Fiber-coupled Diamond Magnetometry with an Unshielded 30 pT/$\sqrt{\text{Hz}}$ Sensitivity

Abstract

Ensembles of nitrogen vacancy centres (NVCs) in diamond can be employed for sensitive magnetometry. In this work we present a fiber-coupled NVC magnetometer with an unshielded sensitivity of (30 $\pm$ 10) pT/$\sqrt{\text{Hz}}$ in a (10 - 500)-Hz frequency range. This sensitivity is enabled by a relatively high green-to-red photon conversion efficiency, the use of a [100] bias field alignment, microwave and lock-in amplifier (LIA) parameter optimisation, as well as a balanced hyperfine excitation scheme. Furthermore, a silicon carbide (SiC) heat spreader is used for microwave delivery, alongside low-strain ${}^{12}\text{C}$ diamonds, one of which is placed in a second magnetically insensitive fluorescence collecting sensor head for common-mode noise cancellation. The magnetometer is capable of detecting signals from sources such as a vacuum pump up to 2 m away, with some orientation dependence but no complete dead zones, demonstrating its potential for use in remote sensing applications.

21 pages, 19 figures, correction to data analysis

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• Performance Evaluation of a Diamond Quantum Magnetometer for Biomagnetic Sensing: A Phantom Study
• A Fully-integrated Diamond Nitrogen-Vacancy Magnetometer with Nanotesla Sensitivity
• Endoscopic fiber-coupled diamond magnetometer for cancer surgery
• High-contrast absorption magnetometry in the visible to near-infrared range with nitrogen-vacancy ensembles
• Diamond-on-chip infrared absorption magnetic field camera
• Two-media laser threshold magnetometry: A magnetic-field-dependent laser threshold
• Precessing magnetic particles as ac magnetic field sensors