by I. Peterson Unlike an ordinary, incandescent bulb, a laser
produces light of a single wavelength. Moreover, the emitted
light waves are coherent, meaning that all of the energy peaks
and troughs are precisely in step. Now, a team at the
Massachusetts Institute of Technology has demonstrated
experimentally that a cloud consisting of millions of atoms can
also be made coherent. Instead of flying about and colliding
randomly, the atoms display coordinated behavior, acting as if
the entire assemblage were a single entity. According to quantum
mechanics, atoms can behave like waves. Thus, two overlapping
clouds made up of atoms in coherent states should produce a
zebra-striped interference pattern of dark and light fringes,
just like those generated when two beams of ordinary laser light
overlap. By detecting such a pattern, the researchers proved
that the clouds' atoms are coherent and constitute an "atom
laser," says physicist Wolfgang Ketterle, who heads the MIT
group. These matter waves, in principle, can b