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This story was originally published by Inside Science News Service.
(ISNS) -- Scientists are pushing to create a space-based quantum communications network that could enable impossible-to-monitor transmissions.
In doing so, they might make it possible for someone named Scotty to really teleport some information into space.
It would be enough "to spook" Albert Einstein, said Thomas Jennewein of the University of Waterloo in Ontario, one of the top researchers in the field.
The encryption research could have immediate practical implications. The process would make use of entangled photons, what Einstein--who resisted the consequences of quantum theory until his death --called "spooky action at a distance."
"If we can use correlations between entangled photons to establish a quantum key, it could be used for secure communications," said Jennewein.
Einstein and two colleagues theorized in 1935 that if you had two quantum systems that interacted, such as two atoms in a molecule, and then separated them, they would remain entangled, meaning their properties would be inextricably linked. Measuring one atom would instantly produce a change in the other no matter how far apart they were.
Einstein believed that there was a universal speed limit: nothing could travel faster than light so he thought such communication—"spooky action"—would be impossible.
But in 1972, a group of U.S. scientists showed that is exactly what happens, at least over the short distances of their laboratory experiment.
Decades before, another physics giant, Werner Heisenberg, proposed in his famous uncertainty principle that merely observing a particle or otherwise disturbing it changes its properties, and--according to quantum theory--so instantly would that of its entangled twin.
Common encryption involves using keys, series of numbers, and letters that code and decode messages. The sender has one key that encrypts the message; the person receiving the message has another which decodes it.
Scientists can envision sending beams of quantum signals from one place to another to produce encryption keys, but there is a problem.
Quantum communications signals have not been able to travel very far on Earth. The current record is 89 miles set in the Canary Islands by Jennewein and a team, then of the University of Vienna. The problem is transmission loss or scattering in the atmosphere.
Even using fiber-optic cables is not the answer, according to Joshua Bienfang, at the National Institute of Standards and Technology, another expert in the field. The chances of a single photon traveling safely more than around 250 miles in a fiber-optic cable is slim, he said.
That's why Jennewein and other researchers are looking to space, where the beams would not scatter in the vacuum. His lab, among others, now has produced a design for such satellites that would test that out.
Jennewein describes a system in which a device in a satellite creates entangled photon pairs and simultaneously transmits one of each pair to two ground stations in beams of millions of photons, all in entangled quantum states. That means both stations should have the same key.
The two stations would compare them. If the transmissions were not intercepted or modified by an eavesdropper, the two keys should be identical. The sender can then send a conventionally encrypted message secure in the knowledge no one is listening.
But, if there is any alteration in the keys, which would happen if anyone intercepted the key message, Heisenberg's theory would strike, and the photons would be altered. The two parties would know if there was an eavesdropper and either resend the keys or try another system.
Several corporations and government research facilities around the world are working on similar satellite systems.
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21 Comments
Add Commentheadline sub Text should probably read "entangled photons," not "entangled photos." Dew knot trussed spill chick too fined awl you're airs.
Reply | Report Abuse | Link to thisThis is uncomfortably close to my theory of time travel via information. http://youtu.be/vRyaevquIX8
Reply | Report Abuse | Link to thisWho doesn't love quantum entanglement? Cool stuff. Very exciting.
Reply | Report Abuse | Link to thisWho doesn't love quantum entanglement? Cool stuff. Very exciting.
Reply | Report Abuse | Link to thisBut "entangled photos" are much more to the point, since most encrypted digital transmissions will likely be pay-per-view videos...
Reply | Report Abuse | Link to thisMakes you wonder if the reason we're not hearing anything from other civilizations, we're not listening with the right technology.
Reply | Report Abuse | Link to thisHmm, I get it this way.
Reply | Report Abuse | Link to thisImagine a new weather satellite in geostationary orbit.
Encrypted images ("photos" made of entangled photons ;)
are transmitted in two radio beams that can actually be rather wide and potentially detected over almost halve the earth.
But if someone else than the intended recipient would tap this information the entanglement would get screwed up.
I thought quantum entanglement couldn't be used to transmit information faster than the speed of light. Eg. Einstein and Rosens' EPR paradox.
Reply | Report Abuse | Link to thisAren't "entangled photos" what tends to get politicians and troubled Hollywood actors in trouble?
Reply | Report Abuse | Link to thisI believe you can transmit information instantaneously (definitely faster than light) thru quantum teleportation. But it doesn't make much sense if you're just communicating over short distances on earth. Light speed is more than enough.
Reply | Report Abuse | Link to thisFor light-year distances, the problem is how to decode the quantum signals to transform them into meaningful information. You need a common code (like a Morse code) that transmitter and receiver both understand. They have to communicate to share this common code. But that's exactly the problem. They can't communicate because they're light-years apart!!
Quantum teleportation experiments have already invalidated the EPR paradox. Instantaneous transmission of signals is possible.
Reply | Report Abuse | Link to thisThe entangled photons are too scattered to be useful on earth - so the photons are generated by a device in satellites in space to avoid scattering - and then the photons are beamed back to earth - how do the photons NOT get scattered when they are beamed back to earth ?
Reply | Report Abuse | Link to thisTo Dr Strangelove & others:
Reply | Report Abuse | Link to thisOn Earth I (& nearby) if entanglement is better than encrypted photons to have UNBREAKABLE encryption, entanglement is faster, perhaps instantaneous, communication: perhaps even "entangled" (double or triple) real people seen as interactive "actors" over infinite distances over Universe(s).
Are you suggesting entangled porn?
Reply | Report Abuse | Link to thisjohnb123-I have for some time been saying in comments that we should be looking at starlight for signals.We would of course be looking for coherent wave function drops using a two slit experiment.I have described just such a device in detail in many comments.The source star wouldn't be the star where another civilization lives,but instead a star that is the same distance away from them as it is to us.Because the star would be the same source there is likelihood that entangled photons would be arriving in both our solar systems.Most likely the receiver/transmitter would have to be in orbit otherwise there would be to much background noise to receive a clear signal.What I am talking about is a real time conversation.Once a signal is found,we would need to decipher it.Chances are that it would have a leader code in something like binary code.this first part of the message would probably be a string of prime numbers,then we would see the language of math to to follow.Once we get that far then each number would be give a name and so forth with the information between is becoming more and more complicated till we could establish a dialog.It at some point that we could see video stream from one another.They would have to be at the same level of development as us,or be ahead of us to have the resources to accomplish the science needed.Who knows what we can learn.If they centuries ahead they might be generous and help us solve many problems.If they are way ahead of us they might be cautious about an exchange of information.What ever happens it will be a very exciting time for both our species.We must be careful as well that we don't get bad information.The deciphering and data much be keep separated from any outside link where our computer systems would be compromised.As I am sure they will be taking the same steps.Who knows there may a whole network of star systems communicating across the galaxy.Imagine all the science,literature,and music of many species that we may encounter.
Reply | Report Abuse | Link to this"Imagine all the science,literature,and music of many species that we may encounter."
Reply | Report Abuse | Link to thisIt would be naive to assume that all races would want us to know about them, and to know about us. In fact, it's easy to imagine a race of psycho-zenophobes (religious zealots?) who want to rid the galaxy of all new-born races like earth for fear of being infected with dangerous ideas. The easiest way to eliminate us is to share dangerous technology, like giving a baby a gun. BANG! Earth is gone.
Even if a race were altruistically motivated to send us new technology, we must determine protocols to safely use it. We can't just ignore it, but who will decide how to use it safely? That's the horns of the dilemma. Looks like we better solve it quick.
I can envision a system where digital transmission of information could be sent across light years in an instant. First the sender and receiver would need to share trillions upon trillions of entangled photons. The sender and receiver pre-designate 1/3 of their photons for sending, 1/3 for receiving, the last 1/3 for data encoding. To initiate a message, the sender would associate a 'data' photon with one of his 'send' photons. Remember the 'send' photon is already entangled with the receivers 'receive' photon. Because of entanglement, the 'receive' photon would assume the quantum state of the send photon (this is from the article). The receiver photon will have a up or down spin; up would indicate '1' and down would indicate '0'. The 1's and 0's could then be used to send standard data streams.
Reply | Report Abuse | Link to thisOf course the structure or 'language' of the data streams would need to be predetermined. And the initial distribution of the entangled photons would need to be done when the sender and receiver are relatively close.
Communicating to Mars by conventional radio takes Approximately 3 minutes, 13 seconds, so quantum communication wouldn't be absolutely necessary. Quantum communication would only be needed when the distances are extreme, meaning the sender and receiver would probably never meet again, but could still communicate.
What is interesting, is you would expect if a space traveler left earth and somehow attained 75% light speed, Einstein says he would age relatively slower, and would out last several generations of earthlings back home. But if the traveler and the earth used quantum communications they would be communicating in real time. So how then could they be aging at different rates?
It seems to conflict at this point, meaning perhaps quantum communication is not possible at all.
So I have a question: If two entangled particles or sub particles are separated and one is sent to Mars, the other stays on Earth. Could use of changes or vibration in one make an immediate same change on the other over that distance?? If so surely a way of instant communication would be apparent?
Reply | Report Abuse | Link to thisI just want the original original.
Reply | Report Abuse | Link to thiswhat can these copies be thinking? who cares? What can the originals be thinking?
"halve the earth." Ooooooo, I hope not.
Reply | Report Abuse | Link to thisI got quantum entangled once. Woke up in the middle of a 4 year hitch in the Air Force. Time Warped. Won't do that again.
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