Real-time Amplitude and Phase Estimation of AC Fields with Diamond Spins

TL;DR

This paper introduces a method to estimate the amplitude and phase of AC magnetic fields in real-time using diamond NV centers, enabling single-shot measurements with high sensitivity and dynamic frequency tuning.

Contribution

It presents a novel single-shot measurement protocol for real-time amplitude and phase estimation of AC fields with NV centers, including error analysis and dynamic frequency adjustment.

Findings

Achieved 78 nT amplitude sensitivity per shot

Achieved 63 mrad phase sensitivity per shot

Demonstrated real-time frequency tuning capability

Abstract

Nitrogen-vacancy centers in diamond have been shown to be capable of detecting AC magnetic fields with high sensitivity, spectral resolution, and spatial resolution. However, most studies so far have focused on the regime of time-averaged or time-correlated measurements, while little attention has been paid to the single-shot regime. Here we show that the amplitude and phase of an AC field can be retrieved from a single pair of two consecutive measurements. We demonstrate this concept by measuring a 4 MHz AC field with a per-shot amplitude and phase sensitivity of 78 nT and 63 mrad, respectively, at a temporal resolution of 320 us. We also investigate the effects and quantify the errors resulting from probe frequency detunings, as well as operating in the strong field regime. Moreover, we showcase the ability of the measurement protocol to dynamically change the probe frequency in real-time. This work advances the use of NV centers for real-time measurements of AC magnetic fields.