Quantum sensors have attracted broad interest in the quest towards sub-micronscale NMR spectroscopy. Such sensors predominantly operate at low magnetic fields. Instead, however, for high resolution spectroscopy, the high-field regime is naturally advantageous because it allows high absolute chemical shift discrimination. Here we propose and demonstrate a high-field spin magnetometer constructed from an ensemble of hyperpolarized 13C nuclear spins in diamond. The 13C nuclei are initialized via Nitrogen Vacancy (NV) centers and protected along a transverse Bloch sphere axis for minute-long periods. When exposed to a time-varying (AC) magnetic field, they undergo secondary precessions that carry an imprint of its frequency and amplitude. The method harnesses long rotating frame 13C sensor lifetimes T2′>20s, and their ability to be continuously interrogated. For quantum sensing at 7T and a single crystal sample, we demonstrate spectral resolution better than 100 mHz (corresponding to a frequency precision <1ppm) and single-shot sensitivity better than 70pT. We discuss the advantages of nuclear spin magnetometers over conventional NV center sensors, including deployability in randomly-oriented diamond particles and in optically scattering media. Since our technique employs densely-packed 13C nuclei as sensors, it demonstrates a new approach for magnetometry in the "coupled-sensor" limit. This work points to interesting opportunities for microscale NMR chemical sensors constructed from hyperpolarized nanodiamonds and suggests applications of dynamic nuclear polarization (DNP) in quantum sensing.
@article{arxiv.2112.11612,
title = {High-Field Magnetometry with Hyperpolarized Nuclear Spins},
author = {Ozgur Sahin and Erica de Leon Sanchez and Sophie Conti and Amala Akkiraju and Paul Reshetikhin and Emanuel Druga and Aakriti Aggarwal and Benjamin Gilbert and Sunil Bhave and Ashok Ajoy},
journal= {arXiv preprint arXiv:2112.11612},
year = {2022}
}