Nanophotonic quantum magnetometry in a spin-dense diamond cavity

Abstract:Quantum sensors based on the nitrogen-vacancy (NV) center in diamond are leading platforms for high-sensitivity magnetometry with nanometer-scale resolution. State-of-the-art implementations, however, typically rely on bulky free-space optics or sacrifice spatial resolution to achieve high sensitivities. Here, we realize an integrated platform that overcomes this trade-off by fabricating monolithic whispering-gallery-mode cavities from a diamond chip containing a high density of NV centers and by evanescently coupling excitation to and photoluminescence from the cavity using a tapered optical fiber. Employing a lock-in-amplified Ramsey magnetometry scheme, we achieve a photon-shot-noise-limited DC sensitivity of $58\,\text{nT}/\sqrt{\text{Hz}}$---the best sensitivity reported to date for a nanofabricated cavity-based magnetometer. The microscopic cavity size enables micrometer-scale spatial resolution and low-power operation, while fiber-coupling provides a path to scalable on-chip integration. Arrays of such sensors could enable NV-NMR spectroscopy of sub-nanoliter samples, new magnetic-gradient imaging architectures, and compact biosensing platforms.

Optics (physics.optics); Quantum Physics (quant-ph)

arXiv:2511.19831 [physics.optics]

(or arXiv:2511.19831v2 [physics.optics] for this version)

https://doi.org/10.48550/arXiv.2511.19831 Focus to learn more arXiv-issued DOI via DataCite

https://doi.org/10.1103/kg8g-r3qk Focus to learn more DOI(s) linking to related resources

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