Semesterübersicht

Semesterübersicht Wintersemester 2024/2025

Sommersemester 2024 - Wintersemester 2024/2025 - Sommersemester 2025

02 Oct 2024

Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

JGU

Sonderseminar: 13:00 Uhr s.t., Lorentz Room

Shilei Ding, Department of Materials, ETH Zürich, 8093 Zürich, Switzerland
Electronic devices based on charge motion have been well-studied and widely used in technological devices. However, the electrons can carry not only charges but also spin and orbital angular momentum. Nonequilibrium spin and orbital currents mediate the transfer of the angular momentum to the neighboring magnetic materials enabling the development of efficient spin orbitronic devices. Decoupling these currents from a flow of electronic charges opens opportunities for the electrical control of the magnetization. In this talk, I will first present the efficient spin torque in the magnetic insulators, including current-driving domain wall motion and the Dzyaloshinskii–Moriya interaction. In the second part of the talk, I will present the orbital torque and orbital Rashba-Edelstein magnetoresistance in the light metal system. The orbital-to-spin conversion plays a crucial role in the orbital torque, and the conversion layer can be ferromagnetic metal itself, 3d, 4f, and 5d non-magnetic metals. Our work indicates the efficient current-induced torque in the insulating system with a lower joule heating, and our results on orbital torques show that the magnitude of the orbital torque can be larger than the spin torque. The results further provide insight into the efficient current-induced torques with orbital current from low-cost, environmentally friendly light metals. Biography Shilei Ding received his B.S. in Physics from Peking University, China in 2016, and he received his Ph.D in Condensed Matter Physics from the School of Physics, Peking University (supervisor: Prof. Jinbo Yang). From 2017-2018 and 2019-2020, he was a guest Ph.D. student in the Lab of Prof. Mathias Kläui at Mainz University, Germany. He is now a Postdoctoral Researcher in the Lab of Prof. Pietro Gambardella at ETH Zurich, Switzerland. His research focuses on nonequilibrium spin and orbital current towards spin orbitronic devices, and he has published more than 30 papers in leading journals, including Physical Review Letters, Nano Letters, Advanced Materials, etc.

Sonderseminar

07 Oct 2024

Theorie-Palaver

Institut für Physik

Sonderseminar: 14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Soumen Kumar Manna, Indian Inst. Tech., Guwahati
Axion-like particles (ALPs), the pseudo-Goldstone bosons arising from the spontaneous breaking of global symmetry, are promising contenders for dark matter. The most extensively studied ALP production mechanism is known as misalignment mechanism, where ALP is presumed to initially remain frozen at a point in the field space until it begins oscillating around the potential minimum and behaves as cold dark matter (CDM). The oscillation initiates once the universe Hubble expansion rate falls below the ALP mass, defining the oscillation frequency. In this work, we examine how electroweak symmetry breaking (EWSB) affects ALP evolution, specifically through a higher order Higgs portal interaction. The interaction is observed to contribute partially to the ALP's mass during EWSB, thus altering oscillation frequencies and influencing the correlation between the scale of symmetry breaking and its mass. The novelty of this study lies in broadening the parameter space satisfying correct CDM relic density, facilitating future exploration through a diverse range of experimental avenues.

Sonderseminar

22 Oct 2024

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

THEP Member, Mainz
Meet and Greet

23 Oct 2024

PRISMA+ Colloquium

Institut für Physik

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

Dr. Simone Burel, LUB Mannheim
Dealing with diversity is structurally anchored in most universities. In public discourse or in work contexts, a distinction is usually only made between the dimensions of diversity specified in the General Equal Treatment Act, such as e.g. age, gender, disabilities. One dimension that is often forgotten, but which is no less relevant for the future of work and our society, is neurodiversity. Neurodiversity means normalizing differences in people's mental states and not dividing them into “mentally ill” and “mentally healthy”. Here, Dr. Simone Burel also reports from her own experience and tells us about different types of neurodiversity (including impostor syndrome, depression, social phobia, anxiety disorder, panic disorder). She will open for us her treasure chest with tips and tricks to realize potential of neurodiverse persons.
Slides here...

24 Oct 2024

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski-Raum, 05-119, Staudingerweg 7

Tomas Kasemets, Dr
Industry Talk on LADE

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Asst.-Prof. Dr. Yuval Shagam, Israel Institute of Technology
The weak force is predicted to break the parity symmetry between left and right-handed chiral molecules, but so far the effect has eluded detection. We are developing a trapped chiral molecular ion version of the search for parity violation (PV). Our candidate molecule, CHDBrI+ is predicted to be preparable via state-selective ionization and to exhibit a large PV shift of a few Hz for the C-H bend vibrational transition, where the transition’s natural linewidth is narrower than the shift. Other transitions such as the C-H stretch are also predicted to have Hz level PV shifts between enantiomers. We plan to probe the PV signature in a racemic, mixed-handedness ensemble of trapped CHDBrI+, using vibrational Ramsey spectroscopy. Our newly developed ion trap is integrated with a pulsed velocity map imaging detector to probe multiple internal state populations of the molecules by separating photo-fragment velocities. This technology will assist in overcoming the molecular complexity and help develop quantum control schemes for our molecule. We will also discuss the advantages chiral molecules have in searches for new physics as well as the status of the experiment.

28 Oct 2024

Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

JGU

11:00 Uhr s.t., Curie Raum (03-431)

Ao Du, ETHZ Zürich, Switzerland
Antiferromagnets (AFM) hold significant promise as ideal candidates for high-density and ultrafast memory applications. Electrical manipulation of exchange bias has emerged as an effective solution to integrate AFMs into magnetic memories as active elements. With this motivation, we demonstrate the electrical detection of antiferromagnetism in three-terminal magnetic tunnel junctions (MTJs) via exchange bias. A polarity-dependent switching of the exchange bias, driven by spin-orbit torque, is observed with a switching time as short as 0.6 nanoseconds. By incorporating spin-transfer torque, we achieve a substantial reduction in the critical switching current density for spin-orbit torque, enabling reconfigurable AND/OR logic functionalities within a single device. Utilizing the stable multi-state behavior and auto-reset features of this MTJ, we propose an all-spin spiking neural network with a low recognition error rate. These findings hold potential for advancing high-performance memories and in-memory computing.

29 Oct 2024

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Yan Luo, Peking U.
Axion-like particles (ALPs) are compelling candidates for new physics and have been extensively studied across a broad mass range, from sub-eV to hundreds of GeV. In this talk, I will discuss our recent works on ALP phenomenology across various experiments. First, I will present the potential for detecting ultralight ALP dark matter through radio telescopes that capture radio signals from axion-photon resonant conversion in the solar corona. We analyse data of the high-sensitivity radio telescope LOFAR, which provides stringent constraints on ALP interaction, contributing to the growing landscape of dark matter searches. I will then turn to collider and beam dump experiments, where we investigate the concurrent effects of ALPs, focusing on how ALP-photon and ALP-electron interactions jointly influence the detection of ALPs and demonstrate how current experimental limits are modified.

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Ekkehard Peik, Physikalisch-Technische Bundesanstalt Braunschweig
Motivated by the prospect of building a nuclear clock, we have demonstrated laser excitation of the low-energy (8.4 eV) nuclear isomer in Th-229, using Th-doped calciumfluoride crystals and a tabletop tunable laser system at 148 nm wavelength. A nuclear resonance fluorescence signal has been observed in two crystals with different Th-229 dopant concentrations, while it was absent in a control experiment using a crystal doped with Th-232. The isomer radiative lifetime in the crystal is 630(15) s. These results open the door towards laser Mössbauer spectroscopy and ideas from "quantum nucleonics". An accurate nuclear clock would show high sensitivity to effects of "new physics" for example in searches for violations of the Einstein equivalence principle. This is work done in a cooperation of PTB and TU Wien: J. Tiedau et al., Phys. Rev. Lett. 132, 182501 (2024)

30 Oct 2024

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Markus Klute, KIT
This talk will explore the physics potential of the Future Circular Collider (FCC), a proposed particle accelerator at CERN, capable of reaching energies and luminosities beyond the capabilities of current machines. We will discuss the FCC’s ability to probe the Standard Model with higher precision, its unique potential to explore the Higgs boson and discover new particles, and its role in addressing open questions in particle physics. The talk will illustrate how the FCC could shape our understanding of the universe at its most fundamental level. Link to presentation slides: https://www.dropbox.com/scl/fi/9l1v2wfsphp7glg9p42ku/2024-10-30-fcc.pdf?rlkey=jsxyz2tfi0bu6of99uofa2yc8&e=1&st=0j7yckpi&dl=0
Slides here...

31 Oct 2024

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Prof. Dr. Simon Stellmer, Universität Bonn
Imagine two light fields propagating in opposite directions along a ring-shaped contour. When set into rotation, the constancy of the speed of light will induce a phase shift between the two light fields. This observation, known as the Sagnac effect, is a very powerful yet simple approach to measure rotation. The first successful measurement of Earth's rotation via the Sagnac effect was performed by Albert A. Michelson and co-workers in late 1924, exactly 100 years ago. I will give a brief review of the historic work, present the current state of the art, and elaborate on potential applications and future developments.

05 Nov 2024

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Maria Laura Piscopo, Nikhef, Amsterdam
Weak decays of heavy hadrons provide an excellent way to test the flavour and QCD structure of the SM. In this talk, I will present recent results and ongoing work on the study of both inclusive and exclusive decays, in both the beauty and charm sectors. Specifically, I will start by discussing the current status of the heavy quark expansion (HQE) and its application to the study of heavy hadron lifetimes. Then, I will describe the analysis of non-leptonic two body $B$- and $D$-meson decays using the framework of light-cone sum rules (LCSR), in light of the observed tensions in channels like $B^0 \to D^+ K^-$, and of the recent discovery of CP violation in the charm sector.

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Juliane Simmchen, University of Strathclyde, Glasgow
Colloids are a beautiful example of the unseen richness of our world, with structures ranging from simple spheres to complex hierarchical structures that have fascinated scientists for centuries. Interfaces on the other side are ubiquitous in nature, industry and scientific setups. Passive colloids are known to show fascinating abilities such as surfactant-like stabilization of emulsions, for example the well-known Pickering emulsions. When tiny colloids are forced out of equilibrium, whether by catalytic processes, thermal effects or simple conjugation with biological objects, the resulting behaviour is fascinating and often offers unexpected parallels to the macroscopic world. We study both active and passive colloids in the presence of liquid interfaces, discovering rich behaviour despite the technical challenges of visualisation. [1] Wittmann, Martin, et al. "Active spheres induce Marangoni flows that drive collective dynamics." The European Physical Journal E 44 (2021): 1-11. [2] Sharan, Priyanka, et al. "Study of active Janus particles in the presence of an engineered oil–water interface." Langmuir 37.1 (2020): 204-210.

06 Nov 2024

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Roman Pöschl, LAL Orsay, France
Calorimeters play a pivotal role in past, present and future experiments in particle physics. Final states of particle physics collision consist to a large fraction of jets. These jets are composed of electrons, photons and charged and neutral hadrons. A central requirement to meet scientific goals at future experiments is to keep the jet energy resolution at a level of 3-4% for jet energies between 45 GeV and around a TeV (or more). There are several proposal to meet this goal, by increasing the granularity of the calorimeters by dedicated precise measurements of hadrons and electromagnetic particles within a jet or by a combination of these features. This seminar will review the requirements to calorimeters in future experiments and the status and outlook on the current R&D to meet these requirements. The seminar will also sketch the potential to apply machine learning for calorimetry and how quantum sensing may dramatically change the design of future calorimeters. Slides: https://docs.google.com/presentation/d/1P0fRA6z8l1XNLxh8bBXHHB0a90VHrjt63EOvA7wNEFg/edit?usp=sharing
Slides here...

12 Nov 2024

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Prem Piramanayagam, Nanyang Technological University, Singapore
Neuromorphic computing or brain-inspired computing is considered as a potential solution to overcome the energy inefficiency of the von Neumann architecture for artificial intelligence applications [1-4]. To realize spin-based neuromorphic computing practically, it is essential to design and fabricate electronic analogues of neurons and synapses. An electronic analogue of a synaptic device should provide multiple resistance states. A neuron device should receive multiple inputs and should provide a pulse output when the summation of the multiple inputs exceeds a threshold. Our group has been carrying out investigations on the design and development of various synaptic and neuron devices in our laboratory. Domain wall (DW) devices based on magnetic tunnel junctions (MTJs), where the DW can be moved by spin-orbit torque, are suitable candidates for the fabrication of synaptic and neuron devices [2]. Spin-orbit torque helps in achieving DW motion at low energies whereas the use of MTJs helps in translating DW position information into resistance levels (or voltage pulses) [3]. This talk will summarize various designs of synthetic neurons synaptic elements and materials [4]. The first half of the talk will be at an introductory level, aimed at first-year graduate students. The second half will provide details of the latest research

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Antonio Pittelli, University of Turin & INFN Turin
Supergravity solutions with orbifold singularities contribute non-trivially to the quantum gravity path integral, unveiling new holographic correspondences. These solutions relate to supersymmetric quantum field theories (QFTs) defined on orbifolds with conical singularities, whose partition functions capture crucial physical insights such as dualities between different models and the entropy of accelerating black holes. From a mathematical perspective, the path integrals of these theories link to topological invariants of the underlying orbifolds, extending known results from smooth manifolds to singular spaces. This talk will present an investigation into supersymmetric QFTs on orbifolds with conical singularities, focusing on general circle fibrations over spindles.

13 Nov 2024

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Arthur Hebecker, University of Heidelberg
I will start with a brief introduction to the UV-problems of gravity and how string theory proposes to resolve them. As we will see, this implies extra dimensions and hence the possibility of different "compactifications", leading to very many possible 4d theories. The idea that more or less any 4d model can be found in this huge "Landscape" has more recently been challenged by the "Swampland" paradigm, proposing to search for general criteria for what can or can not occur in 4d effective theories having a consistent UV completion in quantum gravity. I will discuss some of the most important such "Swampland Conjectures": The "No-Global Symmetries", "Weak Gravity" and "Distance Conjecture". Finally, I will briefly review the phenomenologically very important but less established "de Sitter Conjecture".
Slides here...

14 Nov 2024

GRK 2516 Soft Matter Seminar

Uni Mainz

10:30 Uhr s.t., HS 00.187, Biocenter 1, Hanns-Dieter-Hüsch-Weg 15

Wolfgang Binder, University of Halle
TBA / Joint GK2516 & SFB1551 Seminar
at Zoom

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Dr. Lykourgos Bougas, HIM (Mainz)
Quantum computing is moving beyond its traditional mainframe infrastructure with the realization of room-temperature technologies powered by the nitrogen-vacancy (NV) centers in diamond. At Quantum Brilliance, we are at the forefront of this innovation, developing compact quantum accelerators based on NV centers—artificial atoms that enable fully functional qubits in a solid-state environment. This innovation holds the potential to make quantum computing not only more accessible but also more practical. Our mission is to deliver room-temperature quantum processors that can be deployed across a variety of environments, from centralized data centers to the network edge. To achieve this, we are overcoming key technological challenges, such as the precise arrangement of NV centers at nanometer scales to enable magnetic coupling for multi-qubit operations across nodes. Quantum Brilliance addresses this using a breakthrough 'bottom-up' fabrication technique, leveraging atomically precise surface chemistry and lithography to build scalable diamond devices. Beyond scalability, we are also focused on advancing the performance, miniaturization, and manufacturability of these devices—crucial for achieving high-speed, high-fidelity spin control and efficient qubit readout in low-power, compact systems. These technological advancements are positioning diamond quantum technologies as a leading force in the transition to compact, high-performance quantum computing and quantum information processing. With pre-production prototypes underway, Quantum Brilliance is on track to develop quantum accelerators with over 50 qubits, poised to outperform classical CPUs and GPUs in critical applications within the next five years. In this presentation, I will explore the key innovations driving the performance, miniaturization, and scalability of diamond-based quantum technologies, and how these breakthroughs are set to transform the quantum computing landscape, enabling scalable, mass deployable quantum compute systems.

19 Nov 2024

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Jordi Jose, Universitat Politècnica de Catalunya
Stellar evolution and the origin of cosmic elements constitute a truly multidisciplinary arena that combines tools, developments and achievements in theoretical astrophysics, observational astronomy, cosmochemistry and nuclear physics: supercomputers have provided astrophysicists with the required computational capabilities to study the evolution of stars in a multidimensional framework; the emergence of high-energy astrophysics with space-borne observatories has opened new windows to observe the Universe, from a novel panchromatic perspective; cosmochemists have isolated tiny pieces of stardust embedded in primitive meteorites, giving clues on the processes operating in stars as well as on the way matter condenses to form solids; and nuclear physicists are measuring reactions near stellar energies, using stable and radioactive ion beams. This talk will provide a comprehensive insight into the physics of stellar explosions, with particular emphasis on some recent advances in the modeling of type Ia supernovae, classical and recurrent novae, and type I X-ray bursts.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Konstantin Asteriadis, University of Regensburg
We systematically study potential effects of BSM physics in the e+ e- -> Z H process. To this end, we include all relevant dimension-6 Standard Model Effective Field Theory operators and work to next-to-leading order (NLO) accuracy in the electro-weak coupling. We consider both polarized and unpolarized electron and positron beams and present results for $\sqrt{s}$=240, 365 and 500~GeV and emphasize observables where the NLO predictions differ significantly from the leading order (LO) results. At NLO, a sensitivity arises to operators that do not contribute at tree level, such as the Higgs trilinear coupling , CP violating operators, dimension-6 operators involving the top quark or anomalous Higgs-Z boson couplings, among many others. We compare the prospects of future e+e- colliders to explore these new physics effects with measurements from the LHC, electron EDMs (for CP violating operators), and Z pole measurements.

20 Nov 2024

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Ilaria Brivio, University of Bologna, Italy
The talk will give an overview of LHC probes of Axion-Like Particles (ALPs), whose couplings are parameterized via effective interactions of dimension larger than 5. The first part will introduce the main motivations for studying ALPs and it will discuss the main properties of the ALP EFT, while the second will be dedicated to phenomenological aspects. This will contain a general overview of how ALPs can be searched at colliders, as well as brief discussions of theory constraints stemming from perturbative unitarity and of recent new ideas brought forward in the field, such as the use of non-resonant ALP production in constraining ALP couplings to heavy SM states, and the exploration of ALP couplings beyond dimension-5.
Slides here...

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

10:15 Uhr s.t., Hilbert-Raum, 05-426, Staudingerweg 9

Alexander Kurganov, Prof. Dr.
I will present semi-discrete path-conservative central-upwind (PCCU) schemes for ideal and shallow water magnetohydrodynamics (MHD) equations. These schemes possess several important properties: they locally preserve the divergence-free constraint, they do not rely on any (approximate) Riemann problem solver, and they robustly producehigh-resolution and non- oscillatory results. The derivation of the schemes is based on the Godunov-Powell nonconservative modifications of the studied MHD systems. The local divergence-free property is enforced by augmenting the modified systems with the evolution equations for the corresponding derivatives of the magnetic field components. These derivatives are then used to design a special piecewise linear reconstruction of the magnetic field, which guarantees a non- oscillatory nature of the resulting scheme. In addition, the proposed PCCU discretization accounts for the jump of the nonconservative product terms across cell interfaces, thereby ensuring stability. I will also discuss the extension of the proposed schemes to magnetic rotating shallow water equations. The new scheme is both well-balanced and exactly preserves the divergence- free condition of the magnetic field. The well-balanced property is enforced by applying a flux globalization approach within the PCCU scheme. As a result, both still- and moving- water equilibria can be exactly preserved at the discrete level. The proposed PCCU schemes are tested on several benchmarks. The obtained numerical results illustrate the performance of the new schemes, their robustness, and their ability not only to achieve high resolution, but also preserve the positivity of computed quantities such as density, pressure, and water depth. The talk is based on joint works with Alina Chertock (North Carolina State University, USA), Michael Redle (RWTH Aachen University, Germany),Kailiang Wu (Southern University of Science and Technology, China) and Vladimir Zeitlin (Sorbonne University, France).

Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

JGU

13:00 Uhr s.t., 01 122 Newton-Raum

Dong-Soo Han, Center for Spintronics, Korea Institute of Science and Technology (KIST), Seoul 02456, Republic of Korea
Spintronics has emerged as a promising field for the development of energy-efficient magnetic memory and logic devices by controlling spin states in ferromagnets via spin-orbit coupling1,2. Efficient control of magnetization in ferromagnets is crucial for high-performance spintronic devices, and magnons have gained renewed interest as a potential avenue for achieving this goal with reduced Joule heating and minimized power consumption. In pursuit of this objective, Previous efforts have focused on optimizing magnon transport with minimal dissipation under the belief that dissipation hinders efficient magnetization control. In contrast, we present an unconventional approach that harnesses magnon dissipation for magnetization control instead of suppressing it. Our approach involves a heterostructure consisting of a ferromagnetic metal and an antiferromagnetic insulator, exploiting an intrinsic spin current within the ferromagnetic metal3,4. By combining a single ferromagnetic metal with an antiferromagnetic insulator that breaks spin transport symmetry while preserving charge transport symmetry, we achieve significant spin-orbit torques comparable to those observed in non-magnetic metals, enabling magnetization switching. Through systematic experiments and comprehensive analysis, we confirm that our findings arise from magnon dissipation within the AFI rather than external spin sources. These results provide novel insights into the mechanisms of spin current generation and dissipation, opening up new possibilities for developing energy-efficient spintronic devices. Reference 1. Sinova, J. et al. Rev. Mod. Phys. 87, 1213–1260 (2015). 2. Shao, Q. et al. IEEE. Trans. Magn. 57, 1–39 (2021). 3. Hibino, Y. et al. Nat. Commun. 12, 6254 (2021). 4. Wang, W. et al. Nat. Nanotechnol. 14, 819–824 (2019).

21 Nov 2024

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Prof. Dr. David Hunger, KIT (Karlsruher Institut für Technologie)
Optically addressable spins in the solid state are promising candidates for realizations of quantum networks and quantum computing nodes. We study NV centers in diamond coupled to an optical microcavity to enhance the optical emission and get efficient access to the spin degree of freedom. Studying small ensembles, we observe collectively enhanced emission and non-trivial photon statistics, despite the presence of inhomogeneities and spatial separation between emitters [1]. As an alternative color center, we study SnV centers in diamond, which can possess superior optical coherence properties. We observe hour-long spectral stability and Fourier-limited emission linewidths of individual emitters. We leverage their spin degree of freedom by studying a strained diamond at mK temperature. To avoid Ohmic losses in the microwave line, we fabricate a superconducting coplanar waveguide on a diamond membrane. We demonstrate coherent manipulation of the electron spin and evaluate the decoherence properties for different magnetic field orientations at mK temperature [2]. We furthermore identify strongly coupled nuclear spins and achieve nuclear spin state preparation and coherent control. Prospects for integration into a microcavity for efficient spin-photon interfacing are discussed [3]. A complementary platform is rare earth ion-based materials. I will report investigations of molecular rare-earth-complexes with promising coherence properties for quantum applications [4] and efforts to study single ions coupled to a cavity as qubits [5]. References [1] Pallmann et al., arxiv:2311.12723 [2] Karapatzakis et al., Phys Rev X 14, 031036 (2024) [3] Körber et al., Phys Rev Appl. 19, 064057 (2023) [4] Serrano et al., Nature 603, 241 (2022) [5] Deshmukh et al., Optica 10, 1339 (2023)

Seminar über die Physik der kondensierten Materie (SFB/TRR173 Spin+X und SFB/TR288 Kolloquium, TopDyn-Seminar)

JGU

14:00 Uhr s.t., 01 122 Newton-Raum

Vincent Jeudy, Laboratoire de Physique des Solides, CNRS, Université Paris-Saclay, 91405 Orsay Cedex, France.
The controlled displacement of spin textures as magnetic domain walls (DWs) is at the basis of potential applications to magnetic memory storage, neuromorphic computation... However, DWs are very sensitive to weak pinning defects, which strongly reduce their mobility and produce roughening and stochastic avalanche-like motion. The interplay between weak pinning disorder, DW elasticity, thermal fluctuations and an external drive leads to universal dynamical behaviors also encountered for interfaces in ferroelectrics, contact lines in wetting, bacterial colonies, failure propagation... In this variety of physical systems, the interfaces are expected to present both universal [1] and non-universal (material and temperature) behaviors, which are particularly important to disentangle for understanding the pinning dependent dynamics. In this talk, I will discuss a set of recent studies, which reveal the universal scaling functions accounting for both drive and thermal effects on the depinning and thermally activated creep motion [1] of DWs in thin ferromagnetic films with perpendicular anisotropy. Interestingly a self-consistent phenomenological model describing both the creep and depinning dynamics allows to compare the pinning properties of different materials [2], to address the interaction between DWs and pinning disorder [3] and to analyze the dynamics of other magnetic texture as skyrmions [4]. [1] V. Jeudy et al., Phys. Rev. Lett. 117, 057201 (2016); R. Diaz Pardo et al., Phys. Rev. B 95, 184434 (2017); R. Diaz Pardo et al., Phys. Rev. B 100, 184420 (2019); L. J. Albornoz et al., Phys. Rev. B 110, 024403 (2024) [2] V. Jeudy et al., Phys. Rev. B 98, 054406 (2018) [3] P. Géhanne et al., Phys. Rev. Res. 2, 043134 (2020); C. Balan et al., Appl. Phys. Lett. 122, 162401 (2023) [4] S. Mallick et al., Nat. Commun 15, 8472 (2024)

22 Nov 2024

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:15 Uhr s.t., Hilbert room, 05-426, Staudingerweg 9

Alina Chertock, Prof. Dr.
Many important scientific problems involve several sources of uncertainties, such as model parameters and initial and boundary conditions. Quantifying these uncertainties is essential for many applications since it helps to conduct sensitivity analysis and provides guidance for improving the models. The design of reliable numerical methods for models with uncertainties has seen a lot of activity lately. One of the most popular methods is Monte Carlo-type simulations, which are generally good but inefficient due to the large number of realizations required. In addition to Monte Carlo methods, a widely used approach for solving partial differential equations with uncertainties is the generalized polynomial chaos (gPC), where stochastic processes are represented in terms of orthogonal polynomials series of random variables. It is well-known that gPC- based methods, which are spectral-type methods, exhibit fast convergence when the solution depends smoothly on random parameters. However, their application to nonlinear systems of conservation/balance laws still encounters some significant difficulties. The latter is related to the presence of discontinuities that may develop in numerical solutions in finite time, triggering the appearance of aliasing errors and Gibbs-type phenomena. This talk will provide an overview of numerical methods for models with uncertainties and explore strategies to address the challenges encountered when applying these methods to nonlinear hyperbolic systems of conservation and balance laws.

26 Nov 2024

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Anna Watts, University of Amsterdam
Mapping Neutron Stars – Inside and Out

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Raoul Rontsch, University of Milan
With the measurements made by the experiments at the Large Hadron Collider becoming increasingly precise, it is vital that theoretical predictions reach the same level of precision, including for high multiplicity processes. This necessitates calculations to at least next-to-next-to-leading order (NNLO) in perturbative QCD. One of the challenges in computing such corrections is the treatment of infrared singularities, which arise at intermediate stages of the calculation. Although such singularities must cancel for physical observables, making this cancellation manifest while maintaining fully differential results is challenging, especially at NNLO where singularities from different kinematic limits may overlap in a complicated way. I will discuss the development of the nested soft-collinear subtraction scheme to regulate IR singularities and arrive at a finite physical result at NNLO. I will begin by outlining the method for the production of a color-singlet, and then discuss recent efforts to generalize it to arbitrary hadroproduction processes.

27 Nov 2024

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Lorenzo Bianchini, University of Pisa, Italy
The mass of the W boson, the mediator of the charged weak interaction, can be predicted with a relative precision of about 80 ppm within the Standard Model (SM) of particle physics. The existence of new physics could however affect the W boson mass via quantum loops and shift it with respect to the SM prediction. Thus, a direct measurement of the W mass can be both a sensitive test of consistency of the theory as well as a window to new physics. In this respect, great interest, together with confusion, was raised by the measurement delivered by the CDF Collaboration in 2022 which, besides being the most precise measurement to date, is in disagreement with the SM and also barely consistent with previous measurements. Up until recently, the CMS experiment was the last missing contributor to the W mass effort. The new result by CMS which I will present in this seminar is based on a partial sample of LHC proton-proton collision data collected during the 2016 data-taking period. The W boson mass is extracted using single-muon events via a highly granular maximum likelihood fit of the muon kinematics split by charge and by relying on state-of-the-art tools for the modeling of W boson production and decay. This novel approach enables significant in-situ constraints of experimental and theoretical uncertainties. The CMS result has an uncertainty comparable to the CDF measurement and agrees with the SM. It represents a crucial step in solving the W boson mass puzzle.
Slides here...

28 Nov 2024

GRK 2516 Soft Matter Seminar

Uni Mainz

10:30 Uhr s.t., HS 00.187, Biocenter 1, Hanns-Dieter-Hüsch-Weg 15

Jurriaan Huskens, University of Twente
Multivalency describes many types of interfacial interactions in Nature. For example, hemagglutinin coat proteins of the influenza virus bind non-covalently to multiple sialyl-terminated carbohydrates (SLNs) of a host cell. This interaction is weakly multivalent in nature, and therefore it responds very sensitively to the density of carbohydrates on the cell surface and to the individual affinity of the interacting molecular partners. This behavior explains the large differences between virus affinities observed for mutations in the receptor binding domain. A key aspect of the multivalent interaction of viruses at cell membranes is its strong, non-linear dependence on the receptor density displayed at the surface. We here show the development of surface gradients of receptor-modified supported lipid bilayers (SLBs) to visualize and quantify the receptor density dependence in one microscopic image. This technique is called “Multivalent Affinity Profiling”. The fitting of the data by a thermodynamic model allows quantification of the threshold density, comparison of binding selectivities for different virus strains, and thus offers a molecular and quantitative understanding of the supramolecular binding energy landscape. This supramolecular and nanoscopic picture links fundamental molecular aspects of binding to biological processes of antigenic drift and zoonosis. At a more general level, chemically modified interfaces can be used to study complex (bio)chemical recognition processes, such as the binding of viruses and DNA. Exquisite receptor or probe density control is achieved through surface receptor gradients and by poly-L-lysine chemistry with control over grafting density. Multivalent recognition events are probed and controlled at surfaces and in solution by molecular engineering of the interfaces of the involved building blocks. These concepts can, amongst others, be used to control the self-assembly of vesicles and other materials building blocks and to develop a method to isolate the cancer biomarker hyper-methylated DNA. (Co-hosted with SFB 1551 Seminar Series)
Slides here...
at Zoom

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Dr. Claudiu Genes, MPI für die Physik des Lichts, Erlangen
Superradiance and subradiance are fundamental aspects of the open system dynamics of dense ensembles of quantum emitters exhibiting spontaneous emission rates well below or well above the rate for a single isolated system. At the purely theoretical level, superradiance has been first discussed by Dicke in 1954, in the context of accelerated decay of an ensemble of identical N initially inverted two-level quantum systems. In practice, such cooperative behavior associated with super- and subradiance at low excitation levels, has been observed in the 1930s by Jelley and Scheibe, in the context of molecular aggregates: unexpectedly large absorption cross-sections have been recorded for dye molecules. This has been later explained by Kasha in the 1960s as stemming from the alignment of the transition dipole moments of the many nanometer-spaced monomers forming the aggregate. We analytically tackle such issues with methods of open quantum system dynamics, in particular quantum Langevin equations and master equations. For the problem of Dicke superradiance we identify an exact analytical solution for the time evolution of the density operator, valid for any time t any number N of emitters. In the direction of quantum optics with molecules, we provide analytical models and solutions for the excitation migration between collective electronic levels in molecular aggregates and for processes involving non-radiative transitions due to non-adiabatic couplings of potential electronic landscapes in single large organic molecules. [1] R. Holzinger and C. Genes, Exact solution for Dicke superradiance, arXiv:2409.19040, (2024). [2] R. Holzinger, N. S. Bassler, H. Ritsch and C. Genes, Scaling law for Kasha's rule in photoexcited molecular aggregates, J. Phys. Chem. A 128, 19, 3910 (2024). [3] N. S. Bassler, M. Reitz, R. Holzinger, A. Vibók, G. J. Halász, B. Gurlek and C. Genes, Generalized energy gap law: An open system dynamics approach to non-adiabatic phenomena in molecules, arXiv:2405.08718 (2024).

03 Dec 2024

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Daniel Schmitt, Frankfurt U.
Future gravitational wave (GW) observatories offer an exciting opportunity to explore new physics at unprecedented energy scales. A prominent class of models predicting strong GW signals are quasi-conformal Standard Model (SM) extensions, which offer a mechanism for dynamically generating the electroweak (EW) scale. These models modify the thermal history of the Universe by a substantial period of thermal inflation that typically ends with a strong first-order phase transition. I will show that a large parameter exists where this scenario changes. Instead, QCD chiral symmetry breaking triggers a tachyonic phase transition, driven by classical rolling of a new scalar field sourcing EW symmetry breaking. As the field evolves through a regime where its effective mass is negative, long-wavelength scalar field fluctuations are exponentially amplified, preheating the supercooled Universe. This process generates a strong, unique GW background detectable by future experiments across nearly the entire viable parameter space.

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Andreas von Manteuffel, Universität Regensburg
Perturbative quantum field theory predicts complex phenomena at particle colliders from basic first principles. By comparing precise high energy data with precise theory predictions, one can probe the fundamental laws of nature down to very small distances, and identify possible signals of physics beyond the standard model of particles. In this colloquium, I show how calculating higher order quantum corrections enables a concise interpretation of measurements at the Large Hadron Collider and other facilities. I illustrate how a better understanding of the underlying mathematical structures and the adoption of new computational techniques have pushed the frontier in theoretical predictions.
Slides here...

04 Dec 2024

PRISMA+ Colloquium

Institut für Physik

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

Dr. Larisa Thorne, Johannes Gutenberg-University Mainz
Nearly 70 years since the neutrino was discovered, and 25 years since discovery of neutrino oscillations established its non-zero mass, the absolute neutrino-mass scale remains unknown. Tritium beta decay endpoint measurements currently offer the best upper limit on the neutrino mass. A next-generation experiment with greater sensitivity must overcome one of the major systematics for this kind of measurement: the molecular nature of the beta source. Past and current tritium beta decay experiments use a molecular tritium source in which one of the tritium atoms undergoes decay. A fraction of the decay energy excites the molecule into rotational, vibrational, or electronic excited states; this causes broadening in the molecule's final state distribution (FSD), and has a smearing effect on the beta decay spectrum. In order to achieve a reduced systematic uncertainty due to this FSD smearing, next-generation experiments must switch to an atomic tritium source. I will present an overview of the necessary steps to develop such an atomic tritium source, through the lens of the Project 8 experiment. This multi-institution development program includes dissociation and accommodation cooling down to 10K; further cooling to 10mK via magnetic evaporative cooling; and atom trapping using magnet arrays. In addition to this overview, I will focus on the multitude of tritium-compatible diagnostic tools being developed at JGU Mainz to measure atom flux, atom beam shape, and temperature.
Slides here...

05 Dec 2024

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Prof. Steffen Glaser, Technische Universität München
Analytical and numerical tools of optimal control theory (1) have found widespread applications in NMR and EPR spectroscopy, imaging, and in quantum information processing (2). In the last decade, these tools not only provided pulse sequences of unprecedented performance and capabilities, but also new analytical and geometrical insight and a deeper understanding of pulse optimization problems. The definition of the figure of merit for a pulse sequence is crucial for the optimization for a desired range of applications. In addition to standard figures of merit for excitation, inversion and refocusing pulses, more general figures of merits have made it possible to significantly extend the range of applications. This will be illustrated for recent examples from the field of NMR and the control of trapped cold atoms (3). Furthermore, based on the DROPS (4) and BEADS (5) representations, novel intuitive visualization approaches have been developed to see the dynamics of multi-qubit systems in quantum information processing and beyond. (1) N. Khaneja, R. Brockett, S. J. Glaser, Phys. Rev. A 63, 032308/1-13 (2001); N. Khaneja, S. J. Glaser, R. Brockett, Phys. Rev. A 65, 032301 (2002); N. Khaneja, T. Reiss, C. Kehlet, T. Schulte-Herbrüggen, S. J. Glaser, J. Magn. Reson. 172, 296-305 (2005). (2) S. J. Glaser, U. Boscain, T. Calarco, C. P. Koch, W. Köckenberger, R. Kosloff, I. Kuprov, B. Luy, S. Schirmer, T. Schulte-Herbrüggen, D. Sugny, F. K. Wilhelm, Eur. Phys. J. D 69, 279/1-24 (2015); C. P. Koch, U. Boscain, T. Calarco, G. Dirr, S. Filipp, S. J. Glaser, R. Kosloff, S. Montangero, T. Schulte-Herbrüggen, D. Sugny, F. K. Wilhelm, Eur. Phys. J. Quantum Technology 9, 19/1-60 (2022). (3) Z. Zhang, L. Van Damme, M. Rossignolo, L. Festa, M. Melchner, R. Eberhard, D. Tsevas, K. Mours, E. Reches, J. Zeiher, S. Blatt, I. Bloch, S. J. Glaser, A. Alberti, arXiv:2410.02452 [quant-ph] (2024); L. Van Damme, Z. Zhang, A. Devra, S. J. Glaser, A. Alberti, arXiv:2410.02452 [quant-ph] (2024). (4) A. Garon, R. Zeier, S. J. Glaser, Phys. Rev. A 91, 042122 (2015); D. Leiner, R. Zeier, S. J. Glaser, J. Phys. A: Math. Theor. 53, 495301 (2020). (5) D. Huber, S. J. Glaser, arXiv:2410.01446 [quant-ph] (2024).

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski-Raum, 05-119, Staudingerweg 7

Jürgen Horbach, Prof. Dr.
We consider a class of non-standard, two-dimensional (2D) Hamiltonian models that may show features of active particle dynamics, and therefore, we refer to these models as active Hamiltonian (AH) systems. The idea is to consider a spin fluid where -- on top of spin-spin and particle-particle interactions -- spins are coupled to the particle's velocities via a vector potential. Continuous spin variables interact with each other as in a standard $XY$ model. Typically, the AH models exhibit non-standard thermodynamic properties (e.g.~for temperature and pressure) and equations of motion with non-standard forces. This implies that the derivation of symplectic algorithms to numerically solve Hamilton's equations of motion, as well as the thermostatting for these systems, is not straightforward. However, one can make use of the fact that for Hamiltonian systems the equipartition theorem holds, providing a clear definition of temperature (note, however, that the temperature is not given by the average kinetic energy in this case) [1]. We derive a symplectic integration scheme and propose a Nos\'e-Poincar\'e thermostat, providing a correct sampling in the canonical ensemble [2]. Results for two different AH models are presented: (i) A model proposed by Casiulis et al. [3] shows transition from a fluid at high temperature to a cluster phase at low temperature where, due to the coupling of velocities and spins, a center-of-mass motion of the cluster occurs. The claim in Ref. [3] that this cluster motion is reminiscent of real flocks of birds has been challenged by Cavagna et al. [4]. (ii) We propose an AH model where spins and velocities are coupled such that as a result particles feel a generalized Lorentz force. We show that our model leads to a collective motion of particle clusters that is closer to the behavior of flocks of birds. [1] K. Huang, Statistical Mechanics (John Wiley \& Sons, New York, 1987). [2] A. Bhattacharya, J. Horbach, and S. Karmakar, arXiv:2409.14864 (2024). [3] M. Casiulis, M. Tarzia, L. F. Cugliandolo, and O. Dauchot, Phys. Rev. Lett. {\bf 124}, 198001 (2020). [4] A. Cavagna, I. Giardina, and M. Viale, arXiv:1912.07056 (2019).
at Zoom

10 Dec 2024

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Dierk Raabe, Max Planck-Institute for Sustainable Materials, Düsseldorf
Iron- and steelmaking stand for about 8% of all global greenhouse gas emissions, which qualifies this sector as the biggest single cause of global warming. This originates from the use of fossil carbon carriers as precursors for the reduction of iron oxides. Mitigation strategies pursue the replacement of fossil carbon carriers by sustainably produced hydrogen and / or electrons as alternative reductants, to massively cut these CO2 emissions, thereby lying the foundations for transforming a 3000 years old industry within a few years. As the sustainable production of hydrogen using renewable energy is a bottleneck in green steel making, the gigantic annual steel production of 1.85 billion tons requires strategies to use hydrogen and / or electrons very efficiently and to yield high metallization at fast reduction kinetic. This presentation presents progress in understanding the governing mechanisms of hydrogen-based direct reduction and plasma reduction of iron oxides. The metallization degree, reduction kinetics and their dependence on the underlying redox reactions in hydrogen-containing direct and plasma reduction strongly depend on mass transport kinetics, Kirkendall effects, nucleation phenomena, chemical and stress partitioning, the oxide's chemistry and microstructure, the acquired and evolving porosity, crystal plasticity, damage and fracture effects associated with the phase transformation phenomena occurring during reduction. Understanding these effects, together with external boundary conditions such as other reductant gas mixtures, oxide feedstock composition, pressure and temperature, is key to produce hydrogen-based green steel and design corresponding direct reduction shaft or fluidized bed reactors, enabling the required massive C02 reductions at affordable costs. Possible simulation approaches that are capable of capturing some of these phenomena and their interplay are also discussed.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Gaia Fontana, University of Zurich
Theoretical predictions beyond tree-level are necessary for a meaningful comparison between theory and experiment. Their calculation makes it inevitable to deal with infrared (IR) divergencies, stemming from partons becoming soft or collinear. One way to overcome them is to resort to subtraction schemes. In this talk, I will present the antenna subtraction scheme and the current efforts to extend it to N3LO, focusing on the situation where hard radiators are both in the initial and in the final state. First, I will review the extension of the N2LO initial-final antennae to higher epsilon order and present a purely analytic strategy to fix the boundary conditions of the relevant phase-space integrals (based on the Auxiliary Mass Flow method). Finally, I present the status of the calculation of N3LO initial-final antennae and the theoretical machinery necessary to perform this it, which includes translating phase space integrals into cuts of loop integrals, finding a canonical basis and fixing boundary conditions.

11 Dec 2024

PRISMA+ Colloquium

Institut für Physik

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

Marco Cirelli, Laboratoire de Physique Théorique et Hautes Énergies (LPTHE) Jussieu CNRS & Sorbonne Université
For decades, we have been looking for Dark Matter in the form of WIMPs, but many other possibilities exist. Light DM, intended as having a mass between 1 MeV and about 1 GeV, is one of these possibilities, which is interesting both theoretically and phenomenologically. Testing it via Indirect Detection is more challenging than WIMPs, but X-ray measurements provide a very powerful handle. They currently impose stringent constraints, and allow in perspective to explore further this relatively new region of the parameter space.
Slides here...

12 Dec 2024

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Prof. Ruben de Groote, KU Leuven, Belgien
Laser spectroscopy techniques provide nuclear-model independent access to nuclear properties, such as the electromagnetic moments, spins and charge radii. Advances in radioactive ion beam instrumentation and laser technologies have enabled the study of a wide range of elements and isotopes, pushing out far from the valley of stability towards the drip lines. In this seminar, I will present experimental progress along two important frontiers. I will discuss the use of methods based on laser ionization spectroscopy and how they have allowed us to reach exotic nuclei, such as 94Ag 52K, which have long been out of reach. The role of these measurements in furthering our understanding of the atomic nucleus will also be put into context. Besides using efficient laser ionization and particle detection methods, another important frontier is the precision frontier. I will focus on ongoing research which aims to perform optical and radiofrequency spectroscopy of radioactive ions while they are trapped in a linear Paul trap. I will discuss the status and first commissioning results of a new setup currently under construction at the KU Leuven.

16 Dec 2024

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., THEP social room (Staudingerweg 7, 5th floor)

Thomas Steingasser, Massachusetts Institute of Technology & Black Hole Initiative at Harvard University
The Higgs potential appears fine-tuned, relating to the hierarchy problem, the metastability of the electroweak vacuum and, arguably, the cosmological constant problem. While such behavior is puzzling in conventional particle physics, it is a common feature of dynamical systems. This motivated the conjecture that the Higgs' parameters are set by some dynamical mechanism. In this talk, I will demonstrate how these ideas can be linked — in a mostly mechanism-independent way — to concrete phenomenological predictions that can be tested by realistic future experiments such as the FCC or next-generation GW detectors. Along the way, I will also highlight several lessons learnt for the construction of concrete vacuum selection mechanisms.

17 Dec 2024

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Metin Tolan, Georg-August-Universität Göttingen
Die Star Trek-Physik - Warum die Enterprise 158 kg wiegt und andere galaktische Erkenntnisse

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Di Zhang, Technical University of Munich
In this talk, a new physical basis and a Green’s basis for dimension-seven (dim-7) operators are proposed, which are suitable for the matching of ultraviolet models onto the Standard Model Effective Field Theory (SMEFT) and the deviation of renormalization group equations (RGEs) for the SMEFT dim-7 operators. The reduction relations to convert operators in the Green’s basis to those in the physical basis are achieved as well, where some redundant dim-6 operators in the Green’s basis are involved if the dim-5 operator exists. Working in these two bases, we work out the one-loop RGEs resulting from the mixing among different dimensional operators for the SMEFT dim-7 operators for the first time, and also revisit those from the mixing among dim-7 operators. These results complete the full one-loop RGEs of dim-7 operators and can be used for a consistent one-loop analysis of the SMEFT. On the other hand, we accomplish the full two-loop RGE of the dim-5 Weinberg operator and discuss its effects on the initially massless neutrino.

18 Dec 2024

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Camilo Garcia-Cely, IFIC Valencia, Spain
A decade has passed since the groundbreaking detection of gravitational waves, significantly advancing our understanding of the cosmos. While most current research focuses on detecting gravitational waves at frequencies below a few kHz, there is a growing interest in exploring higher-frequency signals, particularly those of cosmological origin. In the first part of my talk, I will explore the background for these signals within the Standard Model, with a focus on the primary source on Earth: the Sun's high-temperature plasma. I will draw a notable connection to solar axions. In the second part, the discussion will turn to experimental approaches for detecting high-frequency gravitational waves, with particular attention to the potential of axion haloscopes as well polarimetry techniques.
Slides here...

19 Dec 2024

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Prof. Dominique Sugny, Laboratoire Interdisciplinaire Carnot de Bourgogne, Dijon
We apply innovative tools coming from quantum optimal control theory to improve theoretical and experimental techniques in quantum technologies [1,2]. This approach allows us to explore and to experimentally reach the physical limits of the corresponding dynamics in the presence of typical experimental imperfections and limitations. After a pedagogical introduction to these techniques [3], different applications in quantum technologies will be described. Recent theoretical and experimental results for the control of a Bose-Einstein Condensate in an optical lattice will be presented [4]. [1]- Quantum optimal control in quantum technologies. Strategic report on current status, visions ans goals for research in Europe C. P. Koch, U. Boscain, T. Calarco, G. Dirr, S. Filipp, S. Glaser, R. Kosloff, S. Montangero, T. Schulte-Herbruggen, D. Sugny and F. K. Wilhelm EPJ Quantum Technol. 9, 19 (2022) [2]- Introduction to the Pontryagin Maximum Principle for Quantum Optimal Control U. Boscain, M. Sigalotti, and D. Sugny PRX Quantum 2, 030203 (2021) [3]- Introduction to the theoretical and experimental aspects of quantum optimal control Q. Ansel, E. Dionis, F. Arrouas, B. Peaudecerf, S. Guérin, D. Guéry-Odelin and D. Sugny J. Phys. B 57, 133001 (2024) [4]- Quantum state control of a Bose Einstein condensate in an optical lattice N. Dupont, G. Chatelain, L. Gabardos, M. Arnal, J. Billy, B. Peaudecerf, D. Sugny, D. Guéry-Odelin PRX quantum 2, 040303 (2021)

07 Jan 2025

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Hanna Kokko, JoGU Mainz
Do you think you understand sex and death? Why predictions about biological processes require more than just intuition

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Bernd Sturmfels, Max Planck Institute for Mathematics in the Sciences Leipzig
We discuss determinantal varieties for symmetric matrices that have zero blocks along the main diagonal. In theoretical physics, these arise as Gram matrices for kinematic variables in quantum field theories. We also explore the ideals of relations among functions in the matrix entries that serve as building blocks for conformal correlators.

08 Jan 2025

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Kathrin Valerius, KIT
The mass of neutrinos is a fundamental open question in physics, impacting both the Standard Model of elementary particles and cosmology. Precision measurements of weak decay kinematics offer a laboratory-based, model-independent method to probe the absolute neutrino mass scale. The KArlsruhe TRItium Neutrino experiment (KATRIN) seeks to detect the subtle imprint of the neutrino mass in the endpoint region of the tritium beta-decay spectrum. Combining a high-intensity gaseous molecular tritium source with a high-resolution electrostatic filter using magnetic adiabatic collimation, KATRIN has set the most stringent direct neutrino-mass limit at m(ν) < 0.8 eV/c2 (90% C.L.) based on an initial data set. Ongoing data collection and analysis aim for a sensitivity below 0.3 eV/c2. Additionally, KATRIN’s precision beta-spectrum data facilitates searches for new physics beyond the neutrino mass, including sterile neutrinos, Lorentz invariance violation, and non-standard weak interactions. This talk presents the latest results and future prospects of the experiment.

09 Jan 2025

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Dr. Antoine Browaeys, CNRS, Palaiseau, France
Over the last twenty years, physicists have learned to manipulate individual quantum objects: atoms, ions, molecules, quantum circuits, electronic spins... It is now possible to build "atom by atom" a synthetic quantum matter. By controlling the interactions between atoms, one can study the properties of these elementary many-body systems: quantum magnetism, transport of excitations, superconductivity... and thus understand more deeply the N-body problem. More recently, it was realized that these quantum machines may find applications in the industry, such as finding the solution of combinatorial optimization problems. This seminar will present an example of a synthetic quantum system, based on laser-cooled ensembles of individual atoms trapped in microscopic optical tweezer arrays. By exciting the atoms into Rydberg states, we make them interact, even at distances of more than ten micrometers. In this way, we study the magnetic properties of an ensemble of more than a hundred interacting ½ spins, in a regime in which simulations by usual numerical methods are already very challenging. Some aspects of this research led to the creation of a startup, Pasqal.

14 Jan 2025

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Wen-Yuan Ai, Vienna, OAW
The terminal bubble wall velocity in a first-order phase transition (FOPT) is a critical parameter that influences not only the gravitational wave power spectrum but also a wide range of FOPT-related phenomena, including baryogenesis and dark matter production. However, precise computation of this velocity remains challenging. In this talk, I will discuss how to establish bounds on bubble wall velocities using two straightforward approximations: the local thermal equilibrium (LTE) approximation and the ballistic approximation. We perform numerical calculations both for a model-independent analysis and within an example model, the singlet-extended Standard Model.

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Stefan Ulmer, Heinrich Heine-Universtät Düsseldorf
The striking imbalance of matter and antimatter in our universe 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 cryogenic Penning traps, we have performed the most precise comparison of the proton-to-antiproton charge-to-mass ratio with a fractional uncertainty of 16 parts in a trillion [1], and have invented a novel spectroscopy technique, that allowed for the first direct high-precision measurement of the antiproton magnetic moment with a fractional accuracy of 1.5 parts in a billion [2]. Together with our last measurement of the proton magnetic moment [3] this improves the precision of previous magnetic moment based tests of the fundamental CPT invariance by more than a factor of 3000. A time series analysis of the sampled magnetic moment resonance furthermore enabled us to set first direct constraints on the interaction of antiprotons with axion-like particles (ALPs) [4], and most recently, we have used our ultra-sensitive single particle detection systems to derive constraints on the conversion of ALPs into photons [5]. In parallel we are working on the implementation of new measurement technology to sympathetically cool antiprotons [6] and to apply quantum logic inspired spectroscopy techniques [7]. In addition to that, we are currently developing the transportable antiproton-trap BASE-STEP, partly developed at Mainz, to relocate antiproton spectroscopy experiments from CERN’s accelerator environment to dedicated precision laboratory space at Heinrich Heine University Düsseldorf, very recently, the first loaded transport of this trap has been demonstrated successfully I will give a general introduction to the topic, will review the recent results produced by BASE, with particular focus on recent developments towards an at least 10-fold improved coherent measurement of the antiproton magnetic moment, and towards the first antiproton transport. [1] M. J. Borchert et al., Nature 601, 35 (2022). [2] C. Smorra et al., Nature 550, 371 (2017). [3] G. Schneider et al., Science 358, 1081 (2017). [4] C. Smorra et al., Nature 575, 310 (2019). [5] J. A. Devlin et al., Phys. Rev. Lett. 126, 041321 (2021). [6] M. A. Bohman et al. Nature 596, 514 (2021) [7] J. M Conrejo et al., New J. Phys. 23 073045

15 Jan 2025

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Henrique Araujo, Imperial College London, UK
Nature continues to torment us with several well-posed and important questions which we have collectively failed to answer over several decades. What is the composition of the elusive “dark matter” that accounts for most of the mass of the cosmos? And why is the sub-dominant fraction of ordinary matter itself composed of particles rather than antiparticles? These fundamental questions may be answered by “listening in” to a large collection of very quiet atoms at the core of extremely sensitive radiation detectors installed deep underground. The XLZD Rare Event Observatory will address these important topics by searching for the scattering of dark matter particles in a large liquid xenon detector, and by searching for the neutrinoless double-beta decay of Xe-136 nuclei – another process with profound implications for fundamental physics. I will present some of the latest results from the ongoing LZ experiment taking data at the Sanford Lab, and then review the scientific motivation for, and potential reach of, the next-generation effort – XLZD. Finally, I will set out our vision to host the experiment in a newly developed Boulby Underground Laboratory in the UK.

16 Jan 2025

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Dr. Vera Schäfer, MPI Heidelberg
Precision measurements of atomic transition frequencies have become a promising path for testing theories for new physics beyond the standard model. To achieve even higher precision more stable and narrow-linewidth laser sources are required. Superradiant lasers are a candidate for realising a narrow-linewidth, high-bandwidth active frequency reference. They shift the phase memory from the optical cavity, which is subject to technical and thermal vibration noise, to an ultra-narrow optical atomic transition of an ensemble of cold atoms trapped inside the cavity. Our previous demonstration of pulsed superradiance on the mHz transition in 87Sr achieved a fractional Allan deviation of 6.7*10−16 at 1s of averaging. Moving towards continuous-wave superradiance promises to further improve the short-term frequency stability by orders of magnitude. A key challenge is the continuous supply of cold atoms into a cavity, while staying in the collective strong coupling regime. We demonstrate continuous loading and transport of cold 88Sr atoms inside a ring cavity, after several stages of laser cooling and slowing. We further describe the emergence of distinct zones of collective continuous lasing of the atoms on the 7.5kHz transition, 7x narrower than the cavity linewidth, and pumped by the cooling lasers via inversion of the motional states. The lasing is supported by self-regulation of the number of atoms inside the cavity that pins the dressed cavity frequency to a fixed value over >3MHz of raw applied cavity frequency. In the process up to 80% of the original atoms are expelled from the cavity. I will also present a new project in Heidelberg aiming to use precision spectroscopy of highly charged ions to search for a variation of the fine-structure constant.

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski-Raum, 05-119, Staudingerweg 7

Hendrik Ranocha, Prof. Dr.
Compressible computational fluid dynamics (CFD) is an active and fruitful area of research. In this talk, we will focus on time integration methods optimized for CFD applications. We will briefly review the classical Courant-Friedrichs-Lewy (CFL) constraint and present error-based time step size control as an alternative. In particular, we will discuss how the design of the methods influences their efficiency and robustness. Combining theoretical analysis with a data-driven approach, we will present new optimized time integration methods for compressible CFD applications that are available in open-source software.
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21 Jan 2025

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Nancy Paul, Laboratoire Kastler Brossel, Jussieu
From dark matter and dark energy to neutrino oscillations and the lack of antimatter in the universe, there is growing evidence that the Standard Model is incomplete. Tests of Quantum Electrodynamics (QED) with few-electron systems offer a promising avenue for looking for new physics, as QED is the best understood quantum field theory and extremely precise predictions can be obtained for few-electron systems. Unfortunately, despite decades of effort, QED is poorly tested in the regime of strong coulomb fields, precisely the region where new exotic physics may be most visible. I will present a new paradigm for probing higher-order QED effects using spectroscopy of Rydberg states in exotic atoms, where orders of magnitude stronger field strengths can be achieved while nuclear uncertainties may be neglected. Such tests are now possible due to the advent of quantum sensing microcalorimeter x-ray detectors and new facilities providing low-energy intense beams of exotic particles for precision physics. First measurements have been successfully conducted at J-PARC with muonic atoms, but antiprotonic atoms offer the highest sensitivity to strong-field QED. I will present an overview of the PAX project, a new experiment for antiprotonic atom x-ray spectroscopy with a large-area transition edge sensor (TES) x-ray detector and low-energy cyclotron trap at ELENA. Finally, the experimental paradigm can also be reversed such to study low-lying states and access nuclear properties, such as those pursued in the QUARTET collaboration at Paul Scherrer Institute to improve the charge radii of light nuclei. I will present first results from QUARTET, and discuss synergies between atomic and nuclear physics accessible with these experiments.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Jungwon Lim, Max Planck Institute for Physics, Munich
This talk will present the detailed procedure of computing three-loop four-point Feynman integrals with one massive leg and the applications to three-point form factors and Higgs plus jet amplitudes. In the first part, I will discuss technical details of computing three-loop four-point Feynman integrals using differential equation methods. In the second part, I will discuss about the analytic properties of the form factors and recent updates on the form factors and Higgs plus jet amplitude.

22 Jan 2025

PRISMA+ Colloquium

Institut für Physik

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

Dr. Wilf Shorrock, University of Sussex, UK
The NOvA neutrino oscillation experiment has been collecting data for over 10 years. Since the last NOvA analysis, the neutrino dataset has almost doubled, and there have been several improvements to the treatment of systematics and physics models. The most recent results introduce a new low energy electron neutrino sample and give the most precise single-experiment measurement of ?m_32^2 to date. My talk will give an extensive overview of the NOvA experiment and their latest results, as well as looking at the future of NOvA and neutrino oscillation experiments.
Slides here...

23 Jan 2025

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Prof. Dr. Tobias Schätz, Universität Freiburg
The field of ultra-cold chemistry of ions and atoms has been launching the fundamental quest for investigating its quantum regime for decades. A simplifying summary of the quest might be: How do interactions and chemical reactions proceed at extremely low temperatures? The classical picture predicts that all dynamics comes to a standstill as zero velocity is approached. However, deviations are expected since the classical model ceases to be appropriate at microscopic scales and at low temperatures, where particle-wave dualism of matter get’s important. In this regime, quantum effects dominate and reactions are predicted to obey fundamentally different rules. Examples are: (i) collisions of atoms, necessary for a reaction, cannot be described as a billiard-like impact between hard spheres anymore, but rather as interfering waves, interacting at long range, which can coherently amplify or even decoherently annihilate each other. (ii) energy barriers can exceed the available kinetic energy, but nevertheless be efficiently passed via quantum tunnelling, ruling the dynamics. Experimentally, we immerse a single barium (Ba+) ion in a bath of fermionic lithium (Li) atoms. We span temperatures from far above room temperature down deep into the s-wave regime of nano-Kelvin. We report our results on exploiting the collision energy dependence of magnetically tunable atom-ion scattering (Feshbach) resonances and explain how to assign their partial-wave-classification experimentally. In the first half, we will give a basic tutorial on quantum scattering of atom-ion ensembles and distill the substantial differences to atom-atom dynamics. We aim to discuss how to gain control and state-sensitive detection on the level of individual quanta within the merged ion-atom system and to study and establish optically trapping of ions and atoms in general - for example to reveal the quantum dynamics of ion-atom and ion-molecule reactions in absence of any detrimental radio-frequency fields.

28 Jan 2025

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Peter Düben, European Centre for Medium-Range Weather Forecasts (ECMWF)
This talk will outline three revolutions that happened in the past decades in the development of Earth system models that are used to perform weather and climate predictions. The quiet revolution has leveraged better observations and more compute power to allow for constant improvements of prediction quality of the last decades, the digital revolution has enabled us to perform km-scale simulations on modern supercomputers that further increase the quality of our models, and the machine learning revolution has now shown that machine learned weather models are often competitive with physics based weather models for many forecast scores while being easier, smaller and cheaper. This talk will summarize the past developments, explain current challenges and opportunities, and outline how the future of Earth system modelling will look like. In particular, regarding machine-learned foundation models in a physical domain such as Earth system science.

Theorie-Palaver

Institut für Physik

14:00 Uhr s.t., Lorentz room (Staudingerweg 7, 5th floor)

Stéphane Lavignac, Institut de Physique Théorique, Université Paris Saclay
The observed matter-antimatter asymmetry of the Universe cannot be explained within the Standard Model and requires new physics. Interestingly, the simplest extension of the Standard Model that can generate Majorana masses for neutrinos contains all the ingredients needed to create an excess of matter over antimatter in the early Universe, via a mechanism called leptogenesis. In this talk, I will discuss the connections between neutrino masses, CP violation in the lepton sector and the matter-antimatter asymmetry of the Universe, and discuss different leptogenesis scenarios. In particular, I will present recent work about leptogenesis during a cosmological first order phase transition.

29 Jan 2025

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Claudio Gatti, Frascati, Italy
Quantum Sensing for High Frequency Gravitational Waves and Axion Dark Matter: Microwave cavities in strong magnetic fields are among the most promising tools for detecting dark-matter axions and high-frequency gravitational waves. These searches rely on the Primakoff and Gertsenshtein effects, which predict the conversion of axions and gravitational waves, respectively, into electromagnetic radiation in the presence of a strong static magnetic field. In a microwave cavity, this interaction leads to the displacement of the vacuum state of the resonant mode, generating a coherent electromagnetic signal. Given the expected signal weakness, developing detectors with sensitivity beyond the quantum limit is crucial. In the C and X bands of the electromagnetic spectrum, superconducting qubits have demonstrated exceptional performance for this purpose. However, strong magnetic fields pose challenges, requiring either signal transport to a shielded region or the use of magnetically resilient devices. Additionally, qubit state readout errors due to noise and dephasing limit sensitivity. These challenges can be mitigated through quantum non-demolition measurements, either by repeating the measurement over time or employing multiple qubits simultaneously. During the seminar, we will discuss ongoing developments at the COLD laboratory of the INFN Frascati National Laboratories, focusing on non-demolitive measurement techniques and the development of magnetically resilient qubits. 1. R. Moretti et al., “Transmon qubit modeling and characterization for Dark Matter search,” arXiv:2409.05988. 2. A. Rettaroli et al. “Novel two-qubit microwave photon detector for fundamental physics applications,” Nuclear Instruments and Methods in Physics Research A 1070 (2025) 170010. 3. A. D’Elia et al. “Characterization of a Transmon Qubit in a 3D Cavity for Quantum Machine Learning and Photon Counting,” Appl. Sci. 2024, 14(4), 1478. 4. QUAX Collaboration “Search for axion dark matter with the QUAX–LNF tunable haloscope” Phys. Rev. D 110, 022008 (2024).
Slides here...

30 Jan 2025

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

Institut für Physik

14:15 Uhr s.t., IPH Lorentzraum 05-127

Prof. Dr. Dominik Bucher, Technische Universität München
In my talk, I will present a novel approach to magnetic resonance microscopy that exploits nitrogen-vacancy (NV) centers in diamond for optically detected magnetic resonance (ODMR). The fusion of optical microscopy and nuclear magnetic resonance (NMR) spectroscopy bypasses the conventional reliance on k-space sampling and magnetic field gradients for spatial encoding of NMR signals, enabling real-space magnetic resonance imaging (MRI). We demonstrate the capabilities of our widefield optical NMR microscopy technique by imaging NMR signals within a model microstructure, achieving a spatial resolution of approximately 10 μm over an area of ~235 × 150 μm². Each camera pixel captures a complete NMR spectrum, providing comprehensive information on signal amplitude, phase, local magnetic field strengths, and gradients. The integration of optical microscopy and NMR opens up new possibilities for a wide range of applications in the physical and life sciences, which I will discuss in the last part of my talk. These applications include imaging metabolic activity in single cells or tissue slices, analyzing battery materials, and facilitating high-throughput NMR analysis.

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski-Raum, 05-119, Staudingerweg 7

René van Roij, Prof. Dr.
Title: Circuits of Microfluidic Memristors: Computing with Aqueous Electrolytes Speaker: René van Roij, Institute for Theoretical Physics, Utrecht University, The Netherlands Abstract: In this online talk we will discuss recent advances in our understanding of the physics of cone-shaped microfluidic channels under static and pulsatile voltage- and pressure drops. On the basis of Poisson-Nernst-Planck-Stokes equations for transport of aqueous electrolytes through channels carrying a surface charge, we will provide a theoretical explanation for the experimentally observed diode-like current rectification of these channels. At steady electric driving this rectification involves salt depletion or accumulation in the channel depending on the sign of the applied voltage [1], and this effect also explains the observed pressure-sensitivity of the electric conductance. An extension towards an applied AC voltage predicts these channels to be tunable between diodes at low frequencies ωτ<<1, memristors (resistors with memory) at intermediate frequencies ωτ ~ 1, and Ohmic resistors at high frequency ωτ>>1 , with a characteristic (memory retention) time τ proportional to the square of the channel length [2]. We predict that Hodgkin- Huxley-inspired iontronic circuits of short (fast) and long (slow) conical channels yield neuromorphic responses akin to (trains of) action potentials [2] and several other neuronic spiking modes [3]. Next, we show theoretically and experimentally that a tapered microfluidic channel filled with an aqueous nearly close-packed dispersion of colloidal charged spheres is a much stronger memristor than the channel with only surface charges on the channel wall [4]. Upon applying a train of four positive (negative) voltage pulses, each pulse representing a binary “1” (“0”), we map the hexadecimal number represented by this train on an analog channel conductance, which offers opportunities for reservoir computing -we give a proof of principle for the case of recognizing hand-written digits [4]. Finally we will also discuss recent and ongoing work on iontronic information processing. We exploit the mobility of the medium (water) by considering simultaneously applied pulsatile pressure and voltage signals to increase the bandwidth [5]. Finally, the versatile ionic nature of the charge carriers allows for Langmuir-like ionic exchange reaction kinetics on the channel surface [6]. We show that this can give rise to direct iontronic analogues of synaptic long-term potentiation and coincidence detection of electric and chemical signals [7], which are both ingredients for brain-like (Hebbian) learning. References: [1] W.Q. Boon, T. Veenstra, M. Dijkstra, and R. van Roij, Pressure-sensitive ion conduction in a conical channel: optimal pressure and geometry, Physics of Fluids 34, 101701 (2022). [2] T.M. Kamsma, W.Q. Boon, T. ter Rele, C. Spitoni, and R. van Roij, Iontronic Neuromorphic Signaling with Conical Microfluidic Memristors, Phys. Rev. Lett. 130, 268401 (2023). [3] T.M Kamsma, E. A. Rossing, C. Spitoni, and R. van Roij, Advanced iontronic spiking modes with multiscale diffusive dynamics in a fluidic circuit, Neuromorph. Comput. Eng. 4 024003 (2024). [4] T.M. Kamsma, J. Kim, K. Kim, W.Q. Boon, C. Spitoni, J. Park, and R. van Roij, Brain-inspired computing with fluidic iontronic nanochannels, PNAS 121, e23202242121 (2024). [5] A. Barnaveli, T.M. Kamsma, W.Q. Boon, and R. van Roij, Pressure-gated microfluidic memristor for pulsatile information processing, arXiv:2404.15006. [6] W.Q. Boon. M. Dijkstra, and R. van Roij, Coulombic Surface-Ion Interactions Induce Nonlinear and Chemistry-Specific Charging Kinetics, Phys. Rev. Lett. 130, 058001 (2023). [7] T.M. Kamsma, M. Klop, W.Q. Boon, C. Spitoni, and R. van Roij, arXiv:2406.03195
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04 Feb 2025

Physikalisches Kolloquium

Institut für Physik

16:15 Uhr s.t., HS KPH

Almudena Arcones, TU Darmstadt
Our understanding of the origin of heavy elements by the r-process (rapid neutron capture process) has made great progress in the last years. In addition to the gravitational wave and kilonova observations for GW170817, there have been major advances in the hydrodynamical simulations of neutron star mergers and core-collapse supernovae, in the microphysics included in those simulations (neutrinos and high density equation of state), in galactic chemical evolution models, in observations of old stars in our galaxy and in dwarf galaxies. This talk will report on recent breakthroughs in understanding the extreme environments in which the formation of the heavy elements occurs, as well as open questions regarding the astrophysics and nuclear physics involved.

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

Institut für Physik

12:00 Uhr s.t., IPH, Curie-Raum (03-431)

Dr. Michael Buchhold, Universität zu Köln
Understanding and actively shaping quantum entanglement in many-body systems is a key challenge for modern quantum technologies. Recently, monitored quantum dynamics — quantum dynamics with mid-circuit measurements — has emerged as a powerful tool for harnessing entanglement in NISQ devices and simulating non-equilibrium dynamics in condensed matter systems. In this talk, I will discuss our recent understanding of entanglement in monitored quantum dynamics from the viewpoint of emergent many-body phases and universality. Monitored dynamics generate wave functions with robust entanglement structures, which depend only on global properties such as symmetry and dimensionality, thereby defining entanglement phases of monitored quantum matter. We anticipate a symmetry classification of monitored matter akin to equilibrium quantum matter in Hamiltonian systems, which I will introduce using exemplary systems in one and two dimensions. I will also highlight our recent analytical and numerical advances and how they can be applied to engineer entanglement, for instance, in adaptive quantum circuits and driven quantum materials.

Vortrag im Rahmen der QuCoLiMa talks

05 Feb 2025

PRISMA+ Colloquium

Institut für Physik

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

Prof. Dr. Yael Shadmi, Technion, Israel
The LHC experiments are now probing the Higgs interaction for the first time. Over the next two decades, they will supply a wealth of precise measurements of processes involving the Higgs and electroweak gauge bosons, which may provide clues to the origin of the Higgs potential and in particular, to the origin of the weak scale. How do we interpret these measurements? We will describe a model-independent approach, based on just the physical degrees of freedom, namely, the known particles, in terms of amplitudes.

13 Feb 2025

Seminar über Theorie der kondensierten Materie / TRR146 Seminar

F. Schmid / G. Settanni / P. Virnau / L. Stelzl

14:30 Uhr s.t., Minkowski-Raum, 05-119, Staudingerweg 7

Frauke Gräter, Prof. Dr.
Enhancing scale-bridging simulations by machine learning – or substituting them altogether?
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