© Reprinted by permission from Macmillan Publishers Ltd: Nature 445, 623-626 (8 February 2007).
The light pulse is first slowed, compressed, and extinguished in a Bose-Einstein condensate. The holographic imprint that the slowing light pulse created in the condensate starts to travel out of the atom cloud and into free space. After 1.3 milliseconds we have a perfect matter copy of the extinguished light pulse isolated in free space...and we photograph it. The atoms in the traveling matter copy are actually both traveling out in free space and stuck back in the condensate at the same time—remember, this is quantum mechanics. (Unit: 7)