Regensburg Center for Ultrafast Nanoscopy

GRK Colloquium: Prof. Dr. Rainer Hillenbrand & Dr. Alex Weber-Bargioni
2025-01-17 14:00 - 15:45 (Europe/Berlin)
14:00 hProf. Dr. Rainer Hillenbrand:Optical near-field nanoscopyNanoscience research center CIC nanoGUNE in San Sebastian

By recording the radiation scattered by a laser-illuminated atomic force microscope tip, imaging and spectroscopy with nanoscale spatial resolution can be achieved in the broad spectral range from visible to terahertz frequencies. This talk will provide an overview of the technique and discuss some of our recent applications in materials science and polariton imaging.

15:15 hDr. Alex Weber-Bargioni:Controlling and Protecting Quasiparticles in 2-D Quantum MaterialsLawrence Berkeley National Laboratory

In this presentation, we explore how new types of particle-like excitations, known as quasiparticles, can be controlled and stabilized within ultra-thin materials—so-called 2-D solids—by creating carefully designed atomic hetero structures. Quasiparticles are not fundamental particles like electrons or protons, but instead arise from the complex interactions between particles in a solid. They include phenomena such as excitons (bound states of electrons and holes), superconducting states, and polaritons (hybrids of light and matter), as well as more exotic systems like Tomonaga-Luttinger liquids.

Each of these quasiparticles emerges due to the unique symmetries of the crystal structure.By engineering precise atomic-scale patterns (heterostructures) within 2-D materials, we can not only create new types of quasiparticles but also protect and manipulate them for potential applications. For instance, heterostructures that confine matter in zero, one, or two dimensions allow us to control these emergent properties with unprecedented precision. In the first part of my talk, I will focus on excitons—quasiparticles formed by electron-hole pairs. We have investigated excitons in stacks of the 2-D materials WS₂ and WSe₂, which are promising candidates for next-generation quantum technologies. These stacks potentially host Bose-Einstein Condensates, a state where excitons behave like a collective whole. By coupling these excitons to nanoscale light traps (plasmonic cavities), we have been able to study how they emit light, particularly “dark excitons,” which don’t normally emit photons. Additionally, we provide evidence of excitons traveling coherently over distances when coupled to plasmons, forming a new hybrid quasiparticle called a plexciton.In the second part of the talk, I will explore defects in 2-D materials that act as quantum emitters, which are critical for applications like quantum sensing. Using a high-precision technique called photo Scanning Tunneling Microscopy (photo-STM), we examine how tiny imperfections in the crystal structure of MoSe₂ and WS₂—such as missing atoms—create unique energy states within the material’s band structure. These defects can emit single photons, which is a key requirement for quantum technologies. We have also shown how replacing individual atoms in the structure with elements like carbon or cobalt creates well-defined systems similar to color centers in diamonds, opening the door to new sensing and computational devices.Finally, I will discuss how certain 1-D defects in 2-D materials—mirror twin boundaries—act as atomically thin conductors, which display a remarkable transition into a quantum liquid state at low temperatures. These systems give us new insights into highly correlated electron states, including superconductivity.

Venue: RUN auditorium

Young Colloquium:Umgang mit Trends in der Naturwissenschaft - Perspektive des Quantum Computing
2025-01-09 16:15 - 17:00
Prof. Dr. Rainer BlattUniversität Innsbruck

Quantentechnologien bieten das Potenzial für verbesserte Kommunikation, Metrologie, Simulationen und Berechnungen. In diesem Vortrag werden die grundlegenden Funktionsprinzipien der Quanteninformationsverarbeitung kurz vorgestellt und über den Stand der Technik des Innsbrucker Quantencomputers mit gespeicherten Ionen berichtet. Die Rechenkunst mit Hilfe der Quantenphysik wird anhand von Quantensimulationen illustriert,die Wege für eine neue Informationsverarbeitung aufzeigen. Ein kommerziell erhältlicher NISQ-Quantenprozessor wurde von AQT entwickelt und steht bereits für industrielle Anwendungen zur Verfügung.

Prof. Dr. Giulio Cerullo:2D semiconductors: a platform for ultrafast photonics
2025-01-09 14:00 - 15:00
Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo da Vinci 32, 20133, Milano, Italy

Layered materials are solids consisting of crystalline sheets with strong in-plane covalent bonds and weak van der Waals out-of-plane interactions. These materials can be easily exfoliated to a single layer, obtaining two-dimensional (2D) materials with radically novel physico-chemical characteristics compared to their bulk counterparts. The field of 2D materials began with graphene and quickly expanded to include semiconducting transition metal dichalcogenides(TMDs). 2D semiconductors exhibit very strong light-matter interaction and exceptionally intenseand ultrafast nonlinear optical response, enabling a variety of novel applications in optoelectronics and photonics. Furthermore, stacking 2D materials into heterostructures (HS) offers unlimited possibilities to design new materials tailored for applications. In such HS the electronic structure of the individual layers is well retained because of the weak interlayer van der Waals coupling. Nevertheless, new physical properties and functionalities arise beyond those of their constituent blocks, depending on the type, the stacking sequence and the twist angle of the layers. This talk will review our recent studies on the ultrafast non-equilibrium optical response of TMDs and their HS. Using high time resolution ultrafast transient absorption (TA) spectroscopy, we monitor the ultrafast onset of exciton formation in TMDs and the dynamics of strongly coupled phonons. Using helicity resolved TA spectroscopy we time-resolve intravalley spin-flip processes. In HS of TMDs we measure ultrafast interlayer hole transfer, interlayer exciton formation and use two-dimensional electronic spectroscopy to dissect interlayer electron and hole transfer processes. We also show that strong exciton nonlinear interactions can lead to a complete quenching of the Rabi splitting in TMD-based microcavities. The demonstrated ultrafast switching between the strong and weak coupling regimes paves the way for the development of TMD based high speed all-optical circuits and neural networks.

Dr. Francesco Intravaia: Unpacking Electromagnetic Quantum Fluctuation-Induced Interactions
2024-12-13 15:00 - 15:45
Humboldt Universität zu BerlinFluctuations are ubiquitous in both classical and quantum realms, underpinning a wide range of phenomena across physics, from biophysics and chemistry to gravity and cosmology. In the ongoing race toward miniaturization, interest in electromagnetic quantum fluctuation-induced interactions has surged—not only for foundational insights but also for technological applications. While many of these interactions are negligible at macroscopic scales, they become crucial at microscopic scales, posing both challenges and opportunities for modern quantum technologies. Paradigmatic examples include van der Waals and Casimir interactions, which can be either advantageous or disruptive in the design of microscopicdevices.The study of these phenomena draws on a highly interdisciplinary background, merging advances in nonequilibrium physics, quantum electrodynamics, atomic physics, and condensed matter physics. Unpacking electromagnetic quantum fluctuation-induced interactions opens up new perspectives, deepening our understanding of the underlying physics and paving the way for future advancements in the field.

Venue: RUN auditorium

Host: GRK 2905, Rupert Huber

Prof. Dr. Maria Chekhova:Bright squeezed vacuum and its applications in strong-field physics
2024-12-13 14:00 - 15:00
Max-Planck-Institut für die Physik des Lichts, ErlangenStrongly pumped parametric down-conversion produces a state of light that, on the one hand, is as intense as laser light, and on the other hand, has pronounced quantum features. This state, known as bright squeezed vacuum, has zero mean electric field and consists only of quantum fluctuations, enhanced or suppressed on a subcycle scale. Recently, we have used this state to drastically modify the dynamics of strong-field effects, such as non-perturbative harmonics generation and electron ejection from needle tips.

Venue: RUN auditorium

Host: GRK 2905, Rupert Huber

Young Colloquium:Herausforderungen in der Frauen- und Diversitätsforschung für eine nachhaltige Zukunft - Perspektive der Wissenschafts- und Technikgeschichte
2024-12-05 16:15 - 17:30
Prof.in Dr. Andrea ReichenbergerTechnische Universität München

Young Colloquium:Hochschulbildung im 21. Jh. im Kontext einer nachhaltigen Entwicklung: Was können Studierende tun? - Perspektive der Erziehungswissenschaften
2024-11-21 16:15 - 17:30
Prof.in Dr. Mandy Singer-BrodowskiUniversität Regensburg

GRK Colloquium: Complexity with a purpose: Long range collective vibrations steering protein conformational change
2024-11-15 14:00 - 15:00
RUN auditorium

Prof. Dr. Andrea Markelz

University at Buffalo College of Arts and Sciences

The evolutionary advantage of the large-scale structure of proteins surrounding the biochemically active site is not readily apparent. It has been speculated that the structural dynamics provide long-range control of access to the active site. Through anisotropic terahertz micro-spectroscopy (ATM) measurements we find that the photo initiation of orange carotenoid protein’s (OCP) photocycle is accompanied with switching in the protein structural vibrations, before long range structural change can occur. The ATM spectral changes are reversible and calculations reproduce the changes in ATM spectra, with features red shifted from the measurements. Averaging the vibrational displacement autocorrelation matrix over the spectrally relevant region and thermally occupied starting configurations finds changes in the correlations for residues 80-113 with residues 151-164, and for residues 280-291 with residues 265-275. These regions are those previously predicted to be involved in the structural modification necessary for a critical step in the photocycle. The results provide the first evidence that structural vibrational change can actuate conformational change for function.

GRK Colloquium: Dr. Ching-Ju Tsai / Prof. Dr. Sascha Schäfer / Dr. Jörg Standfuss
2024-11-08 13:00 - 16:00
13:00Role Model SpotlightDr. Ching-Ju TsaiLab. for Biomolecular Research,PSI Center for Life Sciences, Switzerland

Debating whether to stay in academia while considering starting a family? The challenge intensifies if your partner is also a scientist, potentially in the same field. Balancing dual careers, raising children, and possibly relocating away from family and friends can be tough.Join us for an engaging “Role Model Spotlight” session, featuring Dr. Ching-Ju Tsai, as she shares her personal experiences and insights on navigating these challenges.We welcome the audience to actively participate by asking questions when we delve into questions like:

Understanding the planable vs. unpredictable aspects of academic careers.Come join us for this insightful discussion, complemented by coffee, tea, and some sweets. We look forward to your participation.

Strategies and support systems for effectively managing dual career paths in academia.

Navigating the unique challenges and opportunities of pursuing a scientific career while raising children.

Critical transitions from earning a PhD to securing a permanent academic position.

14:00Investigating ultrafast nanoscale dynamics with electrons and X-raysProf. Dr. Sascha SchäferRegensburg center for ultrafast nanoscopy

As an introduction to the lecture by Jörg Standfuss, I will give an overview on current methodologies in ultrafast electron and X-ray imaging with a focus on:(1) the key properties of available pulsed sources,(2) a comparison between imaging, diffraction and holograpy approaches and(3) important limitations by beam-induced sample damage.

15:00Photopharmacology Across Time and Space: Molecular Insights via X-ray Free Electron LasersDr. Jörg StandfussLab. for Biomolecular Research, PSI Center for Life Sciences, Switzerland

Structural biology has been critical for our understanding of how proteins work on the molecular level. However, resolving the temporal evolution of biological macromolecules in response to activating stimuli—such as the binding of small molecular ligands or drug molecules—remains a challenge. In recent years, our research group has leveraged X-ray Free Electron Laser facilities to experimentally investigate how retinal-binding rhodopsins, acting as pumps, channels, or light sensors, are activated at the atomic level across a wide range of time scales.In our latest experiments at the Swiss X-ray Free Electron Laser, we explored how photoactive azobenzene compounds, mimicking retinal, can be used to trigger protein dynamics for structural studies. My presentation will focus on the dissociation dynamics of the photopharmacological drug candidate azo-combretastatin A4 from tubulin, capturing events from the initial photochemical reaction in the femtosecond range, through the disruption of high-affinity protein-ligand interactions in nanoseconds, adaptation of the binding pocket in microseconds, and the eventual release of the compound in milliseconds. I will discuss the relevance of these findings for our understanding of how anti-cancer drugs destabilize the microtubule network. Furthermore, I will propose the use of azobenzene-based photoswitches to trigger G protein-coupled receptors and other pharmacologically relevant targets in time-resolved structural biology experiments.

Young Colloquium:Globale Herausforderung gerecht lösen - Perspektive der Sozialethik
2024-11-07 16:15 - 17:30
Dr. Sebastian KistlerUniversität Regensburg

GRK Colloquium:Prof. Dr. Sascha Schäfer
2024-10-25 14:00 - 15:45
tba

Prof. Dr. Sascha SchäferRegensburg center for ultrafast nanoscopy

Young Colloquium: Scientific Perspectives for Global Issues of the 21st century
2024-10-17 16:15 - 17:45
Our society continues to be confronted with a multitude of global challenges: Climate change and the resulting cognitive dissonance, (too) promising future technologies, social justice, successful science and crisis communication, and much more.

The Young Colloquium is a series of lectures initiated by students at the University of Regensburg, now in its second edition. With the subtitle “Scientific Perspectives for Global Issues of the 21st Century”, the aim is to explore the question of how scientists can contribute to solutions and the success of the inevitable transformation.

The event will focus on societally relevant topics, challenges of the 21st century and interdisciplinary questions, which will be explored in an appealing way for students from all faculties. It is intended to broaden the perspective and enable participation in the large pool of specialist and personal knowledge of inspiring lecturers. Its aim is to enable students to apply the skills they have learned during their studies in an interdisciplinary manner and with an awareness of global challenges.

GRK Colloquium:Till Rudack / Shinjae Nam
2024-07-12 14:15 - 16:30
14:15

Prof. Dr. Till Rudack Strukturelle Bioinformatik, Universität Regensburg

15:30Shinjae NamLehrstuhl für Quanten- und Nanowissenschaften F. Gießibl, Universität Regensburg

GRK Colloquium: Non-thermal engineering of solid-state systems via THz driven collective modes
2024-07-10 15:15 - 17:00
In this talk, I will discuss how light-driven collective modes can reveal and dynamically shape the interplay between different microscopic degrees of freedom. Specifically, I will show how the dynamics of a resonantly driven phonon can reveal its anharmonic potential and how a similar scheme can be applied to quasi-2D materials to shape their magnetic ground state.

Dr. Alexander von HoegenMassachusetts Institute ofTechnology, Boston

RUN run
2024-07-09 13:00 - 17:00
For more information click here.

RUN Colloquium: Plasmonic Twistronics: Ultrafast Vector Microscopy
2024-07-05 14:15 - 15:45
Here we introduce a new technique, time-resolved vector microscopy, that enables us to compose entire movies on a sub-femtosecond time scale and a 10 nm scale of the electric field vectors of surface plasmon polaritons. Depending on the shape and geometrical phase, in combination with the helicity of the excitation beam, topological plasmonic quasiparticles are created: skyrmions, merons, as well as quasicrystalline excitations. We observe their complete field vector dynamics at subfemtosecond time resolution. We expand the concept also to plasmonic twistronics, where we can identify skyrmion bags.

Prof. Dr. Harald Gießen

GRK Colloquium: Accurate theoretical methods for structural characterization of complex materials
2024-07-05 10:30 - 12:00
Spectroscopy is crucial for establishing structure-property relationships as it provides detailed information about the molecular composition and electronic structure of materials. This data is essential for correlating specific structural features with material properties, thereby guiding the design and optimization of new materials. I will discuss our recent advances in accurately predicting core-level and vibrational spectra of complex materials. For core-level spectroscopy, we developed highly accurate but computationally expensive methods based on Green’s function theory in the GW approximation. Calculations for amorphous materials, which require computational models with several hundred atoms, were enabled by devising new efficient algorithms and combining these methods with machine-learning approaches. In addition, I will discuss computational approaches to vibrational spectroscopy that not only allow for the structural characterization of the final layered framework materials but also enable the monitoring of synthesis progress.

Dr. Dorothea Golze

GRK Colloquium: Excitations in condensed matter: from theory to real materials II
2024-06-28 14:15 - 15:45
The second lecture on excitations in condensed matter will cover electronic excitations in semiconductors and dielectrics, where the electron-hole interaction in the electronically excited state, the exciton, is key. We will explain how the electron-hole interaction arises from Hartree-Fock theory and discuss the limitations of time-dependent density functional theory and Hartree-Fock for the study of excitons. The lecture will then introduce the GW+Bethe-Salpeter method, the standard for studying excitons in condensed matter with an atomistic description.

Jan Wilhelm

GRK Colloquium: Excitations in condensed matter: from theory to real materials I
2024-06-21 14:15 - 15:45
This lecture series on excitations in condensed matter will explore electronic excitations, linking theoretical concepts and experimental observations. The first lecture will cover ground-state and excited-state solutions of the many-body Schrödinger equation for electrons and nuclei. We will illustrate how these solutions are linked to motion on the nanoscale with examples from ultrafast nanoscience and biochemistry. We will also discuss time-dependent density functional theory, highlighting its success in studying plasmons, the electronic excitations in metals.

Jan Wilhelm

GRK Colloquium: Ultrafast nanoscopy experiments
2024-06-14 14:15 - 15:45
Markus Huber

Advancing optical microscopy to increasingly shorter length- and timescales has been a key process to visualize the connection between nanoscopic elementary dynamics and macroscopic functionalities of matter.

In this colloquium, I will give a basic introduction to the broad field of ultrafast nanoscopy. I will show different approaches of how ultrafast temporal resolution can be combined with nanoscale spatial resolution to see novel dynamics in a variety of materials. The focus will hereby be on coupling of light to sharp metallic tips, the fundamental approach for techniques like ultrafast near-field microscopy, lightwave scanning-tunneling microscopy and near-field optical tunneling emission microscopy.

GRK Colloquium: From structure to function - understanding how proteins tick
2024-06-07 14:15 - 15:45
Prof. Dr. Christine Ziegler

Science-Music Crossover Concert
2024-05-08 19:25 - 21:00

RUN Opening Ceremony
2024-05-08 12:00 - 13:00

Inaugural Symposium
2024-05-06 00:00 - 2024-05-08 23:59
Innovation in fundamental science and in quantum-, nano- and bio-technologies depends on a thorough understanding of the inner workings of custom-tailored materials. High-resolution microscopy has provided still images of the elementary building blocks of matter. Because the nanoworld is constantly in motion, still images are often not enough. For instance, tailoring functionalities of quantum materials or controlling biochemical reactions would be facilitated by direct ultraslow motion pictures visualizing the interplay of the nanoscopic building blocks of matter in space and time.
The bar is set high since the relevant elementary processes often evolve on time scales as short as femtoseconds (1 fs = 10-15 s) or even attoseconds (1 as = 10-18 s). Developing concepts that allow for simultaneous resolution of ultrashort time and length scales is hence one of the key scientific and technological challenges of this century.
Hosted by the brand-new Regensburg Center for Ultrafast Nanoscopy (RUN), the Symposium “The Nanoworld in Motion” will showcase the latest ultrafast nanoscopy principles and their applications to clarify urgent questions on dynamics of systems ranging from individual molecules to complex biomolecular and solid-state nanostructures. For more details, please click here.

GRK 2905 begins!
2024-04-01 00:00 - 23:59
The GRK 2905 will officially begin on April 1st, 2024. For more information click here.
