Feel the Force: Magnetic probe finds lone electron

When a patient undergoes magnetic resonance imaging (MRI), the scanner makes tissues visible by tapping into a magnetlike property of many trillions of protons in the patient’s body. Known as spin, this quantum-mechanical trait also shows up in electrons, atomic nuclei, and many other elementary particles. Now, scientists have devised an ultrasensitive MRI technique and used it to detect the spin of a single electron.