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Science

Quantum Measurements Leave Schrödinger's Cat Alive 210

Posted by samzenpus
from the looking-in-the-box dept.
First time accepted submitter Walking The Walk writes "Your co-workers who keep using Schrödinger's cat metaphor may need to find a new one. New Scientist reports that 'by making constant but weak measurements of a quantum system, physicists have managed to probe a delicate quantum state without destroying it – the equivalent of taking a peek at Schrodinger's metaphorical cat without killing it. The result should make it easier to handle systems such as quantum computers that exploit the exotic properties of the quantum world.'"
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Quantum Measurements Leave Schrödinger's Cat Alive

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  • by Anonymous Coward on Wednesday October 03, 2012 @11:31PM (#41545773)

    The SchrÃdinger's Cat [thinkgeek.com] I bought from Think Geek keeps dying half the time.

    • by mcgrew (92797) *

      I prefer Schrödinger's Fridge. [angryflower.com]

      I don't know if everyone is joking (well, the cartoonist who drew that linked cartoon isn't serious) or everyone misunderstands the concept that whoever does the Bob cartoons is poking fun at. It simply means "you don't know unless you test". The idea that a cat is both alive and dead is ludicrous.

  • by geoffrobinson (109879) on Wednesday October 03, 2012 @11:34PM (#41545787) Homepage

    and extremely pissed off about your experiment.

    http://afternoonsnoozebutton.com/post/9395842065/breaking-news-schrodingers-cat-is-alive-and [afternoons...button.com]

  • by Jonah Hex (651948) <hexdotms.gmail@com> on Wednesday October 03, 2012 @11:40PM (#41545811) Homepage Journal
    This one is as mind bending as the metaphor itself: http://www.youtube.com/watch?v=JNalMWLnt0o [youtube.com] From the youTube description:

    This animation was created for an animation show in London by the very talented Chavdar Yordanov https://vimeo.com/chavdaryordanov [vimeo.com]

    Not my Work! - HEX

    • by Raenex (947668)

      The drawings were decent (except for the hands, the mark of a great cartoonist), but I hate shitty animations that bounce around. The story itself was a simplistic revenge story and uninteresting.

  • by Sun (104778) <shachar@shemesh.biz> on Wednesday October 03, 2012 @11:41PM (#41545815) Homepage

    This wouldn't allow you to gain a "strong" piece of information – whether the cat was alive or dead – but you might be able to detect other properties.

    So, in essence, the main thing they found out is how to do more stuff with qbits without triggering a collapse of the wavelength function.

    Real summary:
    Obscure need which is somehow quantum computing, but not in any way feline, related gets obscure advance.

    Shachar

  • by timeOday (582209) on Wednesday October 03, 2012 @11:41PM (#41545817)
    What? Isn't the proven destructiveness of measuring a quantum system the bedrock of quantum key distribution [wikipedia.org]?
    • by mcrbids (148650)

      Came here to see this point made, was not disappoint.

    • What? Isn't the proven destructiveness of measuring a quantum system the bedrock of quantum key distribution [wikipedia.org]?

      I thought I remembered a recent story saying that researchers had found a method to "peek" at an quantum-encoded message without tipping Bob and Alice off to the fact that they had an eavesdropper. I wonder if this story is related to that.

    • by Yvanhoe (564877) on Thursday October 04, 2012 @12:30AM (#41546003) Journal
      I thought at this point is had become obvious that quantum cryptography was just a nice scam to fund fundamental physics research?
      • I thought at this point is had become obvious that quantum cryptography was just a nice scam to fund fundamental physics research?

        We shouldn't need to scam anyone to fund fundamental physics research.

        • Until the Manhattan project politicians didn't see the need for fundamental physics research. (Winston Churchill being a notable exception). As the nuclear industry becomes, basically, about as exciting as the coal mining industry, the perception of the need recedes. We are back to trying to invent military uses for pure research. But if the monkeys hold the keys to the banana plantation, I think we are justified in pulling wool over the eyes of the monkeys.
        • by Yvanhoe (564877)
          I totally agree, we should need. But we do need.
    • No information is gathered, rather the lifetime / distance of the qubit is extended. Since this caused the frequency of detection to change, I'm going to make an educated guess that the correction signal causes interference and/or destruction of a third channel which could be monitored for manipulation.
  • If the cat isn't dead now, it will be eventually. So you might as well assume it's dead and move on.

  • by irving47 (73147) on Wednesday October 03, 2012 @11:59PM (#41545897) Homepage

    Can we PLEASE call it a Heisenberg Compensator?

  • by Tumbleweed (3706) on Thursday October 04, 2012 @12:01AM (#41545899)
    Stargate SG-1 finally got some science right!
  • by SchroedingersCat (583063) on Thursday October 04, 2012 @12:06AM (#41545915)
    Every time they take a peek, God kills a kitten.
  • just long enough to be eaten by Pavlov's Dog

  • by Penurious Penguin (2687307) on Thursday October 04, 2012 @12:21AM (#41545963) Homepage Journal
    Rather than using small fury creatures with no propensity for entangled behavior, why not use something of similar size, but a bit more gracious and flat? For this I propose the noble sock - an item exhibiting (when in certain steel chambers) extremely random tendencies of existence and non-existence. We all know damned well what to expect of a cat run through a permanent-press cycle. However, no one, not even Martha Stewart knows what to expect of the sock - that ambiguous textile for which any state even science cannot predict.
    • Naw, it's actually easy. The spinning motion of the drier cycle forms a wormhole, and when the socks are transported through it they end up in closets, transformed into coat hangars.
      Go, look in your closet. Did you buy all those hangars? No! Most of them used to be your socks.
    • by hweimer (709734)

      Two words: Bertlmann's socks [cdsweb.cern.ch].

    • by steelfood (895457)

      It works out when you take into consideration socks come in pairs. CP violation states that you will get back a full pair most of the time, but occasionally, you will only get one.

  • More chinks in the armor of the abominable Copenhagen Interpretation. Bohr, Heisenberg and Schreodinger were very smart people, but they couldn't be right about consciousness affecting physics. That's just stupid.
  • New Scientist? (Score:5, Informative)

    by edibobb (113989) on Thursday October 04, 2012 @12:34AM (#41546019) Homepage
    The New Scientist frequently makes quantum leaps in logic. Or was that logic leaps in quantum physics? I GET SO CONFUSED! At any rate, the real article is a bit less sensational.

    http://www.nature.com/nature/journal/v490/n7418/full/nature11505.html [nature.com]
  • by jIyajbe (662197) on Thursday October 04, 2012 @12:58AM (#41546099)

    From the abstract:

    "The act of measurement bridges the quantum and classical worlds by projecting a superposition of possible states into a single (probabilistic) outcome. The timescale of this 'instantaneous'process can be stretched using weak measurements usuch that it takes the form of a gradual random walk towards a final state. Remarkably, the interim measurement record is sufficient to continuously track and steer the quantum state using feedback..."

    The way I read this, they aren't claiming they prevented collapse, nor that they can predict which state it will collapse to; rather, they have (1) increased the time of the collapse of the wave function (via feedback) and (2) been able to "watch" the electron collapse to whichever state it goes to. [N.B.: I am totally open to correction. I haven't paid the $32 for a copy of the paper.]

    So, no Heisenberg compensator here.

    • This is my interpretation, people are blowing this out of proportion for sensationalist news (bad newscientist!)

      That said, IANA Physicist
  • the p -value of their "weak measurements" was 0.5
  • If the state of an entangled set of quantum bits can be known in advance and their states observed without collapsing them, then it stands to reason that a remote communications station with a pre-delivered set of pre-entangled bits could receive a message by observing the collapse the instant the 'transmitter' causes it to happen.

    I wonder if this research provides this possibility, or if there is something inherent to the entanglement/observation process that prevents this.

    • Oh gosh no. First, this does not mean that quantum bits state can be known "in advance" (whatever that means, if you detect the state before collapse, does that mean they could later collapse into a different state? If so, that's pointless. If not, then its already collapsed). The way I read the article, it doesn't mean they can observe state without collapsing, but rather can gain some information about it before collapsing by effectively stretching out the collapse into a series of gradual collapses about
    • i believe the problem is that it might be possible to know what it will collapse into, but we still can't influence how it will collapse.

      so the receiver will know it will likely collapse into state X before actually measuring it...how does that really help anything? you are just sort of measuring it earlier.

  • by wonkey_monkey (2592601) on Thursday October 04, 2012 @02:50AM (#41546477) Homepage

    Quantum Measurements Leave Schrödinger's Cat Alive

    Shouldn't that be "Quantum Measurements Leave Schrödinger's Cat In A Superposition Of Alive And Dead"? If it's decidedly alive then the waveform has collapsed, and isn't that what they're avoiding? (did not read TFA)

  • Schrödinger's cat has surely died of old age by now.
  • by jsternbe (703721) on Thursday October 04, 2012 @05:54AM (#41547127)
    The headline was a bit misleading. You still can't measure a quantum state without having its superposition collapse to what was measured. If I understand what the article is saying properly, these scientists are not able to peak into the box to measure "Schrodinger's Cat's" state of aliveness, but they can still peak to see if the cat is a tabby or a calico. If fur pattern isn't a good quantum number, then that will cause the "cat" to change its spots, but later probes can be used to nudge it back to its original state. Meanwhile, you haven't disturbed the "cat's" aliveness or deadness. The important part seems to be being able to "nudge" certain states with probes to get some information out of the system without really changing it.
  • I believe that the idea is that by peeking, they can see one reality, but, since they didn't technically cause one reality to collapse, they can peek again and then the outcome has a 50% chance to have a different outcome.
  • by korielgraculus (591914) on Thursday October 04, 2012 @07:32AM (#41547667)
    We only managed a quick peek, but the cat is definitely dead. Or asleep. We think.
  • ... isn't that determining the state? The purpose of the cat experiment was to state that it is both alive and dead until observed to be one or the other.

    And for that matter, opening the box does not kill the cat, it just allows you to observe its state. We know that when you open the box there is a set probability of the cat being dead.
  • Jeeze, I'm really starting to think that most people just shouldn't ever talk about Quantum, there's so many misconceptions and misunderstandings that trying to give people a little bit of information, since its so wildly out of context, even in the wrong context (misconceptions), that it only drives them further away from the truth, from reality. People latch onto the wrong points.

    I barely understand Quantum Physics myself and I can tell that TFA makes all kinds of wild leaps in logic. Most of these thi

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