The strong fields associated with few-cycle pulses can drive highly nonlinear phenomena, allowing the direct control of electrons in condensed matter systems. In this context, by employing near-infrared single-cycle pulse pairs, we measure interferometric autocorrelations of the ultrafast currents induced by optical field emission at the nanogap of a single plasmonic nanocircuit. The dynamics of this ultrafast electron nanotransport depends 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 carrier-envelope phase. Quantitative modelling of the experiments enables us to monitor the spatiotemporal evolution of the electron density and currents induced in the system and to elucidate the physics underlying the electron transfer driven by strong optical fields in plasmonic gaps. Specifically, we clarify the interplay between the carrier-envelope phase of the driving pulse, plasmonic resonance and quiver motion.
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The data that support the findings of this study are available from the corresponding author upon reasonable request.
The code and algorithms that support the findings of this study are available from the corresponding author upon reasonable request.
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D.B. and A.L. acknowledge support of the Deutsche Forschungsgemeinschaft through the Emmy Noether programme (BR 5030/1-1) and the collaborative research centre SFB 767. D.B. acknowledges support from the European Research Council through grant no. 819871 (UpTEMPO). G.A. acknowledges project PI2017-30 of the Departmento de Educación, Política Lingüística y Cultura of the Basque Government, and G.A. and J.A. acknowledge funding from project FIS2016-80174-P of the Spanish Ministry of Science, Innovation and Universities MICINN, as well as grant IT1164-19 for consolidated university groups of the Basque Government.
The authors declare no competing interests.
Peer review statement Nature Physics thanks Christian Nijhuis, Olga Smirnova and the other, anonymous, reviewer(s) for their contribution to the peer review of this work.
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Ludwig, M., Aguirregabiria, G., Ritzkowsky, F. et al. Sub-femtosecond electron transport in a nanoscale gap. Nat. Phys. (2019). https://doi.org/10.1038/s41567-019-0745-8