Semesterübersicht – letztes Semester

Semesterübersicht Wintersemester 2020/2021

Wintersemester 2020/2021 - Sommersemester 2021 - Wintersemester 2021/2022

22 Oct 2020

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

Institut für Physik

14 Uhr c.t.

Prof. Dr. Simon Stellmer, Rheinische Friedrich-Wilhelms-Universität Bonn
Our quantum metrology research group has recently been established at the University of Bonn. The overarching goal of our various projects is the improvement of precision measurements in an interdisciplinary context. In my talk, I will present two of our projects. In the first project, we address one of the most pressing fundamental questions in contemporary physics: Why does the Universe contain matter, but almost no antimatter? This matter-to-antimatter asymmetry is understood as massive CP violation, which in turn would show up as a permanent electric dipole moment (EDM) in fundamental particles. I will show how ultracold and even quantum-degenerate Fermi gases of mercury can be used to measure the neutron EDM with a sensitivity that might exceed state-of-the-art limits. The second project is related to geodesy: the rotation of Earth is not as constant as it may seem. On the contrary, it is an amazingly sensitive probe of all kinds of phenomena, ranging from rotational coupling to other celestial objects all the way to mantle/crust coupling and the anthropogenic climate change. We have started to develop novel gyroscopes to measure, via the Sagnac effect, variations in the Earth rotation rate at an unprecedented sensitivity.
at Zoom

29 Oct 2020

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

Institut für Physik

14 Uhr c.t.

Prof. William D. Phillips (Nobel Prize in Physics), National Institute of Standards and Technology (NIST), USA
On 20 May 2019 the International System of Units (the SI) experienced its most revolutionary change since the French revolution produced the metric system. Today, all of the base units of the SI are defined by fixing the values of constants of nature, resulting in a fundamentally quantum system of measurement units. This talk will discuss why such a reform was needed and how it is implemented.
at Zoom

30 Oct 2020

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

10:30 Uhr s.t., Digital meeting

Lukas Stelzl, Institute of Physics
From atomic-resolution ensembles of disordered proteins to simulations of their biomolecular condensates
at Zoom

02 Nov 2020

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Daniel Wenz/Johannes Balz, Institut für Physik
Dark Matter
at Zoom for now

05 Nov 2020

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

Institut für Physik

14 Uhr c.t.

Prof. Dr. Arno Rauschenbeutel, Humboldt-Universität zu Berlin
Correlating photons using the collective nonlinear response of atoms weakly coupled to an optical mode Typical schemes for generating correlated states of light require a highly nonlinear medium that is strongly coupled to an optical mode. However, unavoidable dissipative processes, which cause photon loss and blur nonlinear quantum effects, often impede such methods. In this talk, I will report on our recent experimental demonstration of a proposal that takes the opposite approach [1]. Using a strongly dissipative, weakly coupled medium, we generate and study strongly correlated states of light [2]. Specifically, we study the transmission of resonant light through an ensemble of non-interacting atoms that weakly couple to a guided optical mode. Dissipation removes uncorrelated photons while preferentially transmitting highly correlated photons created through collectively enhanced nonlinear interactions. As a result, the transmitted light constitutes a strongly correlated many-body state of light, revealed in the second-order correlation function. The latter exhibits strong antibunching or bunching, depending on the optical depth of the atomic ensemble. The demonstrated mechanism opens a new avenue for generating nonclassical states of light and for exploring correlations of photons in non-equilibrium systems using a mix of nonlinear and dissipative processes. Furthermore, our scheme may turn out useful in quantum information science. For example, it offers a fundamentally new approach to realizing single photon sources, which may outperform sources based on single quantum emitters with comparable coupling strength [3]. [1] S. Mahmoodian, M. Čepulkovskis, S. Das, P. Lodahl, K. Hammerer, A. S. Sørensen, Phys. Rev. Lett. 121, 143601 (2018). [2] A. Prasad, J. Hinney, S. Mahmoodian, K. Hammerer, S. Rind, P. Schneeweiss, A. S. Sørensen, J. Volz, A. Rauschenbeutel, Nat. Photonics (2020). https://doi.org/10.1038/s41566-020-0692-z [3] European patent pending (PCT/EP2019/075386)
at Zoom

06 Nov 2020

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

10:30 Uhr s.t., Digital event

Jan Rothörl, Institute of Physics, JGU
Coarse-grained Computer Simulations of Skyrmions
at Zoom

09 Nov 2020

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Elisa Ruiz-Chóliz/Phi Chau, Institut für Physik
Axions and ALPs searches
at Zoom for now

10 Nov 2020

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t.

Javier Fuentes-Martin, JGU Mainz
In this talk, I will present a model for third-family quark-lepton unification at the TeV scale featuring a composite Higgs sector. The model is based on a variant of the Pati-Salam model, the so-called 4321 model. The spontaneous symmetry breaking to the SM gauge group is triggered dynamically by a QCD-like confining sector. The same strong dynamics also produces a pseudo Nambu-Goldstone boson Higgs, connecting the energy scales of both sectors. The model predicts a massive U1 vector leptoquark coupled dominantly to the third generation, recently put forward as a possible solution to the B-meson anomalies.
at Zoom

12 Nov 2020

Theoriekolloquium

Die Dozierenden der Theoretischen Physik

16:00 Uhr s.t., usually Newton-Raum, Staudinger Weg 9, 01-122

Markus Heyl & Nicola Pancotti, MPKS, Dresden & Amazon Quantum
We re-start our series of theory colloquiums with a 90 minutes event on applications of machine learning to many-body physics. We will have two Zoom talks of 35 minutes+10 minutes of questions, each. Talk 1 (M. Heyl): Quantum many-body dynamics in two dimensions with artificial neural networks In the last two decades the field of nonequilibrium quantum many-body physics has seen a rapid development driven, in particular, by the remarkable progress in quantum simulators, which today provide access to dynamics in quantum matter with an unprecedented control. However, the efficient numerical simulation of nonequilibrium real-time evolution in isolated quantum matter still remains a key challenge for current computational methods especially beyond one spatial dimension. In this talk I will present a versatile and efficient machine learning inspired approach. I will first introduce the general idea of encoding quantum many-body wave functions into artificial neural networks. I will then identify and resolve key challenges for the simulation of real-time evolution, which previously imposed significant limitations on the accurate description of large systems and long-time dynamics. As a concrete example, I will consider the dynamics of the paradigmatic two-dimensional transverse field Ising model, where we observe collapse and revival oscillations of ferromagnetic order and demonstrate that the reached time scales are comparable to or exceed the capabilities of state-of-the-art tensor network methods. Talk 2 (N. Pancotti): Neural Networks Quantum States, Tensor Networks and Machine Learning Neural Networks Quantum States have been recently introduced as an Ansatz for describing the wave function of quantum many-body systems. In this talk I will give an overview of recent works on Neural Networks Quantum States taking the form of Boltzmann machines. I will explain the motivation for considering Boltzmann machines in machine learning and explain how they can be used to study ground state properties of quantum systems. I will then focus on the expressive power of this class of states and discuss their relationship to Tensor Networks. In particular I will show that restricted Boltzmann machines belong to an exotic class of tensor networks known as String Bond States. This mapping enables us to define generalizations of restricted Boltzmann machines that combine the entanglement structure of tensor networks with the efficiency of Neural Networks Quantum States. This connection sheds light on possible application of tensor networks in machine learning. I will discuss the tight relationship between tensor-network techniques and probabilistic graphical models, an established class of models broadly used in computer science. I finally conclude by presenting possible advantages of using tensor network to tackle machine learning problems.
at Zoom

double seminar

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

Institut für Physik

14 Uhr c.t.

Univ.-Prof. Dr. Tracy E. Northup, Universität Innsbruck
Future quantum networks offer a route to quantum-secure communication, distributed quantum computing, and quantum-enhanced sensing. A current challenge across all experimental platforms is how to move beyond proof-of-principle realizations to the efficient, faithful distribution of quantum states over scalable networks. I will present ongoing work on nodes for quantum networks based on trapped ions in optical cavities, focusing in particular on a connection between remote trapped-ion systems in Innsbruck and the development of fiber-cavity-based interfaces. To conclude, we will consider another role for ions coupled to optical cavities, namely, how they may enable the preparation of macroscopic quantum states of motion, in this case, of levitated nanoparticles. A common theme in this talk will be how an optical cavity can serve as an interface between quantum states encoded in light, in motion, and in the electronic states of an ion.
at Zoom

13 Nov 2020

GRK 2516 Soft Matter Seminar

Uni Mainz

10:30 Uhr s.t., via Zoom

C. Patrick Royall, University of Bristol
Gels are an everyday material, from foods to cosmetics to structures in living organisms. Yet gelation is among the most challenging phenomena in soft condensed matter to understand. Gels are non-equilibrium materials, which already puts them right at the limit of our understanding. As if the were not enough, gels sit at the intersection of the glass transition and failure in amorphous materials. The glass transition has been described as “the deepest problem in condensed matter physics” and failure of amorphous materials continues to evade a meaningful theoretical description [1,2]. Here we describe recent development in our understanding of the nature of colloidal gels [3,4] and explore mechanisms by which gels acquire their unusual “soft” solidity [3,4,6]. In particular, we elucidate the perceived wisdom of materials science that the microscopic structure determines the dynamics and macroscopic behaviour of the material. We develop an intuitive approach based on the local structure of constituent colloidal particles which provides a basic mechanism for local rigidity in the system. We show how this leads to a long—lived yet metastable solid material and provide approaches to understand the mechanisms of failure, which are key to applications in these complex yet everyday materials. [1] Royall CP & Williams SR “The role of local structure in dynamical arrest”, Phys. Rep. 560 1-75 (2015). [2] Royall CP, “Hunting Mermaids in Real Space: Known Knowns, Known Unknowns and Unknown Unknowns” Soft Matter 14 4009-4016 (2018). [3] Royall CP, Williams SR, Ohtsuka, T and Tanaka H, “Direct observation of a local structural mechanism for dynamic arrest”, Nature Materials 7 556-561, (2008). [4] Royall CP, Williams SR and Tanaka H “Vitrification and gelation in sticky spheres”, J. Chem. Phys. 148 044501 (2018). [5] Richard D, Hallett JE, Speck T and Royall CP, “Coupling between criticality and gelation in “sticky” spheres: A structural analysis”, Soft Matter 14 5554-5564 (2018). [6] Royall CP, Eggers J, Furukawa A and Tanaka H, “Probing Colloidal Gels at Multiple Length Scales: the Role of Hydrodynamics”, Phys. Rev. Lett. 114 258302 (2015).

16 Nov 2020

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Martin Rongen, Institut für Physik
The IceCube Upgrade Project
at Zoom for now

17 Nov 2020

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Dieter Ries, University of Mainz
Ultracold Neutrons (UCN) provide a unique tool for fundamental neutron research with long observation times. Once produced e.g. in one of the UCN sources at the TRIGA Mainz research reactor, they can be confined by suitable materials, gravity or strong magnetic fields ultimately only limited by the beta decay lifetime of the free neutron. The τSPECT experiment, which is close to being fully commissioned on-site at JGU, aims for a precision determination of the neutron lifetime, which is currently under scrutiny because different measurement techniques yield incompatible results. Another precision measurement with UCN is the search for a non-vanishing electric dipole moment of the neutron, which would violate CP symmetry. Together with the international nEDM collaboration we have recently published a new upper limit on the neutron EDM and are currently commissioning the next generation experiment "n2EDM" at PSI, Switzerland, which aims to push down the limit by an order of magnitude in the coming years. The current state of and results from the τSPECT, nEDM and n2EDM experiment will be presented.
at Recording of the presentation

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t.

Ana Peñuelas, JGU Mainz
We perform a general model-independent analysis of \(b \to c \tau \bar{\nu}_\tau\) transitions, including measurements of \(\mathcal{R}_D\), \(\mathcal{R}_{D^*}\), their \(q^2\) differential distributions, the longitudinal \(D^*\) polarization \(F_L^{D^*}\), and constraints from the \(B_c \to \tau \bar{\nu}_\tau\) lifetime, each of which has significant impact on the fit. A global fit to a general set of Wilson coefficients of an effective low-energy Hamiltonian is presented working with a minimal set of assumptions: new physics is present only in the third generation of leptons, there are not light right-handed neutrinos, the electroweak symmetry breaking is linearly realized and the CP-conserving limit is taken. The solutions of the fit are interpreted in terms of hypothetical new-physics mediators. The impact of \(F_L^{D^*}\), measured by Belle last year is studied in detail. The difficulty to accommodate this measurement motivates the relaxation of some of our assumptions so the impact of a non-linear electroweak symmetry breaking and the addition of light right-handed neutrinos is studied. From the obtained results we predict selected \(b \to c\tau\bar\nu_\tau\) observables, such as the baryonic transition \(\Lambda_b \to \Lambda_c \tau \bar{\nu}_\tau\), the forward-backward asymmetries \(\mathcal{A}_\text{FB}^{D^{(*)}}\), the \(\tau\) polarization asymmetries \(\mathcal{P}_\tau^{D^{(*)}}\), the longitudinal \(D^*\) polarization fraction \(F_L^{D^*}\) and several additional differential observables.
at Zoom

19 Nov 2020

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

Institut für Physik

14 Uhr c.t., only via ZOOM

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

20 Nov 2020

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

10:30 Uhr s.t., Digital event

William Janke, Institute of Physics
Structure formation of C60 on CaF2 Substrates: Multiscale Modelling
at Zoom

23 Nov 2020

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Viacheslav Filimonov, Institut für Physik
Global Demonstrator and PFM module
at Zoom for now

24 Nov 2020

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Bert Koopmans, Eindhoven University of Technology, The Netherlands
Femto-magnetism meets spintronics: Towards integrated magneto-photonics
at Recording of the presentation

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t.

Davide Racco, Perimeter Institute
The low frequency part of the gravitational wave spectrum generated by local physics, such as a phase transition, is largely fixed by causality, offering a clean window into the early Universe. Due to the difference between sub-horizon and super-horizon physics, it is inevitable that there will be a distinct spectral feature that could allow for the direct measurement of the conformal Hubble rate at which the phase transition occurred. As an example, free-streaming particles present during the phase transition affect the production of super-horizon modes. This leads to a steeper decrease in the spectrum at low frequencies as compared to the well-known causal \(k^3\) super-horizon scaling of stochastic gravity waves. If a sizeable fraction of the energy density is in free-streaming particles, they even lead to the appearance of oscillatory features in the spectrum. If the universe was not radiation dominated when the waves were generated, a similar feature also occurs at the transition between sub-horizon to super-horizon causality. These features can be used to show surprising consequences, such as the fact that a period of matter domination following the production of gravity waves actually increases their power spectrum at low frequencies.
at Zoom

25 Nov 2020

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t.

Matteo Alfonsi, Institut für Physik, ETAP
The XENON1T experiment has recently reported new results from the analysis of low energy electronic recoils data, characterized by the lowest background rate ever achieved in the energy range between 1 and 30 keV. An excess over known background has been observed around 2-3 keV, and this observation has been interpreted in terms of the existence of solar axions, or as an enhancement of the neutrino magnetic moment observed in solar neutrinos, or as an additional background initially not considered. In the latter hypothesis, among the various possibilities considered such as traces of 127Xe or 37Ar or tritium diluted into the active volume, only the tritium hypothesis cannot be confirmed or excluded with the current knowledge of the production and reduction mechanism. In this seminar I will describe the detector operation, the analysis approach and the arguments that allowed us to arrive to such conclusions, trying to address also the additional questions that has been posed by the community.
at Zoom

26 Nov 2020

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

Institut für Physik

14 Uhr c.t.

Dr. James Millen, King's College London, UK
Nanoparticles suspended and cooled in vacuum are seen as ideal candidates for testing the limits of quantum mechanics, beyond state-of-the-art sensing, and tabletop detection of gravitational waves and dark matter. The standard technology involves optical trapping and levitation, though this comes with issues of optical absorption and photon scattering. Away from the optical regime, electromechanics concerns the control of mechanical motion via its coupling to an electrical circuit. Chip-based electromechanical systems are leading quantum technologies, allowing entanglement between different circuit-signals, quantum squeezing, and the coherent conversion of signals between different frequency regimes. I will present our preliminary results in the field of Levitated Electromechanics, where particles are levitated, detected and controlled all-electrically. I will introduce the concept of bath engineering in this system with a preliminary study of non-equilibrium dynamics, and our work towards miniaturization. For more information see www.levi-nano.com
at Zoom

30 Nov 2020

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

All ETAP members, ETAP
Dear all, as announced yesterday in the ETAP seminar, we will take the opportunity next week in the seminar to have a special roundtable. Under normal circumstances, you would meet and see old and new faces during the the summer or Christmas party, or the ETAP seminar. Under the current circumstances, we should have a virtual get together, so I would like to invite as many of you to join the meeting, from student to staff member and even if you normally do not join the seminar. Everyone should give a short introduction to yourself. You can let everyone know, who you are, in which group you are working in, what are you working on and everything else you can fill in one minute. If you can, please use your camera or at least share a picture of you. Maybe we can even make a zoom group picture! Looking forward to seeing many of you next week! Cheers Duc
at Zoom for now

01 Dec 2020

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Eli Zeldov, Department of Condensed Matter Physics, Weizmann Institute of Science, Israel
Energy dissipation is a fundamental process governing the dynamics of classical and quantum systems. Despite its vital importance, direct imaging and microscopy of dissipation in quantum systems is currently mostly inaccessible because the existing thermal imaging methods lack the necessary sensitivity and are unsuitable for low temperature operation. We developed a scanning nanoSQUID that resides at the apex of a sharp pipette acting simultaneously as nanomagnetometer with single spin sensitivity and as nanothermometer providing cryogenic thermal imaging with four orders of magnitude improved thermal sensitivity of below 1 µK [1]. The non-contact non-invasive thermometry enables direct visualization and control of the minute heat generated by electrons scattering off a single atomic defect in graphene [2]. By further combining the scanning nanothermometry with simultaneous scanning gate microscopy we demonstrate independent imaging of work and dissipation and reveal the microscopic mechanisms that conceal the true topological protection in the quantum Hall state in graphene [3]. [1] D. Halbertal, J. Cuppens, M. Ben Shalom, L. Embon, N. Shadmi, Y. Anahory, H. R. Naren, J. Sarkar, A. Uri, Y. Ronen, Y. Myasoedov, L. S. Levitov, E. Joselevich, A. K. Geim, and E. Zeldov, Nature 539, 407 (2016). [2] D. Halbertal, M. Ben Shalom, A. Uri, K. Bagani, A.Y. Meltzer, I. Marcus, Y. Myasoedov, J. Birkbeck, L.S. Levitov, A.K. Geim, and E. Zeldov, Science 358, 1303 (2017). [3] A. Marguerite, J. Birkbeck, A. Aharon-Steinberg, D. Halbertal, K. Bagani, I. Marcus, Y. Myasoedov, A.K. Geim, D.J. Perello, and E. Zeldov, Nature 575, 628 (2019).
at Recording of the presentation

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t.

Saereh Najjari, JGU Mainz
I will introduce a scenario where both the Higgs and a complex scalar dark matter candidate arise as the pNGB of breaking a global \(SO(7)\) symmetry to \(SO(6)\). In our construction the symmetry partners of the Standard Model top-quark are charged under a hidden \(SU(3)_c\) color group. We show how the Large Hadron Collider along with current and next generation dark matter experiments will explore this framework.
at Zoom

03 Dec 2020

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

Institut für Physik

14 Uhr c.t.

Prof. Dr. Andrey Surzhykov, Physikalisch-Technische Bundesanstalt Braunschweig
The Gamma Factory (GF) is a novel research tool, currently considered by CERN as part of its Physics Beyond Colliders initiative. While the main goal of the GF is the generation of high-intensity beams of gamma rays, it will also open up many opportunities in atomic, nuclear and particle physics. In my presentation, I will focus especially on the planned atomic physics activities. In particular, we will discuss how the GF can enable a wide range of ground-breaking studies, from the high-precision spectroscopy of partially stripped ions to testing Special Relativity and fundamental symmetries of Nature. Joint seminar with the MITP workshop on Physics Opportunities with the Gamma Factory: https://www.hi-mainz.de/de/news-events/detail/news/physics-opportunities-with-the-gamma-factory/ Prof. Dr. Andrey Surzhykov, Physikalisch-Technische Bundesanstalt Braunschweig
at Zoom

07 Dec 2020

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Rainer Wanke, Institut für Physik
New results from NA62
at Zoom for now

08 Dec 2020

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Sherry Suyu, TU München
Strong gravitational lenses with measured time delays between the multiple images can be used to determine the Hubble constant (H0) that sets the expansion rate of the Universe. An independent determination of H0 is important to ascertain the possible need of new physics beyond the standard cosmological model, given the tension in current H0 measurements. I will describe techniques for measuring H0 from lensing with a realistic account of systematicuncertainties, and present the latest resultsfrom a program aimed to measure H0 from lensing. Search is underway to find new lenses in imaging surveys. An exciting discovery of the first strongly lensed supernova offered a rare opportunity to perform a true blind test of our modeling techniques. I will show the bright prospects of gravitational lens time delays as an independent and competitive cosmological probe.
at Zoom

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP seminar room

Aldo Cotrone, Florence U. and INFN
I will first review the basics of holography and some properties of the Sakai-Sugimoto model, the top-down holographic theory closest to QCD. Then, in this model I will describe the process of nucleation of bubbles of true vacua in the case of two first-order transitions: the confinement/deconfinement and chiral symmetry breaking/restoration ones. Finally, using these information, I will present the calculation of the gravitational wave spectra generated in these transitions, when the Sakai-Sugimoto model is employed as a dark sector. Prospects of detection will be discussed.
at Zoom

10 Dec 2020

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

Institut für Physik

14 Uhr c.t.

Dr. Lars von der Wense, JILA, University of Colorado, Boulder, USA
A nuclear optical clock based on ^229Th ions is expected to achieve a higher accuracy than the best atomic clocks operational today [1]. Although proposed back in 2003 [2], such a nuclear frequency standard has not yet become reality. The main obstacle that has so far hindered the development of a nuclear clock was an imprecise knowledge of the energy value of a nuclear excited state of the ^229Th nucleus, generally known as the ^229Th isomer. This metastable nuclear excited state is the one of lowest energy in the whole nuclear landscape and - with an energy of less than 10 eV - offers the potential for nuclear laser spectroscopy, which poses a central requirement for the development of a nuclear clock [3]. Recently, a couple of new experiments have led to an improved knowledge about the isomer’s excitation energy [4, 5, 6], thereby constraining the isomeric energy to a value of 8.12 0.11 eV. This new knowledge offers great potential for future laser spectroscopy experiments and the development of a nuclear optical clock. With a wavelength equivalent of 152.7 2.1 nm, the energy is very well accessible by the 7th harmonic of a high-power Yb:doped-fiber frequency-comb [7] and a corresponding spectroscopy experiment is already in preparation [8]. If successful, the experiment would provide the first laser spectroscopy of a nuclear transition, thereby improving our current constraints of the isomer’s energy by six orders of magnitude. In addition, the stabilization of an individual comb-mode to the nuclear transition would result in the immediate development of a nuclear frequency standard. In this presentation I will give an overview over the current status of the nuclear clock development, with a particular focus on the most recent progress. Also the next required steps will be detailed and future perspectives will be given. References [1] C.J. Campbell et al., Phys. Rev. Lett. 108, 120802 (2012). [2] E. Peik and C. Tamm, Eur. Phys. Lett. 61, 181 (2003). [3] L. von der Wense and B. Seiferle, arXiv:2009.13633 (2020). [4] B. Seiferle et al., Nature 573, 243 (2019). [5] A. Yamaguchi et al., Phys. Rev. Lett. 123, 222501 (2019). [6] T. Sikorsky et al., Phys. Rev. Lett. 125, 142503 (2020). [7] C. Zhang et al., Phys. Rev. Lett. 125, 093902 (2020). [8] L. von der Wense and C. Zhang, Eur. Phys. J D 74, 126 (2020).
at Zoom

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

18:00 Uhr s.t., Digital event

An-Chang Shi, MacMaster University, Hamilton, Canada
Self-consistent field theory
at Zoom

11 Dec 2020

Theorie-Palaver

Institut für Physik

15:30 Uhr s.t., MITP seminar room

Alexandros Papageorgiou, University of Minnesota
Motivated by some of the recent swampland conjectures, we study a model of dark energy in which a quintessence axion slowly rolls in a steep potential due to its interactions with a U(1) or an SU(2) gauge field. We compare the differences between the U(1) and SU(2) cases and specify the parameter space for which the model is compatible with observations. We also apply our methodology to studying the transition between a pre-inflationary era and inflation and note some interesting oscillatory effects in the particle production parameter which could lead to interesting phenomenology. Finally we analyze the potential of the "Warm Dark Energy" model to produce gravitational waves observable by PTA, CMB polarization or spectral distortion experiments and find a negative result.
at Zoom

14 Dec 2020

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Hans Steiger, Institut für Physik
The Taishan Antineutrino Observatory - TAO
at Zoom for now

15 Dec 2020

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Baha Balantekin, University of Wisconsin, Madison, USA
Earlier theoretical work on neutrino propagation in dense media, in particular the Mikheyev-Smirnov-Wolfenstein effect describing phase changes in neutrino wave functions resulting from their interaction with the background particles, provided an explanation of the measured distortions of the solar neutrinos. A more complex effect takes place in the denser media inside supernovae and neutron-star mergers, where neutrinos interact not only with the background particles but also among themselves. After reviewing key roles neutrinos play in such environments, this many-neutrino problem and resulting collective neutrino oscillations will be discussed. Implications of correlations between neutrinos in this many-neutrino system for nucleosynthesis and terrestrial detection of supernova neutrinos will be explored.
at Recording of the presentation

16 Dec 2020

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t.

Marina Marinkovic, LMU München
Simulating strong interaction at scale
at Zoom

17 Dec 2020

Theoriekolloquium

Die Dozierenden der Theoretischen Physik

16:00 Uhr s.t., usually Newton-Raum, Staudinger Weg 9, 01-122

Matthew P. A. Fisher, UC Santa Barbara
The inexorable growth of non-local quantum entanglement is the key feature that distinguishes quantum from classical systems. Monitoring an open system (by making projective measurements) can compete against entanglement growth, leading to a many-body quantum Zeno effect. A hybrid quantum circuit model consisting of both unitary gates and projective measurements exhibits a quantum dynamical phase transition between a weak measurement phase and a quantum Zeno phase. Detailed properties of the weak measurement phase - including relations to quantum error correcting codes - and of the critical properties of this novel quantum entanglement transition will be described.
at Zoom

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

Institut für Physik

14 Uhr c.t.

Univ.-Prof. Dr. Markus Arndt, Universität Wien
Physics is currently in a state where many would say, the essential laws of nature are well understood. And it is true that quantum physics has matured for more than a century and has become the basis of a stunning range of modern technologies. And yet, fundamental questions of quantum physics have remained unsolved until today such as its transition into classical phenomenology or its relation to gravity theory. More recently a growing evidence has also suggested that we may actually know only a few percent of the world, missing the entire dark sector in matter and energy. Here I will focus on how to set up universal matter - wave interferometers that can demonstrate and utilize the quantum wave nature of matter. I will present experiments to explore the interface between quantum physics and classical phenomena and shine light on the question of objective wave function collapse. I will discuss how gravity influences all matter-wave interferometry, and many conceivable ways for it may to modify the dynamics of very massive superpositions. Finally, matter-wave interferometers built for that purpose will also mature into sensors for dark matter in a specific energy range. Ideas and prospects are briefly discussed.
at Zoom

Emergent AI Center Seminars

JGU Research Center for Algorithmic Emergent Intelligence

14:00 Uhr s.t., Online

Dr. Jean Anne Incorvia, The University of Texas at Austin
There are pressing problems with traditional computing, especially for accomplishing data-intensive and real-time tasks, that motivate the development of computing devices to both store information and perform computation (in-memory) as well as efficiently implement neuromorphic computing architectures. Magnetic tunnel junction memory elements can be used for computation by introducing a third terminal and manipulating a domain wall, a transition region between magnetic domains, below the junction, called a domain wall-magnetic tunnel junction (DW-MTJ). I will present results on building DW-MTJ devices and circuits with high on/off ratio, as well as modeling their behavior for bio-inspired energy-efficient computing, including spike-timing dependent plasticity, winner-take-all, and leaky, integrate, and fire properties.
at Zoom

18 Dec 2020

GRK 2516 Soft Matter Seminar

Uni Mainz

10:30 Uhr s.t., via Zoom

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

07 Jan 2021

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

Institut für Physik

14 Uhr c.t.

Prof. Dr. Antoine Browaeys, Laboratoire Charles Fabry, Palaiseau, France
This talk will present our effort to control and use the dipole-dipole interactions between cold atoms in order to implement spin Hamiltonians useful for quantum simulation of condensed matter or quantum optics situations. We trap individual atoms in arrays of optical tweezers separated by a few micrometers. We create almost arbitrary geometries of the atomic arrays in two and three dimensions up to about 200 atoms. To make the atoms interact, we either excite them to Rydberg states or induce optical dipoles with a near-resonance laser. Using this platform, we have in particular explored quantum magnetism, topological synthetic quantum matter, and a new light-matter interface.
at Zoom

11 Jan 2021

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Bastian Schlag, Institut für Physik
Vertexing in ATLAS
at Zoom for now

12 Jan 2021

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Zheng-Tian Lu, University of Science and Technology of China
The long-lived noble-gas isotope 81Kr is the ideal tracer for water and ice with ages of 105 - 106 years, a range beyond the reach of 14C. 81Kr-dating, a concept pursued over the past five decades, is finally available to the earth science community at large. This is made possible by the development of the Atom Trap Trace Analysis (ATTA) method, in which individual atoms of the desired isotope are captured and detected. ATTA possesses superior selectivity, and is thus far used to analyze the environmental radioactive isotopes 81Kr, 85Kr, and 39Ar. These three isotopes have extremely low isotopic abundances in the range of 10-17 to 10-11, and cover a wide range of ages and applications. In collaboration with earth scientists, we are dating groundwater and mapping its flow in major aquifers around the world. We are also dating old ice from the deep ice cores of Antarctica, Greenland, and the Tibetan Plateau. For an update on this worldwide effort, please google “ATTA Primer”.
at Recording of the presentation

13 Jan 2021

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t.

Daniele Guffanti, Institute of Physics, JGU Mainz
The Sun, as all the other stars, is fueled for most of its life by the fusion of hydrogen into helium taking place in its core. Neutrinos produced in such reactions are the only direct probe to the innermost part of our star and real time messengers of its engine. Decades of experimental and phenomenological efforts allowed us to study in detail the driving energy production mechanism in the Sun, the proton-proton chain, which is responsible for ~99% of the Sun luminosity. The fusion processes accounting for the remaining 1% are believed to be catalyzed by the presence of Carbon, Nitrogen and Oxygen (CNO-cycle) in the Sun interior, but a direct evidence of the occurrence of such mechanism was still missing. After years-long efforts, the Borexino experiment at the Gran Sasso National Laboratories has recently reported the first direct observation of solar neutrinos produced in the CNO-cycle. In this talk I will present the Borexino findings and I will discuss the importance of CNO neutrinos for astrophysics and for our understanding of the Sun, particularly in connection to its chemical composition.
at Zoom

14 Jan 2021

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

Institut für Physik

14 Uhr c.t.

Tanya S. Roussy, M.A., JILA (University of Colorado Boulder & NIST)
Over the past few decades, accelerators have been the traditional venue for new particle discoveries – but the paradigm is shifting. Accelerator energies are likely to remain on a plateau for some time, while atomic physics & precision measurement are in a remarkable period of progress. Some limits have advanced by a factor of 100 in less than 10 years, and laser technologies are being refined to exquisite levels. New Physics searches are already an established avenue in the atomic physics field; from atomic parity violation, to EDM searches, to equivalence principle tests. Happily, many of these platforms are well-suited to do double-duty as broadband dark matter searches. In this talk, I will explain the basics of our unique trapped-ion electron EDM search, how we used our recent data to constrain the gluon to axion-like particle coupling over seven mass decades, and how we solved some important methodological issues along the way.
at Zoom

Theoriekolloquium

Die Dozierenden der Theoretischen Physik

16:00 Uhr s.t., usually Newton-Raum, Staudinger Weg 9, 01-122

Dries Sels, New York University
Recent technological advances have put us at the brink of having access to small scale quantum computers capable of solving problems that cannot be tackled with classical computers. A limited number of algorithms have been proposed and their relevance to real world problems is a subject of active investigation. Solving problems relevant to chemistry are expected to be the first successful applications of quantum computers. In this talk, I will discuss a particular problem that can be solved efficiently on quantum computers: model inference for nuclear magnetic resonance (NMR) spectroscopy. I will give a broad introduction to quantum computing and NMR metabolomics assuming no prior knowledge of the subject.
at Zoom

15 Jan 2021

GRK 2516 Soft Matter Seminar

Uni Mainz

10:30 Uhr s.t., via Zoom

Nathalie Katsonis, University of Groningen, The Netherlands
TBA

18 Jan 2021

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Eftychia Tzovara, Institut für Physik
ttH(bb) in ATLAS: inclusive and differential cross section
at Zoom for now

19 Jan 2021

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Bernadett Weinzierl, University of Vienna, Austria
Aerosol particles are an important constituent of the global climate system. They not only affect the atmospheric radiation budget through scattering and absorption of solar radiation and through their role as cloud/ice nuclei but also impact air quality and human health. Both natural and human processes contribute to the global aerosol load. Whereas coarse‐mode aerosol (>1 μm diameter) mainly originates from natural aerosol sources, fine mode aerosol is frequently associated with human activities. Although substantial effort has been undertaken in the last decades to improve our knowledge about aerosols and their role in the global climate system, aerosol‐cloud‐radiation interactions still pose the largest uncertainty to estimates and interpretations of the Earth’s changing energy budget (IPCC, 2013). In order to decrease these uncertainties, research is necessary. Thereby, research aircraft like the German Aerospace Center (DLR) Falcon and the NASA DC‐8 provide unique platforms to study the horizontal and vertical distribution of aerosols and their microphysical, chemical and optical properties. In this talk, I will introduce aerosols in general, and discuss their effects on the atmosphere and climate. Furthermore, I will show selected results from airborne field experiments with the DLR research aircraft Falcon and the NASA research aircraft DC8 studying the long‐range transport of mineral dust (SALTRACE project), the global distribution of coarse mode aerosols (ATom project), and aerosol mixtures in the Eastern Mediterranean (A‐LIFE project).
at Zoom

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t.

Danny van Dyk, TUM, Munich
I will discuss theory predictions for exclusive b->s ll decays within the SM and beyond, with emphasis on the hadronic matrix elements. There are two categories of these matrix elements: local form factors, and nonlocal contributions arising from e.g. four-quark operators. I will report the status and report recent progress from QCD-based methods on the non-local hadronic matrix elements arising from intermediate charm states. A particular focus will be a recent derivation of a dispersive bound on the non-local matrix element as discussed in arXiv:2011.09813.
at Zoom

20 Jan 2021

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t.

Jens Erler, JGU Mainz
The precise standard model
at Zoom

21 Jan 2021

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

Institut für Physik

14 Uhr c.t.

Prof. Dr. Hatice Altug, EPFL Lausanne, CH
New health initiatives with global healthcare, precision medicine and point-of-care diagnostics are demanding breakthrough developments in biosensing and bioanalytical tools. Current biosensors are lacking precision, bulky, and costly, as well as they require long detection times, sophisticated infrastructure and trained personnel, which limit their application areas. My laboratory is focused on to address these challenges by exploiting novel optical phenomena at nanoscale and engineering toolkits such as nanophotonics, nanofabrication, microfluidics and data science. In particular, we use photonic nanostructures based on plasmonics and dielectric metasurfaces that can confine light below the fundamental diffraction limit and generate strong electromagnetic fields in nanometric volumes. In this talk I will present how we exploit nanophotonics and combine it with imaging, biology, chemistry and data science techniques to achieve high performance biosensors. I will introduce ultra-sensitive Mid-IR biosensors based on surface enhanced infrared spectroscopy for chemical specific detection of molecules, large-area chemical imaging and real-time monitoring of protein conformations in aqueous environment. Next, I will describe our effort to develop ultra-compact, portable, rapid and low-cost microarrays and their use for early disease diagnostics in real-world settings. Finally, I will highlight label-free optofluidic biosensors that can perform one-of-a-kind measurements on live cells down to the single cell level, and provide their prospects in biomedical and clinical applications.
at Zoom

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

18:00 Uhr s.t.

Scott Shell, UCSB, USA
tba
at Zoom

25 Jan 2021

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Florian Thomas, Institut für Physik
Accelerating Physics computations with GPUs
at Zoom for now

26 Jan 2021

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Viola Priseman, Max-Planck-Institution , Göttingen, Germany
How can we deal with a pandemic like COVID-19 so that neither health nor society and the economy suffer unnecessarily? We inferred the effectiveness of interventions, and developed effective containment strategies. Interestingly, we have identified a metastable state that not only stabilizes low case numbers, but also significantly reduces the necessary contact reductions and lockdowns. In this talk, we will introduce the underlying models, explore different containment strategies, and discuss recent developments.
at Recording of the presentation

Theorie-Palaver

Institut für Physik

17:30 Uhr s.t., MITP seminar room

Zhengkang (Kevin) Zhang, Caltech
Matching a UV theory onto a low-energy EFT can be efficiently accomplished with functional methods. The functional approach is conceptually appealing: all calculations are performed within the UV theory at the matching scale, and no prior determination of an EFT operator basis is required. In this talk, I will present a simple prescription for functional matching up to one loop order, which accommodates any relativistic UV theory that contains generic interactions among scalar, fermion and vector fields. I will also introduce STrEAM (SuperTrace Evaluation Automated for Matching), a Mathematica package that helps streamline the procedure.
at Zoom

28 Jan 2021

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

Institut für Physik

14 Uhr c.t.

Univ.-Prof. Dr. Tanja Mehlstäubler, Physikalisch-Technische Bundesanstalt, Braunschweig
Single trapped and laser-cooled ions in Paul traps allow for a high degree of control of atomic quantum systems. They are the basis for modern atomic clocks, quantum computers and quantum simulators. Our research aims to use ion Coulomb crystals, i.e. many-body systems with complex dynamics, for precision spectroscopy. This paves the way to novel quantum clocks for applications such as relativistic geodesy and improved navigation. The high-level of control of self-organized Coulomb crystals also opens up a fascinating insight into the non-equilibrium dynamics of coupled many-body systems, displaying atomic friction and symmetry-breaking phase transitions. We discuss the creation of topological defects in 2D crystals and present recent results on the study of tribology and transport mediated by the topological defect.
at Zoom

29 Jan 2021

GRK 2516 Soft Matter Seminar

Uni Mainz

10:30 Uhr s.t., via Zoom

Emanuela Zaccarelli, University of Rome
Microgels are soft particles individually made by cross-linked polymer networks which are nowadays widely used as a colloidal model system because of their swelling properties and their responsivity to external control parameters such temperature or pH. In this talk I will briefly illustrate the protocol that we recently developed to synthesize microgels in-silico, providing a realistic description of the particles. I will then focus on the calculation of their elastic properties and of the effective interactions in bulk and at liquid-liquid interfaces and compare the results with the famous Hertzian model. While we find that the validity of such model in bulk is fairly limited[1], when microgels are adsorbed at interfaces, they effectively behave as 2D elastic disks. Such soft interactions are predicted to show a reentrant liquid-glass-liquid behavior at high densities in a range of experimentally accessible conditions, namely for small and loosely cross-linked microgels[2]. [1] L. Rovigatti, N. Gnan, A. Ninarello and EZ, Macromolecules (2019). [2] F. Camerin, N. Gnan, J. Ruiz-Franco, A. Ninarello, L. Rovigatti and EZ, Phys. Rev. X (2020).

01 Feb 2021

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Asma Hadef, Institut für Physik
Scintillator Material Development for Neutron Reconstruction in DUNE Experiment
at Zoom for now

02 Feb 2021

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Andy Brown, ECMWF, Reading, Great Britain
Accurate weather predictions are of huge value to society, being used to inform actions that save lives and money. They are also a scientific success story, with global 5 day forecasts today being as accurate as 2 days forecasts of 30 years go. This talk will summarize the approach used, recent progress and future research and development priorities. These include further advances in understanding and modelling of multiple components of the Earth system (eg atmopshere, land, ocean and sea-ice), developments in observations and data assimilation methods, and bringing together the physical and computational science communities to take full advantage of new supercomputer architectures and advances in data science.
at Recording of the presentation

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t.

Anders Eller Thomsen, University of Bern
RG functions are used in QFT to evolve theories between energy scales and are frequently used in both phenomenology and theory. Starting at the 3-loop order, certain RG functions start exhibiting poles in the dimensional expansion, contrasting with the expectation that they should be finite. In this talk, I will clarify how this issue can be understood and how it is linked with an ambiguity in choosing renormalization constants that goes beyond a simple choice of renormalization scheme. The discussion will lead to a preferred prescription for the RG functions, which guarantees finiteness.
at Zoom

03 Feb 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Oleg Tchernyshyov, Johns Hopkins University
https://www.spice.uni-mainz.de/2021/01/13/on-line-seminar-03-february-2021/
at Zoom and SPICE YouTube Channel

04 Feb 2021

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

Institut für Physik

14 Uhr c.t.

Prof. David Cassidy, University College London, UK
Positronium (Ps) is a hydrogenic atom composed of an electron bound to a positron. Since it contains only leptons Ps is, for all practical purposes, a pure QED system, unaffected by nuclear structure effects. Also, being composed of a particle-antiparticle pair, Ps atoms are metastable, and may decay via self-annihilation, as well as through the usual radiative decay channels seen in regular atoms. The energy levels of Ps can be calculated to arbitrary precision (in principle), and precision spectroscopy of Ps can therefore be used to perform rigorous tests of bound-state QED theory. Moreover, since the theoretical description is limited only by the order of the calculations performed, rather than unknown physical constants or incalculable terms, any observed (and confirmed) disagreement with theory could indicate the existence of “new physics” such as particles or fields not currently included in the Standard Model. In this talk I will describe some new measurements of the Ps n = 2 fine structure, specifically 2 ^3S_1--> 2 ^3P_J (J = 0,1,2) transitions. The experiments were performed using a radioactive isotope-based positron beam coupled to a buffer gas/Penning trap. This allows positron pulses to be generated, which are converted into a dilute Ps gas with in vacuum an initial number density on the order of 10^6 cm^-3. A pulsed dye laser was used to optically excite atoms to the 2 ^3S_1 level, and microwave radiation was used to drive transitions to the 2 ^3P_J levels, which decay radiatively to the ground state before annihilation. The different annihilation decay rates of the ground and excited (S) states allows the fine structure transitions to be monitored via the time spectrum of the Ps annihilation radiation. We found that the measured J = 1 and J = 2 lineshapes exhibited significant asymmetries, whereas a symmetric lineshape was observed for the J = 0 transition. The observed asymmetries are not consistent with the most obvious quantum interference or line-pulling phenomena arising from nearby (off-resonant) transitions, and in the absence of a complete lineshape model we are therefore unable to determine the fine structure intervals for these transtions. Since the J = 0 lineshape did not exhibit any significant asymmetry it was possible to extract a value for the centre frequency: however, the obtained interval was found to disagree with theory by 2.77 MHz, which amounts to 4.5 standard deviations. No mechanism for a line shift of this magnitude has so far been identified.
at Zoom

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

16:00 Uhr s.t.

Dr. Johannes Zierenberg, Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany
Despite decades of research on disease spreading and epidemic outbreaks, the worldwide outbreak of COVID-19 was accompanied by scientific uncertainty resulting in insecure political actions. While scientific knowledge about the disease is initially uncertain until studied in detail, the worldwide available data on infected cases can be used to assess the current stage of the outbreak and allows for short term forecast of potential scenarios. Using a Bayesian framework even allows to incorporate and estimate parameter insecurity. I will present such an approach to infer spreading parameters during the initial outbreak of COVID-19 in Germany, show how to use it for short-term forecasts of potential scenarios, and argue that this approach adds a powerful tool to assist political decision making if the underlying assumptions and limitations are clearly communicated. I will further demonstrate how such models can be used to identify potential weak points in disease control, such as a limited tracing capacity.
at Zoom

05 Feb 2021

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

10:30 Uhr s.t.

Lukas Stelzl, Institute of Physics, JGU Mainz
Multi-scale simulations of disordered proteins and their assemblies
at Zoom

08 Feb 2021

Seminar about Experimental Particle and Astroparticle Physics (ETAP)

Institut für Physik

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

Thomas Honig, Institut für Physik
Higgs Boson Cross Section Measurement in the W-Associated Production and Fully Leptonic Final State at 13 TeV with the ATLAS Experiment"
at Zoom for now

Sonderseminar

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

SFB/TR49 - Prof. Dr. Elmers

16:00 Uhr s.t., der Raum wird separat angekündigt

Ulrich Eckern, Augsburg University
Spin-charge conversion and spectral properties of heterostructures containing half-metals: The role of nonquasiparticle states
at Zoom

09 Feb 2021

Physikalisches Kolloquium

Institut für Kernphysik, Remote Seminar

16:15 Uhr s.t.

Michael Feindt, University of Karlsruhe
This talk will review my personal history as elementary particle physics researcher (having started to work with neural networks at CERN in 1993), professor and entrepreneur (founder of Phi-T (2002) and Blue Yonder(2008)). It was always driven by what today is called Machine Learning and Artificial Intelligence, with emphasis on also predicting and taking advantage from knowledge about uncertainty. Today Blue Yonder, specialized on AI/ML and decision automation in the supply chain from Manufacturing to Retail, has more than 3500 large companies worldwide as customers and has delivered more than 1 trillion predictions. Examples from many different areas (physics, insurance, retail, supply chain) and experience gained over many years will show the tremendous value, but also the difficulties in bringing these methods into real life production in large scale international collaborations and companies - often against resistance.
at Recording of the presentation

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP seminar room

Riccardo Barbieri, SNS Pisa
Motivated by the hierarchy problem and by the pattern of quark masses and mixings, I describe a picture of flavour physics that should give rise in a not too distant future to observable deviations from the SM in Higgs compositeness and/or in B-decays (if LFV confirmed) or perhaps even in supersymmetry, depending on the specific realization.
at Zoom

10 Feb 2021

PRISMA Colloquium

Institut für Physik

13:00 Uhr s.t.

Nicola Neri, Università di Milano
Magnetic and electric dipole moments of fundamental particles provide powerful probes for physics within and beyond the Standard Model. For the case of short-lived particles these have not been experimentally accessible to date due to the difficulties imposed by their short lifetimes. A unique program of direct measurements of electromagnetic dipole moments of strange and charm baryons, and ultimately beauty baryons and the tau lepton, at the LHC is proposed. Novel experimental techniques have been developed, along with feasibility studies and projected sensitivities for different luminosity scenarios.
at Zoom

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Claudia Felser, MPI Chemical Physics of Solids
Magnetic Materials and Topology
at Zoom and SPICE YouTube Channel

11 Feb 2021

Theoriekolloquium

Die Dozierenden der Theoretischen Physik

16:00 Uhr s.t., usually Newton-Raum, Staudinger Weg 9, 01-122

Ehud Altman, UC Berkeley
From physics journals to campaign rallies, in this talk I'll try to explain what drives the remarkable popularity of the Sachdev-Ye-Kitaev model. In the first part I'll survey the evolution of this system from its origins as a solvable toy model of strongly interacting electrons to its current fame as a toy model of a quantum black hole. The latter came with Kitaev's discovery that, like a black hole, the low temperature dynamics of this model saturates the quantum bound on chaos. In the second part of the talk I will discuss how the model can be liberated from its status as a toy model by generalizing the physics from zero spatial dimensions to a genuine higher dimensional field theory. Time permitting I will discuss a specific application of such a field theory to describe unconventional quantum criticality in correlated electron systems.
at Zoom

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

Institut für Physik

14 Uhr c.t.

Dr. Stefan Ulmer, Ulmer Fundamental Symmetries Laboratory, RIKEN, Japan & CERN
The Standard Model of particle physics is both incredibly successful and glaringly incomplete. Among the questions left open is the striking imbalance of matter and antimatter in our universe, which inspires experiments to compare the fundamental properties of matter/antimatter conjugates with high precision. The BASE collaboration at the antiproton decelerator of CERN is performing such high-precision comparisons with protons and antiprotons. Using advanced, ultra-stable, cryogenic particle traps and superconducting detectors with single particle sensitivity, we have performed the most precise measurement of the proton-to-antiproton charge-to-mass ratio with a fractional uncertainty of 69 parts per trillion [1]. In another measurement, we have invented a novel spectroscopy method, which allowed for the first ultra-high precision measurement of the antiproton magnetic moment with a fractional precision of 1.5 parts in a billion [2]. Together with our recent measurement of the proton magnetic moment [3] this improves the precision of previous experiments [4] by more than a factor of 3000. A time series analysis of this recent magnetic moment measurement furthermore enabled us to set first direct constraints on the interaction of antiprotons with axion-like particles (ALPs) [5], and most recently, we have used our ultra-sensitive single particle detection systems to derive narrow-band constraints on the conversion of ALPs into photons [6]. In my talk I will review the recent achievements of BASE and will outline strategies to further improve our high-precision studies of matter-antimatter symmetry. This outlook will involve the implementation of sympathetic cooling of antiprotons using quantum logic methods, the development of the transportable antiproton trap BASE-STEP, and will also review recent experimental progress towards 10-fold improved measurements of the antiproton properties. [1] S. Ulmer et al., Nature 524, 196 (2015). [2] C. Smorra et al., Nature 550, 371 (2017). [3] G. Schneider et al., Science 358, 1081 (2017). [4] J. DiSciacca et al., Phys. Rev. Lett. 110, 130801 (2013). [5] C. Smorra et al., Nature 575, 310 (2019). [6] J. A. Devlin et al., Phys. Rev. Lett., accepted (2021). S. Ulmer1, K. Blaum2, M. Bohman1,2, M. Borchert1,3, J. A. Devlin1,4, S. Erlewein1,2,4, M. Fleck1,5, C. Smorra1, M. Wiesinger1,2, C. Will2, E. Wursten5, Y. Matsuda6, C. Ospelkaus3, W. Quint6, J. Walz7,8, Y. Yamazaki1 1RIKEN, Ulmer Fundamental Symmetries Laboratory, Saitama, Japan; 2Max-Planck-Institut für Kernphysik, Heidelberg, Germany; 3Leibnitz University, Hannover, Germany; 4CERN, Geneva, Switzerland; 5The University of Tokyo, Tokyo, Japan; 6GSI - Helmholtzzentrum für Schwerionenforschung GmbH, Darmstadt, Germany; 7Johannes Gutenberg-Universität, Mainz, Germany; 8Helmholtz-Institut Mainz, Germany;
at Zoom

12 Feb 2021

GRK 2516 Soft Matter Seminar

Uni Mainz

10:30 Uhr s.t., via Zoom

Jens-Uwe Sommer, Leibniz-Institute of Polymer Research Dresden and TU Dresden
The lower critical solution temperature (LCST) transition is introduced as type-II transition which results in many cases from competing effects of hydrogen bonding and hydrophobic behaviour of water-soluble polymers such as PEO and PNIPAm. As a consequence of the new type of phase separation a switch-like temperature response and phase coexistence is predicted for immobilized polymers such as polymer brushes or gels. I will give an introduction to simple theoretical concepts related with the type-II transition. Furthermore, I will demonstrate that mixed solvents can lead to type-II transitions with the prominent example of so-called co-nonsolvency [1]. Computer simulations and experiments confirm the basic conclusions from the theoretical model for polymer brushes [2,3]. Moreover, this phase transition is most likely driving the formation of protein-RNA-droplets in living cells. Using atomistic simulations it is shown for the example of PEO that stretching of the conformations can induce a phase transition far below the LCST which can be explained by the release of hydrogen bonds in the stretched state of PEO [4]. An aquamelt is introduced in general as a system where stretching/flow induces phase separation and subsquent crystallization, very similar to the process of spider-silk spinning in Nature. Aquamelts break the paradigm that solution properties of polymers are independent of conformation statistics. [1]J.-U. Sommer, Gluonic and Regulatory Solvents: A Paradigm for Tunable Phase Segregation in Polymers, Macromolecules 51, 3066 (2018); Adsorption-Attraction Model for Co-Nonsolvency in Polymer Brushes, Macromolecules 50, 2219 (2017) [2]A. Galuschko and J.-U. Sommer, Co-Nonsolvency Response of a Polymer Brush: A Molecular Dynamics Study, Macromolecules 52, 4120 (2019) [3]H. Yong, E. Bittrich, P. Uhlmann, A. Fery and J.-U. Sommer, Co-nonsolvency transition of poly(N-isopropylacrylamide) brushes in a series of binary mixtures, Macromolecules 52, 6285 (2019) [4]S. Donnets and J.-U. Sommer, J. Phys. Chem. B 122, 392 (2018)

Link: https://zoom.us/j/98197416231?pwd=c3ZnV0V6TDhsbkkwMnVDbTVWRG41dz09

16 Feb 2021

Theorie-Palaver

Institut für Physik

14:30 Uhr s.t., MITP seminar room

Nick Evans, Southampton U.
I review arguments that chiral symmetry breaking is triggered when the quark bilinear condensate's dimension passes through one. This is supported by gap equations and more recently holographic models. Confinement may then be a separate property of the pure Yang-Mills theory below the scale of the dynamically generated quark mass, occurring at the scale of the pole in the deep IR running. Theories with more than one representation may have gaps between the condensation scales for the different representations with confinement below the lowest scale. Here, we use perturbative results for the running of the gauge coupling and gamma in asymptotically free SU(Nc) gauge theories with matter in higher dimension representations to seek the best candidate theories where confinement and chiral symmetry breaking can be maximally separated.
at Zoom

17 Feb 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Olena Gomonay, JGU
Seeing or listening: magnetoelastic effects in antiferromagnetic textures
at Zoom and SPICE YouTube Channel

19 Feb 2021

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

10:30 Uhr s.t.

Adam Sieradzan, University of Gdańsk, Poland
UNICORN: UNIfied COarse-gRaiNed model of biological macromolecules
at Zoom

24 Feb 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Sergej Demokritov, University of Münster
Spatio-Temporal Dynamics of Magnon Bose-Einstein Condensates
at Zoom and SPICE YouTube Channel

26 Feb 2021

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

18:00 Uhr s.t.

Marina Guenza, Dept. of Chemistry and Biochemistry, University of Oregon, USA
The Integral Equation Theory of Coarse-Graining (IECG) and its applications.
at zoom

03 Mar 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Ulrich Rößler, IFW Dresden
Improper Dyzaloshinskii spirals and metamagnetic textures - and where to look for them
at Zoom and SPICE YouTube Channel

05 Mar 2021

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

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

14:00 Uhr s.t.

Frank Siebers, Institute of Physics, JGU
Dynamics of Light Driven Circle Walkers
at Zoom

Master Colloquium

10 Mar 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Theo Rasing, Radboud University
All-optical control of magnetism: from fundamentals to brain-inspired computing concepts
at Zoom and SPICE YouTube Channel

17 Mar 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Henning Sirringhaus, University of Cambridge
Charge and Spin transport physics of organic semiconductors
at Zoom and SPICE YouTube Channel

24 Mar 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Christian Back, TUM
Optical and Electrical Detection of Spin-Orbit Fields
at Zoom and SPICE YouTube Channel

31 Mar 2021

SPICE-Spin+X Seminar

TUK and JGU

15:00 Uhr s.t.

Igor Mazin, George Mason University
Dynamic generation of scalar chirality and topological Hall effect in spiral magnets
at Zoom and SPICE YouTube Channel