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Measurement Science and Technology

Hybrid pumping with dual detection: a novel comagnetometer for dual-axis magnetic field and rotation measurement

Jiale Quan, Wenfeng Fan, Longyan Ma, Shuyan Zhang, Yian Xu, Hao Xia, Xiaohan Ge, Haoying Pang, Xusheng Lei, Wei Quan

Published Aug 5, 2026• 0 citations

Abstract

Abstract Quantum sensing has demonstrated exceptional potential in magnetic field and inertial rotation measurements due to its ultra-high sensitivity. Among various implementations, the spin-exchange relaxation-free comagnetometer, as atomic spin sensor, exhibits remarkable sensitivity and strong potential for miniaturization and integration. However, the low-frequency performance of such comagnetometers is fundamentally limited by intrinsic noise due to the coupling between magnetic field ( B ) and inertial rotation signals ( Ω ). In this paper, a novel dual spin-polarization detection scheme for a hybrid-pumping comagnetometer is proposed. By introducing simultaneous detection of two electron spin polarizations combined with longitudinal magnetic field modulation and demodulation, our approach enables decoupling and synchronous measurement of B and Ω . The proposed scheme is experimentally validated on a K–Rb- 21 Ne comagnetometer platform. Experimental results show that the two electron species demonstrate inconsistent behaviors in the self-compensation effect, with their respective self-compensation points occurring at different operating conditions. Finally, by individually calibrating the dual spin-polarization detection outputs, real-time in situ measurements of dual-axis magnetic fields and inertial rotation are achieved, effectively addressing the crosstalk issue between magnetic and inertial signals.

DOI: 10.1088/1361-6501/ae957f

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In atomic spin sensors based on optical pumping, pump beam instabilities can drive atomic spin polarization fluctuations, referred to here as pump-induced spin polarization noise, which may limit sensitivity and long-term stability. Because the local pump field inside the cell can differ from that inferred from external optical diagnostics, it remains difficult to directly quantify the actual in situ spin polarization noise and to evaluate and suppress its contribution to the sensor noise floor. Here, we propose an in situ decoupling method based on spin dynamics, in which a large longitudinal detuning field suppresses magnetic field and rotation responses, while a transverse projection field converts pump-induced fluctuations in longitudinal spin polarization into a measurable transverse spin signal. Demonstrated in a K-Rb-21Ne spin exchange relaxation free (SERF) comagnetometer, the proposed method suppresses the magnetic-field response by approximately 180-fold and enhances the pump-power-noise response by approximately 380-fold, thereby enabling effective separation and evaluation of pump-induced spin polarization noise. The method employs the atomic ensemble as an in situ probe of the spin dynamic response to the local pump optical field. It enables quantitative identification of pump fluctuation associated noise and direct evaluation of optical field stability under actual operating conditions, thereby providing an experimental basis for optical field stabilization and noise suppression assessment in SERF comagnetometers and related alkali atomic spin sensors.

Atomic spin sensors are essential for beyond-the-standard-model exploration, biomagnetic measurement, and quantum navigation. While the traditional DC mode spin-exchange relaxation-free (SERF) comagnetometer achieves ultrahigh sensitivity, further improvements require suppressing technical noise and surpassing standard quantum limit. In this work, we develop a K-Rb- 21 Ne SERF atomic comagnetometer that dynamically polarizes the electron and nuclear spins, shielding signals from direct interference by pump light. We establish a three-phase evolutionary model for hybrid spin ensemble dynamics, yielding a complete analytical solution, and analyze the responses to various spin perturbations. Additionally, we achieve an average 39% suppression of the polarization noise and identify the key factors that limit sensitivity improvements. The dynamically polarized comagnetometer exhibits effective suppression of technical noise and holds the potential to overcome quantum noise limit while offering promising applications in exploring new physics and precise magnetic field measurements.