Number 272 (Story #2), May 23, 1996 by Phillip F. Schewe and Ben Stein 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.)