THz light-matter coupling in a hBN-encapsulated graphene quantum dot

Using transport spectroscopy under coherent THz illumination, we demonstrate THz light-matter coupling in a graphene quantum dot from 100 GHz to 380 GHz. The quantum absorption of THz photons results in a broadening of differential conductance peaks at low frequency and photo-induced satellite current peaks at high frequencies as a signature for photon-assisted tunneling. Our study shows the coherent interaction between the GQD and THz radiation.