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Non-adiabatic light-matter coupling
Quantum electronics
THz nonlinear optics


A record fast THz spectrometer

Exploiting an acousto-optic delay and Er:fiber laser technology, we have built a record fast THz time-domain spectrometer. Our setup requires no mechanical components and is capable of measuring entire THz waveforms in only 28 µs in gapless succession, at a waveform update rate of 36 kHz. As a first demonstration, we image the silhouette of the ancient stone bridge and cathedral of Regensburg which are encoded as a height profile in a rapidly spinning teflon disc, as well as the topography of the greater Tokyo area including Mt. Fuji. Our results open the door to real-time THz imaging and spectroscopy of singular events with numerous novel applications in physics, chemistry, biology, and in the industry.

The work is featured as the cover story of the March 21 issue of Applied Physics Letters, Appl. Phys. Lett. 108, 121101 (2016), and was recently selected as Editor's pick.

Nanoscale strain in an ultrafast phase transition

In collaboration with our colleagues at Vanderbilt University in Nashville and PD Tobias Korn and Prof. Dr. Christian Schüller from Regensburg, we have revealed a previously unseen phenomenon in the model correlated-electron system vanadium dioxide. We performed the first ultrafast near-field experiments on an insulator-to-metal phase transition material, discovering a connection between local strain and ultrafast dynamics in a nanobeam. Our results show that nanoscale strain is built into the insulating state of the beam, predetermining the periodic insulator/metal domain structure that forms along the beam upon heating. Strain tailoring could enable control of these domains in the future, paving the way toward ultrafast nano-optical switches.

The results are reported in Nano Letters.

A quantum carousel for electrons

In collaboration with our theory partners from Marburg, we have shown how intense, single-cycle THz pulses drive electrons in a magnetic field into an extremely nonlinear regime which is in sharp contrast to the predictions of the famous Kohn theorem. Our results spark hope for future quantum information processing at THz clock rates, exploiting the strong nonlinearities and simultaneously long coherence times of Landau resonances.

The results are reported in Nature Physics,
Nature Physics 12, 119-123 (2016).

See also: Article in the Newspaper "Mittelbayerische Zeitung"

Press release: in German/Deutsch

Dr. Michael Porer receives
the Kulturpreis Bayern 2015

Dr. Michael Porer has been awarded with the Kulturpreis Bayern 2015 for his outstanding PhD thesis entitled "Ultrafast low-energy dynamics of strongly correlated systems". The award has been conferred during a prize ceremony in Essenbach on November 18, 2015.

Press release of the Bayernwerk (in German/Deutsch)
Press release of the University of Regensburg (in German/Deutsch)

Best lecture award

Prof. Huber's new lecture "Light matter interaction" has been awarded the prize for the best physics lecture at the University of Regensburg during the summer term 2015.

Fugacious excitons

In a collaboration with the groups of Prof. Dr. Christian Schüller and PD Dr. Tobias Korn from Regensburg and Prof. Dr. Rudolf Bratschitsch from Münster we succeeded in directly accessing internal quantum transitions of Coulomb-bound electron hole pairs in a single atomic layer of tungsten diselenide. With the help of sub-cycle multi-THz spectroscopy, a record fast radiative decay of these excitons within only 150 fs was observed.

The results are reported as a cover story in Nature Materials 14, 889-893 (2015).

This work has been featured in a News and Views Article "2D materials: Ultrafast exciton dynamics" by Xavier Marie and Bernhard Urbaszek, Nature Materials 14, 860-861 (2015).

Press release: in German/Deutsch

On the crest of the wave

In collaboration with our theory partners from Marburg, we have succeed in taking and analyzing a slow-motion movie of the quantum motion of lightwave-driven electrons in a semiconductor. By applying ultrashort and atomically strong electromagnetic waveforms, we excite and accelerate initially bound electrons in gallium selenide which emit extremely broadband radiation - so called high-order harmonics. A newly developed femtosecond correlation scheme now allowed us to exactly clock the emission of these ultrashort light bursts on a timescale much shorter than a cycle of the light wave. The unraveled time structure of high-harmonics sheds light on a new type of strong-field quantum interference between electrons on different quantum paths and opens new routes towards sub-femtosecond solid-state pulse sources.

The results are reported in Nature 523, 572 (2015).

This work has been featured in a News and Views Article "Harmonic radiation from crystals" by P. Hommelhoff and T. Higuchi, Nature 523, 541 (2015).

See also: Article in the Newspaper "Mittelbayerische Zeitung"

Press release: in English | in German/Deutsch

New PhD opening

In a European collaborative project we explore fundamental physics and photonics of novel ultrafast and ultracompact high-power terahertz sources. We now accept applications of excellent candidates holding a master degree (or equivalent) in physics. If you are interested in joining our dynamic group, please send your CV (including potential publications), a brief coverletter and one letter of recommendation to Rupert Huber.

THz metamaterials light up

Using tiny metallic nanoantennas resonant at THz frequencies, we have generated hitherto inaccessibly large, slowly varying electric fields in a semiconductor, causing the material to lighten up brightly through recombination of electron-hole pairs after interband tunneling injection. Our novel technique allows us to shine new light on electrical transport phenomena in this so far unexplored regime.

The results are reported in Phys. Rev. Lett. 113, 227401 (2014).

THz metamaterials light up

We have developed a novel microscope that allows us to record slow-motion movies of tiny nanostructures with groundbreaking time resolution - faster even than a single oscillation cycle of light. With our new microscope, we have directly imaged the super-fast motion of electrons.

The results are reported in Nature Photonics 8, 841-845 (2014).

This work has been featured in the News and Views Article "Nanoscale terahertz spectroscopy" by H. Shigekawa, S. Yoshida and O. Takeuchi, Nature Photonics 8, 815-817 (2014).

Press release: in English   |   in Deutsch/German

See also: article in IEEE spectrum

The dark side of a bright condensate

In collaboration with the "CNRS-Laboratoire de Photonique et Nanostructures" in Paris, we shed light on the dark side of a bright exciton-polariton condensate, for the first time. In our experiment, terahertz pulses were employed to study the build up and decay dynamics of the design-cut half light / half matter quasiparticles via their matter component. The results reveal fundamental differences between conventional photon lasing and polariton condensation and point out possibilities for coherent control of quantum condensates.

The results are reported in Nature Communications 6, 4648 (2014)

Press release: in German/Deutsch

Waves in a sea of electrons

In a collaboration with partners from Germany and Greece, we studied the ultrafast interplay between electrons and crystal lattice and solved a forty year old mystery of solid state physics. With a new type of femtosecond slow motion technique, we have shown that the charge density wave in titanium diselenide, a particularly well studied model system, is composed of two constituent orders. The waves in the sea of electrons in this compound are found to be the result of a cooperative interaction of electrons and crystal lattice. The new approach to capture the dynamics of several orders in a femtosecond slow-motion might become important for a better understanding of related phenomena in solids, such as superconductivity.

The results are reported in Nature Materials 13, 857-861 (2014)

Press release: in German/Deutsch

Best lecture award

Prof. Huber's course "Struktur der Materie I" has been awarded the prize for the best physics lecture at the University of Regensburg during the summer term 2014. This has been the fourth best lecture award for Prof. Huber's courses.

Fabian Langer wins Maiman Competition 2014

Fabian Langer has been awarded the grand prize of the Maiman Outstanding Student Paper Competition at CLEO 2014. He has been honoured for presenting the group's work on dynamical Bloch oscillations.

Press release (German)
Article in the Newspaper "Mittelbayerische"

Strong fields make electrons tremble
Novel quantum motion of electrons
generates record bandwidth radiation

In collaboration with physicists from Marburg University and Paderborn University we found that electrons in atomically strong electric fields do not move straight from one contact to the other, but perform a quantum quiver on a time scale of a femtosecond - the quadrillionth part of a second - and emit extremely broadband light. Remarkably, the oscillating electrons emit high-frequency electromagnetic radiation covering an unprecedented window from the microwave regime to the ultraviolet, setting an impressive bandwidth record for femtosecond sources.

The results are reported in Nature Photon. 8, 119-123 (2014)

This work has been featured in the News and Views Article "Terahertz optics: Terahertz-driven harmonics" by K. Y. Kim and Y. S. You, Nature Photonics 8, 92-94 (2014).

Press release: in English in German/Deutsch

60th anniversary of the Alexander von Humboldt Foundation
News article

In celebration of the 60th anniversary of the establishment of the Alexander von Humboldt Foundation, Mittelbayerische newspaper interviewed Dr. Tyler Cocker and Prof. Rupert Huber to discuss Dr. Cocker's recently awarded Humboldt Fellowship. The article, published on October 24, 2013, highlights the cutting-edge research currently underway in the near-field laboratory.

Best lecture awards
Lecture & tutorial awarded

Dr. Christoph Lange, tutor and stand-in lecturer for Prof. Huber's course "Struktur der Materie I" (structure of matter 1) has been awarded the prize for the best tutorial given at the physics faculty in the summer term 2013.

Prof. Huber's course "Struktur der Materie I" has been awarded the prize for the best physics lecture at the University of Regensburg during the summer term 2013, the third consecutive term that Prof. Huber's courses have been awarded this honor.

ERC Starting Grant
Project QUANTUMsubCYCLE starts

Rupert Huber and his team received a 2012 Starting Grant by the European Research Council. The research work on the project entitled QUANTUMsubCYCLE has now been officially kicked off. The goal of this initiative is to establish a novel class of sub-cycle optics, which harnesses the absolute optical phase and amplitude of few-cycle pulses to control condensed matter faster than a single oscillation period of light.

This project has also been highlighted in the university newsletter signatUR in its edition of april 2013.

Technological developments
News article & conference presentation

An article by local newspaper Mittelbayerische highlights a recent invention of novel optical sensor technology by Olaf Schubert and Rupert Huber. During the first round of the businessplan competition "BPWN 2013" a sketch of a potential spin-off has been placed among the 20 finalists. Another invention by the two physicists, a novel fastscan delay line developed in collaboration with Fastlite, has recently been published in Optics Letters.

Best lecture award


The latest course on "Nonlinear Optics" given by Prof. Huber and the discussion leaders Michael Porer, Olaf Schubert and Dr. Christoph Lange has been decorated with the award of the best physics lecture at the University of Regensburg during the winter term 2012/2013.

The focus of this class was placed on modern concepts and phenomena of light-matter interaction. Starting from a classical description of perturbative nonlinear optics and its manyfold state-of-the-art applications, the discussion proceeded to non-perturbative nonlinearities in quantized few-level systems and high-order harmonic generation. In the final part, a tractable introduction into second quantization as well as key ingredients of quantum optics and quantum electrodynamics were provided. Discussion sections, students' presentations on select topics, and laboratory excursions complemented the lectures.

Best lecture award


Professor Huber's course "Struktur der Materie I" (structure of matter 1) has been awarded the prize for the best physics lecture at the University of Regensburg during the summer term 2012. All demonstration experiments accompanying the lecture were prepared, carried out and explained by Dr. Karoline Bernhard-Höfer.

Image: Part of the lecture team (from left to right: Michael Porer (discussion leader), Christoph Lange (stand-in lecturer), Dieter Schuh (stand-in lecturer), Olaf Schubert (discussion leader) and Rupert Huber (professor). Not shown are discussion leaders Max Eisele and Bernhard Surrer.

Aligned by distortion
Magnetic order trails ultrafast atomic motion


A team including physists from Germany, Switzerland and Korea has discovered that a periodic lattice distortion induced by an extremely short optical pulse facilitates alignment of magnetic moments in a parent compound of iron-based unconventional superconductors. Strikingly, the magnetic order is established within a time shorter than a trillionth of a second. This discovery demonstrates a strong spin-phonon coupling in the novel class of high-temperature superconductors and, thus, provides an important clue for the development of a microscopic theory of superconducting pairing in these materials. The work is reported in the latest issue of Nature Materials (K. W. Kim et al., Nature Materials 11, 497 (2012)) .
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