Quantum teleportation.....

[Dr Mordrid]

This topic is getting weirder by the day....

http://www.space.com/businesstechnology/technology/australia_teleport_020618.html

Today data encoded laser beams...tomorrow????

Dr. Mordrid

[The PIT]

The end of the traffic jam is in sight, well maybe not them.

[Gurm]

The most amazing part is... entanglement works ANYWHERE. I'm more interested in some of the OTHER applications of entanglement, like instantaneous communication between here and ANYWHERE ELSE IN THE UNIVERSE by means of entangled particles.

- Gurm

[cjolley]

Originally posted by Gurm
The most amazing part is... entanglement works ANYWHERE. I'm more interested in some of the OTHER applications of entanglement, like instantaneous communication between here and ANYWHERE ELSE IN THE UNIVERSE by means of entangled particles.

- Gurm

I guess this means SETI might be sending out newly developed WUs if this gets sorted out
chuck

[Gurm]

Well yes, it has astonishing applications. All that "crashing into mars" stuff NASA has been doing lately could be avoided, since they could, in real-time, make course adjustments mid-flight. It would revolutionize the communications industry, since once the transmitter/receiver combination is built, you're done. That's it. Finito.

- Gurm

[Dr Mordrid]

Well....looks like Roddenberry strikes again 'eh? Can you say "subspace communication" without seeing the similarities?

Dr. Mordrid

[Snake-Eyes]

Very cool stuff..

Gene was underestimating the potential technology when he came up with subspace communications, if/when it finally is used for communications that way. I say this because in ST, even subspace comms takes time between transfer and receipt of the information being communicated, even with faster-than-light technology. Instantaneous communications is awesome.

Added benefit:
Can't be observed by outside parties.

Hmm.. That benefit gave me a thought. In all this time searching for evidence of intelligent life out there, not only is the fact that any signals we detect would be from so long ago that the civilization responsible is either extinct, or we would be before they got a reply, but there's the issue of- what if they used technology based on entanglement? We'll never know of their existence based on them communicating with each other if this were to be true.

[Dr Mordrid]

Yup. The whole SETI scheme depends on advanced civilizations still using pulsed or modulated electromagnetic waves, a technology which has only been in existance for about 150 years on earth (yes, it existed before Marconi).

If you adhere to the concept that civilizations will follow similar tracks of technological development then alien communication technologies that are 100+ years in advance of us are likely to be undetectable by us.

As such it's very likely that SETI will only detect civilizations either slightly above or below our level of development. More advanced alien cultures will very likely already be using entanglement or some other even more advanced quantum based technology.

Dr. Mordrid

[moreau]

I do a little physics in my free time.

I don't see in this particular article that this is an instantaneous effect.

Keeping in mind that there is much detail omitted from the article...

The effect they are measuring happens over 1 yard in one nanosecond. Guess what, using those round numbers you get a speed for the information transfer that is roughly the speed of light (actually a little greater, but these numbers are rough).

If lasers are carrying the information, then already the speed of light is inherent.

At another place, they say that they are sending the information via radiowaves, again the speed of light.

just a thought...

Dr. Moreau

[The PIT]

Has anyone considered that ET doesn't want to talk too us. We may be like noisy neighbours to him. It's true that we may be looking for communication in the wrong way though.

[Gurm]

moreau,

This particular article and application, no.

However, previous work on entangled particles has led to photons that are separated by miles and miles and yet react instantly as one. It's the concept of entanglement.

- Gurm

[mallowman]

I, too, have always felt that communication via entagled particles is the real boon of quantum physics. The data rate would be limited only by how quickly you could measure and change some property on an entagled particle and the latency would be a big fat zero, just as Gurm said. The only problem with it is that it would be exclusively point-to-point. So unless there is a way to generate tangled pairs across distances as they are needed it would be ill suited for broadcast and things like the internet. Of course my understanding of the subject is rather limited so maybe this is not actually a problem. That and you'd have to be careful not to drop the entangled particles when servicing the communications system

[ZokesPro]

Originally posted by The PIT
Has anyone considered that ET doesn't want to talk too us. We may be like noisy neighbours to him. It's true that we may be looking for communication in the wrong way though.

They might be biding their time until we come up with a les noisy way of communicating?

[Snake-Eyes]

I'm not sure about the point-to-point nature of entanglement. No, I understand a pair, but what I mean is that is it possible to have one of an entangled pair's changed state cause reactions in other entangled pairs? If so, then is should be possible to create networks of entangled pairs, transmitting the information based on the change to any one of the nodes in the network. Of course, I'd assume that using something along those lines would generate a latency (the delay between the change to the second of the initial pair causing the pairs reacting to IT to change, and increasing based on the distance [in pairs] of another node from the original node..). Still, I'd also expect that latency to be very low.

If it seems like I'm rambling, I sort of am. It's a bit hard for me to explain the concept of what I'm thinking, but I hope it makes sense to someone.

[moreau]

Originally posted by Gurm
moreau,

This particular article and application, no.

However, previous work on entangled particles has led to photons that are separated by miles and miles and yet react instantly as one. It's the concept of entanglement.

- Gurm

Sorry, I've been moving...

This phenomenon was originally worked out in a thought experiment by Einstein, Boris Podolsky and Nathan Rosen in 1935. What they came up with is known as the EPR paradox (an acronym for thier last name).

Consider a reaction in which a particle of zero momentum and spin (a particle whose spin when projected on the z-axis has a magnitude of 1, in units of h-bar) disintigrates into two particles each with spin-one-half. In order for momentum to be conserved, the particles must come out with equal and opposite velocities, and must have their spins anti-aligned.

Now, until we actually ask one of the particles whether it is spin up or spin down (and thereby know what the second particle is), each particle is simultaneously in the spin up and spin down states. It isn't until we measure one that we collapse the wave-function of both particles into one or the other spin states.

Now, the implication of this is that if we measure one particle, causing it to collapse into a definite spin state, then the second particle necessarily choses the opposite spin state instantaneously. That is what bothered Einstein. He did not want any information transfer to occur at greater than c (the speed of light). This led him to suggest the concept of "hidden variables", where he said that if we knew all of the parameters that influenced the outcome of our spin measurements, we could have predicted a priori the outcome, and thus no need to resort to simutaneous states and faster than light information transfer.

In 1964, John Bell suggested a testable, statistical theory that would show, in the case of three state systems, a quantitiative difference between the hidden variable and quantum explanations.

In the late seventies and eighties, experimental tests have verified that the quantum mechanical picture is the correct one, to a degree, though this is still an area of research.


Now, with regards to our current problem. If you are encoding information into particles (including photons) and then using their "entangle variables" to transmit information by collapsing the wavefunction of one particle, I would suggest that there is still a finite time required. The information transfer is indeed instantaneous. However, the agent used to encode the information in the first place must travel at a finite speed to reach the receiver.

Charles