SQUEEZED PHONONS HAVE BEEN PRODUCED for the first time, allowing researchers to temporarily reduce the uncertainties in the positions of atoms in a crystal. Classically, atoms in a crystal are like little balls which vibrate around their equilibrium positions in a lattice. The quantum-mechanical description of this motion is given in terms of particles called "phonons" which carry specific bundles of vibrational energy. According to quantum mechanics, an atom does not have a definite position, but a spread of possible positions. To temporarily reduce these fundamental uncertainties, a University of Michigan team (Roberto Merlin, 313-763-9759) has successfully altered the state of the phonons in a crystal to produce "squeezed" phonons, which act to momentarily reduce the uncertainty in the atoms' positions at the expense of greater uncertainties in the atoms' momenta. In the experiment, described at the March APS Meeting, researchers shine two 70-femtosecond laser pulses on a potassium tantalate crystal. The first pulse momentarily perturbs the frequencies of the individual phonons in the crystal. In classical terms, the net result is to return far-flung atoms closer to their central positions on the lattice while not affecting as much the others which are already close to their central positions. The second pulse measures the change of refractive index in the crystal caused by squeezing and this tells how much the atoms as a whole stray from their central positions. Theoretically predicted since the early 1990s (Update 261) by various groups, squeezed phonons are similar to the previously demonstrated phenomenon of squeezed light (Update 82). (Science, 14 March 1997.)