  When subjected to electromagnetic radiation, the fluctuation of the
electronic current across a quantum conductor increases. This additional noise,
called photon-assisted shot noise, arises from the generation and subsequent
partition of electron-hole pairs in the conductor. The physics of
photon-assisted shot noise has been thoroughly investigated at microwave
frequencies up to 20 GHz, and its robustness suggests that it could be extended
to the Terahertz (THz) range. Here, we present measurements of the quantum shot
noise generated in a graphene nanoribbon subjected to a THz radiation. Our
results show signatures of photon-assisted shot noise, further demonstrating
that hallmark time-dependant quantum transport phenomena can be transposed to
the THz range.
