Atto-femtosecond Control of Coherent Electrons in Low-temperature and Low-dimensional Nanomaterials (ACCEL-Nano)

• Applicant: Professor Dr. Matthias Kling, since 4/2020
• Subject Area: Experimental Condensed Matter Physics ; Optics, Quantum Optics and Physics of Atoms, Molecules and Plasmas
• Term: from 2018 to 2022
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 389759512

Ultrafast nanoelectronic devices operating on atto-femtosecond timescales have received much interest as candidates for devices with unprecedented operating speed. These devices rely on ultrafast electron dynamics in nano-objects driven by ultrashort laser pulses. In a nano-object, if the coherence length of electrons exceeds the size of the object, the electron waves will coherently extend all over the object, thus forming a coherent electron system. Such a system can be constructed using low-temperature and low-dimensional nanomaterials. Realizing spatio-temporal control of such a coherent electronic system would open a door to new types of ultrafast nanoelectronic devices. Because the duration of few-cycle laser pulses is far shorter than the temporal coherence of electrons in the object, electron excitations can be manipulated in time within the coherence time. Manipulating coherent electron systems in space, however, is difficult because the diffraction limit of a laser is typically larger than the electron coherence length. Now it may be possible to achieve nanoscale spatial control of ultrafast electron dynamics by using laser-induced field emission. Applying strong electric fields to a metallic nano-tip enables field emission due to electrons tunneling into a vacuum. This field emission radically propagates from the tip apex and magnifies nanoscale geometrical information on the tip apex to a macroscopic scale, which thus serves as field emission microscopy (FEM). As a result, FEM becomes a powerful tool to investigate nanoscale electronic systems. Because its inherently small source size is comparable to the coherence length inside metals, field emission is also widely used for producing highly coherent electron beams. Illuminating such a nano-tip with femtosecond laser pulses has realized laser-induced pulsed field emission, which generates ultrashort coherent electron pulses from nano-scale areas. Laser-induced electron emission has exhibited many intriguing atto-femtosecond electron dynamics in nanometer areas such as electron-electron interactions, rescattering processes or subcycle emissions. Shortly after accomplishing pulsed field emission, we have produced an ultrafast pulsed field-emission source with emission site selectivity on a few tens of nanometers scale, which would enable nanoscale control of the coherent electronic system that is far beyond the diffraction limit of a laser. Using a laser-induced field emission, we would like in this project to realize spatio-temporal control of coherent electron waves, and apply the technique to investigate and control the atto-femtosecond dynamics of the coherent electronic system in low-dimensional and low-temperature nanomaterials. The planned experiments should also create new directions in ultrafast coherent electron dynamics, surface science, spintronics, time-resolved electron holography and quantum information science.

• DFG Programme: Research Grants
• Cooperation Partner: Markus Bohn
• Ehemaliger Antragsteller: Dr. Hirofumi Yanagisawa, until 3/2020