Twisted Bilayer Graphene Quantum Dots for Chiral Nanophotonics

Twisted bilayer graphene (TBG) is a two-dimensional chiral material whose optical activity is remarkably strong for its atomic thickness. While the chiral optical properties of TBG are currently well understood, the optical activity of quantum dots (QDs) made of TBG has not been analyzed so far. Here, we comprehensively analyze the chiral optical properties of TBG QDs with hexagonal, triangular, and rhomboid symmetries. We show that the dissymmetry factors of TBG QDs can reach 10^–2, greatly exceeding the dissymmetry factors of semiconductor QDs and small chiral molecules. The strong optical activity of TBG QDs is due to the out-of-plane polarized transitions of the p_z electrons and can be controlled by changing the size and shape of the QDs. These unique features make TBG QDs highly attractive for application in chiral nanophotonics.