Sub-femtosecond electron transport in a nanoscale gap

Abstract

We employ near-infrared single-cycle pulse pairs to drive interferometric autocorrelations of the ultrafast current produced by optical field emission at the nanogap of a single plasmonic nanocircuit. This highly nonlinear process depends fully on the precise temporal field profile of the optical driving pulse. Current autocorrelations are acquired with sub-femtosecond temporal resolution as a function of both pulse delay and absolute carrierenvelope phase. In this way, we study the ultrafast dynamics of electronic nanotransport. Quantitative Additional information

Active control of ultrafast electron dynamics in plasmonic gaps using an applied bias

“…We show that a dc field two orders of magnitude smaller than the optical field induced in the gap by an incident single-cycle laser pulse allows for controlling and directing the petahertz currents of the optically emitted electrons and thus the electron transport in the device. The control strategy reported here and based on the dc bias applied between the antenna arms operates simultaneously with earlier studied coherent control using the CEP of the incident pulse [23,35,36]. Our study thus establishes a conceptual basis to extend the application of static or THz fields beyond the control of electron (photo)emission from metallic tips [14][15][16][17][18][19] and electron tunneling [37][38][39].…”

“…On the one hand, the coupling between * andrei.borissov@u-psud.fr electrons and photons in narrow gaps of dimer antennas leads to light emission originating from inelastic electron tunneling events [26][27][28][29]. On the other hand, the highly nonlinear optical field electron emission process [21,24,25,30,31] as well as optically assisted electron tunneling [32][33][34] allow for rectification at optical frequencies and CEP control of the electron transport across the junction [23,35,36].…”

“…These pulses are generated by a homemade laser system based on Er:fibers operating at a repetition rate of 80 MHz. The passively locked carrier-envelope phase can be controlled with subcycle precision and a root-mean-square stability of 10 mrad [35].…”

“…Because of the strong enhancement of the field of the incident laser pulse, the optical field emission and electron transfer processes are dominated by the antenna gap. The main physics behind the experimental observations can thus be captured theoretically using the model system which reproduces the gap geometry of the actual device [35]. In practice we consider two parallel gold cylinders in vacuum, as sketched in Fig.…”

“…The gold nanoparticles are represented using the free electron, jellium metal (JM) approximation [46]. Together with the simplified geometry this allows one to perform the time dependent density functional theory [47][48][49][50] (TDDFT) calculations of the photoemission and transport dominated by the dynamics of valence electrons [7][8][9]35] and account for the plasmon effects [51][52][53]. We use the real-time propagation of the Kohn-Sham orbitals [47] based on the pseudospectral approach [54][55][56][57].…”