# Miniature cavity-enhanced diamond magnetometer

## TL;DR

This paper introduces a compact, highly sensitive diamond-based magnetometer operating at room temperature, utilizing cavity enhancement and NV centers to achieve sub-picotesla sensitivity suitable for biomedical endoscopy.

## Contribution

The work demonstrates a miniaturized cavity-enhanced diamond magnetometer with unprecedented sensitivity, advancing portable magnetic sensing technology for biomedical applications.

## Key findings

- Magnetic-field sensitivity of 28 pT/√Hz achieved
- Projected shot-noise-limited sensitivity of 22 pT/√Hz
- Estimated quantum projection-noise-limited sensitivity of 0.43 pT/√Hz

## Abstract

We present a highly sensitive miniaturized cavity-enhanced room-temperature magnetic-field sensor based on nitrogen-vacancy (NV) centers in diamond. The magnetic resonance signal is detected by probing absorption on the 1042\,nm spin-singlet transition. To improve the absorptive signal the diamond is placed in an optical resonator. The device has a magnetic-field sensitivity of 28 pT/$\sqrt{\rm{Hz}}$, a projected photon shot-noise-limited sensitivity of 22 pT/$\sqrt{\rm{Hz}}$ and an estimated quantum projection-noise-limited sensitivity of 0.43 pT/$\sqrt{\rm{Hz}}$ with the sensing volume of $\sim$ 390 $\mu$m $\times$ 4500 $\mu$m$^{2}$. The presented miniaturized device is the basis for an endoscopic magnetic field sensor for biomedical applications.