Physicists extend entanglement in Einstein experiment

Physicists extend entanglement in Einstein experiment December 6, 2012 by Lisa Zyga feature Physicists extend entanglement in Einstein experiment Enlarge To verify entanglement among the three photons, the physicists measured the times that the photons arrived at a detector. This 2D histogram shows that groups of three photons are all localized to a small region, indicating strong correlations in the arrival times of the three photons. Image credit: L. K. Shalm, et al. ©2012 Macmillan Publishers Limited (Phys.org)—Using a photon fission process, physicists have split a single photon into a pair of daughter photons and then split one of the daughter photons into a pair of granddaughters to create a total of three photons. All three photons, the scientists showed, share quantum correlations between their energies (corresponding to their momentums) and between their emission times (corresponding to their positions). The study marks the first experimental demonstration of energy-time entanglement of three or more individual particles, building on the original two-particle version proposed by Einstein, Podolsky, and Rosen (EPR) 77 years ago. Ads by Google Short Films on Energy - Watch the Energy Film Series That Will Change the Energy Conversation - RationalMiddle.com The physicists, from the University of Waterloo and the University of Calgary, have published their paper on three-photon energy-time entanglement in a recent issue of Nature Physics. As the physicists explain, this new form of entanglement is the three-photon version of the famous EPR correlations for continuous variables (e.g., position and momentum) between two particles. The EPR thought experiment, published in 1935, raised questions about the fundamental concepts underlying the young theory of quantum mechanics. "The Heisenberg uncertainty principle forbids one from simultaneously discovering both the position and momentum of a particle with arbitrary accuracy," lead author Krister Shalm of the University of Waterloo told Phys.org. "EPR pointed out that, if you create a pair of entangled particles, it is possible to measure both the position and momentum of both of them with arbitrary precision. It is still impossible to learn both the position and momentum of each of the individual particles, but, instead, we can learn information about the total position and momentum they share. Entangled particles, in some sense, are the ultimate team players. They lose their own individual identity with all the information in the system contained in the correlations." In the original experiment, EPR tried to demonstrate that the correlations between two particles were so strong that there must be some hidden parameter to explain them that quantum mechanics does not account for. This conclusion seemed to uncover some inadequacies in quantum mechanics. "The original arguments made by EPR in 1935 were designed to show that quantum mechanics, by itself, is not sufficient to describe reality," Shalm said. "This inspired John Bell, who showed that if you take the arguments of EPR that relied on hidden variables to their logical conclusions, you arrive at a contradiction with quantum mechanics. Since then, much work has been devoted to using Bell's work to test quantum mechanics, and extensions of the work have profoundly shaped our understanding of the quantum world." Ads by Google Fun Schrodinger's Cat Tee - Rock this tee like Sheldon Cooper, nerdy, awesome and 100% soft cotton - www.snorgtees.com Building on these studies over the next several decades, physicists have demonstrated many different types of entanglement, which are defined by the number and type of objects that are entangled and the properties of the objects that are entangled. These properties can fit into one of two categories: discrete or continuous, which describe the variable's domain. For example, spin is a discrete variable since its value can only be an integer or half-integer, while emission time is continuous. Entanglement has previously been demonstrated between the discrete variables of 14 ions and the continuous variables of three light beams, but until now entanglement among the continuous properties of three individual particles has remained an open challenge. "What is exciting about our work is that we can take the original arguments made by EPR for two particles and extend them to three particles," Shalm said. "The kind of entanglement that EPR first proposed pertained to continuous variables, like position and momentum, as opposed to discrete variables, like polarization or spin. Discrete variables in photons have traditionally been easier to manipulate. With our system we finally have a viable way to explore the entanglement of continuous variables between three particles." To achieve continuous-variable entanglement among three photons, the physicists split a photon into a pair of daughters using a process called cascaded spontaneous parametric downconversion. Since energy is conserved, each daughter photon has a frequency that is roughly half that of the pump photon. When one of the daughter photons is split, the two granddaughter photons each have a frequency that is about half that of the daughter photons. Although the frequency of each individual photon may vary slightly from exact halving, the total energy of the three photons combined is exactly equal to the energy of the pump photon. In addition, because the splitting process is instantaneous, the three photons must arrive at photon detectors at the same time. Under these production conditions, the three photons share strong spectral correlations and, in theory, possess genuine tripartite energy-time entanglement. This means that the energy values and the emission times of the three photons share correlations that are stronger than those allowed by classical physics. To verify that the three photons possess energy-time entanglement, the physicists had to confirm that the three photons violate a set of inequalities that are an extension of the EPR arguments for two particles. These tests require measuring and comparing the arrival times of the three photons at a single-photon detector. One way to do this is to directly measure each photon's frequency; however, current technology doesn't provide sufficient precision for direct frequency measurements. Instead, the scientists measured the frequency of the pump photon and ensured that energy was conserved in the downconversion process. They also used detectors to measure the arrival times of the photons, but noted that the detectors have a timing jitter of several hundred picoseconds that limited the precision. Even accounting for this uncertainty, the results showed that the three photons do indeed violate the EPR inequalities and are therefore energy-time entangled. Future improvements in detector precision would provide improvements in the measured values of the inequalities by over two orders of magnitude. In addition, new technologies to enhance the observed effects could potentially allow this scheme to be scaled up to larger photon numbers. In terms of applications, this entanglement scheme could be useful in quantum communications because it provides the opportunity to entangle multiple degrees of freedom, generating "hyper-entanglement." If one of the entangled photons could be interfaced with an atomic storage medium while the other two photons are transmitted over telecom fibers to remote quantum nodes, then scientists could create new possibilities for storing and distributing quantum information. Other modifications of the scheme could lead to new fundamental tests of quantum mechanics. "Three particle states that are entangled in their continuous degrees of freedom may allow for a new class of tests for quantum mechanics that could further our understanding of quantum theory and entanglement," Shalm said. "This is also an important technological step. It is a system that lets us exploit optical nonlinearities at the single-photon level. This may have important applications in creating the gates needed in a quantum computer, or in distributing quantum information over a network." In the future, the scientists plan to try to combine the position and momentum entanglement among the three photons with more traditional types of entanglement based on angular momentum and polarization. This kind of combined entanglement could lead to the creation of hybrid quantum systems that possess multiple unique properties of light at the same time. Journal reference: Nature Physics search and more info website Copyright 2012 Phys.org All rights reserved. This material may not be published, broadcast, rewritten or redistributed in whole or part without the express written permission of Phys.org. print this article email this article 46 text-to-speech save as pdf send feedback share to facebook share to twitter share to linkedin share to google share view popular send feedback to editors 4.7 /5 (20 votes) 1 2 3 4 5 Filter Move the slider to adjust rank threshold, so that you can hide some of the comments. Display comments: newest first page 1 / 2 Lurker2358 Dec 06, 2012 Rank: 1.3 / 5 (13) Events which have a common cause or origin are automatically entangled in at least some way. This is not even "entanglement". This is just addition, I think. A plus B equals C B plus A equals C. If C is constant then A and B are mutually determined, by the Commutative property. It works for multiplications too, so halving frequencies and finding that they are in fact halved is just confirming the Commutative property of addition and/or multiplication, and is not necessarily "entanglement" at all, even if it is entanglement, it is a logical entanglement, rather than a physical entanglement. report eloheim Dec 06, 2012 Rank: 3.9 / 5 (10) Please wiki "Entanglement" and "Bell's Inequality" and the article will make more sense. "Even accounting for this uncertainty, the results showed that the three photons do indeed violate the EPR inequalities and are therefore energy-time entangled." This means that doing something to one of the photons has an *instant* effect on the other two. It's almost like the photon's a "hole" in reality, with the far-off location of the other particle(s) immediately on the other side. Somehow those two spots are right next to each other, touching, even though there's nothing in between. I've also found one thing that always gets left out when trying to impress the significance of this process is exactly what "instant" means in context of the finite speed of light. report Lurker2358 Dec 06, 2012 Rank: 1.3 / 5 (12) elcheim: The experiment they've described does not exhibit that "spooky action at a distance" behavior. The only thing it does, as described, is divide a known quantity into two or more quantities which sum back to the original value, and then measures those values. report Noumenon Dec 06, 2012 Rank: 3.7 / 5 (9) @Lurker, If a particle's position is measured accurately, because of the momentum-position uncertainty relation, ...that position state represents a linear sum of many momentum basis states. The momentum is unknown to the degree the position is determined. Likewise there is an uncertainty relation between energy and time of the photon. Since energy is conserved there must be a correlation between the times and frequencies (energies). It is not like splitting up a coin, one heads so the other must be tails. report antialias_physorg Dec 06, 2012 Rank: 5 / 5 (11) This means that doing something to one of the photons has an *instant* effect on the other two. Not quite. If that were the case you could transmit information that way (which you can't). Only determining a property of one (forcing it into a choice of one of its uncertain properties) will instantly tell you everything about the property of the other. Subtle, but crucial. report Lurker2358 Dec 06, 2012 Rank: 1.5 / 5 (8) Not quite. If that were the case you could transmit information that way (which you can't). Only determining a property of one (forcing it into a choice of one of its uncertain properties) will instantly tell you everything about the property of the other. Subtle, but crucial. Temporal entanglement implies that you somehow can transmit information via entanglement, particularly since the "past" in the experiments is also displaced in space by the distance the Earth moved during the allotted time between the start of the experiment and the end. More than one article has been written on here showing both temporal entanglement and reverse causality were found via experiment in an Earth laboratory. This requires information to move from particle B in the future at position B' to particle A in the past at position A' without crossing the space or time between them. Considering the Earth moves very fast this would be a large distance. report Ray W Dec 06, 2012 Rank: 1 / 5 (1) A bit off topic, but reading this article brings a man in the middle question to mind. Intercept a signal between Alice & Bob, split the signal, store one while doubling the other and sending it on to Alice or Bob. Monitor changes in your stored signal as the reciever decodes the signal. Use this information to break the security between Alice & Bob. The trick is doubling the signal without loosing the original entanglement. report Lurker2358 Dec 06, 2012 Rank: 1.7 / 5 (6) http://phys.org/n...tml#nRlv report Telekinetic Dec 06, 2012 Rank: 2.6 / 5 (15) "I've also found one thing that always gets left out when trying to impress the significance of this process is exactly what "instant" means in context of the finite speed of light." - eloheim That is one of the most insightful statements I've read on this forum. You're a thinker. report ROBERTOF Dec 06, 2012 Rank: 2 / 5 (4) No se trata de 3 partículas sino de una sola dividida en 3, así que el principio de incertidumbre rige para el conjunto, no dentro de él. Es como si la partícula original fuese el marco de referencia, quedando la incertidumbre del lado externo de ese marco report TheGhostofOtto1923 Dec 06, 2012 Rank: 2.1 / 5 (11) means in context of the finite speed of light." - eloheim That is one of the most insightful statements I've read on this forum. You're a thinker. -But not a very good one. "When a measurement is made and it causes one member of such a pair to take on a definite value...the other member of this entangled pair will at any subsequent time be found to have taken the appropriately correlated value In Quantum entanglement, part of the transfer happens INSTANTaneously..." -Instantaneously indicates no delay in change of state whatsoever regardless of separation distance. The speed of light indicates a delay proportionate to the separation distance. Temporal entanglement implies that you somehow can transmit information FAIL "...the steps required to read out the teleported quantum state ensure that no information can be communicated faster than the speed of light" -Again, and as always, words are inadequate to describe these things. Thats why physicists use numbers. report Telekinetic Dec 06, 2012 Rank: 2.6 / 5 (15) "But the new experiment shows that direct communication between the photons (at least as we know it) is simply impossible. The team simultaneously measured several properties of both photons, such as phase, when they arrived at their villages and found that they did indeed have a spooky awareness of each other's behaviour. On the basis of their measurements, the team concluded that if the photons had communicated, they must have done so at least 100,000 times faster than the speed of light — something nearly all physicists thought would be impossible. In other words, these photons cannot know about each other through any sort of normal exchange of information." Ghost, you really must stop relying on Wikipedia for proof. They let anyone contribute erroneous information. You better do your homework on entanglement. By the way, are you "lite"? report TheGhostofOtto1923 Dec 06, 2012 Rank: 2.7 / 5 (12) You did not represent the context of your reference honestly: "The researchers found that when each photon reached its destination, it could instantly sense its twin's behaviour without any direct communication. The finding does not violate the laws of quantum mechanics" "The experiment shows that in quantum mechanics at least, some things transcend space-time, says Terence Rudolph, a theorist at Imperial College London." -This is exactly what the wiki article says. You should not reject wiki excerpts solely on the facts that you do not understand them, nor fail to cross-check their veracity. And no I am not lite. Lite frequently downrates me. I state this on my profile page, as well as exposing at least one accuser for the lying stalking dimwit that he is. report Noumenon Dec 06, 2012 Rank: 3.5 / 5 (11) Either Ghost or FrankHerbert is lite. report TheGhostofOtto1923 Dec 06, 2012 Rank: 1.5 / 5 (8) Either Ghost or FrankHerbert is lite. Hey nou do me the honor at least of responding to my research on the specious nature of 'mind' and 'consciousness'. http://medicalxpr...nal.html -You need to update your lexicon. And your profile page. report Pressure2 Dec 06, 2012 Rank: 1.8 / 5 (5) This whole faster than light is nonsense, they are what they are observed to be when measured from the moment they are created. They are nothing more or less than a coin split in 1/2 and then 1/2 is split in 1/2 again. report Pressure2 Dec 06, 2012 Rank: 3 / 5 (6) There is a very good chance the "Lite" a light weight coward loser and works for Physorg and post under another username. report Pressure2 Dec 06, 2012 Rank: 2.6 / 5 (5) That's funny Lite, so I hit upon a nerve! Careful coward you might expose yourself now. report StarGazer2011 Dec 06, 2012 Rank: 4 / 5 (4) This whole faster than light is nonsense, they are what they are observed to be when measured from the moment they are created. They are nothing more or less than a coin split in 1/2 and then 1/2 is split in 1/2 again. This seems to sum it up for me; can anyone explain why 'action at a distance' is actually required to explain this correlation? And before someone rattles on about 'uncertainty' be aware that argument is just putting the cart before the horse; perhaps the existance of corellation between quantum states (entanglement) is actually evidence that the copenhagen interpretation is wrong and that the 'uncertainty' is an artifact of interaction, not a property of the particles (or the universe) themselves. I.e. that postiion and momentum are actually simultanously defined as actual discrete concrete values but not simultaneously measurable due to interaction at the moment of measurment. report Estevan57 Dec 06, 2012 Rank: 3.7 / 5 (12) Either Ghost or FrankHerbert is lite. Yup. Hit the nail on the head with that one. Good call. report Lurker2358 Dec 06, 2012 Rank: 1.8 / 5 (5) Ghost: In the temporal entanglement experiment which was done in an article on here a while back, if the entanglement is what it claims to be, of which I'm not entirely sure, rather than a mere classical causality correlation, then information absolutely must have been communicated between the test object in the "future" set back to the test object in the "past" set. Since the past position of the Earth was very far away from the future position of the Earth, this information must have made quite a decent sized trip instantaneously. The reason is that the two events are otherwise unrelated except that they are both part of the same experiment, and that the experiment is designed to try and entangle the outcomes of events which happen at different times. It appears to work regardless of the delay, even across several days apparently. report Estevan57 Dec 06, 2012 Rank: 3.4 / 5 (10) I noticed that after this post lite (Otto) changed his profile to try to confuse me with others. Hmmm Must have hit a nerve. Amazing how similar the two profiles have become. report Telekinetic Dec 06, 2012 Rank: 2.5 / 5 (16) Send PM to this user PERSONAL INFORMATION First Name: Last Name: Username: lite Member since: June 28, 2012, 7:07 am PROFILE Q&A Birthday: Location: Affiliation: About yourself: ScooterG = Estevan57 = obama_socks = PussyTard & coTards. Above is the profile page of lite. The only poster that uses or has ever used the term "pussytard" is GhostofOtto1923. Ladies and Gentlemen of the jury... report Noumenon Dec 06, 2012 Rank: 3.7 / 5 (9) -You need to update your lexicon. And your profile page. -ghostOtto / lite / FH Why? report Telekinetic Dec 06, 2012 Rank: 2.5 / 5 (13) "Bormann became more and more dominant in the Nazi Party to such an extent that he seemingly controlled domestic legislation and appointments and promotions within the party. With Hitler concentrating his time on the war effort, Bormann was all but left clear to handle domestic policy.In particular he tried to target the church in Nazi Germany. Bormann simply believed that there was no place for a Christian church in Germany and in 1942, he sent a confidential memo to all Gauleiters that the power of the church "must absolutely and finally be broken." And that, fellow commenters, is the origin of GhostofOtto's anti-religious ravings. He sees himself as wearing the mantel of Martin Borman et al. I'll bet he's got a nice little collection of S.S. daggers. They're fakes, sucker. report pages: « prev12next » Please register or sign in to add a comment. 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