Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Log inSign up
Challenges
Datasets
Workspaces
Papers
Discussions
Leaderboard
Blog
Job Board
Q3AS

© 2026 Aqora Quantum S.A.S.

TermsPrivacyLegal Notice

Physical Review Applied

Free-Induction-Decay Magnetometer Based on a Microfabricated Cs Vapor Cell

Dominic Hunter, S. Piccolomo, Jonathan D. Pritchard, N. L. Brockie, T. Dyer, Erling Riis

Published Jul 5, 2018• 68 citations
Publisher

Abstract

Microfabricated atomic magnetometers are important for fundamental research and numerous applications, including geophysical surveying and biological imaging, as they provide a sensitive, accurate, and portable alternative to standard magnetic sensing. The strong scalability and all-optical nature of the free-induction-decay (FID) magnetometer also benefit applications requiring sensor networks. This study shows the advantages of applying synchronous modulation and differential polarimetric detection in an FID setting, for measuring picotesla-level fields using a miniaturized Cs vapor cell.

DOI
10.1103/physrevapplied.10.014002

Related papers

Free-induction-decay magnetic field imaging with a microfabricated Cs vapor cell

Dominic Hunter, Christopher Perrella, Allan McWilliam +7 more

Magnetic field imaging is a valuable resource for signal source localization and characterization. This work reports an optically pumped magnetometer (OPM) based on the free-induction-decay (FID) protocol, that implements microfabricated cesium (Cs) vapor cell technology to visualize the magnetic field distributions resulting from various magnetic sources placed close to the cell. The slow diffusion of Cs atoms in the presence of a nitrogen (N 2 ) buffer gas enables spatially independent measurements to be made within the same vapor cell by translating a 175 μ m diameter probe beam over the sensing area. For example, the OPM was used to record temporal and spatial information to reconstruct magnetic field distributions in one and two dimensions. The optimal magnetometer sensitivity was estimated to be 0.43 pT/Hz within a Nyquist limited bandwidth of 500 Hz. Furthermore, the sensor’s dynamic range exceeds the Earth’s field of approximately 50 μ T, which provides a framework for magnetic field imaging in unshielded environments.

arXiv:2303.10915•Optics Express•Sep 11, 2023•16 citations

Vector Atomic Magnetometer with Free Induction Decay Detection Based on a Microfabricated Vapor Cell

Pengbo Jiang, Qi Li, Jianan Qin +1 more

Atomic magnetometers are highly sensitive instruments widely used for measurements of weak magnetic field. Extracting vector information while maintaining high-precision scalar detection has become the trend in atomic magnetometer development. We introduce a vector atomic magnetometer containing a 5 mm-thick microfabricated vapor cell operating in free-induction-decay mode. By employing orthogonal modulation techniques, the system achieves high-precision in-plane vector magnetic field measurements. The high-precision vector magnetic field measurements are demonstrated in the x–z plane. The sensitivity of the total field detection in the miniaturized atomic magnetometer is 30 pT·Hz−1/2 @11 µT. The average angular error of the decoupled measurement is as low as 4.7 mrad @7.6 µT for vector magnetic fields, providing a new approach for vector magnetic field measurement in miniaturized atomic magnetometers.

Micromachines•Dec 30, 2024•2 citations

Free-induction-decay 4 He magnetometer using a multipass cell

Kaiwen Yi, Yang Liu, Bowen Wang +4 more

Optically pumped magnetometers (OPMs) based on the free-induction-decay (FID) configuration have recently attracted interest owing to their advantages, such as being calibration-free, easy to operate, and showing reduced light shifts induced by the pump light. Currently, alkali-metal vapor cells have been employed in most of the FID magnetometers. However, the relatively narrow linewidth of the magnetic resonance signal and nonlinear Zeeman (NLZ) effects generate bandwidth limitation and heading errors of these magnetometers in the Earth's field, respectively. In this work, we propose a ${}^{4}\mathrm{He}$-based FID magnetometer, which not only has the advantages of being NLZ-free and showing a high bandwidth, but also maintains an enhanced sensitivity assisted by a multipass cell. This magnetometer demonstrates a magnetic field noise floor of $0.34\phantom{\rule{0.2em}{0ex}}\mathrm{pT}/{\mathrm{Hz}}^{1/2}$ with a Nyquist-limited bandwidth of $5$ kHz, which opens another route for atomic magnetometry using FID signals, and exhibits potential for applications in high-frequency magnetic field detection, such as biomagnetic measurements and magnetic communications in the geomagnetic field.

Physical Review Applied•Jul 31, 2024•25 citations

Free Induction Decay Optically Pumped Magnetometers: A Review

Jiarui Liu, Xiao Liu, Yuantian Lu +4 more

Free induction decay (FID) optically pumped magnetometers are among the most sensitive quantum sensors available for high-precision magnetic field measurements. This review summarizes recent advances in FID magnetometers, which represent a critical technological route that suppresses systematic errors by temporally separating atomic polarization from magnetic field detection. This review covers light-modulated optical pumping schemes (such as the Bell-Bloom mode), radio-frequency excitation schemes, and magnetic-field-enhanced pumping schemes. Key technological developments, including chip-scale MEMS fabrication, optical multipass architectures, advanced frequency estimation algorithms, and error suppression methods, are also discussed. Finally, emerging trends toward higher integration, environmental robustness, and intelligent signal demodulation are highlighted. These trends provide insights into the development of next-generation high-performance quantum sensors and their growing role in biomedical and geophysical applications, as well as in fundamental scientific research.

Sensors•Sep 26, 2026•0 citations

Free-induction-decay magnetometer based on synchronous optical pumping and RF pulse modulation

Jinghong Xu, Liwei Jiang, Junhao Liu +7 more

Free-induction-decay (FID) magnetometer is highly suitable for precise magnetic field sensing in unshielded environments with the benefit of exceptional accuracy and large dynamic range. The sensitivity of the FID magnetometer is directly influenced by the signal-to-noise ratio, making it critical to enhance the amplitude of the FID signal. In this study, we propose a FID magnetometer based on synchronous optical pumping and RF pulse modulation. A comprehensive theoretical description of the magnetometer is introduced, followed by simulation and experiment that compare the proposed modulation method with the synchronous optical pumping modulation method and the RF pulse modulation method. The results show that the synchronous optical pumping and RF pulse modulation achieves the enhancement of the FID signal and improves the magnetometer sensitivity. Furthermore, the dead zone of the magnetometer is reduced to the direction of the probe beam. This work is significant for further development of optically pumped magnetometers and provides a new scheme for their applications in unshielded environments.

EPJ Quantum Technology•May 30, 2025•10 citations

Dead-zone-free single-beam atomic magnetometer based on free-induction-decay of Rb atoms

Shrey Mehta, G. K. Samanta, Raghwinder Singh Grewal

Free-induction-decay (FID) magnetometers have evolved as simple magnetic sensors for sensitive detection of unknown magnetic fields. However, these magnetometers suffer from a fundamental problem known as a “dead zone,” making them insensitive to certain magnetic field directions. Here, we demonstrate a simple experimental scheme for the dead-zone-free operation of a FID atomic magnetometer. Using a single laser beam containing equal strength of linear- and circular-polarization components and amplitude modulation at a low-duty cycle, we have synchronously pumped the rubidium (87Rb) atoms with both first- and second-order frequency harmonics. Such a pumping scheme has enabled us to observe the free Larmor precession of atomic spins at a frequency of ΩL (orientation) and/or 2ΩL (alignment) in a single FID signal, depending on the direction of the external magnetic field. We observed that the amplitude of the FID signal does not go to zero for any magnetic field direction, proving the absence of dead zones in the magnetometer. The magnetometer has a sensitivity in the range of 3.2–8.4 pT/Hz in all directions. Our experimental scheme can be crucial in developing miniaturized atomic magnetometers for various practical applications, including geomagnetic applications.

arXiv:2410.15663•Applied Physics Letters•Jan 27, 2025•8 citations
Microfabricated atomic magnetometers are important for fundamental research and numerous applications, including geophysical surveying and biological imaging, as they provide a sensitive, accurate, and portable alternative to standard magnetic sensing. The strong scalability and all-optical nature of the free-induction-decay (FID) magnetometer also benefit applications requiring sensor networks. This study shows the advantages of applying synchronous modulation and differential polarimetric detection in an FID setting, for measuring picotesla-level fields using a miniaturized Cs vapor cell.
Magnetic field imaging is a valuable resource for signal source localization and characterization. This work reports an optically pumped magnetometer (OPM) based on the free-induction-decay (FID) protocol, that implements microfabricated cesium (Cs) vapor cell technology to visualize the magnetic field distributions resulting from various magnetic sources placed close to the cell. The slow diffusion of Cs atoms in the presence of a nitrogen (N 2 ) buffer gas enables spatially independent measurements to be made within the same vapor cell by translating a 175 μ m diameter probe beam over the sensing area. For example, the OPM was used to record temporal and spatial information to reconstruct magnetic field distributions in one and two dimensions. The optimal magnetometer sensitivity was estimated to be 0.43 pT/Hz within a Nyquist limited bandwidth of 500 Hz. Furthermore, the sensor’s dynamic range exceeds the Earth’s field of approximately 50 μ T, which provides a framework for magnetic field imaging in unshielded environments.
Atomic magnetometers are highly sensitive instruments widely used for measurements of weak magnetic field. Extracting vector information while maintaining high-precision scalar detection has become the trend in atomic magnetometer development. We introduce a vector atomic magnetometer containing a 5 mm-thick microfabricated vapor cell operating in free-induction-decay mode. By employing orthogonal modulation techniques, the system achieves high-precision in-plane vector magnetic field measurements. The high-precision vector magnetic field measurements are demonstrated in the x–z plane. The sensitivity of the total field detection in the miniaturized atomic magnetometer is 30 pT·Hz−1/2 @11 µT. The average angular error of the decoupled measurement is as low as 4.7 mrad @7.6 µT for vector magnetic fields, providing a new approach for vector magnetic field measurement in miniaturized atomic magnetometers.
Optically pumped magnetometers (OPMs) based on the free-induction-decay (FID) configuration have recently attracted interest owing to their advantages, such as being calibration-free, easy to operate, and showing reduced light shifts induced by the pump light. Currently, alkali-metal vapor cells have been employed in most of the FID magnetometers. However, the relatively narrow linewidth of the magnetic resonance signal and nonlinear Zeeman (NLZ) effects generate bandwidth limitation and heading errors of these magnetometers in the Earth's field, respectively. In this work, we propose a 4He{}^{4}\mathrm{He}4He-based FID magnetometer, which not only has the advantages of being NLZ-free and showing a high bandwidth, but also maintains an enhanced sensitivity assisted by a multipass cell. This magnetometer demonstrates a magnetic field noise floor of 0.34pT/Hz1/20.34\phantom{\rule{0.2em}{0ex}}\mathrm{pT}/{\mathrm{Hz}}^{1/2}0.34pT/Hz1/2 with a Nyquist-limited bandwidth of 555 kHz, which opens another route for atomic magnetometry using FID signals, and exhibits potential for applications in high-frequency magnetic field detection, such as biomagnetic measurements and magnetic communications in the geomagnetic field.
Free induction decay (FID) optically pumped magnetometers are among the most sensitive quantum sensors available for high-precision magnetic field measurements. This review summarizes recent advances in FID magnetometers, which represent a critical technological route that suppresses systematic errors by temporally separating atomic polarization from magnetic field detection. This review covers light-modulated optical pumping schemes (such as the Bell-Bloom mode), radio-frequency excitation schemes, and magnetic-field-enhanced pumping schemes. Key technological developments, including chip-scale MEMS fabrication, optical multipass architectures, advanced frequency estimation algorithms, and error suppression methods, are also discussed. Finally, emerging trends toward higher integration, environmental robustness, and intelligent signal demodulation are highlighted. These trends provide insights into the development of next-generation high-performance quantum sensors and their growing role in biomedical and geophysical applications, as well as in fundamental scientific research.
Free-induction-decay (FID) magnetometer is highly suitable for precise magnetic field sensing in unshielded environments with the benefit of exceptional accuracy and large dynamic range. The sensitivity of the FID magnetometer is directly influenced by the signal-to-noise ratio, making it critical to enhance the amplitude of the FID signal. In this study, we propose a FID magnetometer based on synchronous optical pumping and RF pulse modulation. A comprehensive theoretical description of the magnetometer is introduced, followed by simulation and experiment that compare the proposed modulation method with the synchronous optical pumping modulation method and the RF pulse modulation method. The results show that the synchronous optical pumping and RF pulse modulation achieves the enhancement of the FID signal and improves the magnetometer sensitivity. Furthermore, the dead zone of the magnetometer is reduced to the direction of the probe beam. This work is significant for further development of optically pumped magnetometers and provides a new scheme for their applications in unshielded environments.
Free-induction-decay (FID) magnetometers have evolved as simple magnetic sensors for sensitive detection of unknown magnetic fields. However, these magnetometers suffer from a fundamental problem known as a “dead zone,” making them insensitive to certain magnetic field directions. Here, we demonstrate a simple experimental scheme for the dead-zone-free operation of a FID atomic magnetometer. Using a single laser beam containing equal strength of linear- and circular-polarization components and amplitude modulation at a low-duty cycle, we have synchronously pumped the rubidium (87Rb) atoms with both first- and second-order frequency harmonics. Such a pumping scheme has enabled us to observe the free Larmor precession of atomic spins at a frequency of ΩL (orientation) and/or 2ΩL (alignment) in a single FID signal, depending on the direction of the external magnetic field. We observed that the amplitude of the FID signal does not go to zero for any magnetic field direction, proving the absence of dead zones in the magnetometer. The magnetometer has a sensitivity in the range of 3.2–8.4 pT/Hz in all directions. Our experimental scheme can be crucial in developing miniaturized atomic magnetometers for various practical applications, including geomagnetic applications.