Self-assembled fluorescent nanodiamond layers for quantum imaging

TL;DR

This paper presents a scalable, cost-effective method for fabricating dense fluorescent nanodiamond layers with NV centers, enabling microscale magnetic imaging and sensing applications.

Contribution

It introduces a novel electrostatic self-assembly technique for creating uniform FND layers suitable for quantum imaging.

Findings

Optimized self-assembly conditions maximize FND density

FND layers enable magnetic field and noise imaging

Demonstrates scalable fabrication for quantum sensing

Abstract

The nitrogen-vacancy (NV) center in diamond is emerging as a powerful tool for imaging magnetic and electric signals at the microscale and below. However, most imaging demonstrations thus far have relied on costly, millimeter-sized bulk diamond substrates, which cannot be easily scaled or integrated with other materials. Here, we report a scalable method for fabricating NV-containing dense and homogenous fluorescent nanodiamond (FND) layers through electrostatic self-assembly and demonstrate the utility of the FND layers for magnetic imaging. We investigate the effect of FND concentration in suspension, substrate immersion time, and solvent pH on the FND density on the substrate. We identify optimized self-assembly conditions that maximize the FND density while minimizing aggregation. Using FND layers on a quartz substrate, we demonstrate magnetic field and magnetic noise imaging at the microscale, based on NV optically detected magnetic resonance magnetometry and T$_1$ relaxometry, respectively. Our results provide a direction for the development of cost-effective and scalable FND layers and surface coatings. This paves the way for on-demand quantum sensing and imaging on a broad range of surfaces based on NV centers and other diamond quantum emitters.