Probing surface noise with depth-calibrated spins in diamond

Area of Science:

• Quantum Sensing
• Materials Science
• Solid-State Physics

Background:

• Nitrogen-vacancy (NV) centers in diamond are promising for nanoscale magnetic resonance imaging (MRI).
• Surface noise significantly impacts the sensitivity and resolution of NV-based nanoscale MRI.
• A quantitative understanding of surface spin noise is crucial for advancing NV-center applications.

Purpose of the Study:

• To identify and characterize the dominant noise sources affecting shallow NV centers near diamond surfaces.
• To develop a method for probing spin noise at calibrated depths within diamond.
• To establish a model for NV dephasing caused by surface electronic spins.

Main Methods:

• Utilized dynamical decoupling techniques applied to shallow NV centers at precisely controlled depths.
• Employed nitrogen delta-doping during diamond growth for controlled NV placement.
• Performed nanoscale depth imaging to correlate NV dephasing with surface properties.

Main Results:

• Demonstrated that a surface bath of electronic spins is the primary source of NV dephasing.
• Determined a correlation rate of 200 kHz for the surface electronic spin bath.
• Showed that this surface spin bath's correlation rate is significantly faster than the bulk nitrogen spin bath.

Conclusions:

• The developed method allows for quantitative characterization of spin noise at material surfaces.
• Surface electronic spins pose a faster dephasing mechanism for NV centers compared to bulk spins.
• This approach enables the study of spin noise in various material surfaces for enhanced nanoscale sensing.