Manipulating charge states in diamond via resonantly-driven near-field interactions with proximal germanium vacancies

We report on the local manipulation of the charge state of vacancies in diamond, where the resonant excitation of a proximal germanium-vacancy (GeV) center provides a local energy source to charge and discharge the vacancy. We observe that GeV frequently exhibits a splitting of the zero-phonon line (with splitting magnitude 100 MHz – 3 GHz) and spectral hopping between the two transitions. We demonstrate that the energetic splitting originates from a second-order Stark shift induced by local charges on vacancies. The charge-state switching then manifests as a hopping between distinct energies of the GeV zero-phonon line. We show that resonant excitation of the GeV can drive the charge state of the local vacancies. We investigate the dynamics of this process and present a theory for the interaction based on the local optical field of the GeV under resonant excitation.