  The charge state dynamics of the nitrogen-vacancy (NV) center in diamond play
a key role in a wide range of applications, yet remain imperfectly understood.
Using single ps-pulses and pulse pairs, we quantitatively investigate the
charge dynamics associated with excitation and fluorescence depletion of a
single NV center. Our pulsed excitation approach permits significant modeling
simplifications, and allows us to extract relative rates of excitation,
stimulated emission, ionization, and recombination under 531 nm and 766 nm
illumination. By varying the duration between paired pulses, we can also
investigate ionization and recombination out of metastable states. Our results
are directly applicable to experiments employing stimulated emission-depletion
imaging, and can be used to predict optimal operating regimes where excitation
and stimulated emission are maximized relative to charge-state-switching
processes.
