Identifying and Mitigating Charge Instabilities in Shallow Diamond Nitrogen-Vacancy Centers.

Area of Science:

• Quantum Information Science
• Solid-State Physics
• Materials Science

Background:

• The charge state of solid-state defects is crucial for their electronic spin properties, which are fundamental to quantum technologies.
• Nitrogen-vacancy (NV) centers in diamond are promising platforms for quantum applications due to their stable electron spins.

Purpose of the Study:

• To measure, analyze, and control the charge-state dynamics of individual near-surface NV centers.
• To improve the initialization fidelity and mitigate charge conversion issues affecting NV center spin measurements.
• To understand and manipulate the local electrostatic environment of NV centers.

Main Methods:

• Characterization of charge-state behavior in individual near-surface NV centers.
• Implementation of logic-based initialization protocols to enhance fidelity.
• Development of measurement protocols to counteract charge conversion effects.
• Identification of tunneling to local electron traps as the ionization mechanism.
• Application of NV-assisted techniques for trap charge-state control and readout.

Main Results:

• Charge-state initialization fidelity of NV^{-} centers varies significantly between individual centers and over time.
• Logic-based initialization effectively mitigates reduced NV^{-} initialization fidelity.
• NV^{-} centers can ionize in the dark on experimentally relevant timescales.
• Charge conversion compromising spin measurements can be mitigated by developed protocols.
• Tunneling to a local electron trap is identified as the dark ionization mechanism.
• Novel NV-assisted techniques enable control and readout of the trap charge state.

Conclusions:

• Understanding and controlling the charge-state dynamics of NV centers is essential for robust quantum technologies.
• The developed methods enhance the reliability and performance of NV centers for quantum applications.
• Control over the local electrostatic environment of NV centers opens avenues for materials design and novel functionalities.