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").

"then later an entirely new beam of light (with identical properties) "

I think, if you understand quantum physics, it's meaningless to say that it's a "new beam of light with identical properties." If it "has the same properties", then it is the "same beam of light." It doesn't just look the same. It is the same in a physical (and meta-physical?) sense.

Then again, I don't really understand quantum physics, so I might be misunderstanding this. I'm telling you what I picked up from Eliezer Yudkowsky's series on quantum electrodynamics.

Perhaps a physicist can elaborate?

it's meaningless to say that it's a "new beam of light with identical properties."

You can think of it as information (bits). The same information that was encoded was decoded later.

It is not as if photons are items on the macro scale, that were somehow labeled (for example, photon #134), then disappeared and reappeared and the scientists compared the label and proclaimed that its the same photon (#134).

Every time light reflects of some surface this happens. The light excites the (electrons in the) material which then gives off 'new' light.

We still call it reflected light as though the photons somehow bounce off. They don't. They get adsorbed and are then re-emitted. But they might as well be the same ones because we can not tell the difference.

There are variations on this, specular reflection (think of a mirror) and diffuse reflection (think of a wall), the difference lies in the direction of the outgoing photons.

> It is not as if photons are items on the macro scale, that were somehow labeled (for example, photon #134), then disappeared and reappeared and the scientists compared the label and proclaimed that its the same photon (#134).

Quantum theory doesnt quite work like that.

What's amazing about this case is that all of the quantum states were maintained as well. The light maintained entanglement with other photons. This is not something that could happen by simply storing information and retrieving it later.

Currently, quantum encryption setups require a fiber optic cable to reach all the way from the sender to the recipient, because repeaters would destroy the entanglement. But with this device, you could store the data in a Bose-Einstein condensate, ship it to the destination, then read the data back out.