Figure 1
APS/Joan Tycko

Figure 1: Experimentalists have shown that a defect in diamond, called a nitrogen-vacancy center, can detect the presence of a single charge on a neighboring defect 25 nm away. The charge sensitivity exists because the spin precession rate of a nitrogen-vacancy center depends on the local electric field and can be read out optically. To demonstrate the single-charge sensitivity, the researchers showed that the resonant frequency of a spin on one defect (the “sensor”) depended on the charge state of a nearby defect (the “target”.)