  Nitrogen-vacancy (NV) and silicon-vacancy (SiV) color defects in diamond are
promising systems for applications in quantum technology. The NV and SiV
centers have multiple charge states, and their charge states have different
electronic, optical and spin properties. For the NV centers, most
investigations for quantum sensing applications are targeted on the negatively
charged NV (NV$^{-}$), and it is important for the NV centers to be in the
NV$^{-}$ state. However, it is known that the NV centers are converted to the
neutrally charged state (NV$^{0}$) under laser excitation. An energetically
favorable charge state for the NV and SiV centers depends on their local
environments. It is essential to understand and control the charge state
dynamics for their quantum applications. In this work, we discuss the charge
state dynamics of NV and SiV centers under high-voltage nanosecond pulse
discharges. The NV and SiV centers coexist in the diamond crystal. The
high-voltage pulses enable manipulating the charge states efficiently. These
voltage-induced changes in charge states are probed by their photoluminescence
spectral analysis. The analysis result from the present experiment shows that
the high-voltage nanosecond pulses cause shifts of the chemical potential and
can convert the charge states of NV and SiV centers with the transition rates
of $\sim$ MHz. This result also indicates that the major population of the SiV
centers in the sample is the doubly negatively charged state (SiV$^{2-}$),
which is often overlooked because of its non-fluorescent and non-magnetic
nature. This demonstration paves a path for a method of rapid manipulation of
the NV and SiV charge states in the future.
