News

A quantum leap in optical microscopy

© Brad Baxley, PtW

Using a conventional tabletop mid-infrared laser, we observed optical signals modulated on Ångström length scales. These signatures stem from light emission from tunneling currents flowing between the most frontier atom of a metallic tip and a sample surface and are driven by the oscillating electric field of the laser light. This tunneling-mediated contrast emerges under relatively weak continuous-wave excitation, although such strong-field effects are typically associated with ultrashort, high-intensity laser pulses.
These results open a pathway toward optical imaging with unprecedented spatial resolution using standard optical setups.

The results were obtained in close collaboration with the group of Tom Siday (University of Birmingham) and have been published in Nano Letters.... more

Observation of an isolated flat band in the van der Waals crystal NbOCl₂

Using photoelectron momentum microscopy, we have mapped the complete two-dimensional band structure of the van der Waals crystal NbOCl₂. Our measurements reveal an almost perfectly flat band that spans the entire momentum space and is well separated from all other, dispersive bands. This uniquely isolated flat band establishes NbOCl₂ as an ideal platform for investigating correlation-driven phenomena, as well as for exploring the role of dispersionless quasiparticles in lightwave electronics and light-induced band engineering.

The results have been obtained in in close collaboration with the group of Ulrich Höfer (Philipps-University Marburg, University of Regensburg) and have been published in Communications Materials. ... more

Cyclotron resonance reveals Dirac bandstructure

© Joshua Mornhinweg, Harvard University

In close collabortaion with the groups of Christoph Lange (TU Dortmund) and Sergey Ganichev (UR), we were able to use contact-free broadband THz magneto-spectroscopy to map the Dirac cone of buried HgTe quantum wells with sub-meV precision, revealing small band gaps and the onset of relativistic Landau quantization.

The results have been published in Applied Physics Letters. ... more

Vincent Eggers receives Outstanding Student Paper Award (2. place)

We congratulate Vincent Eggers on winning the outstanding student paper award (2. place) at the IRMMW-THz 2025 conference in Helsinki with his talk titled "Subcycle Band-Structure Videography of IR-driven Graphene". The prize honours original contributions to the conference from outstanding student attendees.... more

Congratulations to Dr. Manuel Meierhofer on His PhD and New Role as Team Leader

We are delighted to congratulate Manuel Meierhofer on the successful completion of his PhD thesis “Visualizing Lightwave Electronics in Momentum Space.” We are equally excited to share that Manuel will continue with us as Team Leader for Subcycle Photoemission. We look forward to many more years of inspiring research and fruitful collaboration together. Image (from left to right): Ulrich Höfer, Manuel Meierhofer, Rupert Huber.

Best lecture award

Our lecture on physics of atoms and molecules was awarded with the Best Lecture Award of the Faculty of Physics.
Image (from left to right): Peter Menden, Felix Schiegl, Andreas Rank, Simon Anglhuber, Rupert Huber, Michael Aschenbrenner, Karoline Bernhard-Höfer.
Missing: Svenja Nerreter, Katharina Glöckl, Jakob Helml... more

Congratulations to Dr. Johannes Hayes on His PhD

We warmly congratulate Dr. Johannes Hayes on the successful completion of his PhD thesis, “Subcycle Optical Nanoscopy with Atomic-Scale Resolution.” While Johannes will be moving on to new opportunities beyond our group, we sincerely thank him for his contributions and wish him all the very best for the future. Image (from left to right): Rupert Huber, Johannes Hayes.

Prof. Michael Zuerch wins Bessel research award and takes it to Regensburg

© UC Berkeley (Press Release)

We warmly congratulate Professor Michael Zuerch (UC Berkeley) on receiving the prestigious Friedrich Wilhelm Bessel Research Award from the Alexander von Humboldt Foundation. His innovative work in ultrafast X-ray spectroscopy provides new insights into electron dynamics and symmetry in quantum materials. With the price he plans a research stay at the Regensburg Center for Ultrafast Nanoscopy. We are excited to welcome him and look forward to a fruitful collaboration exploring fundamental light–matter interactions on ultrashort timescales.

Svenja Nerreter featured on the Gasthörer podcast

Group member Svenja Nerreter joined the Gasthörer science podcast produced by the University of Regensburg to discuss her Master’s research on ultrafast nanoscopy of carrier dynamics in perovskites, highlighting its potential for next-generation photovoltaics and reflecting on her scientific journey. Listen to the full conversation here.... more

Magnetic order traps quasi-1D excitons

© Brad Baxley, PtW

We explored how the antiferromagnetic spin alignment in adjacent layers of the van der Waals crystal CrSBr confines Coulomb bound electron hole pairs into one dimension. In two back-to-back publications in Nature Materials, we discovered two key signatures of this intriguing process: In a close collaboration with the groups of Mackillo Kira (University of Michigan), Zdeněk Sofer (University of Chemistry and Technology Prague) and Florian Dirnberger (Technical University of Munich), we resolved the internal structure and a strong fine-structure splitting of the excitons.

Visualizing ultrafast electron wave motion in graphene: Coverstory in Nano Letters

© Simon Anglhuber, UR

We explored a novel approach to directly visualize THz surface polariton propagation in both space and time – accessing the polariton’s group and phase velocities, as well as its damping. Through photoexcitation, we even achieved subcycle control of the polariton propagation.

The results obtained in close collaboration with the group of Miriam Vitiello in Pisa (NEST, CNR) and Eva A. A. Pogna in Milano (CNR-IFN) have been published in Nano Letters (Coverstory). ... more

Unlocking Lightwave Electronics

Our review on lightwave electronics together with Mackillo Kira has made it on the cover of Optics & Photonics News. © S. Alvey, University of Michigan

Joshua Mornhinweg receives the dissertation prize of the faculty of physics!

We congratulate Joshua Mornhinweg on being awarded the Dissertation Prize by the Faculty of Physics at the University of Regensburg for his remarkable PhD thesis, titled "Tailoring and Non-Adiabatic Control of Deep-Strong Light-Matter Coupling." This prize, sponsored by the Wilhelm and Else Heraeus Foundation, recognizes an exceptional doctoral thesis in physics and comes with an endowment of €4000.

Josef Riepl receives the Best Tutor Award of the faculty of physics

We are happy to announce that Josef Riepl won the Best Tutor Award of the Faculty of Physics at the University of Regensburg. The price recognizes his outstanding job in teaching and explaining the physics of electrodynamics. Congratulations, Josef!

Vertical voyage in metal halide perovskites

© Brad Baxley, PtW

We have developed an approach based on ultrafast near-field microscopy that has allowed us to probe the nanoscale topography, crystallographic phase and chemical composition of metal halide perovskite films, while simultaneously extracting the ultrafast vertical carrier dynamics from femtosecond shifts in the pump-induced response following photoexcitation. This has revealed a surprising robustness of vertical charge transport towards nanoscale structural and compositional variations.

The results obtained in a close collaboration with the group of Michael Johnston (University of Oxford) have appeared in Nature Photonics. ... more