Physics colloquium in the summer semester 2021

Date: Tuesdays 16.15 (video conference)

Responsible persons: Prof. Nahid Talebi, Prof. Jan Benedikt

Zoom access link




The colloquium will be held as a video conference:
ZOOM Meeting ID: 623 3676 8390
Passcode: 317082

  • 04.05.2021: Prof. Dr. Claudia Draxl (Humboldt-Universität zu Berlin)

    From physics today to publishing and research of tomorrow

    Prof. Claudia DraxlThe growth of data from simulations and experiments is expanding beyond a level that is addressable by established scientific methods. The so-called “4 V challenge” of Big Data –Volume (the amount of data), Variety (the heterogeneity of form and meaning of data), Velocity (the rate at which data may change or new data arrive), and Veracity (uncertainty of quality) – is clearly becoming eminent also in the sciences. Controlling our data, sets the stage for explorations and discoveries. Novel artificial-intelligence tools can find patterns and correlations in data that cannot be obtained from individual calculations / experiments and not even from high-throughput studies. Prerequisites for the ultimate success of data-centric research are a change of our publication culture as well as a FAIR (Finable, Accessible, Interoperable, Re-useable) infrastructure, hosting data from sample synthesis, experiment, as well as theory and computations. I will review the concepts and recent progress of data-driven materials science, addressing the FAIR guiding principles, the importance of Open Data, issues of data quality, and examples of how to turn data into knowledge.

    Inviting person: Prof. Caruso

  • 11.05.2021: Prof. Dr Fabrizio Carbone (École Polytechnique Fédérale de Lausanne)

    Light-Induced phase transitions in strongly correlated systems

    Prof. Fabrizio CarboneUltrashort light pulses offer the possibility to create coherent excitations in solids which evolution can alter the path taken by the material across a phase transition. This can lead to the discovery of exotic out of equilibrium states of matter, and it can provide a unique way to disentangle the different degrees of freedom involved in a phase transition. In this seminar, we will review some recent results obtained by means of ultrafast spectroscopies in strongly correlated systems with a focus on high-temperature superconductors and the prototypical transition metal oxides magnetite and VO2.

    Inviting person: Prof. Talebi

  • 18.05.2021: Prof. Dr. Achim von Keudell (Ruhr-University Bochum)

    Transient atmospheric plasmas – mastering the nonequilibrium

    Prof. Dr. Achim von keudellNon equilibrium atmospheric plasmas form the unique basis for a multitude of applications ranging from thin films, surface modification, plasma chemistry to plasma medicine. In all these cases atmospheric pressure plasmas exhibit an intimate coupling to the bounding surfaces that trigger surface and conversion processes. The complexity of these processes makes a detailed understanding very challenging. Prominent examples are the combination of plasmas and catalysis and of plasmas and electrolysis. Plasmas provide either excited species to change the conversion reaction paths or they alter and may regenerate catalytic surfaces. The analysis requires detailed diagnostics of plasma excitation and surface processes at the plasma-solid or the plasma-liquid-solid interfaces. Three examples are being presented: (i) the conversion of CO2 and of volatile organic compounds is studied in atmospheric pressure plasmas revealing a strong non equilibrium with respect to excitation temperatures and plasma dynamics; (ii) the conversion of water by plasma excitation using nanosecond high voltage pulses that trigger extremely high density plasmas that are governed by field effects at the interfaces and by tunneling in between adjacent water molecules during plasma propagation; (iii) the plasma induced triggering of enzyme driven species conversion in biocatalysis. The work is supported by the SFB 1316 “Transient atmospheric pressure plasmas – from plasmas to liquids to solids”

    Inviting person: Prof. Benedikt

  • 25.05.2021: Guest (institution)



    Inviting person:

  • 01.06.2021: Prof. Dr. Mark J. Kushner  (University of Michigan)



    Inviting person: Prof. Benedikt, Prof. Kersten

  • 08.06.2021: Prof. Dr. Wolfgang Schleich (University Ulm)

    Quantum carpets: A tool to observe decoherence

    Prof. Wolfgang SchleichQuantum carpets [1] - the spatio-temporal de Broglie density profiles- woven by an atom or an electron in the near-field region of a diffraction grating bring to light [2], in real time, the decoherence of each individual component of the interference term of the Wigner function characteristic of Schrödinger cats. The proposed experiments [2] are feasible with present-day technology.

    Quantum carpets

    [1] M. Berry, I. Marzoli, and W. Schleich, Quantum Carpets, Carpets of Light, Physics World 14, 39-44 (2001)
    [2] P. Kazemi, S. Chaturvedi, I. Marzoli, R.F. O’Connell, and W.P. Schleich, Quantum carpets - a tool to observe decoherence, New J. Phys. 15, 013052 (2013)

    Inviting person: Prof. Talebi

  • 15.06.2021: Dr. James McIver (Max Planck Institute for the Structure and Dynamics of Matter)
    Femtosecond science on-chip: Capturing light-induced anomalous Hall currents in graphene

    Many non-equilibrium phenomena have been discovered or predicted in quantum solids driven by femtosecond pulses of light. Examples include photo-induced superconductivity [1] and Floquet-engineered topological phases [2]. These effects are expected to lead to measurable changes in electrical transport. However, the timescales involved far exceed those accessible using conventional fast electronics. In this talk, I will present results on the transport properties of monolayer graphene illuminated by a femtosecond pulse of circularly polarized light [3]. This was achieved using an ultrafast device architecture based on laser-triggered photoconductive switches. We observed a light-induced Hall effect in the absence of an applied magnetic field. The dependence of the effect on a gate potential used to tune the Fermi level revealed multiple features that reflect a Floquet-engineered topological band structure, similar to the band structure originally proposed by Haldane [4]. This includes a ~60 meV wide conductance plateau centered at the Dirac point, where a gap of equal magnitude is predicted to open based on Floquet theory. We find that when the Fermi level lies within this plateau, the non-equilibrium anomalous Hall conductance saturates around ~1.8+/-0.4 e^2/h.

    [1] D. Fausti et al. Science 331, 189-191 (2011)
    [2] T. Oka & H. Aoki. Phys. Rev. B 79, 081406 (2009)

    [3] J.W. McIver et al. Nature Physics 16, 38-41 (2020)
    [4] F.D.M. Haldane, Phys. Rev. Lett. 61, 2015-2018 (1988)

    Inviting person: Prof. Bauer
  • 22.06.2021: Prof. Dr. Günther Hasinger (Director of Science, ESA)

    The present and future of ESA's science program


    Inviting person: Prof. Wimmer-Schweingruber

  • 29.06.2021: Guest (institution)



    Inviting person:

  • 06.07.2021: Prof. Dr. Astrid Veronig (Head of Kanzelhöhe Observatory for Solar and Environmental Research)



    Inviting person: Prof. Heber