Comment Unfortunately, you need real molecules to do this (Score 4, Informative) 175
As the photons enter the cloud of cold atoms, Lukin said, its energy excites atoms along its path, causing the photon to slow dramatically. As the photon moves through the cloud, that energy is handed off from atom to atom, and eventually exits the cloud with the photon.
These are not photons in free space being described. These are photons which have excited electron orbitals in some material.