Recent advances in tabletop quantum sensor technology have enabled searches for nongravitational interactions of dark matter (DM). Traditional axion DM experiments rely on sharp resonance, resulting in extensive scanning time to cover a wide mass range. In this work, we present a broadband approach in an alkali- 21 Ne spin system. We identify two distinct hybrid spin-coupled regimes: a self-compensation regime at low frequencies and a hybrid spin resonance regime at higher frequencies. By utilizing these two distinct regimes, we significantly enhance the bandwidth of 21 Ne nuclear spin compared to conventional nuclear magnetic resonance, while maintaining competitive sensitivity. We present a comprehensive broadband search for axion-like DM, covering 5 orders of magnitude of Compton frequencies range within [ 10 − 2 , 10 3 ] Hz. We set new constraints on the axion DM interactions with neutrons and protons, accounting for the effects of DM stochasticity. For the axion–neutron coupling, our results reach a low value of | g ann | ⩽ 3 × 10 − 10 in the frequency range [ 2 × 10 − 2 , 4 ] Hz surpassing astrophysical limits and providing the strongest laboratory constraints in the [ 10 , 100 ] Hz range. For the axion-proton coupling, we offer the best terrestrial constraints for the frequency ranges [ 2 × 10 − 2 , 5 ] Hz and [ 16 , 7 × 10 2 ] Hz.

Typical weak signal search experiments rely on resonant effects, where the resonance frequency is scanned over a broad range, resulting in significant time consumption. In this study, we demonstrate an accelerated strategy that surpasses the typical resonance-bandwidth limited scan step without compromising sensitivity. We apply this method to an alkali-noble-gas spin system, achieving an approximately 30-fold increase in scanning step size. Additionally, we obtain an ultrahigh sensitivity of 1.29 fT ⋅ Hz^−1/2 at around 5 Hz, corresponding to an energy resolution of approximately 1.8 × 10⁻²³eV ⋅ Hz^−1/2, which is among the highest quantum energy resolutions reported. Furthermore, we use this sensor to search for axion-like particles, setting stringent constraints on axion-like particles (ALPs) in the 4.5–15.5 Hz Compton-frequency range coupling to neutrons and protons, improving on previous limits by several-fold. This accelerated strategy has potential applications in other resonant search experiments.

The existence of exotic spin-dependent forces may shine light on new physics beyond the standard model. We utilize two iron shielded ${\mathrm{SmCo}}_5$ electron-spin sources and two optically pumped magnetometers to search for exotic long-range spin-spin velocity-dependent force. The orientations of spin sources and magnetometers are optimized such that the exotic force is enhanced and common-mode noise is effectively subtracted. We set direct limit on proton-electron interaction in the force range from 1 cm to 1 km. Our experiment represents more than 10 orders of magnitude improvement than previous works.

Recent years have seen rapid development of chip-scale atomic devices due to their great potential in the field of biomedical imaging, namely chip-scale atomic magnetometers that enable high resolution magnetocardiography (MCG) and magnetoencephalography (MEG). For atomic devices of this kind, vertical cavity surface emitting lasers (VCSELs) have become the most crucial components as integrated pumping sources, which are attracting growing interest. In this paper, the application of VCSELs in chip-scale atomic devices are reviewed, where VCSELs are integrated in various atomic bio-sensing devices with different operating environments. Secondly, the mode and polarization control of VCSELs in the specific applications are reviewed with their pros and cons discussed. In addition, various packaging of VCSEL based on different atomic devices in pursuit of miniaturization and precision measurement are reviewed and discussed. Finally, the VCSEL-based chip-scale atomic magnetometers utilized for cardiac and brain magnetometry are reviewed in detail. Nowadays, biosensors with chip integration, low power consumption, and high sensitivity are undergoing rapid industrialization, due to the growing market of medical instrumentation and portable health monitoring. It is promising that VCSEL-integrated chip-scale atomic biosensors as featured applications of this kind may experience extensive development in the near future.

We demonstrate a method for simultaneously measuring the spin polarizations of noble-gas and alkali-metal atoms. Under a low magnetic field, the polarized alkali-metal and noble-gas spin ensembles exhibit novel dynamics in the self-compensation and resonance regimes, which can be used to measure the polarizations. We perform this method on a $\mathrm{K}$-$\mathrm{Rb}$-${}^{21}$$\mathrm{Ne}$ comagnetometer with various operation temperatures and pump-light intensities. The polarization of alkali-metal electrons from 0.245 to 0.964 and the polarization of noble-gas nuclear spins from 0.01 to 0.065 are measured with relative uncertainties less than $12.4\mathrm{\%}$. The measured polarizations are consistent with the theoretical model and are also verified by the traditional polarization-measurement method.

Hybrid spin-exchange optical pumping is widely used in precision measurements and tests of fundamental physics. In these researches and applications, accurate measurement of the spin polarizations of hybrid alkali atoms and noble gas atoms has a significant role. Here we propose a novel method of measuring the spin polarizations of hybrid K-Rb and ²¹ Ne atoms simultaneously. We study the mixture of the slowing-down factors of hybrid alkali atoms due to spin-exchange interactions between hybrid alkali atoms, and the resonance-frequency shift of alkali atoms due to spin-exchange interactions with noble-gas atoms. We investigate the relationship between the hybrid resonance frequency and the polarizations. The spin polarizations of alkali atoms and noble-gas atoms have been measured based on this method, which is from 0.082 to 0.756 and from 0.018 to 0.124 with uncertainties smaller than 10.4 % and 12.7 % respectively. This method is promising for the applications requiring simultaneous and real-time measurement of the polarizations of alkali and noble-gas atoms, such as inertial sensors and tests of fundamental physics.