GRK 2905 - Ultrafast Nanoscopy

RTG Colloquium:Prof. Dr. Jim Freericks
2025-12-02 14:15 - 15:15 (Europe/Berlin)
How to describe pump-probe experiments in quantum materialsGeorgetown University, Washington, USA

I will describe both the challenges, and how to address them, when theoretically modelling ultrafast pump-probe experiments in strongly correlated materials and in materials with strong electron-phonon coupling. After providing an introduction, I will focus on three case studies: (i) examining the response at picosecond times of charge-density waves with ultrashort pulses that drive the electrons; (ii) examining the response on femtosecond times for nonresonant electronic Raman scattering; and (iii) examining how one can measure correlated charge dynamics in f-electronsystems using x-ray photoemission spectroscopy and x-ray absorption spectroscopy.

Venue: H34

RTG Seminar:Assistant Professor Ipsita Mandal
2025-12-04 15:15 - 16:15
Detectable signatures of topology of the bandstructures in 3d semimetalsShiv Nadar Institution of Eminence (SNIoE), India

We will elucidate the nature of the linear-response tensors in planar-Hall and planar-thermal-Hall set-ups, where we subject a 3d semimetal (harbouring nodal points of topological nature) to the combine influence of an electric field (and/or temperature gradient) and a weak (i.e. non-quantising) magnetic field. We will explain why it is essential to include the effects of the intrinsic orbital magnetic moment of the wavepackets in conjunction with the Berry curvature, in order to obtain a holistic picture of the effects of topology of the Brillouin zone in the linear-response tensors. Going beyond the well-studied example of Weyl semimetals, we will discuss the cases of their multifold cousins, harbouring higher Chern numbers. We will highlight how we can compute the exact solutions from the Boltzmann equations, which gets rid of the often-inaccurate results of the naive relaxation-time approximation. Finally, we will outline how to derive surface states, in the form of Fermi arcs, characterising generic nodal points.

Venue: PHY 5.0.21

RTG seminar:Dr. Kirill Voronin
2026-01-12 14:00 - 15:00
Theory of near-field microscopy andquantum optics of anisotropic materials

Donostia International Physics Center, (DIPC) San Sebastian, Spain

The talk presents our recent theoretical advances in near-field microscopy and quantum optics of anisotropic media. First, I discuss an analytic theory of near-field microscopy, its extension to layered structures, and open theoretical challenges elevant for experiments. I then address quantum electrodynamics of strongly anisotropic materials, including quantization of hyperbolic phonon polaritons and emitter–polariton coupling, highlighting open questions and potential directions for future studies.

Venue: RUN Auditorium

RTG Colloquium: Prof. Dr. Rudolf Bratschitsch
2026-01-16 14:00 - 15:00
Title: Magnonic waveguide networks

Ultrafast solid-state quantum optics and nanophotonics, Physical Institute, University of Münster, Münster, Germany

Spin waves (magnons) have emerged as a promising platform for next-generation physical computing. However, current experimental realizations of magnonic waveguides suffer from limited spin-wave propagation lengths and inefficient dispersion tuning capabilities. In my talk, I will present low-loss magnonic waveguides in a thin magnetic insulator film, fabricated with a new maskless silicon ion implantation technique. We demonstrate a large-scale magnonic network, paving the way for wafer-scale magnonic integrated circuits.

Venue: RUN Auditorium

RTG Colloquium:Dr. Anna Rosławska
2026-01-23 14:00 - 15:00
Single-molecule optics with atomic precision

Atomic Scale Optics, Max Planck Institute for Solid State Research, Stuttgart, Germany

Luminescence, photosynthesis, and energy harvesting rely on processes originating at the spatial scale of individual molecules. Investigating the details of these mechanisms requires reaching subnm precision in optics, which becomes possible by combining optical spectroscopy with scanningprobe microscopy. In my talk, I will discuss how atomic-scale optics can be used to study the optical properties of single molecules and to drive photochemistry with sub-nm precision.

Venue: RUN Auditorium

RTG Colloquium:Prof. Dr. Renske van der Veen
2026-01-30 14:00 - 15:00
Fast electrons and hard X-rays for unraveling atomic-scale dynamics in light-energy conversion

Department Atomic-Scale Dynamics in Light-Energy Conversion, Helmholtz Zentrum Berlin

The increasing demand for renewable and low-cost energy motivates intensive research aimed at characterizing and optimizing materials that can efficiently convert (sun) light into usable energy in the form of electricity or chemical fuels. Conventional characterization techniques either lack the spatial resolution necessary to resolve individual atoms, or they lack the temporal resolution required to capture structural rearrangements as they evolve. Our group develops complementary X-ray and electron-based tools to visualize light-induced processes in materials on atomic length and time scales. In this talk I will introduce you to the techniques of ultrafast/time-resolved X-ray spectroscopy and transmission electron microscopy and provide several examples of how these techniques can be used in the fields of solar energy and catalysis.

Venue: RUN Auditorium

RTG Seminar:Dr. Zijian Lyu
2026-02-06 10:00 - 11:00
Attosecond quantum spectroscopy with entangled photon pairs

Peking University, China

Entangled photon pairs provide nonclassical correlations that can be up-converted in strong-field nonlinearities. I will show how these correlations map onto high-order harmonics in solids, enabling correlation-resolved spectroscopy of carrier dynamics. By introducing a two-color driving field, we further achieve ultrafast, in-situ control of the quantum state of the emitted light.

Venue: RUN.0.35

Softskill workshop: Unconscious Bias
2026-02-25 09:00 - 16:00
Venue: RUN 0.35

“Our life is marked by prejudices and unconscious biases that influence our thoughts and actions. In this workshop, we will embark on a journey to become aware of these unconscious biases and develop strategies for better handling them in our daily lives. We will create space for open discussions and respectful exchanges to collaboratively devise solutions and have a positive impact on our personal relationships and society as a whole. This workshop provides an opportunity to gain a deeper understanding of the topic of bias and to take concrete steps towards change.” [J. Handschuh]

Find more information here.

RTG offsite workshop
2026-03-23 08:00 - 2026-03-25 17:00
Hotel Wutzschleife, Rötz

RTG Colloquium jointly held with the Physics Colloquium: Oliver Graydon
2026-04-20 16:00 - 17:00
The role of AI in scientific publishing

Chief Editor Nature PhotonicsSpringer Nature, UK

Artificial intelligence (AI) is set to bring profound transformations in how science is conducted and communicated. This talk with discuss the trends, opportunities, risks and challenges associated with AI from the viewpoint of scientific publishing with a focus on clarifying the present policies and principles at Nature journals and Springer-Nature.

Venue: H34

RTG Colloquium: Zhiyang Zeng
2026-04-24 14:00 - 15:00
Dynamical control of structural order

Condensed Matter Dynamics DepartmentMPI for the Structure and Dynamics of Matter, Hamburg

Coherent excitation of lattice vibrations has emerged as a powerful approach to dynamicallycontrol functional material properties. In this talk, I will present our recent work on using nonlinearphononics—a mechanism that enables the selective displacement of specific lattice vibrations—tomanipulate structural functionalities with light [1,2]. In particular, I will discuss how this approachenables the ultrafast control of chirality [3] and ferroaxial order [4], offering new pathways to tailorsymmetry and drive phase transitions in solids on demand.

[1] Först, et al. Nature Physics 7 (2011): 854-856.[2] Disa, et al. Nature Physics 17 (2021): 611-618.[3] Zeng, et al. Science 387.6732 (2025): 431-436.[4] Zeng, et al. Science 390.6769 (2025): 195-198.

Venue: RUN Auditorium

RTG Seminar: Yiqi Fang
2026-05-21 13:00 - 14:00
Shaping electron dynamics with structured light

FAU Erlangen, Institute of Laser Physics

Laser-excited electron motions allow the investigation of fundamental physical phenomena with unprecedented resolution in time, space and energy. Structured light offers new opportunities to tailor and control the optical response of materials, far beyond the ability of conventional linearly or circularly polarized light. In this talk, I will show the physics and application of structured light when it interacts with bound electrons in atoms as well as when it interacts with electron pulses in free space.

Venue: RUN.0.35

RTG Colloquium: Thomas Taubner
2026-05-22 14:00 - 15:30
Infrared near-field spectroscopy of few-layer graphene

RWTH Aachen, Germany

Infrared scattering-type scanning-near-field optical microscopy (s-SNOM) enables the imaging of nanostructures with sub-diffraction resolution by elastic light scattering at a sharp tip. s-SNOM also boosted the field of 2D materials by enabling real-space imaging of plasmon- or phonon polaritons, e.g., in graphene and hexagonal Boron Nitride (hBN), respectively. Polariton imaging with s-SNOM has allowed for indirectly mapping (grain) boundaries and (stacking) defects in fewlayer Graphene (FLG) via polariton reflection.Here, I will present how spectroscopic IR s-SNOM is able to determine the local stacking order at nanoscale resolution not only of bare few-layer graphene, but also when it is encapsulated below hBN layers. I will explain the contrast mechanisms, mainly based on the characteristic and stacking-dependent interband transitions of FLG, for bilayer graphene, trilayer (TLG) graphene and tetralayer graphene (4LG). We retrieve and reconstruct these characteristic complex optical conductivity resonances from the amplitude and phase of the scattered light, which e.g. allow for the unambiguous assignment of previously undetected ABCB domains in 4LG.Coupling the (stacking-dependent) FLG with phonon polaritons in a hBN TLG heterostructure also leads to coupled polaritons (hyperbolic phonon plasmon polaritons). We explore how they allow for super-resolution imaging of subdiffraction-sized defects in graphene through the hBN cover layer via the so-called hyperlensing effect. Furthermore, we show how resonators for polaritons in 2D materials like hBN can be easily fabricated and optically reconfigured using Phase-Change Materials.

Venue: RUN Auditorium

RTG Colloquium: Gabriele Kaminski Schierle & Clemens Kaminski
2026-06-11 14:00 - 16:00
Biological imaging at the nanoscale

Clemens F. Kaminski, University of CambridgeThe advent of optical super‑resolution imaging together with the ability to label specific cellular components with fluorescent markers has ushered in a revolution in our mechanistic understanding of biological processes. In this presentation, I will provide an overview of current methods used to obtain nanoscale insights into the molecular machinery that supports life at the subcellular level. I will present approaches for tracking protein interactions, using single‑molecule localisation microscopy as well as indirect techniques such as fluorescence lifetime imaging microscopy. I will then discuss methods based on structured illumination microscopy, which enable dynamic interrogation of cellular machinery including lysosomes and the endoplasmic reticulum. Finally, I will offer an outlook on emerging trends and how machine learning is transforming our field.

Coffee break & discussion

Beyond Alzheimer’s: conserved lysosomal dyshomeostasis as a driver of synaptic dysfunction across neurodegenerative proteopathies

Gabriele S. Kaminski Schierle, University of Cambridge

While scientists know that in Alzheimer’s disease, lysosomes (the cell’s “trash cans”) clump together and lose their acidity, they didn’t know if this happens in all neurodegenerative diseases.This study found that this “trash can” breakdown actually happens across many diseases, including ALS, Parkinson’s, and Frontotemporal Dementia. Instead of being spread out normally to clean the whole cell, the lysosomes clump tightly around the cell’s centre.By tracking cell electricity and layout, the researchers discovered that this clumping severely damages brain signalling. Because the lysosomes are stuck in the centre, they can’t reach the distant outer branches of the brain cells to clear out old, broken proteins. This causes waste to build up and shorts out communication between neurons.Ultimately, this suggests that fixing where lysosomes sit and restoring their acidity could act as a single, powerful treatment for multiple brain diseases.

Venue: RUN Auditorium

RTG Seminar: Prasana Kumar Sahoo
2026-06-18 14:00 - 15:00
Engineering excitons in 2D lateral heterostructures for reconfigurable devices

Quantum Materials & Device Research Lab (QMDrL), Materials Science Centre,Indian Institute of Technology Kharagpur, India

Two-dimensional semiconductor lateral hetero-structures (LHS) provide atomically sharp 1D interfaces for controlling charge carriers, excitons, and light. I will present scalable growth of seamless TMD LHS, exhibiting tunable PN junctions, electroluminescence, excitonic transistor operation, and reversible photoconductivity. These materials offer a versatile platform for quantum photonics, exciton-based devices, and low-dimensional quantum systems.

Venue: RUN 0.34

RTG Colloquium: Alice Kunin
2026-06-19 14:00 - 15:00
High-performance time-resolved photoemission experiments of quantum materials

Princeton University

I will discuss our work coupling MHz, kW light sources with momentum microscopy to enable efficient time- and angle-resolved photoemission (tr-ARPES) studies. I will first examine the dynamics of intra- and interlayer excitons in twisted van der Waals heterobilayers. I will then discuss our current work on a new spectrometer to probe ultrafast surface photochemistry in situ with the extension of tr-ARPES beyond ultrahigh vacuum towards more realistic chemical environments.

Venue: RUN Auditorium

RTG Colloquium: Bruno Schuler
2026-07-03 14:00 - 15:00
Probing atomic defects in 2D semiconductors with light-coupled STM

Empa, Switzerland

Two-dimensional (2D) semiconductors provide an exciting platform to engineer atomic quantum systems in a robust, yet tunable solid-state system. This talk explores the intriguing physics of single point defects in transition metal dichalcogenide (TMD) monolayers, investigated through atomically resolved scanning probe microscopy.

We demonstrate electrically induced exciton emission from both pristine MoS₂ and individual charged defects using scanning tunnelling microscope luminescence (STML) on ultrathin hBN decoupling layers [1]. Furthermore, I will present our recent advances in time-resolved THz-STM using QEV maps to achieve state-selective ultrafast charge injection [2]. This approach enables the investigation of charge [3] and exciton dynamics [4] with atomic spatial, millielectronvolt energy, and picosecond temporal resolution.

By combining the structural and electronic properties accessible by conventional scanning probe microscopy with the optical fingerprint from STML and the excited-state dynamics revealed through pump-probe THz-STM, we gain a comprehensive microscopic understanding of localized quantum states in low-dimensional materials.

[1] L. Huberich et al. arxiv: 2510.15676 (2025)[2] L. Bobzien et al. APL Mater. 12, 051110 (2024)[3] J. Allerbeck et al. Nat. Commun. 16, 10806 (2025)[4] L. Bobzien et al. (in preparation)

Venue: RUN Auditorium

Workshop: Drama and the Scientist
2026-07-16 08:00 - 17:00
One-day in person workshop with Julie Stearns (professional theater director & artistic director) for RTG 2905 students.

Theater training for effective communication

Julie Stearns, impuls plus

“Scientists often try to avoid dramatization – but on the stage, the dramaturgy of a performance is the result of techniques that can be learned and applied. This workshop prepares participants for the challenges of interaction in academic and research settings, especially when the goal is to engage and persuade an audience. Through exercises in physical presence and voice, participants develop a new awareness of how to shape their own performance, while also gaining confidence in improvisation.” [J. Stearns, impuls plus]

Venue: RUN Auditorium
