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arXiv:2512.09230

Parallel accelerated electron paramagnetic resonance spectroscopy using diamond sensors

Zhehua Huang, Zhengze Zhao, Fei Kong, Zhecheng Wang, Pengju Zhao, Xiangtian Gong, Xiangyu Ye, Ya Wang, Fazhan Shi, Jiangfeng Du

quant-phphysics.bio-phphysics.chem-phSubmitted Dec 10, 2025• Announced Dec 11, 2025
arXivHTMLPDF

Abstract

The nitrogen-vacancy (NV) center can serve as a magnetic sensor for electron paramagnetic resonance (EPR) measurements. Benefiting from its atomic size, the diamond chip can integrate a tremendous amount of NV centers to improve the magnetic-field sensitivity. However, EPR spectroscopy using NV ensembles is less efficient due to inhomogeneities in both sensors and targets. Spectral line broadening induced by ensemble averaging is even detrimental to spectroscopy. Here we show a kind of cross-relaxation EPR spectroscopy at zero field, where the sensor is tuned by an amplitude-modulated control field to match the target. The modulation makes detection robust to the sensor's inhomogeneity, while zero-field EPR is naturally robust to the target's inhomogeneity. We demonstrate an efficient EPR measurement on an ensemble of roughly 30000 NV centers. Our method shows the ability to not only acquire unambiguous EPR spectra of free radicals, but also monitor their spectroscopic dynamics in real time.

Journal reference
Phys. Rev. Lett. 134, 130801 (2025)
DOI
10.1103/PhysRevLett.134.130801
Comments
15 pages, 4 figures in the maintext

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The nitrogen-vacancy (NV) center can serve as a magnetic sensor for electron paramagnetic resonance (EPR) measurements. Benefiting from its atomic size, the diamond chip can integrate a tremendous amount of NV centers to improve the magnetic-field sensitivity. However, EPR spectroscopy using NV ensembles is less efficient due to inhomogeneities in both sensors and targets. Spectral line broadening induced by ensemble averaging is even detrimental to spectroscopy. Here we show a kind of cross-relaxation EPR spectroscopy at zero field, where the sensor is tuned by an amplitude-modulated control field to match the target. The modulation makes detection robust to the sensor's inhomogeneity, while zero-field EPR is naturally robust to the target's inhomogeneity. We demonstrate an efficient EPR measurement on an ensemble of roughly 30000 NV centers. Our method shows the ability to not only acquire unambiguous EPR spectra of free radicals, but also monitor their spectroscopic dynamics in real time.
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Precision measurements of electric current flow in motors and power converters is indispensable for efficient digital control by monitoring their energy use. Nitrogen-vacancy (NV) centers in a crystalline diamond are promising candidates for sensitive magnetometry and electric current measurements. In a diamond quantum sensor with NV centers, the Zeeman splitting of the electron spin state of the NV center can be utilized to detect magnetic field. This is because the splitting of the spectral line is proportional to the external magnetic field strength, and the arbitrary constant of the gyromagnetic ratio is independent of both frequency and magnetic field. Then, the Zeeman splitting can be measured with optically detected magnetic resonance (ODMR) spectroscopy.
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