Laser-Chilled Atoms Sit for Ultrafast Portrait

Physicists from the University of Michigan recently fired 70-fs pulses from a Ti:sapphire laser to control the random movements of atoms in a potassium-tantalite crystal. The laser was split in two beams, with one arriving at the crystal target a few picoseconds after the first. The first pulse created pairs of phonons -- "squeezed" particles of vibrational energy -- that scattered the second, weaker pulse as it passed through the crystal. By measuring the energy that continued through the crystal, physicists could visualize the crystal's atomic structure.