Posted on 07/31/2011 7:28:30 AM PDT by decimon
The quantum world allows you to answer questions correctly when you don't even have all the information you should need
No-one likes a know-it-all but we expect to be able to catch them out: someone who acts like they know everything but doesn't can always be tripped up with a well-chosen question. Can't they? Not so. New research in quantum physics has shown that a quantum know-it-all could lack information about a subject as a whole, yet answer almost perfectly any question about the subject's parts. The work is published in Physical Review Letters.
"This is something conceptually very weird," says Stephanie Wehner of the Centre for Quantum Technologies at the National University of Singapore, who derived the theoretical result with PhD student Thomas Vidick at the University of California, Berkeley, United States. It's a new phenomenon to add to the list of philosophical conundrums in quantum physics – as strange as the quantum superposition or the quantum uncertainty principle. But the work also has practical motivation: understanding how information behaves in the quantum context is important in emerging technologies such as quantum cryptography and quantum computation.
To frame the problem, consider the example of someone answering questions about a book they have only half-read. If someone has incomplete knowledge about a book as a whole, one expects to be able to identify the source of their ignorance somewhere in the book's pages.
Wehner and Vidick simplify the situation to a book with two pages. They invite the usual quantum players, Alice and Bob, to collaborate. Alice reads the book and is allowed to give Bob one page's worth of information from it.
If Bob only has classical information, it is always possible to work out what he doesn't know. "We show that classically things are, well, sane" says Wehner. In other words, Bob's ignorance can be exposed. Imagine that Bob is a student trying to cheat in an exam, and the notes from Alice cover half the course. An examiner, having secretly inspected Bob's crib notes, could set questions that Bob couldn't answer.
The craziness comes if Bob gets one page's worth of quantum information from Alice. In this case, the researchers show, there is no-way to pinpoint what information Bob is missing. Challenge Bob, and he can guess either page of the book almost perfectly. An examiner could not expose Bob's ignorance even having seen his notes as long as the questions cover no more than half the course – the total amount of information Bob can recount cannot exceed the size of his notes.
It is an unexpected discovery. Researchers had been trying to prove that quantum ignorance would follow classical intuition and be traceable to ignorance of details, and finding that it isn't raises new questions. "We have observed this effect but we don't really understand where it comes from," says Wehner. An intuitive understanding may be forever out of reach, just as other effects in quantum theory defy mechanistic description. However, Wehner and Vidick have begun to design experimental tests and are already formulating a range of ways to explore this strange new frontier. In this work, they devised a means of encoding the quantum information from two pages into one that gave Bob, the quantum know-it-all, the ability to recount all but one bit of the information on either page (the last bit Bob would have to guess). They plan to test whether other encodings would be equally good.
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Journal reference: T. Vidick and S. Wehner, "Does Ignorance of the Whole Imply Ignorance of the Parts? Large Violations of Noncontextuality in Quantum Theory", Physical Review Letters 107, 030402 (2011); http://prl.aps.org/abstract/PRL/v107/i3/e030402. A free preprint is available at http://arxiv.org/abs/1011.6448.
For more information, please contact: Stephanie Wehner Principal Investigator and Assistant Professor Centre for Quantum Technologies National University of Singapore Email: wehner@comp.nus.edu.sg Tel: +65 6601 1478
National University of Singapore
A leading global university centred in Asia, the National University of Singapore (NUS) is Singapore's flagship university which offers a global approach to education and research, with a focus on Asian perspectives and expertise.
NUS has 15 faculties and schools across three campus locations in Singapore – Kent Ridge, Bukit Timah and Outram. Its transformative education includes a broad-based curriculum underscored by multi-disciplinary courses and cross-faculty enrichment, as well as special programmes which allow students to realise their potential.
NUS has three Research Centres of Excellence (RCE) and 21 university-level research institutes and centres.
It is also a partner for Singapore's 5th RCE. The University shares a close affiliation with 16 national-level research institutes and centres. Research activities are strategic and robust, and NUS is well-known for its research strengths in engineering, life sciences and biomedicine, social sciences and natural sciences. It also strives to create a supportive and innovative environment to promote creative enterprise within its community. More at www.nus.edu.sg.
Centre for Quantum Technologies at the National University of Singapore
The Centre for Quantum Technologies (CQT) was established as Singapore's inaugural Research Centre of Excellence in December 2007. It brings together quantum physicists and computer scientists to explore the quantum nature of reality and quantum possibilities in information processing. CQT is funded by Singapore's National Research Foundation and Ministry of Education and is hosted by the National University of Singapore (NUS). More at www.quantumlah.org.
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Idiot authors like this make already difficult subjects virtually impossible to understand.
Not so hard to expose, but devilishly hard for people to recognize it in themselves.
Not entirely sure but I’ll guess it somehow relates to this...
“The EPR paradox (or Einstein–Podolsky–Rosen paradox) is a topic in quantum physics and the philosophy of science concerning the measurement and description of microscopic systems (such as individual photons, electrons or atoms) by the methods of quantum physics. It refers to the dichotomy that either the measurement of a physical quantity in one system must affect the measurement of a physical quantity in another, spatially separate, system or the description of reality given by a wave function must be incomplete.
This challenge to the Copenhagen interpretation of quantum physics (that only the position or momentum of a particle, but not both, can be known with certainty) originated from the consequences of a thought experiment authored in 1935 by Einstein, Podolsky and Rosen. The paper they authored indicated what seemed to be a flaw in the interpretation. The experiment involved two systems that initially interact with each other and are then separated. Then the position or momentum of one of the systems is measured, and due to the known relationship between the (measured) value of the first particle and the value of the second particle, the observer is aware of that value in the second particle. A measurement of the other value is then made on the second particle, and, once again, due to the relationship between the two particles, that value is then known in the first particle. This outcome seems to violate the uncertainty principle, as both the position and momentum of a single particle would be known with certainty.[1]
Einstein struggled to the end of his life for a theory that could better comply with causality, protesting against the view that there exists no objective physical reality other than that which is revealed through measurement interpreted in terms of quantum mechanical formalism. However, since Einstein’s death, experiments analogous to that of the EPR paradox have been carried out, starting in 1976 by French scientists at the Saclay Nuclear Research Centre. These experiments appear to show that the local realism theory is false.[2]”
http://en.wikipedia.org/wiki/EPR_paradox
Obviously you've haven't even read half the article, but are able to discuss parts of the entire article knowledgeably.
"In quantum mechanics, the Heisenberg uncertainty principle states precise inequalities that constrain certain pairs of physical properties, such as measuring the present position while determining future momentum; both cannot be simultaneously done to arbitrarily high precision. That is, the more precisely one property is measured, the less precisely the other can be controlled or determined. One may, at least, be able to identify the average momentum and position of particles using weak measurements. Furthermore, it is possible to imagine a hypothetical apparatus that measures the history of a particular particle's successive positions and momentums while also measuring times and energies to arbitrary accuracies.[citation needed]
Published by Werner Heisenberg in 1927, the principle implies that it is impossible to simultaneously both measure the present position while "determining" the future momentum of an electron or any other particle with an arbitrary degree of accuracy and certainty. This is not a statement about researchers' ability to measure one quantity while determining the other quantity. Rather, it is a statement about the laws of physics. That is, a system cannot be defined to simultaneously measure one value while determining the future value of these pairs of quantities. The principle states that a minimum exists for the product of the uncertainties in these properties that is equal to or greater than one half of ħ, the reduced Planck constant (ħ = h/2π)."
http://en.wikipedia.org/wiki/Heisenberg%27s_uncertainty_principle
should have been never see and greet one another
going after another cup of coffee ...lol
“The original EPR [Einstein–Podolsky–Rosen] paradox challenges the prediction of quantum mechanics that it is impossible to know both the position and the momentum of a quantum particle. This can be extended to other pairs of physical properties.
[edit] EPR paper
The original paper describes what happens to “two systems I and II, which we permit to interact ...”, and, after some time, “we suppose that there is no longer any interaction between the two parts.” In the words of Kumar (2009), it has “Two particles, A and B, [which] interact briefly and then move off in opposite directions.”[6] According to Heisenberg’s uncertainty principle, it is impossible to measure both the momentum and the position of particle B, say, exactly. However, it is possible to measure the exact position of particle A and the exact momentum of particle B. By calculation, therefore, with the exact position of particle A known, the exact position of particle B can be known. Also, with the exact momentum of particle B known, the exact momentum of particle A can be worked out. “EPR argued that they had proved that ... particle B can have simultaneously exact values of position and momentum.”
This is a paradox in Quantum Mechanics: The theory predicts that both values cannot be known for a particle, and yet the EPR experiment shows that they can. “Therefore, the quantum mechanical description of physical reality, EPR conclude, is incomplete.”[7] The paper says: “We are thus forced to conclude that the quantum-mechanical description of physical reality given by wave functions is not complete.”
The EPR paper ends with:
While we have thus shown that the wave function does not provide a complete description of the physical reality, we left open the question of whether or not such a description exists. We believe, however, that such a theory is possible.”
http://en.wikipedia.org/wiki/EPR_paradox
Having read quite a lot about quantum physics, I would tell you that this is pretty much par for the course. It’s exceptionally abstract, and the guys who study it and write about it don’t really understand it themselves. Yet they write these articles making grandiose claims. A lot of it is to drum up public support for their research, no doubt.
In this case, the researchers show, there is no-way to pinpoint what information we Freepers are missing. Challenge us Freepers, and we can guess either part of your sentence almost perfectly.
No need to 'splain yerself...
"par for the course" meaning, they don't really understand the subject themselves so they write in incomprehensible language and manner to cover the fact?
Ya’ll heard the saying: If you can’t dazzle them with your brilliance, baffle them with your bullsh**.
Lol! That makes more sense than anything else I read here!
Following classical principles that require us to figure out cause and effect, a jury determines that there isn't enough information to prove "beyond a reasonable doubt" that Casee was responsible for Caylee's disappearance (and death).
This finding in quantum physics demonstrates that those who instantly deduced that Caylee was missing (and dead) because Casee killed her appear to have arrived at the only correct answer irrespective of "beyond a reasonable doubt".
Is this a failing of our judicial system or our rules of evidence? Or, did quantum physics just now throw us another process to account for?
Well said. I have taught this subject, and IMHO this article is a form of educational malpractice.
You surmise much from scant evidence. This is, after all, but a press release.
Just about any subject can be made at least somewhat understandable to the layperson.
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