the Big Bang, fluctuations in the initial state create structures in the final state which can be measured and used to reconstruct the initial state. I will demonstrate how quantum fluctuations in the initial state of the Little Bang propagate into the experimentally observed final momentum distributions, manifesting themselves as fluctuations in the final flow pattern. A harmonic analysis of the final flows, their transverse momentum dependence and their flow angles (the "Little Bang flow fluctuation spectrum") provides detailed experimental information from which theory allows to extract with precision the spectrum of gluon fluctuations in the initial state, together with the transport coefficients of the quark-gluon plasma fluid created in the collisions.
Donnerstag, 06.06 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Prof. Aniket Bhattacharya, Department of Physics, University of Central Florida, USA

DNA is one of the most important biomolecules in living organism, forms a helix from two intertwined strands with complementary base pairs. Biological functions of a DNA depend on its mechanical properties, which in turn depend on its sequence specificity. Under physiological condition a double stranded DNA (dsDNA) is described as a semi-flexible biopolymer with persistence length of 50 nm, while a single-stranded DNA (ssDNA) is quite flexible. Recently straightening a dsDNA inside a nanochannel is being explored as an alternate method to determine DNA sequences at a single molecule level without replication. First, I will present coarse grained (CG) models for fast computations of DNA conformations and dynamics. I will use scaling arguments validated by Brownian dynamics (BD) simulation results performed on the CG models to demonstrate how the equilibrium DNA conformations change inside a nanochannel, as one varies the persistence length (stiffness) and the channel width [1, 2]. I will then show the transients and the steady states of an initially straightened DNA inside a nanochannel squeezed by a Nano- dozer assay. I will compare the time dependent density profiles from the BD simulation with those obtained from a Nonlinear Partial Differential Equation (NPDE) approach recently introduced by Khorshid et al., and demonstrate how this combined approach can be effectively used to study nonequilibrium dynamics of very long dsDNA segments inside a nanochannel [3]. For stiff chains in nanopores, we further show that chain compression proceeds through a unique folding kinetics driven by repeated double fold nucleation events and growth of nested folds. We show that the folding kinetics can be understood by coupling a theory for deterministic contour spooling across the folds with a dynamically varying energy landscape for fold nucleation. These findings are critical for understanding compression of nanochannel confined DNA in the sub-persistence length (Odijk) regime [4].


1. Aiqun Huang and Aniket Bhattacharya, DNA confined in a two-dimensional strip geometry, Euro Phys. Lett. 106, 18004 (2014).
2. Aiqun Huang, H.-P Hsu, Aniket Bhattacharya, and Kurt Binder, Semiflexible macromolecules in quasi-one-dimensional confinement: Discrete versus continuous bond angles, J. Chem. Phys. 143, 243102 (2015).
3. Aiqun Huan, Walter Reisner, and Aniket Bhattacharya , Dynamics of DNA Squeezed inside a Nanochannel via a Sliding Gasket, Polymers 2016, 8 (10), 352;
4. Simon Bernier, Aiqun Huan, Walter Reisner, and Aniket Bhattacharya, Evolution of Nested Folding States in Compression of a Strongly Confined Semiflexible Chain Macromolecules 2018, 51 (11), 4012–4022

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

Institut für Physik

14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7

Prof. Dr. Sebastian Hofferberth, Department of Physics, Chemistry and Pharmacy, Odense University, Denmark
Mapping the strong interaction between Rydberg excitations in ultracold atomic ensembles onto single photons enables the realization of optical nonlinearities which can modify light on the level of individual photons. This approach forms the basis of a growing Rydberg quantum optics toolbox, which already contains photonic logic building-blocks such as single-photon sources, switches, transistors, and photonic two-qubit gates. For an optical medium smaller than a single Rydberg blockade volume, a large number of individual atoms behave as a single Rydberg "superatom" which can be efficiently coupled to few-photon probe pulses. The strongly enhanced collective coupling and the highly directed collective emission of this system realizes an analogue to waveguide-QED systems, which enables the study of coherent emitter-photon interaction in free-space [1]. In this talk, we present our recent investigation of intrinsic three-photon correlations mediated by a single superatom [2]. We also present our steps towards the formation of multiple superatoms coupled to a single probe-mode to realize a cascaded system of quantum emitters. [1] A. Paris-Mandoki, C. Braun, J. Kumlin, C. Tresp, I. Mirgorodskiy, F. Christaller, H. P. Büchler, and S. Hofferberth, Phys. Rev. X 7, 41010 (2017) [2] N. Stiesdal, J. Kumlin, K. Kleinbeck, P. Lunt, C. Braun, A. Paris-Mandoki, C. Tresp, H. P. Büchler, and S. Hofferberth, Phys. Rev. Lett. 121, 103601 (2018)

Vortrag im Rahmen des SFB/TR 49-Kolloquiums

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

SFB/TR49 - Prof. Dr. Elmers

14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, Raum 03-122

Laurenz Rettig, Fritz Haber Institute of the Max Planck Society, Berlin
Correlated materials are characterized by a variety of couplings between the elementary degrees of freedom, leading to novel ground states with broken symmetries and often intriguing properties. Yet the quantitative determination of those couplings, and their relevance for the formation of broken symmetry ground states and phase transitions remains a major challenge. In particular, in thermal equilibrium the various interactions are present simultaneously in a system, making it difficult to separate them due to their similar energy scale. Studies of those interactions in the time domain in a non-equilibrium system created after ultrafast optical excitation promise a way to separate such contributions by their intrinsically different dynamics. Such an approach, however, is often hindered by the unspecific nature of the employed probes and thus frequently limited to a qualitative discussion of time constants. These limitations can be overcome by using quantitative and complementary time-resolved spectroscopies, which directly address the dynamics of specific degrees of freedom on their individual time scales, in order to determine the couplings between those degrees of freedom and their relevance for a phase transition from their temporal evolution (Fig. 1). In particular, combining femtosecond time- and angle-resolved photoemission spectroscopy (trARPES) and time-resolved x-ray diffraction (trXRD) techniques allows us to follow the ultrafast dynamics of electronic, structural and magnetic degrees of freedom and their orderings individually, yielding direct access to the coupling of the electronic, phononic and spin systems. In my talk, I will discuss these concepts by means of several model systems for correlated materials such as charge- density wave materials or magnetically ordered systems.
Freitag, 07.06 2019

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

Sonderseminar: 11:00 Uhr s.t., MEDIEN-Raum, Staudingerweg 7, 3. Stock, Raum 03-431

Hendrik Meer, Georg-August-Universitt Gttingen
The properties of correlated materials can be manipulated on the femtosecond time scale, hence, allowing in principle for interesting technological applications. However, the microscopic processes responsible for such ultrafast changes are not yet fully understood. The magneto-optical Kerr effect (MOKE) discovered by John Kerr [1] measures the magnetization dependent rotation of light polarization upon reflection from a ferromagnetic sample surface. Thus, in combination with a pump-probe scheme, MOKE and transient reflection measurements give access to the ultrafast dynamics. This talk will give an introduction into ultrafast demagnetization dynamics and time-resolved MOKE (TR-MOKE), as well as highlight some of our recent accomplishments. [1] Kerr, J.: On rotation of the plane of polarization by reflection from the pole of a magnet. In: Phil. Mag. 3 (1877), S. 321

Sonderseminar

Dienstag, 11.06 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP seminar room

Vedran Brdar, MPI Heidelberg
In the first part of the talk I will discuss the low scale (10 - 100 TeV) left-right symmetric model with “naturally” small neutrino masses generated through the inverse seesaw mechanism. The inverse seesaw implies the existence of novel fermion singlets, S, with Majorana mass terms as well as the "left" and "right" Higgs doublets. These doublets provide the portal for S and break the left-right symmetry. The generic feature of the model is the appearance of heavy pseudo-Dirac fermions, formed by S and the right-handed neutrinos, which have the masses in the 1 GeV - 100 TeV range and can be searched at both current and future experiments such as LHC, SHiP, DUNE, and FCC-ee. In the second part of the talk I will introduce the "neutrino option", a recent proposal that the electroweak hierarchy problem is absent if the generation of the Higgs potential stems exclusively from quantum effects of heavy right-handed neutrinos which can also generate active neutrino masses via the type-I seesaw mechanism. In this framework, the tree-level scalar potential is assumed to vanish at high energies. Such a scenario therefore lends itself particularly well to be embedded in a classically scale-invariant theory. I will demonstrate that the minimal scale-invariant framework compatible with the "neutrino option" requires the Standard Model to be extended by two real scalar singlet fields in addition to right-handed neutrinos. In addition, the phase transition connected with scale symmetry breaking is of strong first order with a substantial amount of supercooling. This yields a sizable gravitational wave signal, so that the model can be fully tested by present and future gravitational wave observatories.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Dr. Sabine Hossenfelder, FIAS Frankfurt Institute for Advanced Studies
To develop fundamentally new laws of nature, theoretical physicists often rely on arguments from beauty. Simplicity and naturalness in particular have been strongly influential guides in the foundations of physics ever since the development of the standard model of particle physics. In this lecture I argue that arguments from beauty have led the field into a dead end and discuss what can be done about it.
Mittwoch, 12.06 2019

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7

Aurora Tumino, Kore University of Enna &INFN-LNS, CATANIA
The source of energy that sustains burning stars for millions to billions of years is provided by nuclear reactions that are responsible also for the element nucleosynthesis inside them. Over the past forty years nuclear physicists have been trying to measure the rates of the most relevant reactions, but there is still considerable uncertainty about their values. Although the stellar temperatures are high, on the order of hundred million degrees, they correspond to sub-Coulomb energies. As a consequence, the Coulomb barrier causes a strong suppression of the cross-section, which drops exponentially with decreasing energy. Thus, the corresponding reaction rates are extremely small, making it difficult for them to be measured directly in the laboratory. In addition, the electron screening effect due to the electrons surrounding the interacting ions prevents one to measure the bare nucleus cross-section. Typically, the standard way to get the ultra-low energy bare nucleus cross-section consists in a simple extrapolation of available higher energy data. This is done by means of the definition of the astrophysical S(E) factor which represents essentially the cross-section free of Coulomb suppression. However, the extrapolation may introduce additional uncertainties due for instance to the presence of unexpected resonances or to high energy tails of sub-threshold resonances. A valid alternative approach is represented by the Trojan Horse Method (THM) that provides at present the only way to measure the bare nucleus S(E) factor of a relevant charged particle twobody reaction A + x → c + C in the Gamow energy window, overcoming the main problems of direct measurements. This is done by selecting the quasi-free (QF) contribution of an appropriate three-body reaction A + a → c + C + s, where a is described in terms of clusters x⊕ s. The QF reaction is performed at energies well above the Coulomb barrier, such that cluster x is brought already in the nuclear field of A, leaving s as spectator to the A+x interaction. The THM has been successfully applied to several reactions connected with fundamental astrophysical problems as well as with industrial energy production. I will recall the basic ideas of the THM and show some recent results. I will emphasis in particular those related to the 12C+12C fusion channel in stars, whose reaction rate was found to be strongly enhanced at the relevant temperatures.
Donnerstag, 13.06 2019

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

SFB/TR49 - Prof. Dr. Elmers

14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 03-122

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

Institut für Physik

14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7

Prof. Dr. Guillermo F. Quinteiro, Departamento de Fsica, Universidad Nacional del Nordeste, Corrientes, Argentina
The early '90 witnessed a breakthrough in optics with the development of techniques to generate coherent beams of highly inhomogeneous light, known as optical vortices or twisted light, that exhibits unique features: a phase singularities, orbital angular momentum, topological features, etc. The interest in optical vortices quickly grew and extended beyond optics into diverse areas of physics and even other sciences. After a brief introduction, I will show that optical vortices are indeed strange light fields, challenging our intuition based on plane waves and Gaussian beams. But their odd features are more than a curiosity, they bring about new processes in their interaction with matter. In particular, I will discuss some predicted new effects on semiconductors and possible applications to nanotechnology.
Montag, 17.06 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Joakim Sandroos, ETAP
Unfolding the Atmospheric Neutrino Flux using IceCube/DeepCore
Dienstag, 18.06 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., Social Room (05-427), Staudingerweg 7

Peter Lowdon, cole Polytechnique
Local formulations of quantum field theory imply that gauge theory correlators can potentially contain generalised infrared poles. In this talk I will outline the theoretical significance of these components, and report on recent lattice fit results for the gluon propagator.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Guglielmo Tino, LENS, University of Florence, Italy
The ability to control the quantum degrees of freedom of atoms using laser light opened the way to precision measurements of fundamental physical quantities. I will describe experiments for precision tests of gravitational physics using new quantum devices based on ultracold atoms, namely, atom interferometers and optical clocks. I will report on the measurement of the gravitational constant G with a Rb Raman interferometer, on experiments based on Bloch oscillations of Sr atoms confined in an optical lattice for gravity measurements at small spatial scales, and on new tests of the Einstein equivalence principle. I will also discuss prospects to use atoms as new detectors for gravitational waves and for experiments in space.
Mittwoch, 19.06 2019

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7

Florian Reindl, Institut für Hochenergiephysik, WIEN
Today, the situation in direct dark matter detection is controversial: The DAMA/LIBRA experiment observes an annual modulation signal at high confidence. Furthermore, this signal is perfectly compatible in terms of period and phase with the expectation for a galactic halo of dark matter particles which interact in their NaI target crystals. However, in the so-called standard scenario on dark matter halo and dark matter interaction properties, the DAMA/LIBRA signal contradicts null-results of numerous other experiments. The new experiment COSINUS aims for a model-independent cross-check of the DAMA/LIBRA signal. Such a cross-check is absent up to now and necessarily requires the use of the same target material (NaI). While several experimental efforts are planned or already ongoing, COSINUS is the only experiment operating NaI as cryogenic detector which yields several distinctive advantages: Discrimination between electronic interactions and nuclear recoils off sodium and iodine on event-by-event basis, a lower nuclear recoil energy threshold and a better energy resolution. In this contribution we will review the prototype measurements performed so far, present the plans for the new underground facility foreseen to be installed at LNGS and give an outlook on the COSINUS timescale.
Montag, 24.06 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Maicon Hieronymus, ETAP
Reconstruction of Low Energy Neutrino Events with GPUs at IceCube

Master Kolloquium

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

Fabian Nillius, Mainz
Vector polarimetry at MAMI
Dienstag, 25.06 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP Seminar Room

Johann Usovitsch, University of Dublin
We will give an introduction to Kira a Feynman integral reduction program. Further on we will report about the recent progress made in the development of this program. The development is focused on algorithmic improvements that are essential to extend the range of feasible high precision calculations for present and future colliders. Finally we will introduce the future feature of Kira: reconstruction of rational functions from samplings over the finite field.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Udo Seifert, Universität Stuttgart
All processes in cell and molecular biology, like transport by molecular motors and replication machinery, are subject to thermal noise. Still, life relies on the fact that the result of such processes comes with a small enough uncertainty, i.e., large enough precision. The same holds for (wet) micro- and nano-robotics. While absolute precision is impossible in an environment of finite temperature, an obvious question is whether or not there is a fundamental trade-off between precision and the (free energy) cost of generating or running such processes. After recalling the principles of stochastic thermodynamics, I will introduce the recently discovered thermodynamic uncertainty relation that provides a universal lower bound on the precision any process in steady-state conditions can achieve for a given energy budget. A variant of this relation allows us to extract from experimental data a model-free upper bound on the efficiency of molecular motors. Likewise, for steady-state heat engines, this relation shows that Carnot efficiency can be reached at finite power, in principle, but only at the cost of diverging power fluctuations. I will close with recent insights into the minimal requirements for generating coherent oscillations in (biochemical) networks.
Donnerstag, 27.06 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

William Janke, Institut fr Physik
Kinetic Monte Carlo simulations of the epitaxial film growth of C60
Montag, 01.07 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Andreas Reiss, ETAP
Search for dark matter in events with missing transverse energy and at least one jet with the ATLAS experiment

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

SFB/TR49 - Prof. Dr. Elmers

Sonderseminar: 11:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 03-431

Nan-Lin Wang, International Center for Quantum Materials, Peking University, Beijing, China
Ultrafast optical spectroscopy is a powerful tool to investigate the non-equilibrium physics in complex electronic materials. In this talk, I will present our recent time-resolved terahertz spectroscopy study of two different systems: an underdoped YBa2Cu3O6.45 (YBCO) and a charge density wave (CDW) compound 1T-TaS2. I will discuss the aspects of resonant phonon pumping in YBCO and possible transient superconductivity, as derived from the photoexcited nonequilibrium c-axis response. In 1T-TaS2, we differentiate between the dynamical properties of the commensurate CDW state and the stable photoinduced hidden CDW order. Moreover, we also investigate the transient nonequilibrium processes triggered by weak pumping and illustrate that the fluctuating metallic domain walls may develop in the transient states.

Sonderseminar

Dienstag, 02.07 2019

Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE

14:00 Uhr s.t., Galilei Room, 01-128 (Staudinger Weg 9)

Ran Cheng, University of California, Riverside
Magnons, the quanta of spin‐wave excitations, can transport spin angular momenta over long distances without incurring Joule heating. They are promising alternatives to electrons in building next‐generation nanotechnology. To fully function as electrons, however, magnons should bear an intrinsic degree of freedom similar to the electron spin. In antiferromagnets, spin‐up and spin‐down magnons coexist and form a unique degree of freedom capable of encoding information, which can be controlled through the Dzyaloshinskii-Moriya interaction, temperature gradient, etc. Guided by the resemblance between antiferromagnetic magnons and electrons with spin being an active variable, we propose a series of physical phenomena where magnons can function as electrons in transporting and transferring spin angular momenta, including magnon-induced interlayer coupling, spin Nernst and spin Edelstein effects, and magnonic spin torques in an insulating spin valve with antiferromagnetic spacer. These phenomena introduced a vibrant playground for new fundamental physics and opened the exciting possibility of utilizing magnons as primary information carriers in electronic devices.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Immanuel Bloch, Max-Planck-Institut fr Quantenoptik
Recent experiments with quantum gas microscopes allow for an unprecedented view and control of quantum matter in new parameter regimes and with new probes. In our fermionic quantum gas microscope, we can detect both charge and spin degrees of freedom simultaneously, thereby gaining maximum information on the intricate interplay between the two in the paradigmatic Hubbard model. In my talk, I will show how we can reveal hidden magnetic order, directly image individual polarons or probe the fractionalisation of spin and charge in dynamical experiments. For the first time we therefore have access to non-local hidden correlation properties of quantum matter. Furthermore, I will show how quantum gas microscopy can open new avenues for the for field of quantum chemistry when probing and controlling the formation of huge Rydberg macrodimers in optical lattices.
Donnerstag, 04.07 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Dr. Jiajia Zhou, Beihang University Beijing, China
Onsager principle and its applications in soft matter systems

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

Institut für Physik

14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7

Dr. Lukas Sieberer, Institut für Quantenoptik und Quanteninformation, Universität Innsbruck, Österreich
Quantum simulation enables studying the non-equilibrium dynamics of complex quantum many-body systems in regimes which are inaccessible to numerical methods. With universal digital quantum simulators, time evolution generated by a large class of Hamiltonians can be simulated by approximating the unitary time-evolution operator by a sequence of quantum gates. However, this “Trotterization" introduces an intrinsic source of errors. Our work gives Trotter errors in digital quantum simulation (DQS) of collective spin systems an interpretation in terms of a paradigmatic model system of quantum chaos, the kicked top. In particular, we show that Trotter errors in DQS of collective spin systems remain bounded up to arbitrarily long times in the regime of small Trotter steps, which corresponds to regular motion of the kicked top. Instead, quantum chaos in the top, which sets in above a sharp threshold value of the Trotter step size, leads to the proliferation of Trotter errors. Our results, which can be tested in various experimental platforms ranging from single atomic spins to trapped-ion quantum simulators, show, that DQS with comparatively large Trotter steps can retain controlled Trotter errors. It is thus possible to reduce the number of quantum gate operations required to represent the desired time evolution faithfully, thereby mitigating the effects of imperfect individual gate operations.

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

SFB/TR49 - Prof. Dr. Elmers

14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 03-122

Wei Han, Peking University
Spin current generally means the electron-mediated current with spin polarization after the discovery of giant and tunneling magnetoresistances in 1980s. Recently, new types of spin current in quantum materials have been found, which are mediated by magnons, superconducting (SC) quasiparticles, spinons etc. These quantum materials have exhibited fascinating spin-dependent properties, which are attractive for future spintronics applications [1]. A new direction of using spin current as a probe for quantum materials has been identified. In this talk, I will discuss some primary experimental results to illustrate how spin current could be a powerful probe for new quantum materials. I will discuss the SC quasiparticle-mediated spin current as a probe for spin dynamics of an s-wave superconducting film [2], which might be useful to probe the spin dynamics for unconventional superconducting thin films. I will also discuss the spin superfluid-mediated spin current for the probe of novel quantum phase of spin superfluidity/superconductor ground states. The spin current in canted antiferromagnet Cr2O3 is investigated, which provides important experimental signatures of the spin superfluid ground states [3]. At the end, I will present the current status and my personal outlook of this exciting direction of using spin current as a probe for quantum materials [4].
Freitag, 05.07 2019

Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE

13:00 Uhr s.t., Media Room 03-431 (Staudingerweg 7)

Xiong-Jun Liu, International Center for Quantum Materials, Peking University
Quenching a quantum system involves three basic ingredients: the initial phase, the post-quench target phase, and the induced non-equilibrium dynamics which carries the information of the former two. In this talk, I will introduce how to characterize topological quantum phases by far-from-equilibrium quantum dynamics induced by quench, and further probe dynamically both the topology and symmetry-breaking orders in correlated topological systems. The generic theory is established by showing a dynamical bulk-surface correspondence, which connects the bulk topology of topological phases to dynamical topological pattern of quench dynamics emerging in the so-called band-inversion surfaces (BISs) in momentum subspace, similar to the well-known bulk-boundary correspondence in the real space. In the interacting regime, we show that the complex (pseudo)spin dynamics are governed by a microscopic Landau-Lifshitz-Gilbert-Bloch equation and find that, with the particle-particle interaction playing crucial roles, the correlated quench dynamics exhibit robust universal behaviors on the BISs, from which the nontrivial topology and magnetic orders can be extracted. In particular, the topology of the post-quench system can be characterized by an emergent dynamical topological pattern of quench dynamics on BISs, which is robust against dephasing and heating induced by interactions; the pre-quench symmetry-breaking orders can be read out from a universal scaling of the quench spin dynamics emerging on the BIS, which is valid beyond the mean-field approximation. These results may show insights into the exploration of novel correlation physics with nontrivial topology by quench dynamics. References: [1] L. Zhang, L. Zhang, S. Niu, and X.-J. Liu, Science Bull. 63, 1385 (2018). [2] W. Sun, C.-R. Yi, B.-Z. Wang, W.-W. Zhang, B.C. Sanders, X.-T. Xu, Z.Y. Wang, J. Schmiedmayer, Y. Deng, X.-J. Liu, S. Chen, and J. -W. Pan, Phys. Rev. Lett. 121, 250403 (2018). [3] B. Song, C. He, S. Niu, L. Zhang, Z. Ren, X.-J. Liu, and G.-B. Jo, arXiv:1808.07428; Nature Physics, in press (2019). [4] L. Zhang, L. Zhang, and X.-J. Liu, Phys. Rev. A 99, 053606 (2019). [5] L. Zhang, L. Zhang, Y. Hu, S. Niu, and X.-J. Liu, arXiv:1903.09144v2.
Montag, 08.07 2019

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

12:30 Uhr s.t., Staudingerweg 7, Minkowskiraum

Marcel Weirich, JGU Mainz
Development of Algorithmic Firmware for the Upgrade of the ATLAS Level-1 Calorimeter Trigger System

Institutsseminar Kern- und Hadronenphysik

Institut für Kernphysik

14 Uhr c.t., HS Kernphysik, Becherweg 45

Matthias Molitor, Mainz
Precision Polarimetry by double Mott-Scattering
Dienstag, 09.07 2019

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., THEP Sozialraum

Michael Benzke, Hamburg University
If you want to look for new physics in decays that involve hadrons, you need to consider the related hadronic uncertainties. In this talk I will discuss hadronic uncertainties in the decay B to X_s l^+l^- in the framework of SCET at subleading power. The talk is based on 1705.10366 and work in progress.

Physikalisches Kolloquium

Institut für Kernphysik, Johann Joachim Becher Weg 45

16 Uhr c.t., HS KPH

Prof. Dr. Stephan Paul, TU München, Fakultät für Physik
The study of multibody hadronic final states plays a major role in the spectroscopy of hadrons and the search for exotic states, e.g. at the COMPASS experiment at CERN. New analysis technique thereby offer an unprecedented view into the underlying dynamics and correlations and in addition reveal information on the initial states. Such techniques are now to be employed in the analysis of of heavy mesons and tau leptons. They promise a new measurement technique for the polarization of tau leptons, one of the prerogatives for measuring dipole moments of the heaviest lepton at the Super B-factory.
Mittwoch, 10.07 2019

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

Institut für Physik

12 Uhr c.t., Newton-Raum (01-122), Staudingerweg 9

Dr. Hannah Williams, Department of Physics, Imperial College, London, UK
From studies of fundamental physics to quantum technologies the production of ultracold molecules will have a huge impact across a range of applications. For many years laser cooling, an invaluable tool in cold atomic physics, was considered too impractical for application to molecules. However, laser cooling has recently been demonstrated for a few molecular species. I will present my work with ultracold calcium fluoride. This talk will cover laser cooling and magneto-optical trapping of molecules and recent results demonstrating deep cooling and coherent quantum state control.

Sondertermin und -ort

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t., Lorentz-Raum 05-127, Staudingerweg 7

Michael Spannowsky, Institute for Particle Physics, DURHAM
The discovery of the Higgs boson has for the first time established an arguably elementary scalar sector at the electroweak scale. With a newly discovered and yet unexplored scalar sector novel opportunities arise to address fundamental questions in nature. To maximise our understanding of this sector a concerted effort between collider and non-collider experiments, as well as perturbative and non-perturbative methods is required. I will outline peculiarities of the Higgs sector and point towards possible future research directions to explore the electroweak symmetry breaking potential.
Donnerstag, 11.07 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Saikat Chakraborty, Institut fr Physik
Importance of hydrophobic and steric interactions in modeling supramolecular polymerization

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

Institut für Physik

14 Uhr c.t., Lorentz-Raum (05-127), Staudingerweg 7

Prof. Dr. Francois Treussart, Laboratoire Aimé Cotton, CNRS, Univ. Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay, Orsay, France
Neurodegenerative disorders such as Alzheimer’s disease (affecting 18% of >75 years old population) involve a large network of genes displaying subtle changes in their expression. Abnormalities in intraneuronal transport have been linked to genetic risk factors found in patients, suggesting the relevance of measuring this key biological process. However, current techniques are not sensitive enough to detect minor abnormalities. In 2017, we reported a sensitive method to measure changes in intraneuronal endosomal transport induced by brain disease-related genetic risk factors using fluorescent nanodiamonds (FNDs)[1]. We showed that the high brightness, photostability and absence of cytotoxicity allow FNDs to be spontaneously internalized inside the endosomes neurons in cultures and subsequently tracked with up to 12 nm spatial and 50 ms time resolutions. As proof-of-principle, we applied the FND-tracking assay to transgenic mouse lines that mimic the slight changes in protein concentration (≈30%) found in brains of patients. In both cases, we showed that the FND assay is sufficiently sensitive to detect these changes trough modifications of transport parameters. This nanoparticle tracking based-approach applies also to multiphoton microscopy (MPM), opening the possibility of intracellular transport measurement in vivo thanks to tissue transparency in the excitation wavelength range of MPM. To be able to keep a high framerate while raster scanning MPM infrared focused excitation beam, we use sized≈100 nm KTiOPO4 (KTP) nanocrystals possessing a large nonlinear second order optical response, that were identified as possible cell labels in an earlier work [2]. As a first step toward deep imaging of transport, we have tracked nanoKTP in axons of the periventricular neurons of the optical tectum of living zebrafish (Zf) larvae at the same 20 frames/s rate as in widefield imaging with FND, while keeping a subwavelength precision of localization of ≈150 nm. Surprisingly, in transgenic Zf with a reduced concentration of kinesin-1 family motor kif5a, we have observed improved transport parameters (increase of velocity and runlength, and lower rotational fluctuations) in the direction of motion driven by these family of motors. We are now testing the hypothesis that this results from an improved coordination of kinesin-2 motors when kif5a does not compete for the binding to the microtubule track. Indeed, kinesin-2 family motors are likely to dominate the driving of the late endosomes or lysosome we track. This in vivo intraneuronal transport assay in Zf larvae is a first step toward measurement in mature brain of juvenile fishes (≈1 month old) and mouse brain sections. References [1] S. Haziza, et al. Nat. Nanotechnol. 12, 322 (2017). [2] L. Mayer et al. Nanoscale 5, 8466 (2013)

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

SFB/TR49 - Prof. Dr. Elmers

14:00 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 03-122

t b a, t b a
t b a
Mittwoch, 17.07 2019

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

SFB/TR49 - Prof. Dr. Elmers

Sonderseminar: 14:15 Uhr s.t., MAINZ Seminarraum, Staudinger Weg 9, 03-122

Jamir Marino, Harward University, Cambridge MA, USA
This talk is a journey into non-equilibrium phases of interacting quantum spin chains resulting from quantum quenches or periodic drives. The common ground of our study is a version of Holstein-Primakoff expansion suited to strongly non-equilibrium conditions resulting in a self-consistent theory of spin waves coupled to a dynamical order parameter. We will present three examples: emergent chaotic dynamical ferromagnets in Ising chains with competing short and long range interactions; dynamical stabilisation of an analog of the many-body Kapitza pendulum in long-range interacting spin chains; and finally we will briefly discuss the onset of time crystals in spins collectively coupled to photons.

Sonderseminar

Donnerstag, 18.07 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Dr. Zahra Mokhtari, University of Goettingen
With the aim of contributing to the understanding of the motion of biological agents in porous media, we consider a minimal model fo active elongated particles and show that the motion of such active filaments in a porous medium depends critically on flexibility, activity and degree of polymerization. For given Peclet number, we observe a transition from localisation to diffusion as the stiffness of the chains is increased. Whereas stiff chains move almost unhindered through the porous medium, flexible ones spiral and get stuck. Their motion can be accounted for by the model of a continuous time random walk with a renewal process corresponding to unspiraling. The waiting time distribution is shown to develop heavy tails for decreasing stiffness, resulting in subdiffusive and ultimately caged behaviour.
Donnerstag, 25.07 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Prof. Noriyoshi Arai, Keio University, Japan
Coarse-grained molecular simulation for soft materials and prediction of physical properties combined with machine learning
Donnerstag, 08.08 2019

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

SFB/TR49 - Prof. Dr. Elmers

14 Uhr c.t., MAINZ Seminar Raum, Staudingerweg 9, 3. Stock, Raum 03-122

Prof. Laszlo Szunyogh, Department of Theoretical Physics, Budapest University, University of Konstanz
Thin magnetic films and nanoparticles deposited on different substrates exhibit a rich variety of magnetic structures the knowledge of which is inevitably important for potential technological applications. Our theoretical approach is based on a fully relativistic implementation of the density functional theory in the local spin-density approximation. The magnetic ground state of the system is determined either by means of ab initio spin-dynamics relying on the so-called constrained density functional theory or by mapping the first principles total energy onto a Heisenberg like Hamiltonian to be treated via standard methods of statistical physics such as Monte Carlo simulations or real-time spin-dynamics simulations. The relativistic treatment of the electronic structure allows for a full account of the magnetic anisotropy and of the anisotropic exchange interactions and of the Dzyaloshinskii-Moriya interactions (DMI). Several novel and challenging consequences of the Dzyaloshinsky-Moriya interaction (DMI) have been revealed, such as the chirality of domain walls [1], the non-reciprocity of spin waves [2], the formation of spin-spiral [3] and skyrmion states [4] in ultrathin films. A vast amount of research effort has been concentrated on tuning the balance between interactions preferring collinear and non-collinear ordering by the appropriate choice of magnetic materials and heavy metals with high spin-orbit coupling [5,6,7].
Donnerstag, 29.08 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Dr. Gerhard Jung, Bio and Nano Physics, University of Innsbruck
Static and dynamic properties of confined hard-sphere glasses
Montag, 09.09 2019

Quantengravitation-Seminar

Institut für Physik / THEP

14:00 Uhr s.t., Sozialraum der THEP; Institut fr Physik (05-427)

Prof. Hidenori Sonoda, Kobe University, Japan
I would like to explain why a Wilson Action with a finite cutoff can be gauge invariant (or BRST invariant, or Ward identities are satisfied)
Donnerstag, 12.09 2019

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

K. Binder/ S. Jabbari / A. Nikoubashman / F. Schmid / G. Settanni / T. Speck / M. Sulpizi / P. Virnau

10:30 Uhr s.t., Newtonraum, 01-122, Staudingerweg 9

Prof. An-Chang Shi, McMaster University, Canada
The observation of ordered phases in hard-condensed matter systems such as metallic alloys has a long history in materials physics. In recent years, intricate periodic and aperiodic order has emerged in a host of soft matter systems including supramolecular assemblies, surfactants and block copolymers. The emergence of complex ordered phases in these diverse systems underscores the universality of emergent order in condensed matter. Due their rich phase behavior, block copolymers provide an ideal system to study the origins and stability of periodic and aperiodic order in condensed matter physics. In particular, recent experimental and theoretical studies have revealed that non-classical ordered phases, such as the Frank-Kasper phases and quasicrystals, could be self-assembled from block copolymers as equilibrium or metastable morphologies. We have examined the occurrence of complex spherical packing phases in block copolymer systems using the self-consistent field theory and showed that a key mechanism of forming complex spherical phases is the conformational asymmetry of the blocks. Furthermore, we have predicted that the segregation of different polymeric species in block copolymer blends provides another mechanism to stabilize spherical packing phases with very different sized-spherical domains. In my presentation, I will summarize recent theoretical and experimental progresses on this fascinating topic and discuss possible future research directions.
Donnerstag, 19.09 2019

Seminar Festkörper- und Grenzflächenphysik KOMET - experimentell

Institut für Physik

11:00 Uhr s.t., MAINZ-Seminarraum, Staudingerweg 9, 3. Stock, Raum 03-122

Mickey Martini, Politecnico di Milano
Ferrimagnetic materials are interesting candidates for future spintronics applications due to high frequency dynamics and low net magnetic moment. In my talk, I will present my research on perpendicularly magnetized ferrimagnetic Tb/Co multilayer systems grown on Pt. This heterostructure allows efficient manipulation of ferrimagnetic domains through spin-orbit torques induced by the heavy metal Pt. The latter firstly allows the generation of spin currents from charge currents and secondly breaks the system symmetry by introducing a non-collinear exchange interaction at the Pt/ferrimagnet interface. I will show how the stacking order of the Tb/Co layers dramatically changes the magnetization compensation temperature and how the layer thicknesses result in a different efficiency of the spin-orbit torques.
Dienstag, 24.09 2019

Theory of Condensed Matter: Hard Condensed Matter

Institut für Physik, SPICE

14:00 Uhr s.t., Lorentz Room 05-127 (Staudingerweg 7)

Nikolai A. Sinitsyn, Theoretical Division, Los Alamos National Laboratory (LANL)
Time-dependence of parameters provides a whole new dimension for engineering quantum systems with unusual behavior. The limits of fast and slow (adiabatic) time-dependence are well studied. However, the intermediate regime is very poorly understood today because of the lack of proper theoretical methods and efficient numerical algorithms. This is the place where robust and unusual effects are still waiting to be uncovered. In this talk I will describe the method to study dynamics of interacting spins with simple, e.g., ~t or ~1/t time-dependence of some of the parameters without any approximation. I define what it means for such systems to be integrable and then show three examples that reveal robust dynamic effects. One is the BCS model with decaying superconducting gap, which shows nonadiabatic emergence of a fully thermalized state. Another is the model of cavity QED with linear optical frequency chirp, which demonstrates a sharp phase transition between fast and slow phases. The third model shows the effect of dynamic spin localization in a hysteresis loop of interacting spins. This effect has no counterpart in any known classical or quantum spin model. References: [1] NA Sinitsyn, EA Yuzbashyan, VY Chernyak, A Patra, C Sun. Integrable time-dependent quantum Hamiltonians, Phys. Rev. Lett. 120 190402 (2018) [2] F Li, VY Chernyak, and NA Sinitsyn. Quantum annealing and thermalization: insights from integrability, Phys. Rev. Lett. 121, 190601 (2018)
Mittwoch, 25.09 2019

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

SFB/TR49 - Prof. Dr. Elmers

Sonderseminar: 09:00 Uhr s.t., MAINZ-Seminarraum, Staudinger Weg 9, 3. Stock, 03-122

David P. Landau, Center for Simulational Physics, University of Georgia, Athens, USA
A great triumph of statistical physics in the latter part of the 20th century was the understanding of critical behavior and universality at 2nd order phase transitions. In contrast, 1st order transitions were believed to have no common features. However, we argue that the classic, 1st order "spin-flop" transition (between the antiferromagnetic and the rotationally degenerate, canted state) in an anisotropic antiferromagnet in a magnetic field exhibits a new kind of universality. We present a finite-size scaling theory for a 1st-order phase transition where a continuous symmetry is broken using an approximation of Gaussian probability distributions with a phenomenological degeneracy factor q included. Predictions are compared with high resolution Monte Carlo simulations of the three-dimensional, XXZ Heisenberg antiferromagnet in a field to study the finite-size behavior for L X L X L simple cubic lattices for systems as large as 10^6 spins. Our Monte Carlo data agree with theoretical predictions for asymptotic large L behavior. The field dependence of all moments of the order parameters as well as the fourth-order cumulants exhibit universal intersections at the spin-flop transition with values that can be expressed in terms of the factor q that characterizes the relative degeneracy of the ordered phases. Our theory yields q = pi, and we present numerical evidence that is compatible with this prediction. The agreement between the theory and simulation implies a heretofore unknown universality.

Sonderseminar

Freitag, 27.09 2019

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

SFB/TR49 - Prof. Dr. Elmers

Sonderseminar: 10:00 Uhr s.t., MEDIEN-Raum, Staudinger Weg 7, 03-431

Aimo Winkelmann, Laser Zentrum Hannover
Changes of the symmetry of crystalline phases can lead to changes in element-resolved photoelectron diffraction patterns. In this context, simulations of the expected Kikuchi diffraction patterns allow to estimate the sensitivity of hard X-ray photoelectron diffraction measurement to small changes in a crystal structure. As examples, the tetragonality of strained SiGe thin films and the sensitivity to domain formation in perovskites will be discussed. It will be analyzed how the observed effects should depend on the crystal orientation, allowing the optimization of possible experiments.

Sonderseminar