rationalskepticism.org

Not THAT crazy, Macdoc, because the narrator is playing slightly fast and loose with words when he describes the photons as "bonded, like molecules". I suspect that the reality is that this is not a property of the photons, but more of their interaction with the rubidium atoms of the medium. Strange thing can certainly happen in such media, such as the group velocity of the light slowing almost to a halt (eg, bicycle speed).

EDIT: References from here:
https://physics.aps.org/story/v3/st37