  In the last decade, advancements in attosecond spectroscopy have allowed us
to study electron motion dynamics in condensed matter. The access to these
electron dynamics and, consequently, its control by an ultrafast light field
paves the way for establishing ultrafast optoelectronics. Here, we report the
generation of light-induced quantum tunnelling current in graphene
phototransistors by ultrafast laser pulses in an ambient environment. This
tunnelling effect provides access to the instantaneous field-driven current to
demonstrate the current switching (ON and OFF) on a 630 attosecond (1.6
petahertz speed). Moreover, we controlled the tunnelling current and enhanced
the graphene phototransistor conductivity by controlling the density of the
photoexcited charge carriers at different pump laser powers. Furthermore, we
exploited this capability to demonstrate various logic gates. The demonstrated
light-induced tunnelling current and ultrafast switching were attained under
standard room temperature and pressure conditions. Therefore, the presented
scientific advancement in this work is at the technology readiness level
suitable for its immediate integration into the development of ultrafast,
nearly six orders of magnitude faster, optical transistors, lightwave
electronics, and optical quantum computers.
