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

Microsystems & Nanoengineering

Ultrasensitive SERF atomic magnetometer with a miniaturized hybrid vapor cell

Yintao Ma, Yao Chen, Mingzhi Yu, Yanbin Wang, Shun Lu, Ju Guo, Guoxi Luo, Libo Zhao, Ping Yang, Qijing Lin, Zhuangde Jiang

Published Aug 30, 2024• 62 citations
Publisher

Abstract

Abstract The chip-scale hybrid optical pumping spin-exchange relaxation-free (SERF) atomic magnetometer with a single-beam arrangement has prominent applications in biomagnetic measurements because of its outstanding features, including ultrahigh sensitivity, an enhanced signal-to-noise ratio, homogeneous spin polarization and a much simpler optical configuration than other devices. In this work, a miniaturized single-beam hybrid optical pumping SERF atomic magnetometer based on a microfabricated atomic vapor cell is demonstrated. Although the optically thin Cs atoms are spin-polarized, the dense Rb atoms determine the experimental results. The enhanced signal strength and narrowed resonance linewidth are experimentally proven, which shows the superiority of the proposed magnetometer scheme. By using a differential detection scheme, we effectively suppress optical noise with an approximate five-fold improvement. Moreover, the cell temperature markedly affects the performance of the magnetometer. We systematically investigate the effects of temperature on the magnetometer parameters. The theoretical basis for these effects is explained in detail. The developed miniaturized magnetometer has an optimal magnetic sensitivity of 20 fT/Hz 1/2 . The presented work provides a foundation for the chip-scale integration of ultrahighly sensitive quantum magnetometers that can be used for forward-looking magnetocardiography (MCG) and magnetoencephalography (MEG) applications.

DOI
10.1038/s41378-024-00758-6

Related papers

In-situ determination of spin polarization in a single-beam fiber-coupled spin-exchange-relaxation-free atomic magnetometer with differential detection

Yintao Ma, Zhixia Qiao, Yao Chen +8 more

The electronic spin polarization of alkali-metal-vapor atoms is a pivotal parameter for atomic magnetometers. Herein, a novel method is presented for determining the spin polarization with a miniaturized single-beam spin-exchange-relaxation-free (SERF) magnetometer on the basis of zero-field cross-over resonance. Two separate laser beams are utilized to heat the cell and interrogate the vapor atoms, respectively. Spin polarization can be extracted by measuring the resonance response signal of the magnetometer to the transverse magnetic field under different irradiances. Results of these experiments are consistent well with the theoretical predictions with the maximum deviation less than 4%. The proposed method has the integrated advantages of possessing a simple configuration and in-situ measurement. Furthermore, combined with a homemade optical differential detection system with a factor of approximately three of the power noise suppression, the developed single-beam SERF atomic magnetometer with a measuring sensitivity of 32 fT/Hz 1/2 has been achieved. This demonstrated approach can help guide the development of chip-scale atomic magnetometers for bio-magnetic field imaging applications.

Optics Express•Jan 9, 2023•5 citations

The polarization and the fundamental sensitivity of 39K (133Cs)-85Rb-4He hybrid optical pumping spin exchange relaxation free atomic magnetometers

Jianhua Liu, Dong-Yang Jing, Liang‐Liang Wang +4 more

Abstract The hybrid optical pumping spin exchange relaxation free (SERF) atomic magnetometers can realize ultrahigh sensitivity measurement of magnetic field and inertia. We have studied the 85 Rb polarization of two types of hybrid optical pumping SERF magnetometers based on 39 K- 85 Rb- 4 He and 133 Cs- 85 Rb- 4 He respectively. Then we found that 85 Rb polarization varies with the number density of buffer gas 4 He and quench gas N 2 , pumping rate of pump beam and cell temperature respectively, which will provide an experimental guide for the design of the magnetometer. We obtain a general formula on the fundamental sensitivity of the hybrid optical pumping SERF magnetometer due to shot-noise. The formula describes that the fundamental sensitivity of the magnetometer varies with the number density of buffer gas and quench gas, the pumping rate of pump beam, external magnetic field, cell effective radius, measurement volume, cell temperature and measurement time. We obtain a highest fundamental sensitivity of 1.5073 aT / Hz 1/2 (1 aT = 10 −18 T ) with 39 K- 85 Rb- 4 He magnetometer between above two types of magnetometers when 85 Rb polarization is 0.1116. We estimate the fundamental sensitivity limit of the hybrid optical pumping SERF magnetometer to be superior to 1.8359 × 10 −2 aT / Hz 1/2 , which is higher than the shot-noise-limited sensitivity of 1 aT / Hz 1/2 of K SERF atomic magnetometer.

arXiv:1702.07755•Scientific Reports•Jul 24, 2017•17 citations

Miniaturized atomic magnetometer employing pump-beam modulation

Ziqian Yue, Junjian Tang, Yueyang Zhai

Atomic magnetometers with magnetic field modulation have emerged as pivotal sensors for biomagnetic measurements. However, challenges such as crosstalk between adjacent modulation fields and the complexity of signal circuitry become increasingly serious in the development of array-based equipment with the magnetometers, especially in the miniaturized atomic magnetometer. This paper proposes an all-optical, fully integrated fiber-coupled atomic magnetometer that employs pump beam modulation. A miniaturized atomic magnetometer with a volume of 10 cm³ has been designed, incorporating an active measurement area of 3 × 3 × 3 mm3. The magnetometer operates in the spinexchange relaxation-free (SERF) regime with an 87Rb vapor cell. An amplitude-modulated pump beam directly modulates the rubidium atomic ensembles, rather than the magnetic field modulation. The optical rotation angle is detected by an unmodulated probe beam oriented orthogonally to the pump beam. In light of the discontinuous pumping characteristics, we developed a modified theoretical model to clarify the output response of the proposed atomic magnetometer. The experimental results demonstrate that the new design achieves the same sensitivity as conventional magnetometer configurations with a smaller volume and without crosstalk of the magnetic field. This research highlights the significant potential for advancing the development of highly sensitive, miniaturized atomic magnetometers, making them particularly suitable for applications in magnetocardiography (MCG) and magnetoencephalography (MEG).

Advanced Sensor Systems and Applications•Oct 11, 2024•0 citations

Single-Beam Atomic Magnetometer Enhanced With Elliptically Polarized Reflected Light

An‐Ning Xu, Jin Peng, Yiran Yin +1 more

The ultra-sensitivity magnetometer plays an important role in fundamental physics and applications, including magnetoencephalography (MEG) and magnetocardiography (MCG). The spin-exchange relaxation-free (SERF) atomic magnetometer (AM) has great sensitivity but is limited by the relatively complicated dual-beam structure for application, leading to the development of the compact AM based on one single laser beam. Compared with the single-beam optically pumped magnetometer (OPM) detecting the absorption of the circularly polarized beam, the SERF AM based on an elliptically polarized single beam detecting the optical rotation angle of polarization has a better response, lower laser power, and no need for signal modulation or demodulation. Here, we would like to report an elliptically-polarized single-beam SERF AM enhanced by reflecting the probe beam, increasing the light-atom interaction. Moreover, unlike the previous reflecting AM using the beam splitter, we used a D-shape mirror to extract the reflected beam, avoiding power losses of both incident and reflected beam and destruction of polarization. The sensitivity of our device in the reflecting scheme reaches 5 fT/Hz1/2 at 9–60 Hz, satisfying the need to measure the human MEG/MCG or search for the fifth force. Our research paves the way for developing the compact SERF AM for multiple future applications.

IEEE Sensors Journal•Jun 27, 2024•7 citations

Femtotesla atomic magnetometer with counter-propagating optical sideband pumping

Jin Peng, An‐Ning Xu, Bei Liu

The ultrasensitive magnetometer has a vital importance in fundamental research and applications. Currently, the spin-exchange relaxation-free (SERF) atomic magnetometer has been reported with a sensitivity around the level of fT/Hz 1/2 . To enhance the sensitivity, a gradiometer configuration has usually been introduced to cancel the common-mode noise between two separate channels. However, the signal and response from different channels are not the same due to the attenuation of the pump beam. Here, we proposed a counter-propagating optical sideband pumping method to polarize the atoms, using the electro-optic modulator to modulate the single-pump beam, generating two symmetrically red- and blue-detuned sidebands of frequency. This scheme leads to a significant reduction of undesirable effects coming along with the optical pumping, such as light shifts and spatial inhomogeneity in atomic spin polarization. With the help of this pumping scheme, the two channels have the same magnetic response, and we have built a gradiometer atomic magnetometer with a sensitivity of 0.5 fT/Hz 1/2 ranging from 5 to 40 Hz. Our results propose the possibility of creating larger arrays of atomic magnetometers (AMs) with high sensitivity and spatial resolution based on single-vapor cells for magnetocardiography and magnetoencephalography imaging or searching for exotic spin-dependent interactions.

Optics Letters•Oct 9, 2024•10 citations

Femtotesla Spin-Exchange Relaxation-Free Atomic Magnetometer With a Multipass Cell

Yibo Qi, Bo Li, Shuying Wang +3 more

Miniaturized high-sensitivity atomic magnetometers play a crucial role in biomagnetic measurements. The utilization of multipass cells enhances the sensitivity of atomic magnetometers. This study explores the benefits of employing a multipass cell in spin-exchange relaxation-free (SERF) atomic magnetometers through theoretical and experimental analysis. A signal-to-noise ratio (SNR) model was established by accounting for the optimal detuning frequency of the probe light and low-frequency 1/f noise. This enabled the optimal number of probe light passes through the vapor cell to be determined. Additionally, compact and symmetric reflective optical paths were designed to mitigate polarization gradients in atomic magnetometers with high atomic number density. Experimental results confirmed that the magnetic field sensitivity of the triple-pass configuration (1.8 fT/Hz$^{1/2}$) was 1.89 times that of the single-pass configuration (3.4 fT/Hz$^{1/2}$), consistent with the theoretical analysis. This study provides valuable theoretical guidance for analyzing the SNR performance of SERF atomic magnetometers and demonstrates the potential of multipass cells in enhancing their magnetic field sensitivity. The utilization of multipass cells presents a viable approach toward the realization of highly sensitive and portable miniaturized SERF atomic magnetometers.

IEEE Transactions on Instrumentation and Measurement•Jan 1, 2024•18 citations
Abstract The chip-scale hybrid optical pumping spin-exchange relaxation-free (SERF) atomic magnetometer with a single-beam arrangement has prominent applications in biomagnetic measurements because of its outstanding features, including ultrahigh sensitivity, an enhanced signal-to-noise ratio, homogeneous spin polarization and a much simpler optical configuration than other devices. In this work, a miniaturized single-beam hybrid optical pumping SERF atomic magnetometer based on a microfabricated atomic vapor cell is demonstrated. Although the optically thin Cs atoms are spin-polarized, the dense Rb atoms determine the experimental results. The enhanced signal strength and narrowed resonance linewidth are experimentally proven, which shows the superiority of the proposed magnetometer scheme. By using a differential detection scheme, we effectively suppress optical noise with an approximate five-fold improvement. Moreover, the cell temperature markedly affects the performance of the magnetometer. We systematically investigate the effects of temperature on the magnetometer parameters. The theoretical basis for these effects is explained in detail. The developed miniaturized magnetometer has an optimal magnetic sensitivity of 20 fT/Hz 1/2 . The presented work provides a foundation for the chip-scale integration of ultrahighly sensitive quantum magnetometers that can be used for forward-looking magnetocardiography (MCG) and magnetoencephalography (MEG) applications.
The electronic spin polarization of alkali-metal-vapor atoms is a pivotal parameter for atomic magnetometers. Herein, a novel method is presented for determining the spin polarization with a miniaturized single-beam spin-exchange-relaxation-free (SERF) magnetometer on the basis of zero-field cross-over resonance. Two separate laser beams are utilized to heat the cell and interrogate the vapor atoms, respectively. Spin polarization can be extracted by measuring the resonance response signal of the magnetometer to the transverse magnetic field under different irradiances. Results of these experiments are consistent well with the theoretical predictions with the maximum deviation less than 4%. The proposed method has the integrated advantages of possessing a simple configuration and in-situ measurement. Furthermore, combined with a homemade optical differential detection system with a factor of approximately three of the power noise suppression, the developed single-beam SERF atomic magnetometer with a measuring sensitivity of 32 fT/Hz 1/2 has been achieved. This demonstrated approach can help guide the development of chip-scale atomic magnetometers for bio-magnetic field imaging applications.
Abstract The hybrid optical pumping spin exchange relaxation free (SERF) atomic magnetometers can realize ultrahigh sensitivity measurement of magnetic field and inertia. We have studied the 85 Rb polarization of two types of hybrid optical pumping SERF magnetometers based on 39 K- 85 Rb- 4 He and 133 Cs- 85 Rb- 4 He respectively. Then we found that 85 Rb polarization varies with the number density of buffer gas 4 He and quench gas N 2 , pumping rate of pump beam and cell temperature respectively, which will provide an experimental guide for the design of the magnetometer. We obtain a general formula on the fundamental sensitivity of the hybrid optical pumping SERF magnetometer due to shot-noise. The formula describes that the fundamental sensitivity of the magnetometer varies with the number density of buffer gas and quench gas, the pumping rate of pump beam, external magnetic field, cell effective radius, measurement volume, cell temperature and measurement time. We obtain a highest fundamental sensitivity of 1.5073 aT / Hz 1/2 (1 aT = 10 −18 T ) with 39 K- 85 Rb- 4 He magnetometer between above two types of magnetometers when 85 Rb polarization is 0.1116. We estimate the fundamental sensitivity limit of the hybrid optical pumping SERF magnetometer to be superior to 1.8359 × 10 −2 aT / Hz 1/2 , which is higher than the shot-noise-limited sensitivity of 1 aT / Hz 1/2 of K SERF atomic magnetometer.
Atomic magnetometers with magnetic field modulation have emerged as pivotal sensors for biomagnetic measurements. However, challenges such as crosstalk between adjacent modulation fields and the complexity of signal circuitry become increasingly serious in the development of array-based equipment with the magnetometers, especially in the miniaturized atomic magnetometer. This paper proposes an all-optical, fully integrated fiber-coupled atomic magnetometer that employs pump beam modulation. A miniaturized atomic magnetometer with a volume of 10 cm³ has been designed, incorporating an active measurement area of 3 × 3 × 3 mm3. The magnetometer operates in the spinexchange relaxation-free (SERF) regime with an 87Rb vapor cell. An amplitude-modulated pump beam directly modulates the rubidium atomic ensembles, rather than the magnetic field modulation. The optical rotation angle is detected by an unmodulated probe beam oriented orthogonally to the pump beam. In light of the discontinuous pumping characteristics, we developed a modified theoretical model to clarify the output response of the proposed atomic magnetometer. The experimental results demonstrate that the new design achieves the same sensitivity as conventional magnetometer configurations with a smaller volume and without crosstalk of the magnetic field. This research highlights the significant potential for advancing the development of highly sensitive, miniaturized atomic magnetometers, making them particularly suitable for applications in magnetocardiography (MCG) and magnetoencephalography (MEG).
The ultra-sensitivity magnetometer plays an important role in fundamental physics and applications, including magnetoencephalography (MEG) and magnetocardiography (MCG). The spin-exchange relaxation-free (SERF) atomic magnetometer (AM) has great sensitivity but is limited by the relatively complicated dual-beam structure for application, leading to the development of the compact AM based on one single laser beam. Compared with the single-beam optically pumped magnetometer (OPM) detecting the absorption of the circularly polarized beam, the SERF AM based on an elliptically polarized single beam detecting the optical rotation angle of polarization has a better response, lower laser power, and no need for signal modulation or demodulation. Here, we would like to report an elliptically-polarized single-beam SERF AM enhanced by reflecting the probe beam, increasing the light-atom interaction. Moreover, unlike the previous reflecting AM using the beam splitter, we used a D-shape mirror to extract the reflected beam, avoiding power losses of both incident and reflected beam and destruction of polarization. The sensitivity of our device in the reflecting scheme reaches 5 fT/Hz1/2 at 9–60 Hz, satisfying the need to measure the human MEG/MCG or search for the fifth force. Our research paves the way for developing the compact SERF AM for multiple future applications.
The ultrasensitive magnetometer has a vital importance in fundamental research and applications. Currently, the spin-exchange relaxation-free (SERF) atomic magnetometer has been reported with a sensitivity around the level of fT/Hz 1/2 . To enhance the sensitivity, a gradiometer configuration has usually been introduced to cancel the common-mode noise between two separate channels. However, the signal and response from different channels are not the same due to the attenuation of the pump beam. Here, we proposed a counter-propagating optical sideband pumping method to polarize the atoms, using the electro-optic modulator to modulate the single-pump beam, generating two symmetrically red- and blue-detuned sidebands of frequency. This scheme leads to a significant reduction of undesirable effects coming along with the optical pumping, such as light shifts and spatial inhomogeneity in atomic spin polarization. With the help of this pumping scheme, the two channels have the same magnetic response, and we have built a gradiometer atomic magnetometer with a sensitivity of 0.5 fT/Hz 1/2 ranging from 5 to 40 Hz. Our results propose the possibility of creating larger arrays of atomic magnetometers (AMs) with high sensitivity and spatial resolution based on single-vapor cells for magnetocardiography and magnetoencephalography imaging or searching for exotic spin-dependent interactions.
Miniaturized high-sensitivity atomic magnetometers play a crucial role in biomagnetic measurements. The utilization of multipass cells enhances the sensitivity of atomic magnetometers. This study explores the benefits of employing a multipass cell in spin-exchange relaxation-free (SERF) atomic magnetometers through theoretical and experimental analysis. A signal-to-noise ratio (SNR) model was established by accounting for the optimal detuning frequency of the probe light and low-frequency 1/f noise. This enabled the optimal number of probe light passes through the vapor cell to be determined. Additionally, compact and symmetric reflective optical paths were designed to mitigate polarization gradients in atomic magnetometers with high atomic number density. Experimental results confirmed that the magnetic field sensitivity of the triple-pass configuration (1.8 fT/Hz1/2^{1/2}1/2) was 1.89 times that of the single-pass configuration (3.4 fT/Hz1/2^{1/2}1/2), consistent with the theoretical analysis. This study provides valuable theoretical guidance for analyzing the SNR performance of SERF atomic magnetometers and demonstrates the potential of multipass cells in enhancing their magnetic field sensitivity. The utilization of multipass cells presents a viable approach toward the realization of highly sensitive and portable miniaturized SERF atomic magnetometers.