Voltage-Induced Modulation in the Charge State of Si-Vacancy Defects in Diamond using High Voltage Nanosecond Pulses

Silicon-vacancy defects have been identified as a promising optical transition for quantum communications, quantum control, and quantum information processing. In the work presented here, we demonstrate a voltage-controlled mechanism by which the photoluminescent (PL) emission from silicon-vacancy (Si-V) defects in diamond can be modulated. In particular, we can selectively produce emission from the negatively charged state of this defect (i.e., Si-V^–), which exhibits narrow (Γ = 4 nm) emission at 738 nm at low laser power. This approach uses high voltage (2-5kV) nanosecond pulses applied across top and bottom electrodes on a 0.5 mm thick diamond substrate. In the absence of high voltage pulses, we observe no emission at 738nm. This feature increases monotonically with peak pulse voltage, pulse repetition rate (i.e., frequency), and incident laser intensity. We observe saturation of the PL intensity for pulse voltages above 3.2 kV and frequency above 100 Hz. Based on electrostatic simulations, we estimated the local electric field intensity near the tip of the Cu electrode to be 1.5 x 10⁵ V/cm at these voltages. However, as a function of laser power, we observe a linear dependence of PL intensity without saturation. These saturating and non-saturating behaviors provide important insight into the voltage-induce charging mechanisms and kinetics associated with this process.