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Quantum "Spookiness" Passes Toughest Test Yet by frankg1(m): 1:06pm On Aug 29, 2015 |
It’s a bad day both for Albert Einstein and for hackers. The most rigorous test of quantum theory ever carried out has confirmed that the ‘spooky action at a distance’ that the German physicist famously hated — in which manipulating one object instantaneously seems to affect another, far away one — is an inherent part of the quantum world. The experiment, performed in the Netherlands, could be the final nail in the coffin for models of the atomic world that are more intuitive than standard quantum mechanics, say some physicists. It could also enable quantum engineers to develop a new suite of ultrasecure cryptographic devices. “From a fundamental point of view, this is truly history-making,” says Nicolas Gisin, a quantum physicist at the University of Geneva in Switzerland. Einstein’s annoyance In quantum mechanics, objects can be in multiple states simultaneously: for example, an atom can be in two places, or spin in opposite directions, at once. Measuring an object forces it to snap into a well-defined state. Furthermore, the properties of different objects can become ‘entangled’, meaning that their states are linked: when a property of one such object is measured, the properties of all its entangled twins become set, too. This idea galled Einstein because it seemed that this ghostly influence would be transmitted instantaneously between even vastly separated but entangled particles — implying that it could contravene the universal rule that nothing can travel faster than the speed of light. He proposed that quantum particles do have set properties before they are measured, called hidden variables. And even though those variable cannot be access, he suggested that they pre-program entangled particles to behave in correlated ways. In the 1960s, Irish physicist John Bell proposed a test that could discriminate between Einstein’s hidden variables and the spooky interpretation of quantum mechanics. He calculated that hidden variables can explain correlations only up to some maximum limit. If that level is exceeded, then Einstein’s model must be wrong. The first Bell test was carried out in 1981, by Alain Aspect’s team at the Institute of Optics in Palaiseau, France. Many more have been performed since, always coming down on the side of spookiness — but each of those experiments has had loopholes that meant that physicists have never been able to fully close the door on Einstein’s view. Experiments that use entangled photons are prone to the ‘detection loophole’: not all photons produced in the experiment are detected, and sometimes as many as 80% are lost. Experimenters therefore have to assume that the properties of the photons they capture are representative of the entire set. To get around the detection loophole, physicists often use particles that are easier to keep track of than photons, such as atoms. But it is tough to separate distant atoms apart without destroying their entanglement. This opens the ‘communication loophole’: if the entangled atoms are too close together, then, in principle, measurements made on one could affect the other without violating the speed-of- light limit. Entanglement swapping In the latest paper, which was submitted to the arXiv preprint repository on August 24 and has not yet been peer reviewed, a team led by Ronald Hanson of Delft University of Technology reports the first Bell experiment that closes both the detection and the communication loopholes. The team used a cunning technique called entanglement swapping to combine the benefits of using both light and matter. The researchers started with two unentangled electrons sitting in diamond crystals held in different labs on the Delft campus, 1.3 kilometers apart. Each electron was individually entangled with a photon, and both of those photons were then zipped to a third location. There, the two photons were entangled with each other — and this caused both their partner electrons to become entangled, too. This did not work every time. In total, the team managed to generate 245 entangled pairs of electrons over the course of nine days. The team's measurements exceeded Bell’s bound, once again supporting the standard quantum view. Moreover, the experiment closed both loopholes at once: because the electrons were easy to monitor, the detection loophole was not an issue, and they were separated far enough apart to close the communication loophole, too. “It is a truly ingenious and beautiful experiment,” says Anton Zeilinger, a physicist at the Vienna Centre for Quantum Science and Technology. “I wouldn’t be surprised if in the next few years we see one of the authors of this paper, along with some of the older experiments, Aspect’s and others, named on a Nobel prize,” says Matthew Leifer, a quantum physicist at the Perimeter Institute in Waterloo for Theoretical Physics, Ontario. “It’s that exciting.” A loophole-free Bell test also has crucial implications for quantum cryptography, says Leifer. Companies already sell systems that use quantum mechanics to block eavesdroppers. The systems produce entangled pairs of photons, sending one photon in each pair to the first user and the other photon to the second user. The two users then turn these photons into a cryptographic key that only they know. Because observing a quantum system disrupts its properties, if someone tries to eavesdrop on this process it will produce a noticeable effect, setting off an alarm. The final chink But loopholes, and the detection loophole in particular, leave the door open to sophisticated eavesdroppers. Through this loophole, malicious companies could sell devices that fool users into thinking that they are getting quantum-entangled particles, while they are instead being given keys that the company can use to spy on them. In 1991, quantum physicist Artur Ekert observed that integrating a Bell test into the cryptographic system also would ensure that the system uses a genuine quantum process. For this to be valid, however, the Bell test must be free of any loopholes that a hacker could exploit. The Delft experiment “is the final proof that quantum cryptography can be unconditionally secure”, Zeilinger says. In practice, however, the entanglement- swapping idea will be hard to implement. The team took more than week to generate a few hundred entangled electron pairs, whereas generating a quantum key would require thousands of bits to be processed per minute, points out Gisin, who is a co-founder of the quantum cryptographic company ID Quantique in Geneva. Zeilinger also notes that there remains one last, somewhat philosophical loophole, first identified by Bell himself: the possibility that hidden variables could somehow manipulate the experimenters’ choices of what properties to measure, tricking them into thinking quantum theory is correct. Leifer is less troubled by this ‘freedom-of- choice loophole’, however. “It could be that there is some kind of superdeterminism, so that the choice of measurement settings was determined at the Big Bang,” he says. “We can never prove that is not the case, so I think it’s fair to say that most physicists don’t worry too much about this.” http://www.scientificamerican.com/article/quantum-spookiness-passes-toughest-test-yet/ 1 Like |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Nobody: 1:58pm On Aug 29, 2015 |
99% of all nairalanders don't know the meaning or significance of this post, hence they will pass without commenting. On their way to the politics section to display childlishness and tribalism. If you are not among, you are welcome to comment. Or like. |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Nobody: 2:16pm On Aug 29, 2015 |
See this one above me o what is he feeling like In quantum mechanics, objects can be in multiple states simultaneously I thought that in quantum mechanics - even tho this is what i learned in chem tho im not sure how/if it applies in physics - energies/electrons have quantized energies and can only make jumps (quantum leaps) between states no simultaneous or inbetween ish |
Re: Quantum "Spookiness" Passes Toughest Test Yet by frankg1(m): 2:38pm On Aug 29, 2015 |
MrsPhyno: Did u jux quote sec physics? |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Nobody: 2:42pm On Aug 29, 2015 |
MrsPhyno:hey there! I'm feeling fly actually. What you just said above is very elementary quantum mechanics. Just forget that one here. here we are dealing with another aspect called quantum entanglement. Which basically means that two particles are connected in such a way that action on one affects the other simultaneously. Now in physics, we ask why. What is sending information from one to the other. Or, are they just AWARE of one another? Of course we found that basically nothing was being exchanged between the, and that has made many physicists very angry and frustrated. Including me. So we'be all been trying to prove this wrong, that something else must be going on. And these mumu scientists just spoiled our ministry. |
Re: Quantum "Spookiness" Passes Toughest Test Yet by frankg1(m): 3:20pm On Aug 29, 2015 |
Teempakguy: Quite right sir. |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Nobody: 6:40pm On Aug 29, 2015 |
frankg1:Lol no I didn't quote anyone but u.... I was referring to chemistry actually |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Nobody: 6:53pm On Aug 29, 2015 |
Teempakguy:Lol abeg o. I no be physicist, biology na my tin I jus dey learn work I read this ur essay sha very interesting thanks for teaching me oluko |
Re: Quantum "Spookiness" Passes Toughest Test Yet by seunot: 8:17pm On Aug 29, 2015 |
Very exciting news, though I'm in science field, I always hate it when 'limitations' are proposed and imposed on 'universal possibilities' by scientists based on LIMITED KNOWLEDGE via theories and laws. Its therefore wonderful to see that the speed of light can be exceeded. I'm sure other particles and phenomenon that surpasses SOL will be discovered in the future. Similar breakthroughs are expecting in energy, matter, gravity and so on. It's indeed a brave new world, too bad my country is seriously lagging behind! |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Dekatron(m): 8:40pm On Aug 29, 2015 |
Teempakguy, WHY IS EINSTEIN WICKED NAH?? It was E=MC^2. Now this. . . Him chop winsh? Na only him waka come?? Reason I love NEWTON. English are too smart and interesting a people. Se Germans ehn, they are something. . Leibnitz , Einstein, Wolfgang, Planck alot of them. Their work are usually intimidating. To topic : I HAVE ALWAYS WONDERED AT QUANTUM ENTANGLEMENT. Why are they entangled? How are they telling each other to change depending on whats happening to one? In short : QUANTUM MECHANICS abi nah PHYSICS is TOOOO SCARY and requires VERY HIGH INTELLIGENCE. |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Dekatron(m): 8:45pm On Aug 29, 2015 |
seunot: bro God (though he is a fable) bless you. Instead of them to invest and support science, they are doing competition of SHAKITIBOBO. Like shakitibobo is meaningful. Instead of them to organize science exhibitions, they are doing COMEDY SHOW (Glo). This country tire me, I swear |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Blakjewelry(m): 11:53pm On Aug 29, 2015 |
. |
Re: Quantum "Spookiness" Passes Toughest Test Yet by Blakjewelry(m): 11:54pm On Aug 29, 2015 |
This only goes to show how much genius of a guy Einstein was. Though he hated this idea of what in entails but even your guts cannot change the way quantum feels. |
Re: Quantum "Spookiness" Passes Toughest Test Yet by davien(m): 4:30pm On Aug 30, 2015 |
No information is sent faster than light, one measurement of a quantum linked particle merely tells you what spin the other one is. |
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