Broadband magnetometry by infrared-absorption detection of nitrogen-vacancy ensembles in diamond

TL;DR

This paper introduces a novel infrared-absorption based magnetometry technique using nitrogen-vacancy ensembles in diamond, achieving high sensitivity and efficiency, especially at low temperatures, with potential applications in precise magnetic field measurements.

Contribution

It presents a new method for NV-based magnetometry utilizing infrared absorption, improving measurement contrast and collection efficiency over traditional fluorescence methods.

Findings

Photon shot-noise limited sensitivity of 5 pT in one second at 75 K.

Achieves a noise floor of 7 nTrms in a gradiometer configuration at 110 Hz.

Operation bandwidth extends from dc to a few megahertz.

Abstract

We demonstrate magnetometry by detection of the spin state of high-density nitrogen-vacancy ensembles in diamond using optical absorption at 1042 nm. With this technique, measurement contrast, and collection efficiency can approach unity, leading to an increase in magnetic sensitivity compared to the more common method of collecting red fluorescence. Working at 75 K with a sensor with effective volume $50 \times 50 \times 300$ microns^3, we project photon shot-noise limited sensitivity of 5 pT in one second of acquisition and bandwidth from dc to a few megahertz. Operation in a gradiometer configuration yields a noise floor of 7 nTrms at ~110 Hz in one second of acquisition.