Magnetic field quantum sensors, including superconducting quantum interferometers, laser-pumped atomic sensors (LPAS), and nitrogen-vacancy centers in diamonds, utilize quantum systems or effects to precisely measure magnetic fields. Laser-pumped atomic magnetometers, known for their high sensitivity, compact size, low power consumption, and ease of maintenance, represent a rapidly evolving research area. LPAS are applied in nuclear magnetic resonance (NMR) for obtaining more accurate magnetic resonance spectra of materials and for measuring samples under unique conditions. This expands the detection and analytical capabilities in discerning the fine structure of biological and chemical substances. They are anticipated to serve as an effective complement to high-field NMR techniques.

NMR based on LPAS has been developed rapidly in recent years. Researchers have integrated hyperpolarization technology, sample transmission, and coding technology with high sensitivity and broad bandwidth LPAS. This integration enables the performance of zero- to ultralow-field NMR on various chemical samples. It allows for the acquisition of the samples’ zero- to ultralow-field NMR spectra and facilitates the theoretical analysis of these spectra. Additionally, the researchers have successfully conducted zero- to ultralow-field NMR measurements of chemical reactions within metal sample tubes. This advancement permits non-destructive, real-time monitoring of the polarizability of hyperpolarized samples. Furthermore, combining this with image coding in NMR, zero- to ultralow-field magnetic resonance imaging (MRI) of the human brain and hand has been realized.

LPAS method and technique are crucial for realizing zero- to ultralow-field NMR and MRI. LPAS offers low manufacturing costs, simple maintenance, easy miniaturization, and boasts an ultra-narrow linewidth with high sensitivity of approximately fT/Hz^1/2. Utilizing LPAS technology has transformed zero- to ultralow-field NMR into a powerful tool, especially in fields such as biochemistry. Building on this, the integration of nuclear spin polarization enhancement technologies and sample transport technologies addresses the challenges of performing NMR and MRI in the thermal polarization measurement environment of the sample at zero- to ultralow fields. This integration effectively broadens the application scope of LPAS-based NMR and MRI methods and technologies. By combining these with zero- to ultralow-field NMR coding techniques, high spectral and imaging resolutions are achievable. Additionally, there are fewer restrictions on the materials of the substances being detected, offering innovative directions for the development of NMR measurement and MRI methods in biomedicine and chemical materials.

The development of nuclear magnetic resonance spectrometers based on LPAS has progressed rapidly. However, there are still areas for improvement, such as enhancing the analysis of zero- to ultralow-field NMR spectra, improving the measurement resolution of zero- to ultralow-field NMR spectrometers, and achieving further miniaturization of these spectrometers. Zero- to ultralow-field NMR spectroscopy necessitates the integration of the physical and chemical information of the sample being tested and detailed analysis using controlled coded pulses. The resolution of the spectrometer can be enhanced through the application of hyperpolarization technology and by increasing the sensitivity of LPAS. Miniaturization is a key development trend for zero- to ultralow-field NMR spectrometers. The current size of LPAS has been reduced to centimeter scale, and with advancements in new materials and manufacturing technologies, there is potential for even further miniaturization.