Adiabatic Quantum Electron Pump Produces DC Current

If you know what you're doing and have suitable equipment, you can make a quantum dot, a tiny conducting region that contains anywhere from a handful to several thousand electrons. A number of experimenters have studied the electron transport properties of such dots. Now a group at Stanford University and the University of California, Santa Barbara, has made an open quantum dot, changed the shape of the system cyclically, and found that a finite current flows. This surprising effect requires quantum phase coherence and is observable only at a temperature low enough to preserve quantum phase. The effect was recently reported by Michael Switkes and Charles Marcus (Stanford), and Kenneth Campman and Arthur Gossard (UCSB).