With the rapid development of quantum manipulation technique, atomic spin gyroscope has been demonstrated in recent years. Understanding the sources and the influence of error on the performance of atomic spin gyroscope is important during the design of such devices. The basic principle of atomic spin gyroscope was reviewed and the analysis of error sources presented began with the coupled Bloch equations describing the dynamics of atomic spin gyroscope including magnetic field, light shift and pump-probe non-orthogonality. It was shown analytically that the first order effects of the transverse magnetic fields and imperfections can be eliminated by turning the longitudinal magnetic field on the magnetic field compensation point. The effects of longitudinal magnetic field and light shift imperfections with other terms zeroed contributed only to scale factor of the atomic spin gyroscope. Furthermore, the effects magneto-optical crystal and magnetic shielding due to temperature drift were described and according approaches to suppress these errors were also proposed.
With the rapid development of quantum manipulation technique, atomic spin gyroscope has been demonstrated in recent years. Understanding the sources and the influence of error on the performance of atomic spin gyroscope is important during the design of such devices. The basic principle of atomic spin gyroscope was reviewed and the analysis of error sources presented began with the coupled Bloch equations describing the dynamics of atomic spin gyroscope including magnetic field, light shift and pump-probe non-orthogonality. It was shown analytically that the first order effects of the transverse magnetic fields and imperfections can be eliminated by turning the longitudinal magnetic field on the magnetic field compensation point. The effects of longitudinal magnetic field and light shift imperfections with other terms zeroed contributed only to scale factor of the atomic spin gyroscope. Furthermore, the effects magneto-optical crystal and magnetic shielding due to temperature drift were described and according approaches to suppress these errors were also proposed.
We present a method to determine and suppress the light shift in an atomic spin gyroscope. This method doesn't require additional drive source or frequency modulation, and it is based on the dynamics of an atomic spin gyroscope to determine a clean curve as a function of the frequency of the pump beam that predicts the zero light shift. We experimentally validate the method in a Cs-(129)Xe atomic spin gyroscope and verify the results through numerical simulations. This method can also be applied to an atomic spin magnetometer based on the spin-exchange relaxation-free exchange that experiences light shift. The method is useful for atomic spin devices because it can improve long-term performance and reduce the influence of the laser.
A nuclear spin gyroscope based on an alkali-metal–noble-gas co-magnetometer operated in spin-exchange relaxation-free (SERF) regime is a promising atomic rotation sensor for its ultra-high fundamental sensitivity. However, the fluctuation of probe light intensity is one of the main technical error sources that limits the bias stability of the gyroscope. Here we propose a novel method to suppress the bias error induced by probe light intensity fluctuations. This method is based on the inherent magnetic field response characteristics of the gyroscope. By the application of a bias magnetic field, the gyroscope can be tuned to a working point where the output signal is insensitive to probe light intensity variation, referred to herein as ‘zero point’, thus the bias error induced by intensity fluctuations can be completely suppressed. The superiority of the method was verified on a K–Rb–21Ne co-magnetometer, and a bias stability of approximately 0.01 °/h was obtained. In addition, the method proposed here can remove the requirement of the closed-loop control of probe light intensity, thereby facilitating miniaturization of the gyroscope volume and improvement of reliability.
• A dual-spectrum feedback architecture based on conventional closed-loop control is proposed, enabling real-time compensation for spin polarization error (SPE) in the K-Rb-21Ne atomic spin gyroscope, significantly enhancing long-term stability. • An adaptive dynamic control strategy based on a Lyapunov function is introduced to replace PID control, optimizing control parameters and improving system response speed and stability. • Experimental results show that the method improves SPE suppression by 54.4%, 74.5%, and 74.6% for clustering times of 100s, 500s, and 1000s, respectively. • Interference tests demonstrate that the method effectively eliminates steady-state offsets and enhances the system's adaptability to power density and polarization fluctuations, providing a long-term stability solution for optically pumped atomic devices. The long-term stability of atomic spin polarization plays a critical role in ensuring the sustained stability of atomic gyroscope outputs. However, drift in the laser pumping rate introduces the spin polarization error (SPE), necessitating high-precision closed-loop stabilization. Conventional single-beam-splitting closed-loop control methods overlook the time-varying characteristics of beam-splitting elements during prolonged operation, resulting in incomplete suppression of SPE in long-term measurements. To address this limitation, a dynamic light compensation framework is developed for the analysis and suppression of SPE in an atomic spin gyroscope. The proposed structure enables real-time monitoring of parameter variations in the beam-splitting elements and feeds this information back into the control loop to actively compensate for polarization errors induced by optical drift. Furthermore, an adaptive control method based on nonlinear inversion and disturbance observation is introduced, which estimates the internal state and compensates time-varying parameters in real time, thereby replacing conventional PID control and ensuring optimal closed-loop performance. Experimental results from a K-Rb- 21 Ne atomic gyroscope demonstrate real-time suppression of SPE, with improvements of 54.4%, 74.5%, and 74.6% for clustering times of 100, 500, and 1000 seconds, respectively. Interference tests show enhanced response speed and the elimination of steady-state offsets under power density and polarization disturbances. This method offers a novel solution for achieving long-term stability in optically pumped atomic devices, ensuring sustained measurement accuracy.
Ultrasensitive atomic comagnetometers (ACMs) are invaluable tools for both inertial measurement and fundamental physics research. However, the misalignment between the pump light and the main magnetic field affects the polarization characteristics of nuclear spins of the noble gas atoms, making it a significant source of noise. In this article, an atomic magnetometer response model with the optical-magnetic misalignment error is established, and the mechanism of the influence of optical-magnetic misalignment on nuclear spin polarization is analyzed. An in situ evaluation method and a suppression method of optical-magnetic misalignment error are proposed, and their effectiveness is verified through experiments with varying pump light incidence directions. The experimental results indicate that after optical-magnetic alignment using the proposed method, the spin polarization of the coupled atomic ensemble is enhanced by 20.7%, and the longitudinal relaxation rate of the nuclear spin is reduced by 6.9%. Additionally, the amplitude-frequency response (AFR) of the x-axis magnetic field is reduced by 33.2% at 1 Hz and by 53.1% at frequencies below 0.002 Hz. This indicates an improvement in the transverse magnetic field error suppression capability of the ACMs.
The ultra-sensitive atomic co-magnetometer based on the spin-exchange relaxation-free (SERF) regime is a valuable tool for inertial measurements and fundamental physics research. However, the optical magnetic misalignment effect is a significant source of error in SERF co-magnetometers, limiting their magnetic field suppression ability and long-term stability. This paper establishes a response model of angular velocity and magnetic field for the SERF co-magnetometer. The impact of optical magnetic misalignment on the scale factor, magnetic field amplitude-frequency response, and angular velocity errors caused by magnetic noise is systematically investigated. The results indicate that the scale factor and magnetic field suppression ability decrease as the optical magnetic misalignment angle increases, while the angular velocity errors caused by magnetic noise increase as the misalignment angle increases. Finally, experimental results demonstrate that the optical-magnetic misalignment effect significantly compromises the long-term stability of SERF co-magnetometers, underscoring its substantial influence on the overall performance. This work contributes to understanding the mechanism of optical magnetic misalignment effects on the SERF co-magnetometer and enhances its performance.
Bias stability is one of the most important characteristics of a spin-exchange relaxation-free gyroscope (SERFG). The previous research on the SERFG has demonstrated that atomic density fluctuation induced by the vapor cell temperature fluctuations in a SERFG limits its bias stability. In this paper, a steady-state response model of a SERFG dependent on the vapor cell temperature is established, and a method to reduce the vapor cell temperature error of the SERFG is developed. By adjusting the vapor cell temperature, the SERFG can be tuned to a working point where the output signal is insensitive to the cell temperature fluctuation, i.e., the insensitive point, so that the bias error induced by cell temperature fluctuations can be effectively suppressed. The proposed method is verified by experiments, and experimental results are in good agreement with the model. By using the proposed method, SERFG drift was reduced from 0.051 deg/h to 0.028 deg/h without adjusting the wavelength of the probe laser. This study presents a way to improve the SERFG performance, which is of reference value for quantitative error analysis and miniaturization in atomic gyroscopes.