Electron cycling in quantum confines

From Long Beach, Calif., at a meeting of the American Physical Society

Like a race car forced to stay within certain lanes of a speedway, a lone electron in a circular path should whirl along exclusively in specific allowed orbits, the rules of quantum mechanics say.

In a Harvard University laboratory, physicists have devised an extraordinarily small, low-energy cyclotron in which a single orbiting electron vividly demonstrates that predicted quantum behavior.