FB Physik

Fachbereichskolloquien

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  • 07.04.2022      Prof. Fredrick Olness

    Vortragsankündigung

    The nCTEQ Project: revealing the fundamental character of the strong force

    Science is entering a new era in the investigation of nuclear matter, driven by a wealth of precision data from the JLab, HERA, RHIC, & LHC experiments. The nCTEQ project employs advanced heoretical techniques to analyze these data sets comprehensively. While this analysis is performed within the framework of the QCD parton model, we leverage methods and results from Lattice QCD, Machine Learning, as well as other techniques. This work also forms the foundation for discoveries at the future Electron-Ion Collider (EIC), which will address fundamental questions about nuclei's mass, spin, and internal structure. The culmination of these efforts will produce the most detailed picture to date of nuclei, and advance the opportunity to possibly “solve” the underlying QCD theory of strong interactions.

  • 28.04.2022      Dr. Tilmann Hickel

    Vortragsankündigung

    Design of finite temperature materials properties enabled by innovative digital concepts

    Since the function of materials is controlled by properties and processes on the atomic scale, ab initio based high-throughput methods are valuable strategies in materials design. For computational efficiency, they are however often restriction to T=0K calculations, while many technologically relevant materials properties and thermodynamic stabilities change when going from low to high temperatures. On the other hand, the constantly increasing performance of digital tools for simulation and data-driven science enables more targeted material development including these kinds of finite-temperature effects. A flexible infrastructure, including data management and workflow solutions is required to make this symbiosis user-friendly efficient.

    Within this presentation, examples from ab initio thermodynamics for the design of phase stabilities in hard-magnetic alloys and defect-phases in advanced high-strength steels will be demonstrated. We will discuss physical concepts with a focus at the impact of magnetic excitations. At the same time, the examples will be used to derive requirements and present solutions for a digital infrastructure. An outlook will be given to current strategies with the NDFI initiative NFDI-MatWerk.

  • 05.05.2022      Prof. Gustav Holzegel

    Vortragsankündigung

    Black Holes

    Black Holes feature among the most fascinating predictions of Einstein’s theory of general relativity. In the past decades fundamental progress has been made both at the experimental level (e.g. detection of gravitational waves from black hole mergers, the event horizon telescope) and at the level of their mathematical understanding, which is the topic of my talk. I will begin by discussing the geometry of the most important black hole solutions and review some classical results from the “golden age” of black hole physics (1963-1973). I will then outline how these classical results (and heuristic principles) can be combined with modern techniques from the theory of partial differential equations to produce a deepened understanding of the stability properties and the singularity structure of black holes.

     

  • 12.05.2022     Prof. Marco Bernasconi

    Vortragsankündigung

    Phase change materials for data storage: insights from atomistic simulations

    Telluride materials such as the GeSbTe ternary alloys or the GeTe compound have been deeply investigated over the last two decades for a wide range of applications ranging from optical disc (DVDs and Blu-ray disc) to non-volatile electronic memories (phase change memories, PCM) and neuromorphic computing.

    These applications rest on a reversible and very rapid (50 ns) transformation between the amorphous and crystalline phases upon heating due to laser irradiation in the optical disc or to Joule effect in the electronic memories. The encoding of the digital information exploits a large difference in the optical reflectivity or in electronic conductivity between the two phases.  Materials in this class, named phase change materials, feature a very rich portfolio of intriguing properties that make them suitable for application in the different data storage devices.

    In the Colloquium I will review our contribution to the microscopic understanding of the functional properties of phase change materials that we gained from atomistic simulations either based on electronic structure calculations within Density Functional Theory or from large scale molecular dynamics simulations based on machine learning techniques.

  • 19.05.2022      Prof. Giacomo Indiveri und Prof. Elisabetta Chicca

    Bitte beachten: Dieses besondere Kolloquium wird vom CRC Intelligent Matter organisiert, deshalb findet es zu ungewohnter Zeit ( 15 Uhr s.t.) und an einem unüblichen Ort (Center for Soft Nano Science SON) statt.

    Link zur Vortragsankündigung auf der Webside des CRC 1459 Intelligent Matter

    Ankündigung   Abstracts

    Prof. Giacomo Indiveri, ETH Zürich

    Neuromorphic Intelligence: Electronic Circuits for Emulating Neural Processing Systems and Their Application to Pattern Recognition.

    Prof. Elisabetta Chicca, University of Groningen

    Exploiting Temporal Dynamics in Neuromorphic Sensing

    Prof. Christian Pester, Penn State University

    Design of Advanced Functional Surfaces using Oxygen-Tolerant Photopolymerization

     

  • 02.06.2022      Dr. Luciano Musa

    Vortragsankündigung

    Uncovering the quark-gluon plasma: scientific and technological challenges

    The semiconductor technology that fueled the rapid growth of the information technology industry in the past 50 years, also plays a key role in the remarkable development of detectors for High-Energy Physics (HEP) experiments. The amazing evolution of CMOS transistors in terms of speed, integration, and cost decrease, allowed a continuous increase of density, complexity and performance of sensors, front-end and readout circuits for HEP. This enabled the development of detectors that can measure the properties of hundreds of millions of particles generated every second in high-energy collisions of proton and heavy-nuclei beams at the CERN Large Hadron Collider. The advent of 2D and 3D pixel sensors paved the way to a new generation of detectors, which allow to measure the trajectory and velocity of particles with a precision of micrometers and picoseconds respectively, and to resolve very complex patterns of collision events with tens of thousands of particles generated simultaneously. After a brief overview of CMOS sensors and their most recent developments and applications in HEP, I will discuss their use in the ALICE experiment and their key role to study the quark-gluon plasma, the state of primordial matter that is thought to have existed in the first instants of the Universe.

  • 23.06.2022      Prof. Joshua Robinson

    Vortragsankündigung

    Creating and Exploring Novel Atomically-Thin Materials and Heterostructures


    The last decade has seen an exponential growth in the science and technology of two-dimensional materials.  Beyond graphene, there is a huge variety of layered materials that range in properties from insulating to superconducting. Furthermore, heterogeneous stacking of 2D materials also allows for additional “dimensionality” for band structure engineering. In this talk, I will discuss recent understandings on the importance of 2D layer-count on doping efficacy and activation, development of atomic layer deposited boron nitride, and creating 2D allotropes from traditionally 3D materials for photonic and quantum applications. Our recent works demonstrate that confinement heteroepitaxy (CHet), where elements can be intercalated between graphene and silicon carbide, is an effective way to realize 2D allotropes of traditional 3D materials (e.g. 2D Ag, Ga2O3, Pb, etc.). The quantum confinement effects include metal-to-semiconducting behavior (2D-Ag), enhancement in superconducting transition tempatures (2D-Ga), and symmetry breaking that leads to enormous non-linear susceptibility.

     

  • 30.06.2022     Prof. Pepijn Pinkse

    Vortragsankündigung

    Quantum Authentication, Quantum Communication, and Quantum Information Processing

    Quantum technology comes in many flavors. In this talk I will discuss some results from the AQO group at the UT in the areas of quantum authentication, authenticated communication and quantum information processing with integrated photonics:

    A physical unclonable key (PUK) is a unique key which cannot be physically copied with existing technology. Multiple-scattering samples form good PUKs. We have demonstrated authentication by quantum-secure optical readout of a PUK [1] and more recently, we have devised a quantum communication scheme based on PUKs [2]. In order to investigate the limits of state-of-the-art nanofabrication techniques, we started making multiple-scattering media by direct laser writing, as illustrated in the figure. A new class of PUKs we realized in the form of complex integrated photonic circuits.      

    For the purpose of achieving and exploiting a quantum advantage for computational tasks, scalable multiphoton interference with extreme programmability and ultralow loss is required. We believe the best way for that purpose is large-scale integrated photonics, which we are pursuing together with UT spin-off Quix Quantum. A programmable integrated photonic processor [3] recently allowed us to demonstrate quantum photodynamics [4], an indistinguishability witness [5] and an analog simulation of open scattering channels [6].

  • 07.07.2022     Dr. Florian Beutler

    Cosmology with the Dark Energy Spectroscopic Instrument (DESI)

  • 14.07.2022     Dr. René Wittmann

    Vortragsankündigung

    Topology of orientational defects of smectic colloidal liquid crystals in extreme confinement

    Abstract: Samples of liquid crystals exhibit a variety of topological defects and can be exposed to external constraints such as extreme confining geometries. Focusing on smectic colloidal liquid crystals, we present a general classification scheme of the intrinsic structure, dictated by the interplay between the intrinsic layering and the externally imposed boundary structure. Thereby, we demonstrate that the topological defects in two [1] and three [2] spatial dimensions emerge in the form of spatially extended grain-boundaries, which are characterized by coexisting nematic and tetratic orientational order. To illustrate these intriguing topological properties, we present particle-resolved results in a large range of confinements, obtained by Monte-Carlo simulations and fundamental-measure-based density functional theory of hard anisotropic bodies, as well as real-space microscopy of colloidal rods, whose structural details agree on a quantitative level. Moreover, in topologically nontrivial domains with additional interior boundaries, we analyze the stability of different competing states possessing a distinct orientational and positional topology [3].

    [1] P. A. Monderkamp, R. Wittmann, L. B. G. Cortes, D. G. A. L. Aarts, F. Smallenburg and H. Löwen, Phys. Rev. Lett. 127, 198001 (2021).
    [2] P. A. Monderkamp, R. Wittmann, M. te Vrugt, A. Voigt, R. Wittkowski and H. Löwen, Phys. Chem. Chem. Phys. 10.1039/D2CP00060A (2022).
    [3] R. Wittmann, L. B. G. Cortes, H. Löwen and D. G. A. L. Aarts, Nat. Commun. 12, 623 (2021).