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

Journal of Applied Physics

Observation and analysis of the spatial frequency response of an atomic magnetometer

Haifeng Dong, Ling-Xiao Yin, Ai-Xian Li, Nan Zhao, Jing-Ling Chen, Ming-Jie Sun

Published Jan 11, 2019• 4 citations
Publisher

Abstract

An atomic magnetometer is an ultra-high-sensitivity sensor that measures magnetic fields by means of atomic spin polarization. The spatial frequency response (SFR), which describes the spin polarizations corresponding to the field at different spatial frequencies, is an important property of atomic magnetometers. To characterize the SFR, one must generate a spatially varying field with scannable spatial frequencies (in units of mm−1), a concept that is similar to that in the time domain. However, it is much more difficult to generate a varying magnetic field spatially using traditional magnetic coils than it is to do so temporally. We generate an equivalent field Bysin⁡(ξx) with spatial frequency ξ from 0.14 mm−1 to 36.5 mm−1 by modulating the pump laser beam with a digital micromirror device and then obtain the SFR of a Cs atomic magnetometer by measuring the spin polarization of Cs at different spatial frequencies. The experimentally obtained SFR agrees well with the response calculated based on the Bloch equations and Fick’s second diffusion law. We also discuss a new definition of spatial resolution that can be used to characterize and compare the background spatial resolutions of different atomic magnetometers.

DOI
10.1063/1.5049609

Related papers

Spin Spatial Frequency Response of Atomic Magnetometer

Ling-Xiao Yin, Jing Ling Chen

We describe a method for measuring the spin spatial frequency response in a Cs vapor cell by using a digital micro-mirror device (DMD) to modulate the pumping light both spatially and temporally. An equivalent space-alternative magnetic field is created by this way. The pumping light through the Cs vapor cell is measured and analyzed in spatial frequency domain. We obtain the spatial frequency response of the Cs vapor cell from 1.4 cm-1to 364.9 cm-1. The theoretical results of the spatial frequency response according to Fick's second diffusion law agree with the experimental results. This method provides an alternate approach for spatial characterization and three-dimensional imaging of spins.

Key engineering materials•Nov 1, 2018•1 citation

A Novel Measurement Method for Spin Polarization Three Axis Spatial Distribution in Spin-Exchange Relaxation Free Atomic Magnetometer

Xiujie Fang, Jin Chun Li, Yanning Ma +5 more

The measurement of atomic spin polarization distribution in spin-exchange relaxation free (SERF) magnetometer is an important topic for improving the sensitivity and consistency of multi-channel magnetic field measurement applications. A novel spin polarization spatial distribution measurement method is presented based on the transient response of the magnetometer after modulating the pumped light with a chopper. Polarization is obtained by a slow-down factor based on the fast spin-exchange interaction effects. Longitudinal and transverse polarization distributions are measured simultaneously without interrupting the operation of the SERF status. Under different oscillating magnetic fields, the spin polarization is measured at the cell centroid. Residual magnetic field inside the magnetometer is obtained from the linear relationship between the precession frequency and the oscillating magnetic field. The one-dimensional polarization distributions in the x, y, and z axes are measured using a digital micromirror device with a resolution of 0.25 cm. The measurement results conform to the Lambert-Bier absorption law and the Gaussian distribution law. Furthermore, 7 × 7 two-dimensional spatial distribution measurements of polarization on the xy and yz planes are performed. Nonuniformity of 1.04 in the xy plane and 1.82 in the yz plane in the built magnetometer. Compared with other measurement methods, the distribution measurement method proposed is independent of optical depth and suitable for low polarization and high polarization applications. Based on the results of the proposed measurement method of spin polarization spatial distribution, further compensation can improve the application consistency of multi-channel magnetic field measurements and improve the sensitivity of single-channel differential measurements.

Photonics•Mar 20, 2023•2 citations

High spatial resolution multi-channel optically pumped atomic magnetometer based on a spatial light modulator

Xiujie Fang, Kai Wei, Tian Zhao +5 more

Ultra-sensitive multi-channel optically pumped atomic magnetometers based on the spin-exchange relaxation-free (SERF) effect are powerful tools for applications in the field of magnetic imaging. To simultaneously achieve ultra-high spatial resolution and ultra-high magnetic field sensitivity, we proposed a high-resolution multi-channel SERF atomic magnetometer for two-dimensional magnetic field measurements based on a digital micro-mirror device (DMD) as the spatial light modulator for a single vapor cell. Under the optimal experimental conditions obtained via spatial and temporal modulation of the probe light, we first demonstrated that the average sensitivity of the proposed 25-channel magnetometer was approximately 25fT/Hz 1/2 with a spatial resolution of 216µm. Then, we measured the magnetic field distribution generated by a gradient coil and compared the experimentally obtained distributions with those calculated via finite element simulation. The obtained g value of 99.2% indicated good agreement between our experimental results and the theoretical calculations, thereby confirming that our proposed multi-channel SERF magnetometer was effective at measuring magnetic field distributions with an ultra-high spatial resolution.

Optics Express•Aug 14, 2020•46 citations

Study on the sensitivity of laser-pumped cesium atomic magnetometer

Nan Li, Huang Kai-Kai, Xuanhui Lu

A cesium atomic magnetometer based on laser-pumped rf resonance has been investigated and demonstrated experimentally. Atoms are polarized and pumped to dark states by circularly polarized light. When there exists a magnetic field, the corresponding magnetization will be precessing around the magnetic field at Larmor frequency. By means of adding a resonant rf magnetic field, the atoms will be depolarized and absorb photons again. By detecting the spectrum of the transmitted light, one can obtain the information about the external magnetic field. We build an 894nm external cavity diode laser with a frequency stabilization device, and a low noise magnetic field measurement environment. After the optimization of the magnetometer parameter and closed-loop measurement, an ultimate sensitivity of 19 fT/Hz1/2 and an intrinsic sensitivity of 1.8 pT/Hz1/2 have been achieved with the spatial resolution smaller than 2 cm.

Acta Physica Sinica•Jan 1, 2013•4 citations

Determination of Spin Polarization in Spin-Exchange Relaxation-Free Atomic Magnetometer Using Transient Response

Junpeng Zhao, Ming Ding, Jixi Lu +5 more

A novel method to determine the spin polarization and its distribution for a spin-exchange relaxation-free (SERF) atomic magnetometer are proposed in this paper. The Larmor precession frequency is measured using the fast Fourier transform (FFT) analysis result of the transient response of the magnetometer under the excitation of a series of the step-changed magnetic field. The spin polarization is extracted from the slow-down factor of the precession frequency. The variation of the spin polarization with different pump light intensities and the distribution of the spin polarization along the direction of the pump light are analyzed, and the experimental results are well consistent with the theoretical predictions. The expanded uncertainties of the experimental results vary from 2% to 11% with the increase of the spin polarization and the reason for this variation is analyzed. The advantage of this method is that it allows the accurate measurement of the spin polarization in the pump beam direction within the SERF regime operating state, and it is unaffected by the large optical depth of the vapor cell.

IEEE Transactions on Instrumentation and Measurement•Apr 27, 2019•67 citations

Sub-femtotesla Multi-channel Atomic Magnetometer

Iannis K. Kominis, Thomas W. Kornack, Joel C. Allred +1 more

Abstract The magnetic field is one of the most fundamental and ubiquitous physical observables, carrying information about all electromagnetic phenomena. For the past 30 years, superconducting quantum interference devices (SQUIDs) operating at 4 K have been unchallenged as ultrahigh-sensitivity magnetic field detectors1, with a sensitivity reaching down to 1 fT Hz-1/2 (1 fT = 10-15 T). They have enabled, for example, mapping of the magnetic fields produced by the brain, and localization of the underlying electrical activity (magnetoencephalography). Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have approached similar levels of sensitivity using large measurement volumes2, 3, but have much lower sensitivity in the more compact designs required for magnetic imaging applications4. Higher sensitivity and spatial resolution combined with non-cryogenic operation of atomic magnetometers would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain. Here we describe a new spin-exchange relaxation-free (SERF) atomic magnetometer, and demonstrate magnetic field sensitivity of 0.54 fT Hz-1/2 with a measurement volume of only 0.3 cm3. Theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01 fT Hz-1/2. We also demonstrate simple multichannel operation of the magnetometer, and localization of magnetic field sources with a resolution of 2 mm.

APS•May 1, 2003•0 citations
An atomic magnetometer is an ultra-high-sensitivity sensor that measures magnetic fields by means of atomic spin polarization. The spatial frequency response (SFR), which describes the spin polarizations corresponding to the field at different spatial frequencies, is an important property of atomic magnetometers. To characterize the SFR, one must generate a spatially varying field with scannable spatial frequencies (in units of mm−1), a concept that is similar to that in the time domain. However, it is much more difficult to generate a varying magnetic field spatially using traditional magnetic coils than it is to do so temporally. We generate an equivalent field Bysin⁡(ξx) with spatial frequency ξ from 0.14 mm−1 to 36.5 mm−1 by modulating the pump laser beam with a digital micromirror device and then obtain the SFR of a Cs atomic magnetometer by measuring the spin polarization of Cs at different spatial frequencies. The experimentally obtained SFR agrees well with the response calculated based on the Bloch equations and Fick’s second diffusion law. We also discuss a new definition of spatial resolution that can be used to characterize and compare the background spatial resolutions of different atomic magnetometers.
We describe a method for measuring the spin spatial frequency response in a Cs vapor cell by using a digital micro-mirror device (DMD) to modulate the pumping light both spatially and temporally. An equivalent space-alternative magnetic field is created by this way. The pumping light through the Cs vapor cell is measured and analyzed in spatial frequency domain. We obtain the spatial frequency response of the Cs vapor cell from 1.4 cm-1to 364.9 cm-1. The theoretical results of the spatial frequency response according to Fick's second diffusion law agree with the experimental results. This method provides an alternate approach for spatial characterization and three-dimensional imaging of spins.
The measurement of atomic spin polarization distribution in spin-exchange relaxation free (SERF) magnetometer is an important topic for improving the sensitivity and consistency of multi-channel magnetic field measurement applications. A novel spin polarization spatial distribution measurement method is presented based on the transient response of the magnetometer after modulating the pumped light with a chopper. Polarization is obtained by a slow-down factor based on the fast spin-exchange interaction effects. Longitudinal and transverse polarization distributions are measured simultaneously without interrupting the operation of the SERF status. Under different oscillating magnetic fields, the spin polarization is measured at the cell centroid. Residual magnetic field inside the magnetometer is obtained from the linear relationship between the precession frequency and the oscillating magnetic field. The one-dimensional polarization distributions in the x, y, and z axes are measured using a digital micromirror device with a resolution of 0.25 cm. The measurement results conform to the Lambert-Bier absorption law and the Gaussian distribution law. Furthermore, 7 × 7 two-dimensional spatial distribution measurements of polarization on the xy and yz planes are performed. Nonuniformity of 1.04 in the xy plane and 1.82 in the yz plane in the built magnetometer. Compared with other measurement methods, the distribution measurement method proposed is independent of optical depth and suitable for low polarization and high polarization applications. Based on the results of the proposed measurement method of spin polarization spatial distribution, further compensation can improve the application consistency of multi-channel magnetic field measurements and improve the sensitivity of single-channel differential measurements.
Ultra-sensitive multi-channel optically pumped atomic magnetometers based on the spin-exchange relaxation-free (SERF) effect are powerful tools for applications in the field of magnetic imaging. To simultaneously achieve ultra-high spatial resolution and ultra-high magnetic field sensitivity, we proposed a high-resolution multi-channel SERF atomic magnetometer for two-dimensional magnetic field measurements based on a digital micro-mirror device (DMD) as the spatial light modulator for a single vapor cell. Under the optimal experimental conditions obtained via spatial and temporal modulation of the probe light, we first demonstrated that the average sensitivity of the proposed 25-channel magnetometer was approximately 25fT/Hz 1/2 with a spatial resolution of 216µm. Then, we measured the magnetic field distribution generated by a gradient coil and compared the experimentally obtained distributions with those calculated via finite element simulation. The obtained g value of 99.2% indicated good agreement between our experimental results and the theoretical calculations, thereby confirming that our proposed multi-channel SERF magnetometer was effective at measuring magnetic field distributions with an ultra-high spatial resolution.
A cesium atomic magnetometer based on laser-pumped rf resonance has been investigated and demonstrated experimentally. Atoms are polarized and pumped to dark states by circularly polarized light. When there exists a magnetic field, the corresponding magnetization will be precessing around the magnetic field at Larmor frequency. By means of adding a resonant rf magnetic field, the atoms will be depolarized and absorb photons again. By detecting the spectrum of the transmitted light, one can obtain the information about the external magnetic field. We build an 894nm external cavity diode laser with a frequency stabilization device, and a low noise magnetic field measurement environment. After the optimization of the magnetometer parameter and closed-loop measurement, an ultimate sensitivity of 19 fT/Hz1/2 and an intrinsic sensitivity of 1.8 pT/Hz1/2 have been achieved with the spatial resolution smaller than 2 cm.
A novel method to determine the spin polarization and its distribution for a spin-exchange relaxation-free (SERF) atomic magnetometer are proposed in this paper. The Larmor precession frequency is measured using the fast Fourier transform (FFT) analysis result of the transient response of the magnetometer under the excitation of a series of the step-changed magnetic field. The spin polarization is extracted from the slow-down factor of the precession frequency. The variation of the spin polarization with different pump light intensities and the distribution of the spin polarization along the direction of the pump light are analyzed, and the experimental results are well consistent with the theoretical predictions. The expanded uncertainties of the experimental results vary from 2% to 11% with the increase of the spin polarization and the reason for this variation is analyzed. The advantage of this method is that it allows the accurate measurement of the spin polarization in the pump beam direction within the SERF regime operating state, and it is unaffected by the large optical depth of the vapor cell.
Abstract The magnetic field is one of the most fundamental and ubiquitous physical observables, carrying information about all electromagnetic phenomena. For the past 30 years, superconducting quantum interference devices (SQUIDs) operating at 4 K have been unchallenged as ultrahigh-sensitivity magnetic field detectors1, with a sensitivity reaching down to 1 fT Hz-1/2 (1 fT = 10-15 T). They have enabled, for example, mapping of the magnetic fields produced by the brain, and localization of the underlying electrical activity (magnetoencephalography). Atomic magnetometers, based on detection of Larmor spin precession of optically pumped atoms, have approached similar levels of sensitivity using large measurement volumes2, 3, but have much lower sensitivity in the more compact designs required for magnetic imaging applications4. Higher sensitivity and spatial resolution combined with non-cryogenic operation of atomic magnetometers would enable new applications, including the possibility of mapping non-invasively the cortical modules in the brain. Here we describe a new spin-exchange relaxation-free (SERF) atomic magnetometer, and demonstrate magnetic field sensitivity of 0.54 fT Hz-1/2 with a measurement volume of only 0.3 cm3. Theoretical analysis shows that fundamental sensitivity limits of this device are below 0.01 fT Hz-1/2. We also demonstrate simple multichannel operation of the magnetometer, and localization of magnetic field sources with a resolution of 2 mm.