  III-Nitride quantum dots have emerged as a new chip-scale system for quantum
information science, which combines electrical and optical interfaces on a
semiconductor chip that is compatible with non-cryogenic operating
temperatures. Yet most work has been limited to optical excitations. To enable
single-spin based quantum optical and quantum information research, we
demonstrate here quantized charging in optically active, site-controlled
III-Nitride quantum dots. Single-electron charging was confirmed by the voltage
dependence of the energy, dipole moment, fine structures and polarization
properties of the exciton states in the quantum dots. The fundamental energy
structures of the quantum dots were identified, including neutral and charged
excitons, fine structures of excitons, and A and B excitons. The results lay
the ground for coherent control of single charges in III-Nitride QDs, opening a
door to III-Nitride based spintronics and spin-qubit quantum information
processing.
