The 'great smoky dragon' of quantum physics

March 10, 2016

University of Vienna physicists have, for the first time, evaluated the almost 100-year long history of quantum delayed-choice experiments—from the theoretical beginnings with Albert Einstein to the latest research works in the present. The extensive study now appeared in the renowned journal Reviews of Modern Physics.

Since the 17th century, science was intrigued by the nature of light. Isaac Newton was certain that it consists of a stream of particles. His contemporary Christiaan Huygens, however, argued that light is a wave. Modern quantum physics says that both were right. Light can be observed both as particles and as waves—depending which characteristic is measured in an experiment, it presents itself more as one or the other. This so-called wave-particle dualism is one of the foundational principles of quantum physics. This questions our common sense: can one and the same indeed be of two contradictory natures at the same time?

Measuring the undefined

In the 1970s, the American physicist John Archibald Wheeler (1911-2008) metaphorically compared the fundamental indefiniteness of quantum mechanical phenomena with a "great smoky dragon": One can see the tail, that is the source of the particles, and the head, which are the measurement results. But in between the whole body is covered in smoke. And this smoke cannot be removed: Only the measurement defines the phenomenon, not the other way round. To put this concept into a concrete setting, Wheeler proposed his famous delayed-choice . In this thought experiment, the choice to determine the particle or wave nature is delayed or even changed during the experiment. Thereby, one and the same phenomenon, for instance light, manifests itself as a particle or as a wave in the same experiment. It can therefore indeed be both, depending on the time and nature of the measurement.

In the past decades, quantum physicists have tried to experimentally test Wheeler's thought experiment to empirically substantiate the wave-particle duality. Xiao-song Ma from the Nanjing University, Johannes Kofler from the Max Planck Institute of Quantum Optics, and Anton Zeilinger from the University of Vienna and the Institute for Quantum Optics and Quantum Information (IQOQI) of the Austrian Academy of Sciences have now shown the success of this endeavor in an extensive study, which sums up and evaluates the whole history of delayed choice experiments.

While the concept of wave-particle duality can be traced back to Albert Einstein's explanation of the photoelectric effect via photons in 1905, it took until the 1980s that the first delayed-choice experiments were realized. "Only through the development of modern quantum optical techniques for the fast and precise measurement of light it was possible to put Wheeler's thought experiment into practice", says Xiao-song Ma, lead author of the study.

Important for quantum cryptography and quantum computers

"Experiments of this kind confront us with fundamental questions of quantum physics", adds Anton Zeilinger. "However, they also have significance for future applications such as in quantum cryptography or the development of quantum computers." Delayed-choice experiments can be applied to the quantum mechanical phenomenon of entanglement, which is important for the security of quantum communication. Regarding quantum computers, there are certain scenarios where delayed-choice experiments can increase the computation speed. The authors of the study, which now appeared in the journal Reviews of Modern Physics, expect that delayed-choice experiments will continue to bring further insights into as well as practical applications for technologies basing on them.

Explore further: Quantum physics mimics spooky action into the past

More information: Xiao-song Ma et al. Delayed-choice gedanken experiments and their realizations, Reviews of Modern Physics (2016). DOI: 10.1103/RevModPhys.88.015005

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arom
1 / 5 (4) Mar 10, 2016
In the 1970s, John Archibald Wheeler metaphorically compared the fundamental indefiniteness of quantum mechanical phenomena with a "great smoky dragon"…

In the past decades, quantum physicists have tried to experimentally test Wheeler's thought experiment to empirically substantiate the wave-particle duality…

"Experiments of this kind confront us with fundamental questions of quantum physics", adds Anton Zeilinger…


So it seems that what we have to do is finding how the magic dragon work, i.e. the mechanism which explain the wave-particle duality …
http://www.vacuum...19〈=en
Hyperfuzzy
1 / 5 (3) Mar 11, 2016
This is silly. The particle emits waves wither it enters the slit or not. The "photon" is 1/surface area of the sphere about the particle. It is a field not a particle. Who makes this $hit up? OK, a thought experiment, aren't we in enough trouble over-thinking physics?
Whydening Gyre
not rated yet Mar 11, 2016
Spin.
FineStructureConstant
5 / 5 (3) Mar 16, 2016
The particle emits waves wither it enters the slit or not
If the particle were to "emit a wave", it would lose energy and the wave would simply spread out. But there is no wave, since there IS nothing (i.e. no "ether" or other putative fluid filling space) to wave or move. Your dime-store particle scenario can do nothing to explain the double-slit experiment, which can be said to
demonstrate... the fundamental limitation of the ability of the observer to predict experimental results, Richard Feynman called it "a phenomenon which is impossible […] to explain in any classical way, and which has in it the heart of quantum mechanics. In reality, it contains the only mystery [of quantum mechanics]." Feynman was fond of saying that all of quantum mechanics can be gleaned from carefully thinking through the implications of this single experiment - Wiki
, quoting the well-known bongo-player and Nobel laureate Richard Feynman. Ever heard of him?
compose
Mar 16, 2016
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FineStructureConstant
5 / 5 (4) Mar 16, 2016
We have classical quantum mechanics analogy from 2005
Your point being?

Your link leads to an article in PO describing the interactions between "an oil droplet and its associated surface wave". As the authors of that paper acknowledge in respect of the QM double-slit experiment:
if one observes the interference [of a single particle after negotiating the two slits], then everything is as if the particle had passed through both slits. These results are entirely predicted in the formalism of theoretical quantum mechanics, even though it is difficult to get an intuition for them
.

The oil droplet experiment is interesting in itself, but teaches us nothing about QM. Weasel is as weasel does...
compose
Mar 16, 2016
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compose
Mar 16, 2016
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compose
Mar 16, 2016
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compose
Mar 16, 2016
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compose
Mar 16, 2016
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Phys1
5 / 5 (1) Mar 16, 2016
The risk of interpretations is that they lead us astray, which is what happened to compose.
The only interpretation I know that does not do this is the one of L.E. Ballentine.
His book can be found as a pdf on the internet.
compose
Mar 16, 2016
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Phys1
5 / 5 (1) Mar 16, 2016
@Hyperfuzzy
This is the most difficult fundamental problem of modern physics
and you solve it in 6 incoherent sentences?
Phys1
5 / 5 (1) Mar 16, 2016
a phenomenon which is impossible to explain in any classical way, and which has in it the heart of quantum mechanics
Some textbook weasel phrases are more difficult to eradicate than others. We have classical quantum mechanics analogy http://phys.org/n...ic.html, i.e. more than ten years already.

Are you calling Feynman a textbook weasel?
I don't believe the shit I read here.
Repeat that if you dare.
compose
Mar 16, 2016
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Phys1
5 / 5 (1) Mar 16, 2016
I'm not aware of any astray - do you?

"astray" is an adverb, so what do you mean?
The problem is, the statistical interpretation of QM doesn't describe the real situation fully. We can see it even at the case of most familiar double slit experiment. At the http://i.imgur.com/NiCORMZ.gif we can see the result of double slit experiment with long-wavelength photons, on the right the result with short wavelength photons.

What is the source of the picture ?
Statistics is the same, nevertheless the outcome of experiment is still different.

At first sight the detection might be to blame.
Ensemble interpretation cannot account to it, deBroglie/pilot wave interpretation can. Which theory is better, after then?

QM is the same so if the two experiments give different results this has nothing to do with interpretation.
compose
Mar 16, 2016
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Phys1
5 / 5 (1) Mar 16, 2016
Feynman textbooks are still OK at their factual basis, nevertheless their formal superficial philosophy becomes obsolete fast.

Remember, the Feynman lectures render verbatim what Feynman said to an audience on a particular occasion.
Yes he was very pragmatic. If you asked those questions you would be left behind and miss out on the real action was probably his attitude. They are still not answered so he had a point. Nevertheless, I also think the story does not end there.
compose
Mar 16, 2016
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FineStructureConstant
5 / 5 (2) Mar 16, 2016
You may like this way of reasoning or you may not - but it still doesn't mean, you've found a hole in its logic
Quite frankly, I'm struggling to find the logic among the holes which pepper your "reasoning"!
It's an intentional strategy: the priests of mainstream science don't want to lose their informational monopoly
- and it's here that you lay yourself bare to ridicule: there's no deep conspiracy in science to misinform or dupe the public. You and others like you may find the math to be too great a hurdle to clear in order for you to understand the science, but it's this simple: neither the science, nor modern technology, could exist without the math.

Try inventing the computer, or an MRI machine, or a Mars rover by touchy-feely wave analogy: you might just as well use kiddie's play dough (plasticine). These things are all made possible by math, the math is here to stay, and it's necessarily going to get more complex as time goes by.

compose
Mar 17, 2016
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compose
Mar 17, 2016
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FineStructureConstant
5 / 5 (1) Mar 17, 2016
The scientists believe as a single man
Hoo boy, are you out of touch! Physics departments, like so many others, are staffed by people (yes, scientists are people, with all of their idiosyncrasies) who are often at war with each other because they hold differing views on certain aspects of the theory. Astronomy / astrophysics / math departments, sociology, archaeology, philology, geology: you name it, there's strife.

Dense aether, dense schmaether: if you want to convince others, including those academics safely ensconced in their life-tenure ivory towers, as well as those plain old lecturers with much less job security, then PUBLISH. And publish in a respected, peer-reviewed journal; otherwise, you're just p*ssing into the wind.

As far as de Broglie/Bohm goes,
Since the 1990s, there has been renewed interest in formulating extensions to de Broglie–Bohm theory, ..(Wiki)
so there are people (i.e. "mainstream" scientists who are conducting research in the field.
compose
Mar 17, 2016
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Captain Stumpy
5 / 5 (1) Mar 17, 2016
It's an intentional strategy: the priests of mainstream science don't want to lose their informational monopoly
@ZEPH
sorry, this is still BS

the problem you have with mainstream science is that it requires (keyword= *requires*) you to present evidence for a claim, and then replicate and validate said evidence

this is where you pseudoscience idiots fail every time, and then when you do, you claim "conspiracy" and make the statements like you do above b/c of your personal failure and the fact that science proves you wrong, an idiot, and believing in something "without evidence" - aka a faith, which you promote like a fanatic, making you religious
The attitude of mainstream science is based on so-called pluralistic ignorance
no, that is the attitude of pseudoscience like yours

that and D-K along with delusional fanatical adherence to known debunked beliefs
again, you built a devotion to and around your *beliefs* making your pseudoscience a religion
Captain Stumpy
5 / 5 (1) Mar 17, 2016
@zeph cont'd
The scientists believe as a single man, the dense aether concept is BS and that it has been disproved by experiments (because they didn't actually understand their physical meaning)
and here is the problem with that...
the reality is that *you* personally don't understand the meaning of the evidence, not that the evidence wasn't understood by the scientists

this can be proven by your adherence to known failed beliefs
Oh, & BTW... scientists don't "believe as a single man" anything, they simply followed the evidence and accepted it's conclusions and figured out (unlike you) that further continuance towards the proposed hypothesis would be stupidly invested time and money and a waste of valuable resources which found (ta-da) the Higgs, Gravity Waves, CMBR, or any other research out there which paid off

what is a pseudoscience conspiracy theorist to do when their livelihood is debunked?
well, as you proved - they repeat the mantra (see your quote/posts)
Phys1
5 / 5 (1) Mar 17, 2016
QM is the same so if the two experiments give different results this has nothing to do with interpretation
Nope,

If that is the case then there is more then one kind of QM and then you are not comparing different interpretations but different theories.
Phys1
5 / 5 (2) Mar 17, 2016
and miss out on the real action was probably his attitude
It's an intentional strategy: the priests of mainstream science don't want to lose their informational monopoly - so that they pretend, that the questions which they're dealing with are principally unsolvable. Their attitude isn't so different from attitude of medieval priests or tribal shamans, who prohibited normal people to experience the drugs on their own - actually the more, the more they did experiment with drugs by itself. The informational monopoly also protects the modern shamans ...

That's crap, compose. Feynman was an unconventional, creative, playful genius. His lectures have taught and inspired whole generations of phsycists.
To call such a man a shaman or a high priest you must be profoundly confused.
Phys1
5 / 5 (2) Mar 17, 2016
Who is compose. Some time ago there was a crank here who permanent claimed that evidence and math based consensus was pluralistic ignorance.
He must have gotten himself kicked off PO and came back 3 weeks ago as compose.
Phys1
5 / 5 (2) Mar 17, 2016
Docile it was. The moron is back.
compose
Mar 17, 2016
This comment has been removed by a moderator.
Captain Stumpy
5 / 5 (1) Mar 17, 2016
Who is compose - Docile
@Phys1
compose/docile is ZEPHIR, the aether religion acolyte
(and he uses the pluralistic ignorance argument a lot, BTW)

more zephir names:

tirahobis, pehawev, yefeb, bikuxem, retejap, xanuxul, debokolin, gipagajege, yejen, godivecu, befa, rovodeh, vudamezire, cuyajuyino, yolepugor, begalifowi, megayugo, juhodo, bibigak, fetem, sosamuca, serijopi, kefof, kuresehe, sator, rihumoyax, otero, Doiea, Technico, nesac, tirahobis, pahawev, yefeb, bikuxem, retejap, xanuxul, debokolin, gipagajege, yejen, godivecu, befa, rovodeh, vudamezire, cuyajuyino, yolepugor, megayuyo, begalifowi, juhodo, bibigak, fetem, susamuca, Lesea, Deisa, vse97513, zetazov, kuresehe, sator, rihumoyax, Eset, Masuzole, Timen, porah, zesuja, leticu, fewitofosa, rhsthjnty, Dethe, Losik, Accata, lajib, hewewa, ciduvutus

just a small sample of names used on PO alone
Captain Stumpy
5 / 5 (1) Mar 17, 2016
"Truth, like gold, is not to be obtained by its growth, but by washing away from it all that is not gold." — Leo Tolstoy
@zeph
problem is that "truth" is entirely subjective unless, and this is important, unless everyone abides by the same set of rules to govern what truth really is

this is the power of the scientific method that you refuse to accept
it's "truth" demonstrates (repeatedly) that you are a believer in a faith (as in, there is no evidence supporting your belief)

by definition of the scientific method, this makes you a religious acolyte, not one who seeks "truth"

therefore, proselytizing about your beliefs makes you a chronic liar just as much as any creationist here

i will reiterate this for you:
just because *you* can't understand the evidence doesn't mean that no one else can either
Phys1
5 / 5 (1) Mar 17, 2016
@compose
You just flushed yourself, docile.
compose
Mar 17, 2016
This comment has been removed by a moderator.
Phys1
5 / 5 (1) Mar 17, 2016
LOL, http://i.imgur.com/LDpsrvh.gifv. It's rather difficult to deny the ignorance of mainstream physics proponents, once we have public demonstration of it right here. The other scientists just think and "argue" in similar way.

Is it true, what CS writes about you ,
that you have accounts all or many of these names?
Please deny or confirm.
Uncle Ira
3 / 5 (2) Mar 17, 2016
Who is compose. Some time ago there was a crank here who permanent claimed that evidence and math based consensus was pluralistic ignorance.
He must have gotten himself kicked off PO and came back 3 weeks ago as compose.


Ol Zephir-Skippy has been around here for 10 or 9 years. He always comes back. After a couple of years of him, he kind of grows on you. (And he is a lot more science smart than Bennie-Skippy and Really-Skippy.)
Uncle Ira
1 / 5 (1) Mar 17, 2016
LOL, http://i.imgur.com/LDpsrvh.gifv. It's rather difficult to deny the ignorance of mainstream physics proponents, once we have public demonstration of it right here. The other scientists just think and "argue" in similar way.

Is it true, what CS writes about you ,
that you have accounts all or many of these names?
Please deny or confirm.


That's not even half of them,,,,
ValeriaT, Yashi17, Netello, Franklins, Callista, Simplimco, Pejico, Writela, Sikla, Jizby, Zwentoo, etc and so on and forever.
vidyunmaya
not rated yet Mar 19, 2016
Sub; IYL 2015 transcends to Conscious Spirit-cosmology-origins
Cosmic consciousness helps revise Cosmology- My book 2000.
Cosmology vedas Interlinks-Divine Frames-magnetic Fields- Uplinks Knowledge Base
Sciennce to philosophy and Nature Provides various Facets of light- see Heart of the Universe-
Cosmos Quest-4-Nature Divine By Vidyardhi Nanduri
http://www.youtub...ure=plcp
Invisible -visible matrix is part of Cosmic Function of the Universe. The super-imposition
of this matrix is presented by me at the Galactic Plane- see COSPAR-2013, Bangkok conference and Highlighted in my ESA proposals
around Sun and more in books. 15 books at www[dot]lulu [dot]com-spotlight-jnani108

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