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Published online 2 July 2008 | Nature 454, 8-9 (2008) | doi:10.1038/454008a
News
Reincarnation can save Schrödinger's cat
Physicists reverse quantum–classical transition.
It's one of the most perplexing questions in physics: how does the seemingly exotic behaviour of tiny particles in the quantum realm collapse to create the classical reality observable in matter that is at least a molecule big? Now, an experiment further muddies the distinction between the two realms by demonstrating that it is possible to halt the transition from the quantum to the classical in its tracks — and reverse it. The achievement could provide quantum computing with a crucial capability (See 'A fix for quantum computers').
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I appreciate that someone named Katz is working to save [Schrodinger's] cats.
I find it disturbing that Nature is now reporting "news" from an non-peer reviewed source of pre-prints (arXiv.org). I would hope the editors will maintain higher standards in the future by waiting for official publication of results.
This is indeed a piece of exciting if not nerve-cracking news. The experiments have been carefully conducted, the hypothetical projection made, only waiting to be verified or refuted by independent replication. Dancing with quantum physics can be likened with dealing with demons of the minutest scale. Once we were told that before the box is opened, the Schrodinger’s cat is both alive AND dead. As soon as there is an intervention and the box is opened, the cat is either alive OR dead. Now we are told that it is possible to arrest the transition from the quantum state to the classical state and even reverse the process. The cat is finally reincarnated, isn’t this wonderful? Will it not spell a new dawn for quantum computer technology? Perhaps someone would want to think to rewrite The Tao of Physics. (Tan Boon Tee)
You mean "NEWS" was dead when you opened the box in which it was kept? Thanks to we find it alive here.
(1) It's but another example of "quantum trickery" generously supported by the particularly "rigorous" and "objective" enterprise of official science explicitly postulating supernatural mysteries as a basis for all its constructions (and now also for "really miraculous" quantum computers always strangely delayed though in their real-world appearance). In reality, one may deal here with a case of repeated quantum measurements of the same quantum system, but provided with unlimited "quantum hype" and misleading "cat" analogies. If a quantum system is measured, it irreversibly collapses, but usually only "for a moment" of measurement, after which it continues its quantum existence (though in a probabilistically changed state), unless you destroy it intentionally and explicitly (which can be done, after all, to any, even classical system). If, in a simpler setting, one fixes the electron passage through a particular slit in a classical two-slit experiment, then one irreversibly destroys indeed the related "quantum" features (like wave interference pattern), but a rapid enough electron need not be "totally destroyed" by this measurement moment and will continue its further propagation as a quantum particle that can be variously measured again as such, etc. The same is true for greater quantum systems provoking a misleading "cat" analogy. After which, especially in the case of more complicated (extended) systems, every Katz can add up its own cat (hello, Deborah) and other infinitely misleading verbal decorations (after all, those "quantum interpretations" have always been a whole branch of science!), but quantum collapse remains a one-stage, irreversible process. It is as irreversible as time itself because such kind of complex-dynamic interaction processes is what constitutes the very essence of real time and its irreversible flow, at various levels of interaction and resulting structure formation (http://arXiv.org/abs/physics/0211071). The lowest-level structure formation (alias "quantum collapse") cannot be "split" just because it's the most elementary one: if you try to split it into "stages", it will first "resist" to a certain degree (not too much!), but then can either be totally destroyed as a system or produce another indivisible and irreversible collapse, to another, probabilistically determined state. (2) By contrast, I don't agree with Brian Kessler's opinion above that pre-printed results should not even be described in Nature News and discussed. If we accept such approach then we lose a huge part of so much needed creativity (let alone simple interest) in science. Science, and especially today's science, is a "dish" that is good while it's still hot, and it also tends to "irreducibly collapse" to something much less interesting soon after the first announcement of a result. The problem is not here, it is in the invariably uncritical, passive presentation of ANY (both officially unpublished and published!) results by PROFESSIONAL science journalists, in Nature and elsewhere. They tend to see their task only in direct, obedient "translation" of the presented professional-science results (always from an "officially high" laboratory) to a "half-exact", quasi-ordinary language presumably better understandable to various interested "non-specialists". But that's certainly not enough, especially at the Nature level of popularity, because there is no useful discussion without (constructively) critical attitude: we just obtain a mechanical repetition of subjective authors' views, all their advances but also mistakes including. While such strangely "complaisant" practice is but another manifestation of effectively totalitarian structure of science today (see http://arxiv.org/abs/0705.4562 ), one can find a detailed, constructive proposition for another, causally complete, realistic understanding of quantum mechanics and fundamental physics elsewhere (see http://arXiv.org/abs/physics/0601140 and http://arXiv.org/abs/physics/0401164 for recent reviews). It is only such, dynamically complete, realistic and demystified version of fundamental physics that can serve as a reliable basis for further progress avoiding those infinite series of tricks with quantum mysteries, quantum computers and other "officially supported" frauds of the explicitly deficient and fruitless doctrine of unitary science.
It seems that some of the commentary has gotten a little inflammatory and inflated. There is no fraud here: quantum physicists merely tend to forget the differences between a model of something and the real thing. Quantum physics presents a very nice model of many aspects of behavior, but has clear shortcomings in other areas. We just have to get more comfortable with saying "I don't know", rather than confusing a model with reality.
What's odd to me about this is that there have been many many experiments in which particles separated in space, but "united" into a single coherent system, are observed, when one of them is disturbed, to both, simultaneously, *no matter how far apart they are*, decohere into two particles with opposite spins, or whatever. Now, if this decoherence over space takes place in the same (infinitesimal?) interval no matter how far apart the particles are, surely there's something wrong about the reasoning in this experiment? How can these particles decohere in a finite time in this situation, yet analogously decohere instantly in spatially-separated experiments? I'd appreciate someone's answer to this... Thanks.