The very first of "Hal's Picks", back in 1995, was the announcement of the first experimental observation of a Bose-Einstein condensate. This can be considered as a new phase of matter, in which atoms in a cold cluster lose their separate identities, because their deBroglie wavelengths exceed the dimension of the group in which they find themselves. This month, researchers at MIT announce that they have observed interference between globs of these atoms that are allowed to leak in pulses out of the magnetic trap in which they are produced. Science calls this an "atom laser", because the wavepackets are coherent, as are the photons of a laser. The analogy with ordinary photon lasers is not complete, however, because there isn't any "amplification" in this system, the second letter in the acronym "laser". I loved the quote from one of the research team, Keith Burnett, in the accompanying news article, "It's not just a little crappy demonstration but a big, juicy interference pattern", when referring to the fringes that are reproduced on the week's magazine cover.
M. R. Andrews, C. G. Townsend, H.-J.Miesner, D. S. Durfee, D. M. Kurn, and W. Ketterle