Spin-echo-based magnetometry with spinor Bose-Einstein condensates

Abstract

We demonstrate detection of a weak alternate-current magnetic field by application of the spin-echo technique to $F=2$ Bose-Einstein condensates. A magnetic field sensitivity of 12 pT$/\sqrt{\mathrm{Hz}}$ is attained for an atom number of $5\ifmmode\times\else\texttimes\fi{}{10}^{3}$ at a spatial resolution of 100 $\ensuremath{\mu}$m${}^{2}$. Our observations indicate magnetic field fluctuations synchronous with the power supply line frequency. We show that this noise is greatly suppressed by application of a reverse phase magnetic field. Our technique is useful in order to create a stable magnetic field environment, which is an important requirement for atomic experiments which require a weak bias magnetic field.