Active stabilization of terrestrial magnetic field with potassium atomic magnetometer

Abstract

This paper introduces a magnetically quiet environment where the magnetic-field noise is actively suppressed using an optically pumped potassium magnetometer. In a large dynamic range of Earth’s magnetic fields, the magnetic-resonance signals of potassium are completely separated in frequency, and we experimentally demonstrate that one of them could be used to measure and compensate magnetic-field noise. The magnetic-field noise floor after stabilization is ∼100 fT/Hz under a bias field ranging from 20 to 100 μT. This method could be useful for fundamental-physics experiments and biomedical sciences where a large dynamic range of quiet magnetic fields is needed.

Precision measurement and suppression of low-frequency noise in a current source with double-resonance alignment magnetometers

“…Rosner et al reported a nonmagnetic drift optically pumped cesium magnetometer with a measured sensitivity of 35 fT at integration time of 200 s and stability below 50 fT between 70 s and 600 s. [13] Ding et al used an optically pumped potassium magnetometer to suppress the magnetic noise actively and achieved a noise floor of about 100 fT/ √ Hz under a bias field from 20 µT to 100 µT. [14] As for the OPM in the study of current noise suppression, Shen et al used an optically pumped Cs atomic magnetometer to suppress the noise of a commercial CS and reached a noise level of 600 pA/ √ Hz at 1 Hz. [10] In those studies, the magnetometers they used belonged to double resonance orientation magnetometers (DROMs).…”