Entangle me up, Scotty.

[CubOfJudahsLion]

http://abcnews.go.com/Technology/wireStory?id=2529533.

They actually did it, and I don't mean a couple of atoms. I don't think I'll be ditching my car to make near-instantaneous "qubit trips" to work anytime soon, but still an interesting development.

[Oblivion]

FTL Communication arrives before FTL Travel... interesting...

[dandandaman]

FTL Communication arrives before FTL Travel... interesting...

Not if "teleportation" continues to need something (in this case laser light) to transport the "teleported" information

Dan

[Oblivion]

hehe. Sorry. Just scanned the article.

[klauss]

The idea of teleportation is that of transmitting quantum states, which cannot be copied (thus only teleported), but the process isn't FTL, as dan said, since it requires the standard transportation of two binary bits.

That is, one QBit gets transported as two binary bits, in a rather complex way.
This is really not to say that a QBit holds 2 bits of information. In fact, it can be proven that QBits hold infinite amounts of information - but that information cannot be retrieved in full. A shame. But you can extract a random portion of it - cool, that's what makes quantum computing so powerful.

I too thought teleportation was FTL before I got to study the subject a tiny bit at school, so... it happens...

[micheal_andreas_stahl]

Ummmm? You lost me.

[klauss]

Simplifying stuff: QBits are entities which can only be "measured" once, yielding a random bit (one or zero) with a probability that depends on the "quantum operators" applied since the last measurement.

As probabilities are real numbers, you can thus store one real number in a QBit by manipulating it until you encode the desired probability. Since real numbers require infinite bits to be accurately represented, you can thus store in this way infinite amount of bits. But... retrieving that probability requires several measures, but the information inside a QBit gets destroyed after a measurement. Thus, you cannot retrieve this potential information.

But, with some cleverness, you can do lots of stuff with it. Quantum computing exploits this quaint property, and achieves nondeterministic turing machines (which are so powerful compared to normal ones - computers - that the analogy between a toy steam engine and a space rocket falls short), though only a few successful algorithms are known, and building such computers is incredibly difficult.

Anyway, though QBits store infinite information, it cannot be retrieved. Thus... how do you copy one QBit?
This is, you can't - it can be proven. I've never seen such proof, but it's been done, I've been said, and I believe it.

But... you can "teleport it" - that is, copy it somewhere else while at the same time destroying the original copy. You transfer the quantum state (the information within the QBit) to another physical support such that the old support no longer holds the information.

That is teleportation. A quite abstract thing, but an incredibly important one to master in the field of quantum computing.

[micheal_andreas_stahl]

Sooo, it is impossible. I know that all those on that ship that those scientists made invisible went mad.

[Zeog]

Thus... how do you copy one QBit?
This is, you can't - it can be proven. I've never seen such proof, but it's been done, I've been said, and I believe it.

The proof is actually quite simple. In order to make a copy you need whatever you want to copy and a target where you want the copy to be. The target's initial state is arbitrary and doesn't matter to you. But once you did the copy procedure the information about the initial state of the target is completely lost as the target is now a perfect copy. Therefore a copy procedure is a irreversible process. In quantum physics however every operation on a qubit has to be reversible (for fundamental reasons). The loss of information is no option in quantum physics. So the basic laws of quantum physics contradict the concept of copying (and deletion as well). q.e.d.

(Now, please don't get confused. In the simple picture a measurment process is irreversible as well which contradicts what I was saying. But that's the simple picture. In the full picture it is reversible, but practically irreversible. )

[micheal_andreas_stahl]

Weeeelllllllll, that was a little simpler, but it was still confusing. My brother has done coding and knows all that stuff and he is a VERY good teacher but he does not like teaching me stuff like that as i'm rather thick. though that is slowly changing.

[Oblivion]

...you're getting thin?!!! lol

I remember some odd bit of sci-fi series somewhere...

about it being impossible for two exact duplicates of something to exist at the same time. That the idea?

[micheal_andreas_stahl]

...you're getting thin?!!! lol

Welll i at lest get things through eaiser.

[klauss]

I think he meant whether you were getting through things easier

[micheal_andreas_stahl]

Ummm?

[Sir Cyrus]

I'm an idiot when it comes to anything scientific, but does this mean that if it was modified we could potentially have, say, 100000 MBit internet connections?
Forgive my stupidity.

[Zeog]

"100000 MBit internet connection", hmm, let's see...
That's 100 Gbit/s. The record that I know of is more than 101Gbit/s by the team of professor Steven Low between Los Angeles and Pittsburgh.
Yes, we can have those!

[klauss]

Anyway, that's not related to quantum stuff.
I remember quantum cryptographic links to be on the order of a few Mbps.
The problem is that you need a huge source of single photons, since only 1 or 2% (I'm pulling this from memory, don't expect great accuracy) survive the "entanglement" procedure - ie, 99% of them get discarded.
Remember: it's not easy controllably producing photons one by one, and yet at high rates.

Teleportation is different, but not that different. So, when it comes to quantum communications, I'd expect lower rates, rather than higher.

But for normal communication links, though, the relatively recent development of turbo codes imply a sensible increase in bandwidth efficiency. So... probably yes, faster and/or cheaper internet will probably be a thing of the future.

[Oblivion]

and then we'll all be Andolians. lol