This work could lead to miniaturized, battery-powered devices for medical and materials imaging, contraband detection, and geological exploration. Magnetic field detectors are already being used in these areas, bur existing technologies have drawbacks: Some rely on gas-filled chambers; others work only in narrow frequency bands, limiting their utility.
Synthetic diamonds with nitrogen vacancies (NVs) — defects that are extremely sensitive to magnetic fields — have long held promise as the basis for efficient, portable magnetometers. A diamond chip about one-twentieth the size of a thumbnail could contain trillions of nitrogen vacancies, each capable of performing its own magnetic-field measurement.
In the past, the problem has been aggregating all those measurements. Probing a nitrogen vacancy requires zapping it with laser light, which it absorbs and re-emits. The intensity of the emitted light carries information about the vacancy’s magnetic state.