Attosecond Electron Transport in Plasmonic Nanostructures

Abstract

This thesis presents a demonstration of controlling electric current between two nanoscaled electrodes on an attosecond time scale (the scale of 10-18 seconds). The ultrafast electrical control is enabled by harnessing the carrier wave of near-infrared light pulses as an alternating-current bias. Light pulses spanning only a single oscillation cycle, serving as an ultrashort voltage bias, are focused on a single nanoelectrode pair. The exact shape of the electric field cycle determines how single electrons are being transported between the two electrodes. The lightwave-driven current takes place for a period of only a few hundred attoseconds and its direction can be freely set via the carrier-envelope phase (CEP) of the pulses.The thesis is presented in five chapters. After an introductory chapter, the thesis provides the required background knowledge. Vital to the experimental success was to build an innovative laser system. It is based on the sophisticated Erbium-fiber laser technology and generates 4-femtosecond-long light pulses in the near-infrared spectral range, with a pulse duration of excactly a single optical cycle. The system operates at a high pulse repetition rate of 80 MHz and passively stabilizes the CEP. An additional novelty is that the CEP can be freely adjusted. The laser source is described in the third chapter. The fourth addresses the manufacturing and electrical characterization of the nanoelectrodes. The fabrication was carried out by electron beam lithography with a resolution reaching the limit set by this technology. A gap size of 8 nanometers between the electrodes is achieved in a reproducible manner. The experimental results on the optically driven attosecond electron transport are subject of the last chapter.