Number 272, May 23, 1996 by Phillip F. Schewe and Ben Stein ADVANCES IN BOSE-EINSTEIN CONDENSATES: First produced last year by a NIST-University of Colorado group, Bose-Einstein condensates (BECs) comprise a new state of matter in which gas atoms, cooled to near-absolute-zero temperatures, overlap with each other and collapse into a common quantum state, where they behave essentially as a single "superparticle." At the American Physical Society Division of Atomic, Molecular and Optical Physics meeting last week at the University of Michigan, Wolfgang Ketterle and his colleagues at MIT (617-253-6815) announced that they had produced a Bose-Einstein condensate of 5 million atoms, 10 times bigger than any previous BEC. At 150 microns long and 8 microns wide, the condensate was large enough to be directly observed for the first time. The MIT researchers shone some laser light onto the condensate and imaged the scattered light with a sensitive camera. What they saw was a direct image of an atomic matter wave with a half wavelength of 150 microns. Performing the first study of the BEC's mysterious optical properties, the MIT group found that the sodium condensate acts as a lens and that the light scattered off the condensate is anisotropic: in other words, it scatters light preferentially in certain directions. To produce the condensate, the researchers used a combination of lasers and magnetic fields in a special configuration in which cloverleaf-shaped coils generate magnetic fields that tightly confine the atoms while allowing the setup's 11 lasers to pass easily into the trapping region. ATOM PHOTONICS. A Colorado-NIST group first showed that atoms could be sent down narrow, hollow tubes guided by laser light (see Update 245). The latest in a series of "atom optics" innovations, this technique might prove to be useful in some new form of lithography. Scientists at the Kanagawa Academy of Science and Technology (Japan, Haruhiko Ito, haruhiko@net.ksp.or.jp), the Tokyo Institute of Technology, and Seoul National University use an alternative process. Whereas the Colorado scheme uses one laser beam to introduce atoms from a rubidium gas into a 20-micron-wide tube and a second laser beam to guide them down the tube, the Japanese scheme achieves a higher rate of guidance (fraction of atoms successfully transmitted through a tube) by sending a collimated beam of Rb atoms into hollow 7- and 2-micron-wide optical fibers, where they are guided by a single laser beam. In their case the laser light acts as "evanescent waves," reflecting the atoms only when the atoms approach the fiber wall but otherwise not interacting with (and heating) them when then are not near the wall. By probing the atoms with additional laser beams as the atoms emerge from the 3-cm-long fiber, one can effectively separate the two stable Rb isotopes present in the atom flow. By using an additional sharpened fiber, the researchers hope to manipulate atoms transmitted through the fiber with nanometer accuracy. (H. Ito et al., Physical Review Letters, 10 June 1996.) THE GALILEO PROBE that penetrated Jupiter's atmosphere in December 1995 found only a fraction of the water expected. Further analysis of the probe data has turned up additional surprises. Wind speed at the surface was clocked at 150 m/sec; at the lower depths the speed did not fall off but actually increased to 200 m/sec. Lightning at Jupiter was observed to be less frequent than on Earth. Torrance Johnson of JPL, speaking at this week's meeting of the American Geophysical Union in Baltimore, said that now that all of the probe data had been downloaded, new software was being installed on the Galileo spacecraft to better prepare it for upcoming tasks, such as the June flyby of the moon Ganymede. Galileo will pass as close as 900 km and will take the best-ever pictures of the scarred moon.