News

Attosecond clocking of Bloch electrons

Together with the group of Mackillo Kira (Michigan), we use multi-terahertz light fields to force electron-hole pairs in semiconductors onto closed recollision paths. Attosecond clocking of these trajectories reveals how many-body correlations like strong Coulomb interactions modify the charge carrier dynamics. This novel concept offers a completely new access to exotic phase transitions and quantum dynamics important for future electronic and quantum-information technologies.

The results have been published in Nature.... more

Joshua Mornhinweg receives IRMMW-THz 2022 best student paper award

We congratulate Joshua Mornhinweg on winning the first prize of the best student paper award of the 2022 International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) in Delft with his talk titled nonlinear subcycle dynamics of ultrastrong light-matter interaction. The prize honours original contributions to the conference from outstanding student attendees.... more

Venue

TU Delft, Netherlands

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): Manuel Meierhofer, Martin Zizlsperger, Felix Schiegl, Rupert Huber (professor), Christian Meineke, Johannes Hayes, Marlene Liebich
Missing: Lukas Kastner... more

Intersubband Polariton-Polariton Scattering

We studied the ultrafast dynamics of intersubband polaritons in the mid-infrared together with the groups of Raffaele Colombelli (Paris), Christoph Lange (Dortmund) and Iacopo Carusotto (Trento). Stimulated scattering occurs between these polaritons for resonant excitation, which we observe directly within the polaritonic bandstructure. This scattering mechanism could enable Bose-Einstein-condensates of intersubband polaritons for novel quantum computers and on-chip mid-infrared light sources.

The results have been published in Physical Review Letters.... more

Light-field-driven tunneling currents in a Schottky diode

In collaboration with the group of Heiko Weber (Friedrich-Alexander-Universität Erlangen-Nürnberg) we investigated mid-infrared light-field-driven tunneling currents in a Schottky diode, consisting of epitaxial graphene on silicon carbide. Our study gives insights into the intrinsic speed limits of rectification currents in these devices and paves the way towards light-field-driven electronics with increased functionality, such as transistors and logic circuits.

Press release (UR) in German

The results have been published in Science Advances.... more

Generating intense sub-half-cycle terahertz pulses

We developed a novel, flexible and scalable emitter of extremely asymmetric and intense terahertz field transients together with the groups of Dominique Bougeard (UR) and Mackillo Kira (University of Michigan) as well as collaborators from the Helmut Schmidt University and the Justus Liebig University Gießen. Making use of shift currents and local charging dynamics in asymmetrically coupled epitaxial semiconductor heterostructures, we generated waveforms exhibiting less than an oscillation half-cycle, peak fields above 1.1 kV cm^-1 and spectra spanning into the mid-infrared, marking a milestone for next-generation high-repetition-rate (multi-)terahertz sources.

Press release (University of Michigan) in English
Press release (Mirage) in English
Press release (Laser Focus World) in English

The results have been published in Light: Science & Applications.... more

Martin Zizlsperger receives Maiman Student Paper Award

We congratulate Martin Zizlsperger on winning the 2022 Maiman Student Paper Award, one of the most prestigious and honoured student awards in optics and photonics worldwide. Press release (UR) in German.

Resolving the exciton Mott transition on the nanoscale

In collaboration with the group of Ermin Malic (University of Marburg), we used ultrafast near-field microscopy to study the Mott transition of strongly-bound excitons in an atomically thin heterostructure of WSe2, unveiling pronounced nanoscale modulation in the dynamics of the transition. These findings underscore how nanoscale disorder plays a pivotal role in the dynamics of many-body phase transitions within a broad range of van der Waals materials.

The results have been published in Nano Letters. ... more

Quantum cascade laser turns extremely nonlinear

Collaborating with partners from Germany, France, UK and Sweden we observed high-order terahertz nonlinearities directly in a free-running quantum cascade laser. With field-resolved two-dimensional spectroscopy we revealed up to eight-wave-mixing processes in a regime of negative absorption as well as the laser’s sub-cycle gain dynamics. High-order nonlinearities of this kind have the potential for various future applications, ranging from efficient intracavity frequency conversion and mode proliferation to passive mode locking.

The results have been published in Light: Science & Applications.... more

Columbus research grant for former team member Prof. Chaw-Keong Yong

The Ministry of Science and Technology of Taiwan has awarded our former team member and close collaborator Chaw-Keong Yong, who was recently appointed assistant professor at National Taiwan University, with the Columbus research grant. This fellowship recognises his work on 2D quantum materials and ultrafast optical spectroscopy as well as his extensive collaborative works with scientists across the world. The grant provides Prof. Chaw-Keong Yong with the opportunity to establish a competitive research group exploring quantum optoelectronic properties of atomically thin materials using ultrafast optical microscopy.

"Kulturpreis Bayern" for Dr. Fabian Mooshammer

Dr. Fabian Mooshammer has received the "Kulturpreis Bayern" for his PhD Thesis "Multi-terahertz nanotomography of van der Waals quantum materials". The prize honours people who enrich our society with their commitment, their work and their enthusiasm for art, culture and science.... more

Topological high-harmonic generation

Together with the groups of Klaus Richter (UR), Ferdinand Evers (UR), Ulrich Höfer (University of Marburg) and collaborators from the Novosibirsk State University, we discovered a novel generation mechanism of high-order harmonics in the surface state of a topological insulator. When quasi-relativistic electrons are accelerated through the Dirac point by an intense lightwave, they abruptly reverse their velocity allowing for purely non-integer high-harmonic generation. The lightwave-driven currents reveal intriguing aspects of the quantum mechanical nature of electrons in topological matter.

Press release (idw) in German
Press release (idw) in English

The results have been published in Nature.... more

Ultrafast terahertz nanoscopy: Coverstory in Nature Photonics

In collaboration with the group of Jaroslav Fabian (UR) and together with Tyler Cocker and Jessica Boland, we implemented a novel concept to map out ultrafast interlayer tunneling and recombination dynamics of excitons in van der Waals heterostructures in a contact-free manner. The new technique provides spatiotemporal access to tunnelling processes in insulating, conducting, or superconducting systems, on nanometer length and femtosecond time scales, conceptually bridging the gap between near-field microscopy and light-wave driven STM.

Press release (idw) in German
Press release (idw) in English

The results have been published in Nature Photonics. ... more

Congratulations on the "DTZ-Nachwuchspreis"

Fabian Mooshammer received the PhD award by the German terahertz center (Deutsches Terahertzzentrum e.V.) for his thesis "Multi-terahertz nanotomography of van der Waals quantum materials". The biennial award was conferred in the annual meeting on May 7.... more

Tailored Subcycle Nonlinearities of Ultrastrong Light-Matter Coupling

Together with the groups of Dominique Bougeard (UR) and Cristiano Ciuti (Université de Paris), we explored a novel regime of light-matter interaction, where both the Rabi frequency induced by a coherent driving field and the vacuum Rabi frequency set by a cavity field are comparable to the carrier frequency of light. The resulting subcycle nonlinearities may facilitate novel nonclassical light sources, quantum phase transitions, or cavity chemistry with virtual photons.

The results have been published in Physical Review Letters. ... more