Light-field control of electric current in metal-dielectric nano-circuits

The advent of intense few-cycle near infrared (NIR) laser pulses with stable and tunable carrier envelope phase (CEP) has enabled the control of electromagnetic fields with attosecond time precision [1]. Here we aim at exploiting these few-cycle NIR optical fields with well-defined CEP to generate and control the motion of charge carriers within heterogeneous nanoscaled solid state interfaces. We demonstrate the generation of directly measurable photocurrents in unbiased metal-dielectric-metal nanogaps, whose magnitude and directionality can be tuned with the laser CEP. This effect vanishes with the increase of the laser pulse duration. We claim that such phenomenon is the signature of optically induced electron tunneling at the heterogeneous interface, with subsequent acceleration of the charge carrier in the ultrashort laser field.