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Science

Quantum State Created In Largest Object Yet 265

Posted by samzenpus
from the hoping-each-time-that-his-next-leap-will-be-the-leap-home. dept.
SpuriousLogic writes "A team of researchers have created a 'quantum state' in an object billions of times larger than ever before. From the article: 'Such states, in which an object is effectively in two places at once, have until now only been accomplished with single particles, atoms and molecules. In this experiment, published in the journal Nature, scientists produced a quantum state in an object billions of times larger than previous tests. The team says the result could have significant implications in quantum computing.'"
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Quantum State Created In Largest Object Yet

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  • Re:so how big is it? (Score:1, Informative)

    by Anonymous Coward on Thursday March 18, 2010 @12:26PM (#31524844)

    TFA says both "trillions of atoms" and "barely visible with the naked eye"

  • Re:so how big is it? (Score:5, Informative)

    by Dan East (318230) on Thursday March 18, 2010 @12:31PM (#31524926) Homepage Journal

    "With this experiment, we've shown that the dividing line can be pushed up all the way to about a trillion atoms."

    "The "quantum resonator" can be seen with the naked eye."

  • Re:so how big is it? (Score:5, Informative)

    by Yvanhoe (564877) on Thursday March 18, 2010 @12:44PM (#31525104) Journal
    That's the problem with vague claims in an article. We don't know if the weight is billions of times bigger or if the diameter is. Therefore we don't know if we have 6x10^9 atoms or 6x10^27 atoms. It doesn't even give an order of magnitude -> epic fail of scientific journalism.
  • by JamesP (688957) on Thursday March 18, 2010 @12:57PM (#31525264)

    No, they did something similar to this: http://en.wikipedia.org/wiki/Quantum_harmonic_oscillator [wikipedia.org]

    When you take an oscillator and put tiny amounts of energy into it it will behave in a QM way.

  • Re:so how big is it? (Score:5, Informative)

    by waxigloo (899755) on Thursday March 18, 2010 @01:00PM (#31525320)

    According to the researchers' website the nano-mechanical resonator is a few micrometers in diameter:
    http://www.physics.ucsb.edu/~clelandgroup/research.html [ucsb.edu]

    The previous record was a buckyball.

  • by Adaeniel (1315637) on Thursday March 18, 2010 @01:06PM (#31525396)
    Here is the link to the naturenews article if anyone would like it: http://www.nature.com/news/2010/100317/full/news.2010.130.html [nature.com]
  • Re:so how big is it? (Score:2, Informative)

    by Beorytis (1014777) on Thursday March 18, 2010 @01:09PM (#31525424)
    It's 30 micrometers long, according to this article on the Nature [nature.com] website.
  • Re:so how big is it? (Score:2, Informative)

    by MMatessa (673870) on Thursday March 18, 2010 @01:09PM (#31525428)
    This ars technica article [arstechnica.com] says it's about 50 micrometers long.
  • by climate_control (1381507) on Thursday March 18, 2010 @01:20PM (#31525564)
    Similarly macroscopic quantum states have been achieved in superconductors. So the significance of this work is that macroscopic superposition is accomplished with a mechanical system, not an electronic one. The Nature article that the BBC is referring to: http://www.nature.com/nature/journal/vaop/ncurrent/full/nature08967.html [nature.com] The BBC removed the scale bar, which shows that the resonator is about 70 microns long, with an "active region" 40 microns long. But the resonant frequency is still up in the GHz, so they only have to cool to 0.1K, which is not so hard these days.
  • by roguegramma (982660) on Thursday March 18, 2010 @01:23PM (#31525620) Journal

    I don't know about this experiment, but in the double-slit experiment, you can confirm that the photons pass the slit unobserved(in wave form) when you get a peculiarly structured hit pattern on the wall with the photoreactive film that can only result from the adding and cancelling of two wave distributions.

    According to the Everett interpretation, http://www.hedweb.com/manworld.htm [hedweb.com], the universe will split at the time of the observation, not at the time of being placed in wave state, at least that is what section "Q7 When do worlds split?" says.

    IMO, the worlds split according to wave functions only to an uninformed observer, which we are most of the time; but we still got enough information to mess up measurements enough so that we can't prove the everett interpretation(At least my impression was that it hasn't been proven yet).

  • by radtea (464814) on Thursday March 18, 2010 @01:25PM (#31525648)

    Once they've placed this object in a quantum state, how do they verify that it's "occupying two states at once?"

    Interference phenomena. The article is light on detail, but presumably they excite the system into a superposition of (mechanical) normal modes and then observe the motion, or the position of some part of it, at a later time and find that it is in a classically forbidden region.

    For example, suppose they excite it into two modes that interfere to produce a node at some point, so there is no motion there, but there would be if there it was in one mode or the other. Then monitoring the motion at that point would allow you to determine if the system was in a superposition of two quantum states rather than one or the other.

    With regard to the many-worlds interpretation: it doesn't answer the really important question. Neither does consistent histories or any of the decoherence-based approaches. The really important question is, "Why is there a classical world at all?" That is, these theories purport to show that we can get along just fine without the wavefunction ever undergoing "collapse", so in some sense all possible quantum outcomes of an experiment are permitted. But they never answer (or even ask), "Why is it only via interference phenomena that we are aware of these effects? Why aren't we aware of the other components of the wavefunction all the time? Why is there a classical world at all? Is it a feature of consciousness or the physics that permits beings like us to exist, that we are selected by a basically anthropic process to be able to experience only the narrowest subset of existence? If so, how?"

    Apart from that, the article is badly misleading: it seems to suggest that anyone anywhere thinks there is anything interesting about the physical size or number of particles involved the detectability of quantum phenomena. It has been known for decades that this is not the case: the number of available modes is what matters, and any sufficiently cold object can become arbitarily large without exhibiting classical behaviour. Furthermore, phenomena like the Mossbaure Effect told us something similar half a century or so ago. It's probably time for the popular press to stop talking about the quantum equivalent of the luminiferous aether and get with the 21st century.

  • by earlymon (1116185) on Thursday March 18, 2010 @05:59PM (#31530388) Homepage Journal

    I think the subject line says it all, but I want a transporter that puts me in two places at once, then destroys the first me leaving the copied me.

    Spoiler alert, stop now if you haven't seen it:

    The name of the movie is The Prestige - it was on the Sci-Fi or some such channel recently. Trailer: http://www.youtube.com/watch?v=bH6CoVlD5xc [youtube.com]

  • Re:so how big is it? (Score:3, Informative)

    by iris-n (1276146) on Thursday March 18, 2010 @10:29PM (#31532534)

    You do integrate through both slits, but that does not mean that every photon has actually gone through them. It's a mathematical technique.

    What one proves experimentally is that if the which-path information exists (somewhere), there's no interference pattern. To infer from this that it went through both slits is, at best, non-sequitur, and at worse, philosophy.

    Also

    But from photon's perspective...

    there's no photon's perspective. It makes no sense to try to Lorentz-transform you into a referential that's moving at the speed of light. I understand that you're trying to take a limit somewhere, but you can't, it's not well-defined (mathematically), and leads one to nonsensical conclusions.

"Pascal is Pascal is Pascal is dog meat." -- M. Devine and P. Larson, Computer Science 340

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