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Physicists Claim First Observation of a Quantum Cheshire Cat 148

Posted by Soulskill
from the it-is-both-smiling-and-not-smiling dept.
KentuckyFC writes "Last year, a group of theoretical physicists suggested a bizarre experiment based on a quantum phenomenon known as weak measurement. Unlike ordinary measurements that always change the state of a quantum object, a weak measurement extracts such a small amount of information that it leaves the quantum state intact. For example, a weak measurement can detect the presence of a photon by the deflection it causes when it bounces off a mirror. However, this does not change the photon's quantum state. The new idea was to make two weak measurements on a quantum system that is in a superposition of states, the goal being to separate the location of this quantum system from its properties, like a Cheshire cat. Now a group of experimentalists say they've observed a quantum Cheshire cat for the first time in an experiment involving neutrons. They passed a beam of neutrons through a magnetic field to align their spins and then sent them through an interferometer in which the neutrons pass down both arms of the experiment at the same time. They then used weak measurements to locate the neutrons in one arm while measuring their magnetic properties in the other. Voila! A quantum Cheshire cat."
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Physicists Claim First Observation of a Quantum Cheshire Cat

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  • by 3seas (184403) on Friday January 10, 2014 @06:30PM (#45921775) Journal

    Did they kill the cat, by looking?

  • Chesire Cat (Score:3, Funny)

    by BorgDrone (64343) on Friday January 10, 2014 @06:41PM (#45921921) Homepage

    Is it just me or does that sound a lot like a Heisenberg Compensator ?

    Beam me up!

    • by PopeRatzo (965947)

      Is it just me or does that sound a lot like a Heisenberg Compensator ?

      Yeah, either that or some other Big Bang episode.

  • by medv4380 (1604309) on Friday January 10, 2014 @06:44PM (#45921951)
    Why the acid trip Alice in wonderland analogy? Does it convey additional information about what they're doing, or is it just obfuscating what they're doing. I vote obfuscation, but it might just over my head right now. Stupid, grinning cat with no head.
    • I guess that it being a cat is the most obvious reference possible. As for it being the Cheshire Cat, I suppose that it's because said cat can willfully be either comprised as a regular cat, an abnormal cat (composed of say, just a head), or nothing at all.

      • Re: (Score:3, Informative)

        by Em Adespoton (792954)

        Its because the CC's attributes can be in one place while its body is somewhere else... after all, it can be between the state of abnormal and nothing: the last thing to fade is the smile (not the teeth and lips, but the smile) and it can interact without in fact being there.

    • I think it's an analogy to try and make people understand the principles of information and metadata when related to a physical object - indeed when that data cannot be 'read' directly the use of an acid trip may well be the best way of describing it!.

      For the majority of people, I would imagine, the concept of weak measurements would be a little boring, if not confusing. A bit of (spatially separated magnetic) spin is probably required to get noticed.
    • by Anonymous Coward

      I vote banning medium.com links.

    • by retroworks (652802) on Friday January 10, 2014 @07:10PM (#45922193) Homepage Journal

      Per the article:

      "The paradox arises when the team carried out two weak measurements. The first found the presence of neutrons in one arm while the second noted their magnetic properties in the other arm. “The neutrons behave as if particle and magnetic property are spatially separated while travelling through the interferometer,” they say. In other words, they observed a quantum Cheshire cat."

      Per the peer review: "Twas brillig, and the slithy toves. Did gyre and gimble in the wabe: All mimsy were the borogoves, And the mome raths outgrabe."

      • by Zalbik (308903)

        “The neutrons behave as if particle and magnetic property are spatially separated while travelling through the interferometer,”

        Is it just me, or does anyone else find that completely freaky? Ok, I kinda get how quantum effects don't really occur in a "location", but at a superimposed potential of different locations....but having different properties measured at different locations just freaks me out...

        • by mikael (484)

          Maybe they only had one of each instrument at each arm. What happened when measured both position and magnetic field on both arms?

        • by aiht (1017790)

          “The neutrons behave as if particle and magnetic property are spatially separated while travelling through the interferometer,”

          Is it just me, or does anyone else find that completely freaky? Ok, I kinda get how quantum effects don't really occur in a "location", but at a superimposed potential of different locations....but having different properties measured at different locations just freaks me out...

          I didn't find it freaky, but I did respond oddly; I burst into a delighted giggle. I'm still grinning like an idiot, and not because of the Cheshire Cat reference.
          This news makes me very happy.

    • by kaoshin (110328) on Friday January 10, 2014 @07:47PM (#45922463)
      Quantum Cheshire Cat [scientificamerican.com]
    • by Anonymous Coward

      Why the acid trip Alice in wonderland analogy?

      Because an acid trip is the only thing in this world that's as weird as quantum physics.

    • by sjames (1099)

      Probably because since Schrodinger, cats have been associated with quantum physics. In this case, the seemingly non-local Cheshire cat is more relevant.

    • by femtobyte (710429)

      Calling this a "Cheshire Cat state" is giving it a name --- which is not the same as the thing, or what the thing is (cf. H. Dumpty, 1872). If you want a full technical description of what this state is, that will be readily found in the papers describing it (with no obfuscation intended); however, it might be a bit lengthy to use as a name. On the other hand, a little innocuous wordplay creates a unique and memorable identifier, from which a reader could look up the specifics --- i.e. a good name. Note als

    • Once upon a time, scientists explained everything with "cat" analogies. One day a "science journalist" misread one as being a "car" analogy, and it's been downhill ever since. Scientists make discoveries and announcements, and the next day we get articles on newscientist.com about how cars like to drink milk and chase mice.
    • by chihowa (366380) *

      Alice's Adventures in Wonderland was published in 1865 (73 years before LSD was synthesized) by man who has no known connections to drug use. The Cheshire cat [wikipedia.org] itself predates even Lewis Carroll.

      The only "acid trip" aspect of any of this is a Disney movie from 1951 (which is admittedly very trippy).

    • by nickol (208154)

      This is a decent analogy. A smile without a cat and an acid trip without any acid (invented almost a century later).

    • by drkim (1559875)

      This refers to the fact that a property, like polarization, of a photon is thought of as a property of the photon (like a grin is a property of a physical cat, or 'red' could be a property of paint, etc.)

      In this case they can measure the magnetic properties of the photon in the absence of the photon itself. (i.e. like the 'grin' without the cat; à la the Cheshire Cat.)

  • and Curioser
  • by Nightlight3 (248096) on Friday January 10, 2014 @06:48PM (#45921973)

    "a weak measurement extracts such a small amount of information that it leaves the quantum state intact."

    That's not correct description -- the quantum state is changed, albeit less than with projective measurement. The paper itself [arxiv.org] calls it in the abstract "minimal disturbing" measurement, not the "non-disturbing" measurement.

    • Sounds like it was both observed and not observed ...
  • by Anonymous Coward

    We must stop looking into things like this. Quantum physics is fairy magic. Let's leave it at that!

    • by Tablizer (95088)

      must stop looking into things like this. Quantum physics is fairy magic. Let's leave it at that!

      Indeed. One day our experiments may end up winning Earth the Galactic Darwin Award.

      Is Mars still taking one-way colonizers? Then LHC can make all the mini black holes it wants.

      • If for some reason they do end up with a black hole at LHC, then Mars itself will get a one-way trip to Earth...
        • by Tablizer (95088)

          No, its gravity doesn't change.

        • Nah, it just took a space marine to fix that the first time it happened. Something about demons and the moons of mars and certain doom. All the footage is strangely low-resolution, though.

        • by Jeremi (14640)

          If for some reason they do end up with a black hole at LHC, then Mars itself will get a one-way trip to Earth...

          My understanding is that if someone did somehow create a black hole that gobbled up the Earth, the resulting object would be in the same location as Earth and would have the same mass as Earth; it would just be much, much smaller.

          So not only would Mars not be effected, even Earth's moon would not notice any difference.

      • If quantum suicide is right, then if the LHC is producing black holes, you'd better stay on Earth: On earth, you'd always be in the branch where no black holes are produced, while on Mars you'd see Earth disappear in a black hole and know that the very moment something goes wrong on Mars, you've got no hope to get any help from Earth.

        Well, thinking more about it, maybe your best bet is to make your decision based on a quantum random experiment.

    • by Anonymous Coward

      Everything looks like fairy magic until you figure it out. If it works, it's worth researching it until you reach a dead end or come up with a better solution.

      That said, I'm drawing the line if I have to wear a sparkly dress and dance under the moonlight.

  • I'm going to toss this out there but I expect the answer to be "no."

    Does this solve the issue with using quantum entanglement as a possible means of FTL communications? I'm under the impression that quantum entanglement can't be used for this because the act of looking at the particle would change the state. But this seems to be away around that.

    So am I wrong here and why?

    • Re: (Score:2, Funny)

      I'm going to toss this out there but I expect the answer to be "no."

      [...]

      So am I wrong here

      N... yes. Probably. But I don't know why, sorry.

      This [wikipedia.org] might help. Or it might not. It's late.

    • I'm going to toss this out there but I expect the answer to be "no."

      Does this solve the issue with using quantum entanglement as a possible means of FTL communications? I'm under the impression that quantum entanglement can't be used for this because the act of looking at the particle would change the state. But this seems to be away around that.

      So am I wrong here and why?

      The issue is that the information has to be minimal enough to not be verifiable -- so you could never guarantee that it's the same neutron you're measuring. But I guess if you had enough of them, you MAY be able to send a message through the properties. But that would involve quantum entanglement on a massive scale; something we can't do yet. Plus, these quantum measurements are usually done on things that can only be measured reliably for very short periods of time... which doesn't give time to get them

      • so you could never guarantee that it's the same neutron you're measuring.

        Sure you can - just use one neutron. I thought the problem was that, while you can measure the neutron and know instantly what your partner will have measured, this doesn't allow communication. It's like two people listening to the same radio broadcast. They both have the same information (and can know [well, assume with a high degree of confidence, technically] that they both have it) but there's no way to use this knowledge to pass information between each other.

        Knowing if a particle's wavefunction has be

    • by jfengel (409917)

      Here's the thing: not only does entanglement not sent information faster than light, it doesn't send any information at all. Nothing that happens on your end affects the particle at the far end. You've learned something about the particle at the far end by doing the experiment, but only about properties it possessed before the particles were separated, not about anything that happened to it after the fact.

      Now, you have to be very careful here, since the "property" I'm talking about is a quantum property, no

  • by mrwolf007 (1116997) on Friday January 10, 2014 @06:53PM (#45922041)

    At issue is whether the result is really paradoxical or simply an ordinary consequence of the way the experiment is set up. For example, perhaps the experiment measures the properties of different neutrons in each of these places.

    Personally i dont even understand why those guys are thinking they are measuring the properties of the same neutron.

    • by wonkey_monkey (2592601) on Friday January 10, 2014 @07:24PM (#45922295) Homepage

      Personally i dont even understand why those guys are thinking they are measuring the properties of the same neutron.

      (Most insightful part of comment highlighted.) Because they're scientists with more knowledge of physics than you or me?

      I don't understand why you'd automatically assume they haven't measured the same neutron. When someone with more physics degrees than me makes a new claim about physics, I tend to default to the understanding that I'm not entirely qualified to go jabbering on the internet that they've probably just got it wrong - certainly without giving any reason beyond "I don't get it so it can't be right."

      Perhaps they have got it wrong; time will tell. I think it's safe to assume that at the very least they remembered to rule out the obvious alternative explanations before publishing.

      • by tftp (111690)

        I tend to default to the understanding that I'm not entirely qualified to go jabbering on the internet that they've probably just got it wrong

        That's not what GP was saying. He was asking WHY they thought those two neutrons to be one. He did not call them idiots who cannot count, for example :-) The GP's question is valid and insightful, that's why it got moderated as such.

        I'd like to hear a simple explanation myself. Unfortunately, none is provided above. Appeal to authority is not good enough.

        • He was asking...

          That's kind of my point - he wasn't asking a question. He made a statement in what reads like a disingenuous tone ("i dont even understand why...")

        • Oh yes, and also:

          The GP's question is valid and insightful, that's why it got moderated as such.

          [...]

          Appeal to authority is not good enough.

          ;)

      • Because they're scientists with more knowledge of physics than you or me?

        I don't understand why you'd automatically assume they haven't measured the same neutron.

        Because, quoting the article:

        In this experiment, the neutrons pass through a magnetic field to ensure that the spins are aligned in the same direction.

        Nice, get a couple of them, guaranteed to have the same magnetic properties. Sounds fine. Lets go on.

        They then enter the interferometer where the beam is split so that the neutrons pass down both arms of the device before recombining to produce an interference pattern picked up by a pair of detectors.

        Fine. Split them up like a normal double slit experiment. As stated, neutrons in both arms.
        But now we have a paradox?

        The paradox arises when the team carried out two weak measurements. The first found the presence of neutrons in one arm while the second noted their magnetic properties in the other arm.

        As stated above, there are neutrons in both arms. They find evidence of presence of neutrons in one arm (obviously, since they are in both arms) and measure magnetic properties in the other arm (obviously, since there neutrons there as well).
        The result is so blatan

        • by Carnildo (712617)

          Fine. Split them up like a normal double slit experiment. As stated, neutrons in both arms.

          If it's like the standard double-slit experiment [wikipedia.org], each neutron travels through both arms of the interferometer. Under quantum mechanics, any particle behaving in a wave-like manner can do this sort of thing, even if the particle is of a type (such as a neutron) that people normally think of as being a discrete object.

          This is where my understanding gets fuzzy, but I think what they've done is rig things up so that the

          • If it's like the standard double-slit experiment [wikipedia.org], each neutron travels through both arms of the interferometer.

            Incorrect, quoting wikipedia:

            Furthermore, versions of the experiment that include particle detectors at the slits find that each photon of light passes through one slit (as would a classical particle), but not through both slits (as would a wave).

            The experiment might have been interesting if the scientists had shot single neutrons instead of stream of multiple neutrons.

            • by wonkey_monkey (2592601) on Saturday January 11, 2014 @10:10AM (#45925913) Homepage

              Incorrect, quoting wikipedia:

              Furthermore, versions of the experiment that include particle detectors at the slits find that each photon of light passes through one slit (as would a classical particle), but not through both slits (as would a wave).

              That doesn't mean that in versions without particle detectors the photons don't go through both slits.

              Any photons which are detected are forced to have gone through one slit or the other. If the detectors are 100% efficient, all the photons will be absorbed so there'll be no interference pattern to detect. If the detectors aren't 100% efficient (or not present) any undetected photons will go on to produce the interference pattern - meaning they must have gone through both slits (since the experiment produces the same result when photons are emitted one at a time).

              The experiment might have been interesting if the scientists had shot single neutrons instead of stream of multiple neutrons.

              It still is interesting, because (as I understand it) they detected the presence of neutrons only in one arm and their spins only in the other.

              • If the detectors aren't 100% efficient (or not present) any undetected photons will go on to produce the interference pattern - meaning they must have gone through both slits

                No. Sorry to be pendantic, but its kinda necessary with stuff like this.
                They merely behave like a classic wave. This does not mean the photon (or better a particle like an electron which actually has non-relativistic mass) actually goes through both slits. And barring some duplication or splitting and instant mass teleportation the "moment the universe needs to decide" (the measurement) it doesnt go through both slits at the same time. But paradoxly still behaves like classic wave.

                It still is interesting, because (as I understand it) they detected the presence of neutrons only in one arm and their spins only in the other.

                Well, they theoretice that

                • To be pedantic, do you have some sort of real distinction between a particle appearing to go through both slits and a particle going through both slits? Is your statement that it doesn't go through both slits based on something objective, a personal belief, or "not even wrong"? Is there some sort of physics experiment that shows it only goes through one slit, or are you simply too sane to grok quantum mechanics?

                  Waves can go through two slits at the same time, as you can see in any sort of ripple tank.

                  • Simply put, if you extend the slit length, like in an interferometer, you will never detect "half an electron" in either side. So yes, all measurements indicate that every single electron only goes through exactly one slit.
                    Do an experiment that can somehow detect the presense of a partial electron and i will gladly change my opinion.

                    • However, the behavior is very different when you measure which slit an electron goes through as opposed to not measuring. Therefore, something different is happening when you don't measure the slits. The interference pattern created while sending one electron at a time through the apparatus suggests it goes through both slits, and there's absolutely no evidence against it.

                    • and there's absolutely no evidence against it.

                      Well, except for the math being used. You are implying that overlapping states are actually that, instead of just discrete possibilities for one state or another. Schrödingers cat is said to be neither dead or alive. Why? Simply because of the unknown state. It doesnt even have anything to do with atomic decay or whatever, just with the uncertainty provided by a random event generator.
                      Its even more hillarious when you look at Schrödingers millionaire. Schrödingers millionare is known to play

                    • Um, the math being used? If an electron simply goes through one slit or the other, it doesn't produce an interference pattern. We can test that by testing which slit the electron goes through, and, sure, no interference pattern. If we don't observe that, we get the interference pattern. Clearly, the electron is doing something different, and this rather implies not going through just one slit. It isn't that we don't know which of two states the electron is in, it's that the electron behaves differentl

        • Because, quoting the article [...] [t]hey find evidence of presence of neutrons in one arm (obviously, since they are in both arms)

          Reading through the paper - which, admittedly, is mostly beyond me - suggests that while they were able to measure the particle's spin in path I and location in path II, they weren't able to measure the spin in path II and the location in path I. So the neutrons aren't "in" both arms.

          From the paper:

          We observe that an absorber in path I does not change the measurement outcome, while a magnetic field does. In contrast to that the absorber has an effect in path II, while the magnetic field has none. The neutrons behave as if particle and magnetic property are spatially separated while travelling through the interferometer.

          There's also an earlier bit which says:

          This [the use of absorbers in the paths] already tells us that the neutrons' population in the interferometer is obviously higher in path II than it is in path I.

          -----

          The result is so blatantly obvious.

          Isn't it likely that the reason it seems so blatantly obvious is that you haven't understood what they claim to have achieve?

          In that case the article is utter crap for not mentioning it.

          There's only so far a science article writt

      • by oldhack (1037484)

        Perhaps they have got it wrong; time will tell. I think it's safe to assume that at the very least they remembered to rule out the obvious alternative explanations before publishing.

        I highlighted what you considered "insightful". Listen to your own advice and keep your jabbering within your pay grade.

    • by Anonymous Coward
      They aren't measuring the "same" neutron, they're measuring groups of spin-aligned neutrons against each other.
    • the same neutron

      That expression has no meaning in the context of quantum mechanics. You measure a neutron, and then you measure a neutron. You can't apply "same" or "another" to those phrases.

  • Weak measurements (Score:5, Interesting)

    by SoftwareArtist (1472499) on Friday January 10, 2014 @07:16PM (#45922235)

    Here's a more familiar example of a weak measurement. QM says you can't measure the magnetic moment of a single particle along two perpendicular axes at the same time. And yet, you can easily measure the magnetic moment of a bar magnet along two perpendicular axes at the same time. How is that possible? The bar magnet's moment is just the sum of the ones from all the particles that make it up. So by measuring the total magnetic moment, aren't you measuring the moments of all the individual particles, and hence violating the uncertainty principle?

    The answer is no. When you measure the total moment of a macroscopic magnet, you only need to interact very very weakly with any individual particle, so the experiment only has a tiny effect on the state of each one. The more particles you sum over, the less information you need about each one, so the less restrictive the uncertainty principle becomes.

    But the mathematical details of the explanation are curious. Weak measurements were originally proposed based on time reversible interpretations of QM, in which the future can affect the past and it's basically arbitrary which direction you call "forward in time". It was later shown that other interpretations also predicted them - of course they must, since the interpretations are mathematically equivalent. But the explanations are very different. Other interpretations explain them through an incredibly complicated series of cancellations, whereas in time reversible QM the explanation is straightforward, almost obvious. So is this evidence that time reversible QM is correct? At the moment, that question is more philosophy than science, but it's interesting to think about.

    • by khallow (566160)

      QM says you can't measure the magnetic moment of a single particle along two perpendicular axes at the same time. And yet, you can easily measure the magnetic moment of a bar magnet along two perpendicular axes at the same time.

      The uncertainty principle says that you can't measure two properties to a greater precision than the norm of the commutator of those two properties as operators. For a single particle, that value tends to be large relative to the size of the magnetic moment components while in a bar magnet the values of the magnetic moment are much larger, being ensembles of many particles (usually 20+ orders of magnitude larger) while the commutator doesn't increase so.

      So is this evidence that time reversible QM is correct?

      How can a theory be more correct than an equivalent th

      • How can a theory be more correct than an equivalent theory?

        Yes, I simplified a bit to keep my post from getting too long. There are tons of interpretations of QM: dozens we know about, and probably lots of others that no one has thought of yet. Some are "pure interpretations", meaning they make no predictions beyond the ones made by QM itself. No experiment can ever distinguish between two pure interpretations. But a lot of them aren't pure interpretations. They still reproduce the prediction of QM to high accuracy, but in principle an experiment could disting

        • by khallow (566160)

          But right now that evidence doesn't exist

          There will never be enough evidence to uniquely distinguish one theory (or rather equivalence class of theories) from every possible one of the rest (not to mention the unfalsifiable stuff). But we have been able to filter out a lot of theories (for example, most hidden variable theories have been ruled out).

          • (for example, most hidden variable theories have been ruled out).

            Actually that's not true. Only some very limited classes of hidden variable theories have been excluded. Bell's theorem is based on a set of very doubtful assumptions that weren't well understood until decades after it was first introduced. For example, it requires locality (which is now widely suspected to be false) and no retrocausality (which, assuming CPT invariance really is an exact symmetry, is almost definitely false). It also requires a really wacky assumption that your choice of what measureme

            • by khallow (566160)

              For example, it requires locality (which is now widely suspected to be false) and no retrocausality (which, assuming CPT invariance really is an exact symmetry, is almost definitely false). It also requires a really wacky assumption that your choice of what measurement to perform is uncorrelated with the values of hidden variables at the place and time where you make the choice

              Sorry to step on a nerve with my not-completely-well-founded assertion, but I have different views of every assertion you made above.

    • by Boronx (228853)

      They already found out that the universe is not left-right symmetric. Doesn't that mean it's also not time symmetric ? In addition to the rather large amount of circumstantial evidence, of course.

      • As far as we can tell, CPT invariance [wikipedia.org] is an exact symmetry of the universe. So the details are slightly more complicated, but time, charge, and parity are elements of a single symmetry.

  • by Applehu Akbar (2968043) on Friday January 10, 2014 @08:13PM (#45922653)
    Holy crap! I forgot to feed my cat! Being a physicist, I now have no idea whether he's alive or dead.
  • by PPH (736903)

    Or Schrodinger?

    If we are going to use bad analogies, could we please stick to cars?

  • by Anonymous Coward

    Why is it that 90% of the comments on this interesting subject are silly attempts to make a joke?
    Is it perhaps that the smart audience of /. left this place and I am stuck with the 4chan crowd?

    It used to be that these subjects generated a lot of interesting discussion. IANAP but I always learned something from them. Now I just went through 47 comments and only 4 are somewhat interesting. I feel like I am wasting my time.

    • by artor3 (1344997)

      Because no one on this site is smart enough to really understand the topic. That's always been the case. Even those times in the past where you thought you were learning something, it was most likely from a post by someone half-remembering their undergrad physics classes.

      • Bash physics:
        echo $0
        quit

        Only for the analogy to be correct, the script cannot have a name, location, an OS, or user running it. Now the object is to come up with a theory (as to what the hell $0 is) that's currently unable to be disqualified. GO!

        Now you're doing (something just like) physics! And since this is the case, not only are there no people on this site able to "understand the topic", but neither are the folks on any other site. In my opinion, physicists are trying to count to zero, in t
        • by aiht (1017790)

          not only are there no people on this site able to "understand the topic", but neither are the folks on any other site. In my opinion, physicists are trying to count to zero, in the most intelligent way possible.

          I will give you the benefit of the doubt and trust that you are actually aware that the doodad you used to post this comment does not work by magic, even though you seem to be implying that physics is pointless.

    • It may be because of the same reason that you're posting as AC. Also, this article is a bit... odd. It's not announcing any sort of breakthrough, just theory. And who isn't tired of theories, especially on Slashdot.
  • by Anonymous Coward

    The quantum world doesn't work that way. A photon passing through glass will exit the exact same point every time, based on the superposition of all interactions that it had the probability of transversing. You can't cheat. Your measurements are not accurate.

  • by Anonymous Coward

    I am a fucking physicist and I have absolutely no idea what is happening in the experiment related to the Cheshire Cat. If this is some sort of sci-fi/fantasy lingo, it is not on the Wikipedia disambiguation page for Cheshire Cat, and it really bothers me when I see physics articles delivered to the general population that aren't even sensible to an expert in the field.

  • by Anonymous Coward

    If Schrodinger had lab assistants I can imagine this dialogue:

    "A box arrived for you today, Dr.Schrodinger. I took the liberty of opening it for you. Why did you order a dead cat?"

  • They haven't even ever quantum entangled something as large as a neutron.

    They have quantum entangled photons. The amount of energy in a neutron compared to the run of the mill photon is off the scale.

    I'm drawing a blank as to what the hell any of this article is supposed to mean, quite frankly ...
    • They haven't even ever quantum entangled something as large as a neutron.

      From Wikipedia [wikipedia.org] (although I'm not exactly sure what "has been demonstrated with" means):

      ...has been demonstrated experimentally with photons, electrons, molecules the size of buckyballs

  • What about entanglement? Does that means I can not entangle two particles, send one far away, change its state, and weak-read the state change on the first article so that entanglement is not lost and I can do it over and over?

    • by manu0601 (2221348)
      Oops, sorry: I see other posted the same question in the meantime. Too bad one cannot cancel its own post. Perhaps I can still mod me down redundant :-)
  • (theoretical physicists whiz kids waving hands really close in front of mr. Q's face)

    "We're not touching you.... we're not touching you... we're not touching you.... haha hah haaha.. we're not touching you..."

    Newsflash: Quantum Physicists Discover New Quantum State: ANNOYED - Story at 11.
  • From the article:

    At issue is whether the result is really paradoxical or simply an ordinary consequence of the way the experiment is set up. For example, perhaps the experiment measures the properties of different neutrons in each of these places.

    Uncertainty here kind of negates the credibility of the whole experiment, doesn't it?

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