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An experiment devised in Griffith University's Centre for Quantum Dynamics has for the first time demonstrated Albert Einstein's original conception of "spooky action at a distance" using a single particle.
In a paper published in the journal Nature Communications, CQD Director Professor Howard Wiseman and his experimental collaborators at the University of Tokyo report their use of homodyne measurements to show what Einstein did not believe to be real, namely the non-local collapse of a particle's wave function.
According to quantum mechanics, a single particle can be described by a wave function that spreads over arbitrarily large distances, but is never detected in two or more places.
This phenomenon is explained in quantum theory by what Einstein disparaged in 1927 as "spooky action at a distance", or the instantaneous non-local collapse of the wave function to wherever the particle is detected.
"Einstein never accepted orthodox quantum mechanics and the original basis of his contention was this single-particle argument. This is why it is important to demonstrate non-local wave function collapse with a single particle," says Professor Wiseman.
"Einstein's view was that the detection of the particle only ever at one point could be much better explained by the hypothesis that the particle is only ever at one point, without invoking the instantaneous collapse of the wave function to nothing at all other points.
"However, rather than simply detecting the presence or absence of the particle, we used homodyne measurements enabling one party to make different measurements and the other, using quantum tomography, to test the effect of those choices."
"Through these different measurements, you see the wave function collapse in different ways, thus proving its existence and showing that Einstein was wrong."
I don't like it, and I'm sorry I ever had anything to do with it.
(Erwin Schrodinger talking about Quantum Physics)
Counterfactual quantum cryptography (CQC) is used here as a tool to assess the status of the quantum state: Is it real/ontic (an objective state of Nature) or epistemic (a state of the observer's knowledge)? In contrast to recent approaches to wave function ontology, that are based on realist models of quantum theory, here we recast the question as a problem of communication between a sender (Bob), who uses interaction-free measurements, and a receiver (Alice), who observes an interference pattern in a Mach-Zehnder set-up. An advantage of our approach is that it allows us to define the concept of "physical", apart from "real". In instances of counterfactual quantum communication, reality is ascribed to the interaction-freely measured wave function (ψ) because Alice deterministically infers Bob's measurement. On the other hand, ψ does not correspond to the physical transmission of a particle because it produced no detection on Bob's apparatus. We therefore conclude that the wave function in this case (and by extension, generally) is real, but not physical. Characteristically for classical phenomena, the reality and physicality of objects are equivalent, whereas for quantum phenomena, the former is strictly weaker. As a concrete application of this idea, the nonphysical reality of the wavefunction is shown to be the basic nonclassical phenomenon that underlies the security of CQC.
originally posted by: neoholographic
So like I said, the mystics, Philosophers and Spiritualist have been right all along. It's amazing that people like Plato and Parmenides could grasp these things without the scientific knowledge we have today.
How? The experiment matches scientific prediction so it confirms science.
Yet another blow to scientific realism.
It is perhaps only a slight exaggeration to say that scientific realism is characterized differently by every author who discusses it
What we observe is consistent with our model of quantum mechanics. I can't say there's no mystery in QM, as we don't have all the answers, but that's no reason to invoke claims of quantum woo.
Quantum woo is the justification of irrational beliefs by an obfuscatory reference to quantum physics.
...The logical process runs something like this:
I want magic to exist.
I don't understand quantum.
Therefore, quantum could mean magic exists.
Concepts such as "non-locality" or "quantum probability waves" or "uncertainty principle" have become social memes of a kind where people inherently recognize that something "strange" is going on. Practitioners of fraudulent and silly ideas can tap into this feeling of mystery to push their sham concepts...
originally posted by: Bicent76
S&F thank you.
the older I get, the less I understand....
I hope we can settle as a species with the fact we do not really understand our reality...
Yet I do not suggest we stop trying...
We just need to get a grip.....
: mystical 1a
: of or relating to mysteries or esoteric rites : occult
: of or relating to mysticism or mystics
a : mysterious
b : obscure, enigmatic
c : inducing a feeling of awe or wonder
d : having magical properties
Posting the experiment is fine and there's no dispute about that. It's the claim that it shows mystics were right all along that's in dispute as it does no such thing.
originally posted by: Bicent76
a reply to: neoholographic
yea I find it interesting you immediately get attacked on ats, for posting the results of a experiment on ats...
If macrorealism were true, repeated measurements, at different times, of a single macroscopic system would only be statistically correlated up to a certain degree, giving what they called the Leggett–Garg (LG) inequality.
"According to [macrorealism], the [object] always moves on a specific trajectory, independent of our observation," says Andrea Alberti at the University of Bonn, Germany.
By carrying out this "null result" measurement technique in the middle step, the researchers could determine the atom's location without directly interacting with it. By repeating this experiment many times, and seeing when the fluorescence is detected, the researchers can tell which wave the atom was in (and therefore its position) and also that the atom was not disturbed in any way. If macrorealism was true, the null measurement would not affect the outcome of the final fluorescence measurement, and the total amount of correlation of the atom's position in time could be explained classically – but this is not the case. Indeed, the blurring that happens in the quantum walk leads to a stronger total correlation than is possible under macrorealism. This is mathematically demonstrated via the LG inequality violation, clearly showing that macrorealism cannot apply to the caesium atom.
The results of Alberti's experiment seem to nail down for sure that a caesium atom obeys the laws of quantum mechanics, and that macrorealism does not apply. In the future, similar experiments with even larger masses and with longer superposition times will help to either narrow down the inherent boundary that lies between the quantum and classical world, or banish it once and for all and lay the foundations for a more advanced quantum theory.
Sheldon Goldstein, a professor of mathematics, physics and philosophy at Rutgers University and a supporter of pilot-wave theory, blames the “preposterous” neglect of the theory on “decades of indoctrination.” At this stage, Goldstein and several others noted, researchers risk their careers by questioning quantum orthodoxy.