The ability to measure tiny magnetic fields with good sensitivity can be found in many applications, from biological imaging to prospecting for buried treasure. However, the most sensitive magnetometers that operate in ambient conditions tend to be power-hungry, bulky, and heavy. Shrinking the size to just several millimeters and the power consumption to hundreds of milliwatts, Schwindt et al. have fabricated a sensitive magnetometer using microelectromechanical technology. A cloud of rubidium atoms trapped in a micromachined vapor cell is used to sense the magnetic field. The magnetic field splits the energy levels of rubidium atoms, and the extent of the splitting depends on the strength of the magnetic field. Changes in the magnetic field are then detected and tracked optically by the relative absorption changes of a laser light tuned to the split energy levels. It could be that in the not-too-distant future we could be using handheld battery-operated magnetometers. -- ISO
Appl. Phys. Lett. 85, 6409 (2004).
