These images collected by Princeton University scientists show (top) the first direct image of the dancing pattern of electrons on the edge of the bismuth-antimony bulk crystal, which is a quantum Hall insulator; (center) a schematic and another image showing the electron distribution in three dimensions; and (bottom) a schematic and an image conveying the distribution of edge-electrons in two dimensions.

Images: Zahid Hasan

Princeton scientists who worked on the experiment in which the quantum Hall effect was seen in a material without the presence of an applied magnetic field included: (from left) Zahid Hasan, an assistant professor of physics; David Hsieh, a graduate student; Robert Cava, chair of the Department of Chemistry; and Yew San Hor, a postdoctoral fellow.

Photo: Brian Wilson