Low noise magnetic fields in ultracold experiment

Abstract

Ultracold atomic and molecular experiments rely on low noise ambient magnetic fields for precision spectroscopy and studying Feshbach resonances with narrow linewidths, which can be on the order of 1 [mu] T. The ambient field is impacted by both the Earth's magnetic field and technical noise from surrounding electrical equipment, which can vary through the day. We built an apparatus using an Arduino microprocessor to record the ambient fields with magnetometers located outside the vacuum chamber containing the atoms and output transformed waveforms at 30 Hz intervals to be feed forwarded to the coils and cancel both the average field and fluctuations. We achieved an RMS of 37 nT along one axis in the magnetic fields in our test setup using this apparatus, reducing the 60 Hz component by 30 dB and the 180 Hz component by 20 dB.