A Highly Drift-stable Atomic Magnetometer for Fundamental Physics Experiments

TL;DR

This paper presents a highly stable cesium atomic magnetometer with exceptional sensitivity and stability, suitable for fundamental physics experiments requiring precise magnetic field measurements over extended periods.

Contribution

The design achieves unprecedented stability and sensitivity in a non-magnetic cesium magnetometer, enabling new possibilities in low-energy particle physics research.

Findings

Sensitivity of 35 fT at 200 s

Stability below 50 fT between 70 s and 600 s

Residual offset of < 15 pT

Abstract

We report the design and performance of a non-magnetic drift stable optically pumped cesium magnetometer with a measured sensitivity of 35 fT at 200 s integration time and stability below 50 fT between 70 s and 600 s. To our knowledge this is the most stable magnetic field measurement to date. The sensor is based on the nonlinear magneto-optical rotation effect: in a Bell-Bloom configuration a higher order polarization moment (alignment) of Cs atoms is created with a pump laser beam in an anti-relaxation coated Pyrex cell under vacuum, filled with Cs vapor at room temperature. The polarization plane of light passing through the cell is modulated due the precession of the atoms in an external magnetic field of 2.1 muT, used to optically determine the Larmor precession frequency. Operation is based on a sequence of optical pumping and observation of freely precessing spins at a repetition rate of 8 Hz. This free precession decay readout scheme separates optical pumping and probing and thus ensures a systematically highly clean measurement. Due to the residual offset of the sensor of < 15 pT together with the cross-talk free operation of adjacent sensors, this device is uniquely suitable for a variety of experiments in low-energy particle physics with extreme precision, here as highly stable and systematically clean reference probe in search for time-reversal symmetry violating electric dipole moments.