arXiv subjects

Andrew Lowther

Publications and source records attributed to Andrew Lowther.

2 recordsLinked to original sources

arXiv2026

The Impact of Internal Electric Fields on Accurate Diamond Magnetometry

Nitrogen-vacancy (NV) center spin ensembles are a promising platform for accurate vector magnetometry, as they offer measurements referenced to a spin Hamiltonian in an anisotropic crystal with native vector sensing capabilities. However, charged dopants within the diamond produce random internal electric fields (RIEFs) that shift NV spin-transition frequencies, and their impact on the accuracy of NV magnetometry has not been investigated. Here, we characterize RIEFs' effect on NV spin-transition spectra and propose an analytical fitting function to improve accuracy in their presence. We build a Monte Carlo RIEF model that reproduces the asymmetric lineshapes observed in experimental optically detected magnetic resonance (ODMR) spectra, and use it as a testbed to quantify RIEF-induced errors by simulating ODMR spectra including RIEFs and comparing reconstructed magnetic fields to the known model input. With standard analysis approaches, we observe systematic errors exceeding the g-factor uncertainty in fields below $\sim$ 5 mT, while the proposed fitting function reduces the error by nearly an order of magnitude. Our results demonstrate that RIEFs can play a significant role in the systematic error budget for NV magnetometry, and offer a path towards improved accuracy in NV quantum sensing.

quant-ph↗

arXiv2025

Bias-field-free operation of nitrogen-vacancy ensembles in diamond for accurate vector magnetometry

Accurate measurement of vector magnetic fields is critical for applications including navigation, geoscience, and space exploration. Nitrogen-vacancy (NV) center spin ensembles offer a promising solution for high-sensitivity vector magnetometry, as their different orientations in the diamond lattice measure different components of the magnetic field. However, the bias magnetic field typically used to separate signals from each NV orientation introduces inaccuracy from drifts in permanent magnets or coils. Here, we present a novel bias-field-free approach that labels the NV orientations via the direction of the microwave (MW) field in a variable-pulse-duration Ramsey sequence used to manipulate the spin ensemble. Numerical simulations demonstrate the possibility to isolate each orientation's signal with sub-nT accuracy in most terrestrial fields, even without precise MW field calibration, at only a moderate cost to sensitivity. We also provide proof-of-principle experimental validation, observing relevant features that evolve as expected with applied magnetic field. Looking forward, by removing a key source of drift, the proposed protocol lays the groundwork for future deployment of NV magnetometers in high-accuracy or long-duration missions.

quant-ph↗