Optical techniques developed by us provide a unique platform to study electron transport and dynamics in single molecules trapped in the tunnel junction of on-chip quantum nanodevices. In efforts to achieving this goal, we have recently demonstrated an in-situ real-time tracking of collective electron oscillations in a nanodevice comprised of gold bowtie nanoantennas, by recording photo-assisted tunnelling currents generated by such oscillations8. The collective electron oscillations show a non-instantaneous response to the driving laser fields with a decay time of nearly 10 femtoseconds. We also reported a direct and local sampling of nonlinear (2nd and 3rd order) electron oscillations in the nanodevice, for the very first time. Electron oscillations with an oscillation period as short as ~ 900 attosecond were traced for the first time. Looking into the future, we anticipate our approach to eventually enable the direct sampling of polarization response of single molecules trapped in the junction of the nanodevice as well as enable time-resolved studies on electron transport through a single molecule on attosecond time scales, which is a key goal in realizing single-molecule light-wave electronics.

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