Princeton investigators detected channels of conducting electrons that form between two quantum states on the surface of a bismuth crystal subjected to a high magnetic field. These two states consist of electrons moving in elliptical orbits with different orientations. The researchers found that the current flow in these channels can be turned on and off, making these channels a new type of controllable quantum wire. The team further found that at the boundary, the conducting channels formed a valley-polarized domain wall, between two regions on the crystal where the electron orbits switched orientations abruptly. While the larger number of lanes would seem to suggest better conductivity, the repulsion between electrons counter-intuitively causes them to switch lanes, change direction, and get stuck, resulting in insulating behavior. With fewer channels, electrons have no option to change lanes and must transmit electrical current even if they have to move “through” each other—a quantum phenomenon only possible in such one-dimensional channels.