https://doi.org/10.1140/epjqt/s40507-025-00378-7
Research
Spin-amplification SERF atomic magnetometer based on direct feedback
1
School of Instrumentation and Optoelectronic Engineering, Beihang University, 100191, Beijing, China
2
Hangzhou Institute of Extremely-Weak Magnetic Field Major National Science and Technology Infrastructure, 310051, Hangzhou, China
3
Hefei National Laboratory, 230088, Hefei, China
a
ziqiyuan@buaa.edu.cn
b
tangjunjian@buaa.edu.cn
Received:
12
December
2024
Accepted:
4
June
2025
Published online:
11
June
2025
We demonstrate that atomic spin trajectories on the Bloch sphere can be manipulated through direct feedback, achieving spin amplification. This method is applied to Spin-Exchange Relaxation-Free (SERF) magnetometers where a feedback loop introduces a magnetic field positively proportional to the transverse spin polarization, which significantly amplifies the low-frequency response signal by an order of magnitude. Experimental results show that the feedback mechanism improves the signal-to-noise ratio and effectively strengthens the system’s ability to suppress technical noise. In addition, this feedback-enabled magnetometer exhibits superior sensitivity at lower spin polarization, reducing reliance on optical power and thereby facilitating scalability in multi-channel systems. This approach can be extended to various physical systems utilizing atomic spins, such as quantum memory and quantum metrology.
Key words: Spin-amplification / Spin-Exchange Relaxation-Free (SERF) / Magnetometer / Direct feedback / Noise suppression / Multi-channel
© The Author(s) 2025
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