Researchers Find "Fattest Schrodinger Cats Realized to Date"

By Veronique Greenwood | April 7, 2011 9:38 pm

What’s the News: On a quest to discover at what size the kooky quantum physics that governs atoms (teleporting!) gives way to the ho-hum classical physics that governs humans (no teleporting), scientists have shown that if conditions are right, a molecule of a record 430 atoms can be in two states at once, like Schrödinger’s infamous cat. For the last three decades, researchers have been watching progressively larger objects under special conditions to see how big of an item they can catch showing quantum behavior. This molecule, which was created by a team at University of Vienna and their collaborators for the experiment, is the largest on record.

How the Heck: The researchers shot a beam of molecules through a series of three sets of slits—an updated and modified version of the classic double-slit experiment—and measured exactly where the molecules arrived at the end of the beam. Graphs of where the molecules arrived show a fluctuating pattern indicating interference between the parts of the beam going through different slits. Since the molecules interfered with each other (not something well-behaved classical molecules do) that means they went through the slits in a superposition of multiple quantum states—the same way Schrödinger’s cat is in a superposition of alive and dead states.

What’s the Context:

  • Scientists who study this transition, called the “quantum-classical boundary,” seek to understand how classical physics arises from quantum physics. At some point between single atoms and the collections of 7 x 1027 atoms that make up humans, the cumulative effect of all those atoms interacting with each other and their environment becomes the effect we call classical physics.
  • Physicists call the phenomenon behind the quantum-classical boundary “decoherence.” Simply put, as soon as atoms start to interact irreversibly with objects close to them, be they other atoms or some aspect of their environment, their zany superpowers seem to disappear.
  • A major breakthrough in this field came in 1999, when Anton Zeilinger and his team at the University of Vienna found that buckyballs—soccer ball­–shaped molecules of 60 carbon atoms—had properties of both waves and particles, a distinctly quantum trait. The lead author on this paper, Markus Arndt, was on that team.

The Future Holds: More experiments, larger objects. Arndt, in an interview with Nature News, said that although custom-made molecules are easiest to handle, researchers could look for quantum behavior in viruses, pending the resolution of some technical difficulties.

Reference: Gerlich, S. et al. Quantum interference of large organic molecules. Nat. Commun. 2:263 doi: 10.1038/ncomms1263.

CATEGORIZED UNDER: Physics & Math
MORE ABOUT: quantum mechanics
  • http://poweroftheunknown.wordpress.com/ POTU

    There is no magical cut-off between small and large objects. All sizes of objects are in multiple quantum states, up to and including the entire universe. This is Everett’s ‘Many Worlds’ interpretation of quantum mechanics.

    The unknown part is why our consciousness only experiences 1 universe out of many parallel universes. It’s a similar question as to why we only experience 1 moment in time (now) out of the whole of eternity.

  • MorePlease

    @POTU:

    What do you think a good thing to read would be for me to get a grasp on the ideas you’re saying? I’ve heard all of these ideas before but I’ve never found a good, thorough source that seemed to make sense of them and step through them piece by piece. Do you (or anyone else) have any suggestions?

  • shayne

    “The unknown part is why our consciousness only experiences 1 universe out of many parallel universes. It’s a similar question as to why we only experience 1 moment in time (now) out of the whole of eternity.”

    Please don’t use physics as a crutch for mysticism. Both of these questions are extremely well understood, and have been understood for hundreds of years. Many worlds, assuming its true, which we don’t know, offers no refuge for superstion here.

    The reason you only experience 1 moment of time is not a mystery. Its because your only in one period of time, the present. The future hasn’t happened yet so it can’t be experienced because it doesn’t exist, however you DO experience the past via stored memory in your brain.

    The reason you can’t experience multiple universes is because your only present in the one your in. You MIGHT experience some of the outcomes of the resultant physics of it, but you cant experience another universe, because backwards in time only one universe, the one your in is visible (Its a directed tree graph and backwards in time points at the root thus memory can only consist of a single universe) and of course because you can not experience the future (it hasnt happened yet and thus doesnt exist) so therefore you can never experience more than one universe.

    Please don’t import silly mysticism into science.

  • el es jay

    Note to all above on question of being conscious in multiple universes: T’would be best to start by being fully conscious in one universe at a time. Even in one language at a time. Even in one grammar, syntax and spelling at a time.–lsj

  • ian moone

    re: more please
    google search “great science textbooks dvd library”

  • http://www.hats.com christine j sojka

    as far as i know physicists hold the view that time doesn’t exist.time is just an illusion caused by the unfolding of the physical world.

  • Sid

    Very interesting post but one minor correction. You state that the 430 atom molecule is larger than insulin. If you mean has more atoms, then this is incorrect: insulin has 1680 atoms.

  • guineapigdude

    reminds me of Schroedinger’s cat lady, from drabble cast.

    also could this be used as a way of communication?

  • ivan

    @sojka…I was under the impression that time does exist, but an exclusive forward progression of time (the arrow of time) is illusionary. It would help if I was familiar with the maths!

  • Veronique Greenwood

    @Sid: Good catch! Fixed now.

  • lollolloloh

    BREAKING: Time Exists, According to Science

    http://en.wikipedia.org/wiki/Dimension#Time

  • chadachada

    Cool article!

  • Kainsin

    POTU is correct and it’s not mysticism. Many Worlds (while most likely not 100% accurate in its current form) is actually a simpler solution via Occam’s Razor than waveform collapse.

    @MorePlease and anyone else that’s interested, start reading here:

    http://lesswrong.com/lw/r5/the_quantum_physics_sequence/

  • Rich

    @Potu:

    I believe you are correct. But I think consciousness is nothing more than the illusion of experiencing 1 instance at a time. The same thing, expressed in two different ways, essentially. The illusion of choice is another expression of this.

  • Rich

    @Shayne:

    I don’t believe you are correct, and furthermore I don’t believe you understand what Potu is even talking about. Don’t attack it as “mysticism” because it mystifies you.

  • Weezy

    What type of discussion is being made here? Obviously it appears that there is a large amount of philosophical interaction. The “could-bes” and the “what-ifs” are merely speculation based on ideas that have not been proven, but rather cannot be disproven. Scientific theories are still not proven, but they are educated correlations based on detailed observations.

    Philosophy and science cannot coexist. Science is the process of making sense of the world around us using specific rules, and philosophy is merely the pondering of all possibilities. Why respond to a this post suggesting that the perspective covered is wrong or misinformed? Philosophy itself rejects the idea that anything can be proven at all, thus negating the argument that science is wrong.

    There is no way to prove that multiple universes even exist for 100% certainty, nor that we are not an elaborate program for another consciousness. To truly appreciate this post, rather than suggest it is not true, read it for what it is. The fact that there is no way to disprove it makes it just as viable as any other theory. Occam’s razor is merely a suggestion of logic, not a law of physics. “Plurality should not be posited without necessity” simply means that one should examine solutions with the least amount of variables before moving to the complex ones, not that the complex ones are incorrect.

  • Torbjörn Larsson, OM

    So I don’t understand why the article compares with humans. It should obviously be with cats! :-D

    But, a nitpick:

    Physicists call the phenomenon behind the quantum-classical boundary “decoherence.” Simply put, as soon as atoms start to interact irreversibly with objects close to them, be they other atoms or some aspect of their environment, their zany superpowers seem to disappear.

    Decoherence is likely not irreversible.

    At least as far as experiments shows. There is one first that probes decoherence more directly than these by studying coupling to photons in a cavity. It showed that you can go into and back out of partial decoherence reversibly. (I’m sure you can all google it.)

    That accords with Hardy’s toy model of quantum mechanics, where he recovers it by way of a probability formulation. There it is classical mechanics which is discrete (pre and post states) and quantum mechanics which is continuous (continuous transformation between states).

    Of course you can observe irreversibility, which is what observation builds on. But it is no more mysterious than having reversible and irreversible interactions of thermodynamical systems.

  • Torbjörn Larsson, OM

    @ Weezy:

    Indeed, what are you discussing?

    - We can’t “prove” theories. But we can test them to see which we can discard. If we can’t know what is wrong, we can’t know what is correct.

    And beyond testing, competition on the market of ideas means there will be only one; we know the process converges.

    That is a valid, tested theory of science. You can easily run a meta test on actual numbers of successfully tested theories up to a many sigma certainty test of testing itself!

    - As for quantum mechanics, the arguable existence of the decoherence process and its as of yet validity under special relativity means that theories of quantum mechanics can tentatively be rejected: classical “instant collapse” copenhagen, consciousness collapse.

    So this is a putative test that many world theory can pass. It is further _based_ on decoherence instead of being compatible with it like remaining copenhagen theories. And it is the most parsimonious. It has two axioms less than others in an axiomatic formulation, so a minimum of parameters.* Therefore it is favored by many theoretical physicists (Tegmark poll.)

    In the same way that it looks like multiverse cosmology can be observed and tested (read Cosmic Variance’s posts here), it is likely that many worlds theory can be probed.

    ———————–
    * In theoretical physics it is not the number of variables that is minimized but the sum of degrees of freedom. In a model each variable is preceded by parameters that tells of freedom of the model.

    The value of those parameters is what the theory predicts, so that is the number of tests that needs to be performed to fully test it.

    The degree of freedom can be minimized if the model can be put on unit free basis, so that is the true sum of freedoms. *That is the real independent number of ways the model changes when parameters changes.* (In loose words, it is the topology of the model.)

    So it tells of complexity of the model, and how easy it is to get it wrong. It also tells you how many times you risk reversal between models under testing, and that parsimony minimizes that. That is two reasons to use “parsimony first” in a research strategy.

    The last reason is that one can observe that nature “prefers” simpler theories in practice. Not always, but most often.

    So that is not what is meant when one loosely says quantum mechanics has “no hidden variables”. That is true but inconsequential here.

    But one can also show that quantum mechanics minimizes the number of needed parameters compared to classical mechanics. So quantum mechanics is truly more parsimonious than classical mechanics.

  • Torbjörn Larsson, OM

    @ Weezy:

    Occam’s razor is merely a suggestion of logic, not a law of physics.

    As I noted in the earlier comment, there is indeed such a “law” or rather a really solid correlation (with outliers).

    Why that is one can speculate over.

    Degrees of freedom translates to algorithmic complexity. Anthropically universes that prefers parsimony are simpler, less messy, so more likely to have life.

    Also, such physics need less resource to produce a reaction on an action. Everything else alike that translates to time. That should also be a win in the anthropic sense, more productivity of universes and life both. In an eternal inflationary cosmology these are exponentially competitive advantages, so even small differences from “simplest possible” would get prohibitively punished.

    Finally, consider cooling in an expanding universe and the spontaneous symmetry breakings that follows.

    A maximum symmetric, chaotic initial state is simple enough. Many symmetries (charges; laws) but then also likely divided into simple similar ones.

    Similar to the suggestion above the later processes of symmetry breaking would only add smaller amounts of additional parameters as each universe cools.

  • Weezy

    First, let me start by saying that I am a strong advocate for Everett’s views. The existing presence of all possibilities on an unending plane of branching universes would explain many things and is quite fascinating. I am by no means suggesting that it is false.

    Occam’s razor is not a “law” in the common sense. For instance, for a simple mathematical problem such as 1+1, Occam’s razor would tell us to first examine the initial quanties of a+b in a base-10 system (since that would be the simplest method). However, what if you add 1+1 visually in a linear pattern? 1+1 now becomes 11 and is equal to 10+1 (in base-10). Furthermore, if you view 11 in a binary system, it becomes 3. In hexadecimal it becomes 16.

    I am not necessarily saying that we do not exist in a multiverse, but rather that, just because it makes logical sense, does not mean that it is fact. Likewise with subatomic particles — just because they behave one way, does not mean that the macro-universe is also bound by such a pattern. I am simply saying that I would not be so bold as to say ‘there is no magical cut-off’ since both views for and against universal wavefunction remain unproven.

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