A Single-Atom Laser

A single-atom laser, a device employing a single trapped atom to resonantly emit light back and forth between two reflective mirrors, has been created by Jeffrey Kimble at Caltech. Although single-atom lasers have been demonstrated before (See PNU #204), Kimble's is the first to use a single atom nearly at rest, and not a parade of atoms in a dilute beam entering a reflective cavity one at a time. The singleness of the source means that the number of photons emitted by the laser over a certain time interval is, while not exactly predictable (which would be outlawed by Heisenberg's uncertainty principle), much less jittery than emission from multi-atom lasers. The emission is weak by laser standards---only about 100,000 photons per second---but this quiet, more controllable form of photons should aid future quantum information schemes. (McKeever et al., Nature, 18 September 2003.)