Lightwave valleytronics in WSe2 – Publication by B4 (SW Koch) in Nature
As part of their ongoing theory-experiment collaboration, members from project B4 (group of Prof. S.W. Koch) jointly with colleagues from Regensburg (group of Prof. Huber) and the University of Michigan (former co-PI in B4 Prof. Kira) demonstrate how to control and manipulate the quantum states of optically excited electrons in modern quasi-two dimensional semiconductor materials. In particular, they show that the valley pseudo-spin in a tungsten diselenide system can be switched at ultrafast speeds by applying an intense light field.
Energy-landscape in a WSe2-semiconductor depicted as blue hills. Electrons are accelerated from one valley to the next (yelloworange) with the colored arrows indicating change of the valley-pseudospin. (Ill.: F. Langer, Univ. Regensburg; use only in context of paper published).
In today’s information technology, quantum effects still play a mostly supporting role. This should change in the future, as research into quantum information technology paves the way towards efficient storage, processing and communication – eventually replacing “Moore’s law” with its own. The basis are robust and quickly switchable electronic states provided by the so-called “valley pseudospin” that can be changed when energized electrons are optically driven between distinct energetic valleys in the hexagonal layered materials.
This controlled ultrafast switching between the occupation of different bandstructure minima provides an important step in the new area of light driven electronics, opening the field for lightwave valleytronics. Ultimately this may become important in developing room-temperature quantum signal processing.
Publication
F. Langer, C. P. Schmid, S. Schlauderer, M. Gmitra, J. Fabian, P. Nagler, C. Schüller, T. Korn, P. G. Hawkins, J. T. Steiner, U. Huttner, S. W. Koch, M. Kira & R. Huber, Lightwave valleytronics in a monolayer of tungsten diselenide,
Nature 557 (2018) 76-80, DOI: 10.1038/s41586-018-0013-6
See also press release (
Uni Marburg in German;
UMICH Ann Arbor in English), a video (UMICH Ann Arbor) and articles
in
Oberhessische Presse and Rhein-Neckar-Zeitung.
Contact
Prof. Dr. Stephan W. Koch
Dept. of Physics, Philipps-Universität Marburg
SFB 1083 Project B4 (SW Koch)
Tel. +49 (0)6421 28-21336
Email: Stephan.W.Koch@physik.uni-marburg.de
Pedro Miguel Echenique, external member of SFB 1083 and former PI of guest project “Electron dynamics at organic/inorganic interfaces from first principles” has been awarded a honorary membership of the European Physical Society (EPS). The EPS Council reserves this rare distinction to a maximum of 30 living individuals with exceptional achievements in physics. Current honorary members include four scientists from Germany and one from Spain (https://www.eps.org/page/distinction_honorary).
