  We report on a 2x2 array of radio-frequency atomic magnetometers in magnetic
induction tomography configuration. Active detection, localization, and
real-time tracking of conductive, non-magnetic targets are demonstrated in air
and saline water. Penetration in different media and detection are achieved
thanks to the sensitivity and tunability of the sensors, and to the active
nature of magnetic induction probing. We obtained a 100% success rate for
automatic detection and 93% success rate for automatic localization in air and
water, up to 190 mm away from the sensors' plane (100 mm underwater). We
anticipate magnetic induction tomography with arrays of atomic magnetometers
finding applications in civil engineering and maintenance, oil&gas industry,
geological surveys, marine science, archeology, search and rescue, and security
and surveillance.
