Light-induced quantum tunnelling current in graphene.

In the last decade, advancements in attosecond spectroscopy have allowed researchers to study and manipulate electron dynamics in condensed matter via ultrafast light fields, offering the possibility to realise ultrafast optoelectronic devices. Here, we report the generation of light-induced quantum tunnelling currents in graphene phototransistors by ultrafast laser pulses in an ambient environment. This tunnelling effect provides access to an instantaneous field-driven current, demonstrating a current switching effect (ON and OFF) on a 630 attosecond scale (1.6 petahertz speed). We show the tunability of the tunnelling current and enhancement of the graphene phototransistor conductivity by controlling the density of the photoexcited charge carriers at different pump laser powers. We exploited this capability to demonstrate various logic gates. The reported approach under ambient conditions is suitable for the development of petahertz optical transistors, lightwave electronics, and optical quantum computers.