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Author Topic:   Teleportation
GDR
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Posts: 6202
From: Sidney, BC, Canada
Joined: 05-22-2005
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Message 1 of 9 (662194)
05-13-2012 10:39 AM


I found this interesting. It only talks about security and military uses here but I imagine this technology will lead to the type of changes in our lives that computers have brought. Most of you would have a far greater idea of that than I would.
http://www.technologyreview.com/blog/arxiv/27843/
Chinese Physicists Smash Distance Record For Teleportation
The ability to teleport photons through 100 kilometres of free space opens the way for satellite-based quantum communications, say researchers
KFC 05/11/2012
Teleportation is the extraordinary ability to transfer objects from one location to another without travelling through the intervening space.
The idea is not that the physical object is teleported but the information that describes it. This can then be applied to a similar object in a new location which effectively takes on the new identity.
And it is by no means science fiction. Physicists have been teleporting photons since 1997 and the technique is now standard in optics laboratories all over the world.
The phenomenon that makes this possible is known as quantum entanglement, the deep and mysterious link that occurs when two quantum objects share the same existence and yet are separated in space.
Teleportation turns out to be extremely useful. Because teleported information does not travel through the intervening space, it cannot be secretly accessed by an eavesdropper.
For that reason, teleportation is the enabling technology behind quantum cryptography, a way of sending information with close-to-perfect secrecy.
Unfortunately, entangled photons are fragile objects. They cannot travel further than a kilometre or so down optical fibres because the photons end up interacting with the glass breaking the entanglement. That severely limits quantum cryptography's usefulness.
However, physicists have had more success teleporting photons through the atmosphere. In 2010, a Chinese team announced that it had teleported single photons over a distance of 16 kilometres. Handy but not exactly Earth-shattering.
Now the same team says it has smashed this record. Juan Yin at the University of Science and Technology of China in Shanghai, and a bunch of mates say they have teleported entangled photons over a distance of 97 kilometres across a lake in China.
That's an impressive feat for several reasons. The trick these guys have perfected is to find a way to use a 1.3 Watt laser and some fancy optics to beam the light and receive it.
Inevitably photons get lost and entanglement is destroyed in such a process. Imperfections in the optics and air turbulence account for some of these losses but the biggest problem is beam widening (they did the experiment at an altitude of about 4000 metres). Since the beam spreads out as it travels, many of the photons simply miss the target altogether.
So the most important advance these guys have made is to develop a steering mechanism using a guide laser that keeps the beam precisely on target. As a result, they were able to teleport more than 1100 photons in 4 hours over a distance of 97 kilometres.
That's interesting because it's the same channel attenuation that you'd have to cope with when beaming photons to a satellite with, say, 20 centimetre optics orbiting at about 500 kilometres. "The successful quantum teleportation over such channel losses in combination with our high-frequency and high-accuracy [aiming] technique show the feasibility of satellite-based ultra-long-distance quantum teleportation," say Juan and co.
So these guys clearly have their eye on the possibility of satellite-based quantum cryptography which would provide ultra secure communications around the world. That's in stark contrast to the few kilometres that are possible with commercial quantum cryptography gear.
Of course, data rates are likely to be slow and the rapidly emerging technology of quantum repeaters will extend the reach of ground-based quantum cryptography so that it could reach around the world, in principle at least.
But a perfect, satellite-based security system might be a useful piece of kit to have on the roof of an embassy or distributed among the armed forces.
Something for western security experts to think about.
Ref: arxiv.org/abs/1205.2024: Teleporting Independent Qubits Through A 97 Km Free-Space Channel
Edited by Adminnemooseus, : Add bunch of blank lines between (apparent) paragraphs.

He has told you, O man, what is good ; And what does the LORD require of you But to do justice, to love kindness, And to walk humbly with your God.
Micah 6:8

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fearandloathing
Member (Idle past 4144 days)
Posts: 990
From: Burlington, NC, USA
Joined: 02-24-2011


Message 2 of 9 (662196)
05-13-2012 11:04 AM
Reply to: Message 1 by GDR
05-13-2012 10:39 AM


Cool, thanks for info.
If I understand it correctly, and we could increase the distances, then it could make real-time communication possible with space probes or a mars base ect. That would be very useful in many ways such as an emergency. That is the first thing that pops into my mind.
Edited by fearandloathing, : No reason given.

"No sympathy for the devil; keep that in mind. Buy the ticket, take the ride...and if it occasionally gets a little heavier than what you had in mind, well...maybe chalk it off to forced conscious expansion: Tune in, freak out, get beaten."
Hunter S. Thompson
Ad astra per aspera
Nihil curo de ista tua stulta superstitione.

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frako
Member (Idle past 305 days)
Posts: 2932
From: slovenija
Joined: 09-04-2010


Message 3 of 9 (662201)
05-13-2012 12:00 PM
Reply to: Message 2 by fearandloathing
05-13-2012 11:04 AM


Cool, thanks for info.
If I understand it correctly, and we could increase the distances, then it could make real-time communication possible with space probes or a mars base ect. That would be very useful in many ways such as an emergency. That is the first thing that pops into my mind.
Better then that it could mean direct control of probes and rovers on mars or other places like Jupiter moons.

Christianity, One woman's lie about an affair that got seriously out of hand
Click if you dare!

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xongsmith
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From: massachusetts US
Joined: 01-01-2009
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Message 4 of 9 (662202)
05-13-2012 12:19 PM
Reply to: Message 1 by GDR
05-13-2012 10:39 AM


I am skeptical that this will ever be useful. You have to physically separate the two or more quantum entangled entities before you can use them across the distance you want. I would think that placing half-pairs of earth-based quantum-entangled stuff up on a satellite will be subject to a large noise factor that would collapse the entanglement before you could transmit the info reliably. And then you would not be able to use the stuff again, so you have to be constantly refueling the satellite with more entangled stuff. Seems hard to implement.
But I really don't know the physics well enough and concede that this may possibly be useful.
Perhaps someone more qualified can explain?

- xongsmith, 5.7d

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jar
Member (Idle past 393 days)
Posts: 34026
From: Texas!!
Joined: 04-20-2004


Message 5 of 9 (662203)
05-13-2012 12:25 PM
Reply to: Message 4 by xongsmith
05-13-2012 12:19 PM


But when you look at the potential markets, for example true real time UNIVERSAL MPORGs, it is just a matter of putting the X in X-Box.

Anyone so limited that they can only spell a word one way is severely handicapped!

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crashfrog
Member (Idle past 1466 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


Message 6 of 9 (662204)
05-13-2012 12:27 PM
Reply to: Message 1 by GDR
05-13-2012 10:39 AM


I think this article deeply confuses the concept of quantum-entanglement cryptography with teleportation.
If they're transmitting photons, which it's clearly stated that they are, then it's not teleportation, now is it? They're transmitting entangled photons, not teleporting them, and the reason you'd want to do that is because it defeats a "man in the middle" attack against the communications channel - the act of receiving the photons disrupts the entanglement, and it's impossible to re-entangle them again, so you'd know if you were receiving the transmission direct from your partner, or if a third-party had intercepted and re-transmitted.
This doesn't allow for any sort of FTL communication because there's no teleportation of anything. This is just a kind of special transmission of photons with cryptographic implications. They're not overcoming the speed of light.

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crashfrog
Member (Idle past 1466 days)
Posts: 19762
From: Silver Spring, MD
Joined: 03-20-2003


(1)
Message 7 of 9 (662205)
05-13-2012 12:28 PM
Reply to: Message 2 by fearandloathing
05-13-2012 11:04 AM


If I understand it correctly, and we could increase the distances, then it could make real-time communication possible with space probes or a mars base ect.
Well, you don't understand it correctly, but it's not your fault because the writer of the article didn't understand it either.
FTL communication is not possible by this method.

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fearandloathing
Member (Idle past 4144 days)
Posts: 990
From: Burlington, NC, USA
Joined: 02-24-2011


Message 8 of 9 (662206)
05-13-2012 12:37 PM
Reply to: Message 6 by crashfrog
05-13-2012 12:27 PM


I could be wrong, but this leads me to believe otherwise about real-time communication over distance using lasers, space is a better place then the atmosphere. Up and down-link to satellites could still use RF and laser for orbit to orbit coms.
quote:
Quantum teleportation experiments have used beams of light to encode qubits. The encoded beam of light, described as quantum entangled, is split in two, then, when a qubit at one receiver is observed and takes a defined form, the 'other half' of the same qubit at the other receiver takes the same defined form at the same moment, regardless of the distance separating the receivers. It is not possible to predict which state a qubit will take before it is observed, so no useful information can be encoded into an entangled stream which cannot be encoded into a regular light or laser beam.
Quantum teleportation - Wikipedia
AbE, after having a little more time to read and look into this it seems I am a moron once again. Skimming over a article or paper is always asking for trouble, especially when the subject is far beyond my understanding as a lay person.
Hope every one had a good mothers day.
Edited by fearandloathing, : No reason given.
Edited by fearandloathing, : No reason given.
Edited by fearandloathing, : No reason given.

"No sympathy for the devil; keep that in mind. Buy the ticket, take the ride...and if it occasionally gets a little heavier than what you had in mind, well...maybe chalk it off to forced conscious expansion: Tune in, freak out, get beaten."
Hunter S. Thompson
Ad astra per aspera
Nihil curo de ista tua stulta superstitione.

This message is a reply to:
 Message 6 by crashfrog, posted 05-13-2012 12:27 PM crashfrog has not replied

  
Big_Al35
Member (Idle past 799 days)
Posts: 389
Joined: 06-02-2010


Message 9 of 9 (732630)
07-09-2014 7:51 AM


Doesn't this work better with entangled electrons?
Of course the amount of energy required to create a superconductor which provides the source of entanglement, added to the cost of transporting your paired particle over vast distances, and finally computers at both ends to manage and decode the data means that this may never get of the ground.
Ohhh...did I mention the hassle and expense of ensuring that the particles remain entangled for the life cycle. Thought not!
Edited by Big_Al35, : No reason given.

  
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