Press release: Ultrafast control over electron pulses

Nr. 126/2014 - 02.07.2014

Physicists at the University of Göttingen control current flow in nanostructures with terahertz fields

(pug) The rapid improvement in the performance of modern electronics, like those used in smartphones, is based on increasingly smaller and faster processors. For the first time, researchers at Göttingen University have now demonstrated on metallic nanotips that they can actively control currents at terahertz frequencies – 1000 billion cycles per second. Currently, the speed of computer processors is given in gigahertz or the equivalent of one billion cycles per second. To propel future speeds into the terahertz range, entirely new technologies are needed which naturally lead from electronics to optics. Novel concepts from so-called light-wave electronics employ controlled light fields and extremely short laser pulses to govern electron currents on the nanoscale. The current issue of Nature Physics presents the latest progress in this field, obtained by researchers from the University of Göttingen.

In their experiments, the research group of Professor Claus Ropers at the Faculty of Physics superimposed light pulses and electrical terahertz pulses and observed their mututal coupling. “Our measurements give us a direct sampling of the electrical response of the nanostructure to the ultrashort input signal. This lets us observe how the current strength and the speed of electrons follow the ultrafast terahertz transient at the nanotip without delay,” explains doctoral candidate Lara Wimmer.

Even though a number of physical hurdles will have to be overcome before terahertz frequencies will be used in computer processing, direct application possibilities are already emerging from the current results in ultrafast spectroscopy and imaging, one focus of the research group. Doctoral candidate Georg Herink explains, “The unique electron dynamics in the terahertz field allows for a fine tuning of the velocity distribution in an electron pulse. This optimization aims at the shortest pulses for time-resolved electron microscopy, which we are developing here in Göttingen.“

Original publication: Lara Wimmer et al.: Terahertz control of nanotip photoemission, Nature Physics 10, 432–436 (2014), doi: http://dx.doi.org/10.1038/nphys2974

Contact address:
Professor Claus Ropers
Georg-August-Universität Göttingen
Faculty of Physics – IV. Physical Institute
Friedrich-Hund-Platz 1, 37077 Göttingen
Phone +49(0)551 39-4549, e-mail: cropers@gwdg.de
Website: www.uni-goettingen.de/de/91116.html