Two teams have independently reported the phase-coherent amplification of matter waves. The technique promises to lead to the development of active matter-wave devices with applications in metrology and atom optics.

Researchers at the Massachusetts Institute of Technology in Cambridge, who reported their results in the Dec. 9, 1999, issue of Nature, pumped a Bose-Einstein condensate of sodium atoms with two off-resonance laser pulses. A group from the University of Tokyo, Gakushuin University in Tokyo and the National Institute of Standards and Technology in Gaithersburg, Md., which used rubidium, published its results in the Dec. 17, 1999, issue of Science.

In each case, optical Bragg diffraction spawned seed matter waves, with a gain in atoms dependent on the intensity of the pump pulse.