Atom lasers produce highly controlled beams of atoms with desirable properties similar to the light beams produced by optical lasers. The raw ingredients for such devices are ultracold clumps of atoms called "Bose-Einstein condensates," which overlap with one another and fall into the same quantum state, which means that the atoms are highly coordinated with each other. Atom laser devices simply extract beams or pulses of atoms from these BECs.
First announced in 1997, atom lasers are still in an early stage. By March 1999, 4 groups of physicists reported designs for them. This figure shows beams from the 4 atom laser designs. MIT researchers reported the first atom laser design in January 1997. The MIT atom laser (first figure on left) produces pulses of sodium atoms; each pulse expands to form a crescent-moon shape.
The next atom laser beam, composed of rubidium atoms, was produced at the Max Planck Institute for Quantum Optics in Munich, Germany; announced in March 1999, it is the first example of a continuous atom laser beam. Previous designs were only able to produce pulses of atoms.
The Yale design, described in November 1998, traps rubidium atoms in a web of light waves known as an optical lattice; eventually, the atoms fall because of gravity, and they fall as coordinated clumps.
Shown at the bottom is the atom laser design announced by researchers at NIST-Gaithersburg in March 1999. Unlike the other designs, which produce vertical beams dragged down by gravity, the NIST design can produce atom laser beams in any direction (sodium atoms are shown here). The NIST device produces a "quasi-continuous" beam, pulses of atoms so close together that they overlap.
Atom lasers will provide greatly improved sources of atoms for measuring time, gravitational acceleration, and rotation. Potentially they can be manipulated to create sophisticated nanostructures. (Individual figures courtesy of the authors; composite figure courtesy of NIST.)
Further reading: "New Atom Lasers Eject Atoms or Run CW," by Gloria Lubkin, in the April 1999 issue of Physics Today (pp.17-18).