They mislabeled the event when they said that the light was "converted" into matter. This is sad because I think many people will miss the greatness of what was really done because of it. A large (long) beam of light (everything about it) was stored in a very small amount of matter, then recreated exactly. It wasn't light like what was there before, diffracted from new light (like a hologram), it was the same light.
Once this becomes practical, we have practically infinite data storage, not to mention the underpinnings of computing with pure light, so perhaps practically infinite computational speed as well.
Saying "the same" about light (and other subatomic particles) is meaningless. If the have the same state, then are the same, in the sense that they are indistinguishable.
So it was "just like" what was there, but not "the same" photon in the sense the photon did not exist for a while, and was recreated. And at the same time it was also "the same" photon, in the sense that the before and after photons are not distinguishable.
It should be noted that the "no cloning" theorem adds a twist: It says you can not copy a photon. This means that the matter that stored the photon can not be induced to create another one (like a hologram does).
So in that sense it was the "same" photon - because you can only ever create the original, and no additionals.
True, true. Saying a lot of things about subatomic particles is meaningless. Their behavior doesn't map to english very well. The point is that that information could be stored in the beam basically at the photon level, trapped in matter, and then pulled out later. That's as cool as ultracold atoms.
So if you could figure out just how much storage, you could use Moore's law to figure out just when this will become practical? If "nearly infinite", then this will likely never happen (unless you go with the "accelerating returns").
Once this becomes practical, we have practically infinite data storage, not to mention the underpinnings of computing with pure light, so perhaps practically infinite computational speed as well.