Subpicotesla atomic magnetometry with a microfabricated vapour cell
V Shah, Svenja A. Knappe, P Schwindt, John E. Kitching
Highly sensitive magnetometers, capable of measuring magnetic fields below 1 pT, impact areas as diverse as geophysical surveying1, the detection of unexploded ordinance, space science3, nuclear magnetic resonance (NMR), and perimeter and remote monitoring. Recently, it was shown that laboratory optical magnetometers, based on the precession of the spins of alkali atoms in the vapor phase, could achieve sensitivities in the fT range comparable to8-10, or even exceeding11, those of superconducting quantum interference devices (SQUIDs). We demonstrate here an atomic magnetometer based on a microfabricated alkali vapor cell of interior volume 6 mm3, with sensitivity below 70 fT/sqrt(Hz). In addition, the experiment demonstrates a highly simplified optical configuration that requires only a single, low-power laser. This result suggests that millimeter-scale, low-power, inexpensive femtotesla magnetometers are feasible. Such an instrument would greatly expand the range of applications in which atomic magnetometers could be used.