BEC Dominates, Plastic Laser Shines, and Universe Expands

摘要

Papers on Bose-Einstein Condensation (BEC) keep thundering through the Physics Top Ten. This period has two BEC newcomers, #3 and #5, as well as two triers at #11 and #12, which will probably break through in the next period. Meanwhile, the MIT paper on collective excitation moves up two places to #4, notching up 89 citations to date. First created in the laboratory in 1995 by Eric A. Cornell (coauthor of #5) and collabo- ' rators in Boulder, Colorado, BEC has been the subject of intense investigation ever since. Laser cooling and trapping followed by evaporative cooling is used to bring clouds of atoms down to the microkelvin temperature needed to produce the macroscopic quantum effect in which the cloud behaves as a single atom. In January of 1997 Wolfgang Ketterle's group at MIT produced a primitive "matter laser" using a BEC of sodium atoms.