"Magnetic microscope image of three nanomagnetic computer bits. Each bit is a tiny bar magnet only 90 nanometers long. In the image on the left, the bright spots are at the ""North"" end of the magnet, and the dark spots are at the ""South"" end. The ""H"" arrow shows the direction of magnetic field applied to switch the direction of the magnets. (Source: Jeongmin Hong and Jeffrey Bokor, study in Science Advances.)"