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.
Barack O-quanta?
Wouldn’t a quantum know-it-all equal God? Isn’t that all they have defined here?
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.
Which has nothing to do with Quantum Physics, and more to do with the human 'reasoning' process.
"This is something conceptually very weird,"
Only because you can get a grant for something that is pretty much common sense.
Alice reads the book and is allowed to give Bob one page's worth of information from it.
So the results of the test are dependent on Alice's skills as well as Bob's. Nothing like having multiple variables to make the results of a test invalid.
If Bob only has classical information, it is always possible to work out what he doesn't know.
Human beings are quite resourceful, but the ability to 'work out' the unknown is another factor that is not a constant. Some do better than others.
An examiner, having secretly inspected Bob's crib notes, could set questions that Bob couldn't answer.
Yeah..... well IF we KNEW where the ELECTRON was, we wouldn't have to LOOK to tell, and it wouldn't move because we looked. The examiner looking at Bob's crib notes alters the results of the test. If we just understood what the test was 'for', then maybe we could see how it relates to quantum physics. The only thing I could find was this:
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 use of COULD and ALMOST seems to leave a lot of wiggle room, and make the 'test' seem questionable. Polar Bears could move to my city and almost Almost clean up the environment.
The craziness comes if Bob gets one page's worth of quantum information from Alice.
It all seems logical. The only reason to say 'craziness' is this pre-conceived idea that it is quantum(unpredictable).
In this case, the researchers show, there is no-way to pinpoint what information Bob is missing.
Only due to the way the test was designed.
Challenge Bob, and he can guess either page of the book almost perfectly.
Well, maybe not perfectly. He does have a 50/50 chance.
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.
Again, the test is rigged so that Bob succeeds once he reaches 50%, and the testers must allow mistakes due to memory loss of what he was told.
It is an unexpected discovery.
Only to them.
Researchers had been trying to prove that quantum ignorance would follow classical intuition and be traceable to ignorance of details,
Making a false assumption to there is an easy target to hit.
... and finding that it isn't raises new questions.
$$$$$Grants.
"We have observed this effect but we don't really understand where it comes from,"
I would tell them, but they know it all and would never listen to me.
What is a quantum know-it-all , and how much worse are they than a classical know-it-all?
Enlighten me on what exactly the "finding" was. And how it relates to the prior understanding.
What the never heard of “context”
“Physicists show that quantum ignorance is hard to expose” - ain’t that the truth.
Thanks
It’s been quite obvious for a number of millenia that human thought processes occur within and as a consequence of quantum physics.
It’s been quite obvious for a number of millenia that human thought processes occur within and as a consequence of quantum physics.
Check what decimon told you at #19. It’s all very clear!
Your *ss is 'very clear'. No one yet has been able to explain what this "finding" in quantum physics actually was. You obviously don't know. Those interested will have to try to track down the news elsewhere.
I would say 'misunderstand'.
The whole quantum physics problem is based on a misunderstanding, yet having to come up with an answer. We predict 'where' an electron should be, yet when we attempt to locate it, it has magically teleported somewhere else. As if that can happen.
Our 'prediction' on an electron's location is based on improper assumptions about it's orbit and speed.
Once we understand that, and can measure it, then we will understand what they are calling quantum physics and why it behaves as it does.
The 'uncertainty', or 'unpredictability' of matter is more of a failure of ours than an attribute of physics, even though they are latching onto how to identify the same principle effect operating in other areas.
The simplest clue to the effect is 'chaos'. Nothing follows the same exact plan, in the Universe. Every thing has it's variances, and it is because of this that the possibility to create almost anything exists. It is this chaos or quantum effect that gives the Universe the way to create an unlimited and infinite number of forms of matter.
Planets and moons do not follow exactly circular orbits around their star/host/nucleus and neither do electrons.
I heard that Heisenberg was stopped once by a policeman
for speeding in his car, when the officer asked
Heisenberg, “Hey, did you know how fast you were going?”,
then Heisenberg said, “No, but I knew where I was!”
That is not what experts in the field believe. They claim the uncertainty is an inherent part of (quantum) reality.
The Planck number is called a constant, but it is a variable, used mainly because there are things we don't understand about how it all works. But we are good at finding new ways to use math to make it look like we know.
In one Quantum reality, I scored 100% on every Quantum reality exam I took.
Some say all of the so-called "constants" vary over long periods of time. Perhaps as the universe expands the quantum fabric of space (quantum 'foam'/vacuum energy) thins and its properties change.
The 'finding' was that some grad students were able to create some 'published works' for their academic credit and resume, and to get funding to continue the study through the college from the government.
The 'finding' that they mentioned in the article was that their illogical assumption turned out not to be true, and the most logical one did.
So basically they are getting credit for finding out they were wrong.
And you want me to what?
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