Active stabilization of kilogauss magnetic fields to the ppm level for magnetoassociation on ultranarrow Feshbach resonances

TL;DR

This paper introduces a highly precise magnetic field control system capable of stabilizing over 1000 G fields to the ppm level, enabling improved control for ultracold molecule formation via narrow Feshbach resonances.

Contribution

The authors develop and demonstrate an active stabilization system combining a battery-powered current source with fluxgate sensors for ppm-level magnetic field control in ultracold experiments.

Findings

Achieved magnetic field stability of 2.4(3) mG at 1050 G

Demonstrated ppm-level precision in magnetic field control

Validated system performance through microwave spectroscopy of ultracold Rb atoms

Abstract

Feshbach association of ultracold molecules using narrow resonances requires exquisite control of the applied magnetic field. Here we present a magnetic field control system to deliver magnetic fields of over 1000 G with ppm-level precision integrated into an ultracold-atom experimental setup. We combine a battery-powered current-stabilized power supply with active feedback stabilization of the magnetic field using fluxgate magnetic field sensors. As a real-world test we perform microwave spectroscopy of ultracold Rb atoms and demonstrate an upper limit on our magnetic field stability of 2.4(3) mG at 1050 G [2.3(3) ppm relative] as determined from the spectral feature.