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Project B.3.2

Fig. B.3.3: Scheme for demonstrating light-field control of electric current in condensed matter.

Light-controlled electric current: exploring the limits of electronics

In a wide-bandgap solid electrons can be promoted into the conduction band via absorption of a UV laser pulse or via optical field-induced interband tunneling. Subsequently, these injected charge carriers can be accelerated by the electric field of a synchronised few-cycle NIR or MIR waveform. If the optical excitation is confined to less than a half cycle of the infrared field the latter may drive a macroscopic current towards nanoscaled electrodes. This current would depend on the laser waveform. Initially, we will focus on hybrid nano-interfaces consisting of a wide bandgap material contacted to metal electrodes (Fig. B.3.3). An ultrafast carrier injection from the valence band will be provided by either an intense few-cycle VIS / NIR pulse or by an ultrashort UV pulse. The subsequent drift of the charge carriers will be induced and controlled by CEP-stable few-cycle laser pulses or by synthesised light fields developed in Project B.3.1. To understand the interplay of strong-field nonlinear phenomena, lightinduced coherent dynamics and dephasing due to scattering we will extend the standard methods of quantum kinetics such as the many-body density-matrix approach and non-equilibrium Green’s functions. At a later stage, this control scheme will be extended to single organic molecules contacted to a metal nanojunction. If successful, this study will constitute a first step towards a single-molecule optical transistor. We aim to gain fundamental insight into the physical processes governing the light-field-induced / controlled dynamics of electrons in heterogeneous condensed matter systems and complement findings in Projects B.1.4, B.3.3 and B.3.5.