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This study investigates the effects of power broadening on nonlinear magneto-optical rotation (NMOR) magnetometers. As the laser power increases, the interference between two partially resolved transitions of 87Rb induced by velocity-changing collisions can be exacerbated by power broadening, resulting in a reduction of the rotation rate, and the shift of the optimal laser frequency corresponding to the maximum rotation rate. The theoretical model of NMOR is established using a four-level double Λ scheme, which takes into account power broadening effects, and experimentally studied in a single-beam NMOR magnetometer with a buffer-gas filled cell. The results indicate that the significant enhancement in rotation rate can be achieved by tuning the laser frequency to the optimal detuning based on our model. This study holds considerable importance for the improvement of magnetic field sensitivity in NMOR magnetometers. [Display omitted] • Introducing the power broadening into the four-level double Λ system for modeling NMOR. • Revealing that power broadening exacerbating the interference between two partially resolved transitions. • The dependence of the laser frequency in NMOR on laser power was reported for the first time. [ABSTRACT FROM AUTHOR]

Alkali metal-noble gas comagnetometers operated in the regime of spin-exchange relaxation-free (SERF) have been widely used in fundamental physics tests and rotation sensing as gyroscope. Spin-exchange relaxation is an important systematic bias of the comagnetometer, which could limit sensitivity significantly. However, the suppression effect of the spin-exchange relaxation has not been examined quantitatively so far. Herein, we systematically investigate the relaxation of the alkali metal atoms and find that the spin-exchange relaxation is not completely eliminated under the normal operating condition of the K-Rb-21Ne comagnetometer. In addition to the optical pumping rate, the spin-exchange relaxation still plays a dominant role in the broadening of electron Zeeman resonances due to the large electron magnetic field. This is the first demonstration that the alkali metal atoms are operated in the near-SERF regime in the alkali metal-noble gas comagnetometer with a large election magnetic field, which will shed light on the way to reduce the relaxation of the alkali metal atoms and enhance the sensitivity of the comagnetometer. [ABSTRACT FROM AUTHOR]

The spin-exchange relaxation of electron spins directly affects the sensitivity of the atomic magnetometers. Rapid determination of the spin-exchange relaxation is essential. In this work, we propose a novel method for measuring the spin-exchange relaxation that allows being operated in the range of zero to earth-scale magnetic field. The longitudinal and transverse relaxation are synchronously extracted from the magnetic resonance linewidth and radio-frequency field amplitude corresponding to the maximum slope of the dispersive resonance curve. The spin-exchange relaxation is further obtained from the difference. The experimental results are consistent with the conventional linewidth fitting method in near-zero magnetic field and with the theoretical expectation in earth-scale magnetic field. This method not only improves authenticity compared to the conventional linewidth fitting method by considering the effect of rf field on relaxation, but also provides a fast and reliable measurement of the spin-exchange relaxation in earth-scale field. • A novel measurement of spin-exchange relaxation applicable in earth-scale field. • The transverse and longitudinal relaxation can be synchronously extracted. • Provide a way to evaluate the effect of spin-exchange relaxation suppression method. [ABSTRACT FROM AUTHOR]

We propose a feasible method that enables suppression of crosstalk induced by the additional transverse (sinusoidal/noise) magnetic field near the modulation frequency of the arrayed single-beam optically-pumped magnetometers (OPMs), which is usually generated by adjacent channels, by locking the remanence to zero through a closed-loop control. Based on a miniaturized 87Rb atomic cell of 3 × 3 × 3 mm, our method can significantly suppress the modulation magnetic field crosstalk. In addition, the magnetic field control circuit structure is optimized by investigating the effect of magnetic field noise on the sensitivity of the magnetometer. The sensitivity of OPM can reach 16 f T / H z 1 / 2 between 10 and 100 Hz. These crosstalk amplitude results show good agreement with theoretical analysis. Our method is especially advantageous for future high-resolution magnetocardiography and magnetoencephalography systems where dense array with large amount of miniaturized magnetometers are required. • We quantify the effect of modulation crosstalk magnetic field on the OPM output. • Locking the remanent to zero through closed-loop control can suppress crosstalk. • Low-noise magnetic field driving circuit and closed-loop can improve sensitivity. [ABSTRACT FROM AUTHOR]