Physicists control quantum particles by looking at them?
| February 19, 2014 | Posted by News under News, Physics |
Scientists from the FOM Foundation and Delft University of Technology have manipulated a quantum particle, merely by looking at it in a smart way. By adjusting the strength of their measurement according to earlier measurement outcomes, they managed to steer the particle towards a desired state. The scientists published their results online on 16 February 2014 in Nature Physics.
AbstractQuantum measurements not only extract information from a system but also alter its state. Although the outcome of the measurement is probabilistic, the backaction imparted on the measured system is accurately described by quantum theory1, 2, 3. Therefore, quantum measurements can be exploited for manipulating quantum systems without the need for control fields4, 5, 6. We demonstrate measurement-only state manipulation on a nuclear spin qubit in diamond by adaptive partial measurements. We implement the partial measurement via tunable correlation with an electron ancilla qubit and subsequent ancilla readout7, 8. We vary the measurement strength to observe controlled wavefunction collapse and find post-selected quantum weak values8, 9, 10. By combining a novel quantum non-demolition readout on the ancilla with real-time adaptation of the measurement strength we realize steering of the nuclear spin to a target state by measurements alone. Besides being of fundamental interest, adaptive measurements can improve metrology applications11, 12, 13 and are key to measurement-based quantum computing14, 15. – Manipulating a qubit through the backaction of sequential partial measurements and real-time feedback, M.S. Blok, C. Bonato, M.L. Markham, D.J. Twitchen, V.V. Dobrovitski, R. Hanson, Nature Physics. DOI: 10.1038/nphys2881
How does this relate to the quantum Zeno effect? Readers?
Hat tip: Daniel Quinones
30 Responses to Physicists control quantum particles by looking at them?
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Simply stunning!
-Q
Indeed. We’ll be able to predict the weather much more accurately once we can steer clouds by looking at them.
I can influence my children by how I look at them…does that count? 😎
lol w/ EDTA … Proof kids brains are a kind of quantum computers perhaps? 😛
You guys have no idea how difficult it is to trap photons and manipulate them.
Introducing mind-reader slevaRajan.
from the article:
So, if you don’t like that the cat might be dead (nucleus pointing down), you back off the strength of your measurement until you get a reading telling you that the cat might be more alive than dead (nucleus pointing up) and then once you get that reading you increase the strength of the measurement, as long as the measurement continues to give you a more alive than dead state, until you finally have complete information/knowledge that the cat is fully alive.
This seems to me to be another fairly strong confirmation of free will’s axiomatic position within quantum mechanics.
Of somewhat related note:
Which begs the question, ‘can we get a cat to stare at an unstable particle so as to prevent its own death?’
JGuy@7,
You don’t need to be mind reader to see how grossly misunderstood QM is.
Obviously selvaRajan has not met BA, our resident expert on QM.
selvaRajan @ 8
That may be largely true. But where are you looking to make this assessment here? Nobody said anything obviously telling in the comments.
It seems you were making a sweeping claim about either:
1. Everyone reading this thread. But there’s no way you can claim to see how grossly misunderstood an unseen readership (apart from being something like a mind reader).
..or..
2. About four tiny preceding comments that were only either an “wow” type expression, a weather joke, a kids joke, and a responsive laugh. Where’s the “obvious misunderstanding” of QM there??????? LOL!
That’s not to make a claim on the truth value of your statement, but to point out that it’s baseless to judge group’s complete ignorance from such context. So, it’s more obviously an incredibly presumptive (if not worse) to call a group absolutely ignorant on a point that wasn’t even entertained by the group (especially if it includes an unnamed readership).
Again, what you said might be true. But that doesn’t mean it’s justified.
It just seems that we are getting more info each year that the universe behaves more like a great thought then a great mechanism , and if our minds didn’t observe it into existence there is only one great mind I can think of that thought it into existence 🙂
tragic mishap, I certainly don’t claim to be an ‘expert’ on quantum mechanics. In fact I can barely decipher some of the cutting edge papers coming out of present research:
VCQ – Vienna Center for Quantum Science – publications
http://vcq.quantum.at/publicat.....tions.html
But tragic mishap, in so far as God has granted me the wisdom to understand quantum mechanics, what little bit I do understand from Quantum Mechanics is that it is completely incompatible with the presuppositions of materialism and is very comforting to the presuppositions of Theism. For instance:
i.e. I have seen nothing within quantum mechanics to trouble my belief in God as the foundation of reality, in fact recent experiments, such as Leggett’s Inequality, have only greatly strengthened my base Theistic beliefs that God sustains the universe. On the other hand, I do find much within Quantum Mechanics that SHOULD cause the atheistic materialist to be severely concerned that his base beliefs are wrong.
New video clip upload:
Quantum Mechanics – Double Slit and Delayed Choice Experiments – video
https://vimeo.com/87175892
Money quote at the 9:10 minute mark of the video
“That’s the enigma. That our choice of what experiment to do determines the prior state of the electron. Somehow or other we had an influence on it which appears to travel backwards in time.”
Also of humorous note in the video are Max Tegmark and Sean Carrol, (who are atheists who both believe in the epistemologically self-defeating many worlds scenario), both basically scratching their heads and saying, ‘We really don’t know why conscious observation would have such a dramatic impact in the double slit experiment’.
wallstreeter43 @ 11
Interesting comment. Thanks.
Closing the (last) ‘free will’ loophole: Using distant quasars to test Bell’s theorem – February 20, 2014
Excerpt: Though two major loopholes have since been closed, a third remains; physicists refer to it as “setting independence,” or more provocatively, “free will.” This loophole proposes that a particle detector’s settings may “conspire” with events in the shared causal past of the detectors themselves to determine which properties of the particle to measure — a scenario that, however far-fetched, implies that a physicist running the experiment does not have complete free will in choosing each detector’s setting. Such a scenario would result in biased measurements, suggesting that two particles are correlated more than they actually are, and giving more weight to quantum mechanics than classical physics.
“It sounds creepy, but people realized that’s a logical possibility that hasn’t been closed yet,” says MIT’s David Kaiser, the Germeshausen Professor of the History of Science and senior lecturer in the Department of Physics. “Before we make the leap to say the equations of quantum theory tell us the world is inescapably crazy and bizarre, have we closed every conceivable logical loophole, even if they may not seem plausible in the world we know today?”
http://www.sciencedaily.com/re.....112515.htm
bornagain77:
…except that there doesn’t seem to be any free will involved in the experiment. The strength of the second measurement is adjusted based on the result of the first measurement, but whether that adjustment is handled by an unconscious mechanism or manually by the experimenter is not documented (or if it is, I missed it; full paper is here). Actually, even if the adjustment is done by a conscious agent, they’re performing the adjustment based on a fixed rule, i.e. without exercising free will.
As I’ve pointed out before, most of these QM tests don’t directly involve either conscious choice or conscious observation. For example, in the delayed-choice entanglement swapping experiment, the “participants”, (referred to as Alice, Bob, and Victor), are all actually non-intelligent, non-conscious mechanisms (consisting of beam splitters, particle detectors. etc). Specifically, “Victor” contained a quantum random number generator that “chose” what measurement to make.
The proposed experiment using distant quasars is similar in this respect: it proposes using the properties of light from distant sources to choose which measurements to make. Unless you think the quasars and/or photons are conscious, they’re clearly invoking unconscious free will.
(Also, the “free will” involved here is actually causal independence, not libertarian free will, so it’s irrelevant anyway.)
The fact that these effects appear in experiments that do not involve conscious agents means they inherently cannot demonstrate anything about consciousness. In order to demonstrate that consciousness has any effect here, you’d have to perform essentially the same experiment both with a conscious agent and a non-conscious replacement, and get different results. I’ve never heard of this being done; can you point to an example?
To forestall the obvious (but wrong) response: the two-slit experiment doesn’t meet this criterion, because the interference pattern vanishes even if the which-slit information is “observed” by a non-conscious mechanism.
Well Gordon, so do you have a choice to argue against free will or not? Or is this something that you have absolutely no control over? But then again in epistemologically self-defeating your many worlds atheistic worldview, how can there ever truly be a ‘you’ to know that he was being subjected to forces beyond his own ‘free will control’? Hopefully one of your quasi-infinite selfs can begin to see how insane this all is! 🙂
i.e. If I truly cannot choose what state I want a particle pointing in beforehand, (nucleus up; cat alive), as you hold in your insane atheistic many-worlds worldview, then I certainly have no hope of ever changing the particles of your brain (since you claim to have no mind) to believe something other that what the particles of your brain dictate to ‘you’ (whatever the illusion of ‘you’ is in your worldview) to believe beforehand!
i.e. In your worldview all power belongs to the material particles, there is no logic and reason to argue with, nor a you to contain logic and reason in the first place, nor any other selves to argue against, nor any truth to argue for, nor purpose and meaning to argue about. All is in ruins in the atheists’ worldview! And you have chosen to have no choice to believe otherwise! Rock on dude!
An very peculiar statement they made in the ‘Closing the (last) ‘free will’ loophole’ paper is this,,,
Reminds me of this quote:
Yet apparently little do the authors of ‘Closing the (last) ‘free will’ loophole’ paper know, as counter-intuitive as the results of quantum mechanics are, that denying free will (and mind) as foundational to reality is truly the worldview that ends up being ‘inescapably crazy and bizarre’.
Moreover, this psychopathic characteristic inherent to the atheistic/materialistic worldview is born out empirically, in that people who do not believe in they have a free will and a mind/soul tend to be more psychopathic than the majority of normal people in America who do believe in a soul/mind. You can pick that psychopathic study of atheists around the 14:30 minute mark of this following video:
Or as Dr. Sheldon succinctly put it in his refutation of multiverse scenarios:
semi related to the epistemological mess that is the atheist’s preferred (freely chosen) worldview:
Fallacies of Contemporary Neuroscience: “A Vast Collection of Answers, with No Memory of the Questions” – Michael Egnor – February 20, 2014
[Scruton:] Neuroenvy… consist[s] of a vast collection of answers, with no memory of the questions. And the answers are encased in neurononsense of the following kind:
‘The brains of social animals are wired to feel pleasure in the exercise of social dispositions such as grooming and co-operation, and to feel pain when shunned, scolded, or excluded. Neurochemicals such as vasopressin and oxytocin mediate pair-bonding, parent-offspring bonding, and probably also bonding to kith and kin…’ (Patricia Churchland).
As though we didn’t know already that people feel pleasure in grooming and co-operating, and as though it adds anything to say that their brains are ‘wired’ to this effect, or that ‘neurochemicals’ might possibly be involved in producing it. This is pseudoscience of the first order, and owes what scant plausibility it possesses to the fact that it simply repeats the matter that it fails to explain. It perfectly illustrates the prevailing academic disorder, which is the loss of questions.
http://www.evolutionnews.org/2.....82351.html
Ridiculing my views (especially a misunderstanding of my views) does nothing to validate your argument that QM supports a special role for consciousness; attacking materialism on bases other than conflict with QM tests doesn’t do anything to save your argument either.
I pointed out a serious problem in your argument from QM: the experiments you claimed to show a special role for consciousness don’t actually involve consciousness. At this point, there are several intellectually honest responses you might make:
1) You might show that my claimed refutation is wrong. I don’t see how this could be possible, since the mismatch between your claims and the experiments is very basic and simple; but I’ve been mistaken many times before (and undoubledly will be again). But if you want to do this you must show clearly that I am wrong on this specific point, not about various other things.
2) You might modify your argument to fix the problem I pointed out. For example, you might find an experiment that tested conscious vs. non-conscious observation (or conscious choice vs. simple randomness) and got different results, and reformulate your argument on that basis.
(BTW, if you actually found such an experiment it would have very important consequences. For example, it would allow us to test whether animals are conscious.)
If you go this route, there is one significant thing you must do going forward: from now on, use the modified (valid) argument, rather than repeating the current (invalid) version of your argument.
3) You could admit that the argument doesn’t work, and withdraw it. This shouldn’t be a big deal; we’re all human here, and we all make mistakes (at least, everyone who’s tried anything nontrivial has made mistakes). The important thing is to be able to realize that you’ve made a mistake, learn from it, and move on. As Piet Hein put it:
4) You could also withdraw the argument without admitting it’s invalid It’s entirely reasonable to say something along the lines of “I think my argument is basically valid, but I don’t see a way to support it right now.” or “Hmm, I need to think about this some more…”
However, if you go this route, it’s important that you not not re-make the same argument later, without answering (or at least noting) the counterargument.
What you cannot legitimately do (and it looks to me like you’re trying to do — again, I may be mistaken), is to replace the original argument with a different one, without acknowledging any problem with the original argument.
If you want to replace your original (refuted) argument with a different argument, you really should withdraw the original argument first (see options 3 and 4), then propose an alternate argument for your position. And again, you should not re-use the original (refuted) argument later (unless you fix it first).
(BTW, as I implied earlier, some of your ridicule is based on misunderstanding of my views. For instance, while I like the many worlds interpretation of QM, I don’t particularly believe it’s true; I realize that reality does not always conform to my personal preferences. My actual position is that we simply don’t have enough evidence to distinguish which interpretation is correct, and therefore that we shouldn’t prejudge the question. Also, I lean toward believing in free will, although I’m pretty sure I define it differently than you do. I also disagree with most of your new arguments against materialism and/or atheism, but I don’t want to get distracted from your original QM arguments.)
Gordon, you are the one who believes, besides Darwinian evolution, that he is a quasi infinite number of many-world selves each splitting off from each other every time an observation of a photon is made (instead on admitting consciousness is involved, which you experience first hand), I really don’t need to ridicule your base belief (which you are too shy to talk about) since it pretty much ridicules itself. In so far as you think my opinion worth anything (which it is clear you do not) I consider your worldview beyond ridiculous, indeed, it is insane!
correction: you are the one who LIKES, besides Darwinian evolution, that he is a quasi infinite number of many-world selves,,, 🙂
I like pink unicorns 🙂
In that case, we appear to be at an impasse: you consider my views insane, and I consider you intellectually dishonest for refusing to deal with counterarguments. But before we write each other off completely, let me ask you a bit more about your own views on QM. Specifically, do you subscribe to the idea that collapse is triggered by conscious observation?
Consider the Bell’s theorem test run between La Palma and Tenerife (full paper here). In this experiment, polarization measurements were fed through an electronic circuit, then to a computer where they were recorded on a hard disk. Presumably, sometime later a human looked at the results. In this case, did the measurement results:
1) Collapse to definite values by the time they were recorded on HD (indicating that collapse was triggered by something other than human observation)?
2) Collapse some time later, when a human got around to looking at the collected results?
3) Something else?
What about the results of measurements that never got looked at by a human? For instance, in this experiment they had the two sets of results analysed for coincidences (i.e. both detectors picked up matching photons from the same pair), and the non-coincident detections were discarded (presumably without being looked at by a human). Are those unobserved results still in a superposition today?
Gordon, I don’t argue with people who think they are the king of England either.
Since I don’t think I’m the king of England, I have no idea what that has to do with the subject.
But alas Gordon, in some other infinite parallel universe YOU ARE King of England! 🙂
Matthew 7:5
You hypocrite, first take the plank out of your own eye, and then you will see clearly to remove the speck from your brother’s eye.
That’s not how MWI works. Deterministic things are the same in all worlds; things like 2+2=4 hold universally, and the same applies at the physical level. The only things that vary between worlds are those that are indeterminate at the quantum level.
What about things that are quantum-random? Let’s take a simple case: suppose I flip 500 quantum-random coins. MWI says the universe splits into 2^500 worlds, one for each possible combination of flips. (Note: actually, it’s a 2^500-way superposition; “world” is just a way of describing this without getting into QM terminology.) There’ll be worlds where fantastically improbable things happen: one where I flipped 500 heads in a row, one where I flipped 500 tails, etc. But the probability that I (as an inhabitant of the universe) will actually experience the all-heads world is only 1 in 2^500 — it’s nearly guaranteed that I’ll find myself in a world where I flipped roughly equal numbers of heads and tails, because that’s true in the vast majority of the worlds.
Ok, that was a simple case, and I ducked some tricky questions. But there are reasonable arguments that MWI leads to the same observed probabilities as all the other (viable) interpretations. Weird stuff is happening in a few worlds, but we don’t live there so why should we care?
“That’s not how MWI works.”
Says who? you?
But alas once you open Pandora’s box of the Random infinities with MWI, there is no shutting it. i.e. YOU ARE the king of England in some infinite parallel universe no matter how unlikely it is in this one. Just because they believe that 2+2=4 in that imaginary parallel universe does not prevent that possibility from being true in your MWI.
Finely Tuned Big Bang, Elvis In Many Worlds, and the Schroedinger Equation – Granville Sewell – audio
http://www.metacafe.com/watch/4233012
This is my l