A few years ago, two different groups succeeded in slowing and then storing a pulse of light in atomic vapor. In that work, the properties of incoming photons were vested in the spin orientations of the atoms in the vapor; the light pulses no longer existed but could later be reconstituted into propagating light beams. A new experiment has brought light to a halt and left it intact as an optical entity. Harvard’s Mikhail Lukin and his colleagues began, as in the earlier work, by converting the incoming light pulse into a corresponding ensemble of spins in a gaseous medium. But then they brought a pair of counter-propagating control beams to bear on the medium. Those beams not only eased the optical pulse back into existence but also created a standing-wave pattern that generated spatially varying atomic absorption. The atoms then acted like a stack of mirrors that trapped the...

You do not currently have access to this content.