Vector SERF magnetometers
For applications demanding the highest possible magnetic field sensitivity, the spin-exchange relaxation-free (SERF) magnetometer offers the world's highest magnetic field sensitivity. By operating in a magnetically-shielded enclosure with low ambient magnetic field, it is possible to achieve very long spin coherence time in a very dense atomic vapor. A laser monitors polarized spins as they rotate by a small amount in response to small magnetic field signals. The resulting sensor system has performance exceeding SQUID-based systems.