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Femtotesla 4He magnetometer with a multipass cell
Optics Letters
|October 14, 2022
Summary
We developed a novel magnetometer using a multipass helium-4 cell, achieving femtotesla sensitivity. This enhanced nonlinear magneto-optical rotation (NMOR) device offers high bandwidth for biomagnetic applications.
Area of Science:
- Atomic physics
- Magnetometry
- Quantum optics
Background:
- Nonlinear magneto-optical rotation (NMOR) is a sensitive technique for magnetic field measurements.
- Previous magnetometers often require heating or cryogenic cooling and have limited bandwidth.
Purpose of the Study:
- To develop a highly sensitive and wide-bandwidth magnetometer.
- To enhance magneto-optical rotation using a multipass gas cell.
- To explore potential biomagnetic applications.
Main Methods:
- Utilized a single-beam nonlinear magneto-optical rotation (NMOR) technique.
- Employed a multipass 4He gas-discharge cell to increase optical path length (22 passes).
- Measured magnetic fields based on nonlinear Faraday rotation.
Main Results:
- Achieved a noise floor of 9 fT/Hz^1/2, approaching the photon-shot noise limit.
- Demonstrated a 3 dB bandwidth of 4.3 kHz due to wider linewidth in metastable-state 4He atoms.
- The magnetometer operates without heating or cryogenic cooling.
Conclusions:
- The multipass cell significantly enhances NMOR sensitivity.
- The developed 4He magnetometer offers femtotesla sensitivity and kilohertz bandwidth.
- Potential applications in magnetocardiography and magnetoencephalography are highlighted.
