THz excited state level spacing in encapsulated graphene quantum dots

We report a high-quality encapsulated graphene quantum dot that exhibits stable Coulomb diamonds and excited states with a spacing of 0.4 THz. We performed the first transport spectroscopy measurement under THz illumination of a large quantum dot. The photocurrent map allows to measure with high precision a non-linear chemical potential renormalization of the graphene electrodes via the interaction with the quantum dot states.