 and Tenerife, researchers opened the door to a quantum mechanism for sending messages that cannot be intercepted)
UNBREAKABLE CODE: By transmiting polarized photons between the Canary Islands of La Palma (pictured above) and Tenerife, researchers opened the door to a quantum mechanism for sending messages that cannot be intercepted
Image: © FIRELY PRODUCTIONS/CORBIS
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DENVER — The reach of the spooky quantum link called entanglement keeps getting longer. A team has transmitted entangled photons some 144 kilometers (89 miles) between La Palma and Tenerife, two of Spain's Canary Islands off the coast of Morocco. Physicist Anton Zeilinger of the University of Vienna, the group's leader, presented the results to his colleagues this week at the American Physical Society conference.
The distance achieved is 10 times farther than entangled photons have ever flown through the air. When two photons or other particles are in this state, what happens to one determines the fate of the other, no matter how far apart they are. Zeilinger compares the phenomenon with throwing a pair of dice that land on matching numbers every time.
Using a laser, the researchers created entangled pairs of photons on La Palma and fired one member of each pair to a European Space Agency (ESA) telescope on Tenerife, which had to make rapid, small adjustments to receive the photons, Zeilinger says. In another presentation, physicist Richard Hughes of Los Alamos National Laboratory described recent experiments in which his group fired a series of nonentangled photons 185 kilometers down a conventional optical fiber.
In both cases, researchers demonstrated that they could transmit randomly oriented, or polarized, photons, which are suitable for sending messages that cannot be intercepted without garbling the information. Called quantum keys, such transmissions could allow users to scramble messages in a way that is potentially unbreakable.
Quantum keys are limited in range because they typically have to be transmitted as single photons—entangled or not—which can become lost in noise. But the photons cannot be reproduced without destroying the information they contain. Researchers are therefore keen to find out how far they can travel.
Hughes says his group employed highly sensitive detectors normally used in astronomy. "It's a basic science result establishing the limits of what you can do," he says. "It looks very feasible to go much farther than 185 [kilometers] using these detectors," he adds, perhaps 200 kilometers or more.
Zeilinger has set his sights much higher—literally. He is lobbying the ESA to fund an experiment that would shoot entangled photons to the International Space Station and back to Earth, which he says could expand the range of entanglement and quantum key distribution to 1,500 kilometers.
Zeilinger says such an effort would cost about $50 million and require refined new light sources and receivers as well as the support of ESA member countries. If the project gets the go-ahead, he says the experiment may take a decade to set up.
Back on Earth, Zeilinger is part of a consortium of European research groups, called SECOQC, which is working on a fiber-optic quantum key network that would crisscross Vienna. He says the group plans the first demonstration of the network next fall.
Researchers say they do not know when or if banks, governments or other institutions would want to adopt quantum keys. "One of the biggest hurdles would be finding someone who wants to use it and convincing them it's secure," Hughes says. Standard encryption, he notes, "certainly works for me when I'm buying stuff from Amazon."
Zeilinger adds that the new quantum key transmitters are still millions of times slower than conventional fiber-optic communications, making them impractical for the time being.
So why does he do the experiments? For the fun of testing entanglement's reach, he says. "I am dreaming of an experiment where you do it between Earth and [the] moon. [And] if this Mars mission ever takes off," he says, "they are [going to be] bored for nearly a year … so they might as well do an entanglement experiment with Earth."
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7 Comments
Add CommentWhy don't we try this? Its an idea I had some 40 years ago,when I first heard about the two slit experiment.Just because we don't understand something doesn't mean we can't make use of it.Let us look for wave funtion drop in distance stars we are looking at,witch others who are as advanced as us and are doing at the same thing. Why wait for a radio measage, when we can talk right now?
Reply | Report Abuse | Link to thisOk here,s what a two slit transmiter -receiver would look like.You take one laser beam,and put it through a beam spliter twice at one at end.Now you send one beam to the first two slit experiment in this one you place a fiber optic in lighted area of the interferance pattern,with optic going to photodetector,in the off position.Next you send the second beam to another.experiment,only this time, you place the optic in dark area of the pattern with detector on,now you send the third beam to another location,say one of mirrors up on moon.Now you repeat the first experiment from above at a different location.When you turn the first detector on ether end it causes the wave funtion to drop in the second detector on both ends,thus activating the detector connected to dark area.With the first detector off=0,and on=1,and the same in second,now you communicate. Next you try it on star light.Good luck.
Reply | Report Abuse | Link to thisOk here I am again,I am kinda surprised that no one has questioned my logic,or at least tried to tell me that talking using the two slit experiment by looking at same distance stars and looking for wave funtion drop, just as others out there are doing the same thing on different planets. with others on thier world saying this is imposible.Take note SETI untill my theory is proven wrong,there may hundreads maybe thousands of worlds tring to talk with us using this form of instant communcation.As for the meassage we might receive, more than likely it would be string of repeating prime numbers,but caution must be used,Who knows what kind of information may be sent to us. the computers used should closeded looped with no outside conection what so ever.As for what message we send back,I suppose that would up to the entire world,and should be done with care, who knows the many ways we could offend someone we know nothing about,since we have a long history of doing so right here on Earth.May we the people of Earth have good luck in this next step in history and where it may lead us.
Reply | Report Abuse | Link to thisWell, I found it jack.123. It would have been easier for you to have told me just to enter those id words into the seach box (which is what I did).
Reply | Report Abuse | Link to this.Here, I think you got lost in the beam. Entanglement doesn't happen ahead of time. It happens but in real time. Forget the beam. Do the experiment with just three photons. The one you send as a "portable note pad" for the receiver to manipulate while you watch yours back at home, still cannot travel to that person you want to talk to faster than the maximum velocity of wavwfront propogation You haven't developed a new communication science, you've just built a different kind of receiver.
.Now if you take the two plates of a capacitor and charge it so one electron is held in the charge area and separate the plates, what you do to one electron shows up at the other plate! Even if they're fifty miles apart, they react instantaneously. but , you've forgotten the time it took to separate them! If you took hundreds of years to get them apart, say here and rigel7 you wouldn't be able to use it for the hundred years it took to get there. Once there though, yes, 'c' would seem to be defeatable but only in a sense that can accommodate information, not matter..
Michael-It isn't happening ahead of time its happening at the same time or close to it, when they or we are looking at a star the same distance away from each of us it doesn't matter how long ago the light traveled from the source as long as the photons are ariving here or there at the same time,thus the photons from the same source and are entangled,from the start and when we or them do the experiment ,we see that they or we have done so, no matter how far away we are from each other,and the effect is in real time like talking on telephone.The thing is to filter out the noise ,thus the non-random pulses happening so fast that it couldn't be anything in natural doing it, so you would know what was information and what wasn't.This could be the test that would let us get on the galatic keyboard,having a civilization advanced enough to discover the two slit experiment ,and the technology good enough to to commuicate with it .The same thing would be true if you had a satellite the same distance from Mars and Earth and,and on board it split a laser beam with the beams going to both, when you did the experiment on one end it would be seen at the other in real time with out a delay. faster than light.
Reply | Report Abuse | Link to thisMichael-Sorry what I ment to say was galatic switchboard kinda like an interstellar party line,can you imagine what kind of gossip would be going on out there.Norman Rockwell would have loved it.Still making mistakes I see faster should have been Faster,I guess we should have someone better at writing and math than me,talking with these guys,wouldn't want to start a war, throwing rocks at each other could get messy.
Reply | Report Abuse | Link to thisMichael - I think you should look into General Relativity's explanation of E&M. "Instantaneous" is very much a relative term.
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