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. Almost 90 years later, by splitting a single photon between two laboratories, scientists have used homodyne detectors-which measure wave-like properties-to show the collapse of the wave function is a real effect. This phenomenon is the strongest yet proof of the entanglement of a single particle, an unusual form of quantum entanglement that is being increasingly explored for quantum communication and computation. "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." http://m.phys.org/news/2015-03-quantum-einstein-spooky-action-distance.html Full text paintakingly pasted and editted for you yuri ;-)
Every time I think of what it truly means to be instantaneous, I am humbled. Spooky is underselling it, if anything.
"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. \nThis 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." \nAll of a sudden, reading Kant... now... has a whole new flavor and taste for me! Wow. - "If I remove the thinking subject the whole corporeal world must at once vanish: it is nothing save an appearance in the sensibility of our subject and a mode of its representations."
Very interesting connection! Reality is a sea of possibility, made actual by the presence and observation of the observer.
Well, seeing as possibility, per se, is not immanently localizable, would that mean (particulated) matter is not as well?
I think reality is localized upon observation, changing from wave function to particle, if i understand your question.
Yes, you understand my question properly. So allow me to ask another one. lol If every single particulate that comprises a given object, like a cup in the cupboard, is, as the article says (that is, is not constrained in a collapsed state), then does that mean that QM actually assures us that the cup itself is not (and neither the cupboard being) localizable and discrete ("collapsed") in-itself, i.e., without relation to "observers"?
I love reading about this stuff, especially the double slit experiment, but it's too much for my primitive brain to handle!
I am not sure if this interpretation is ubiquitous amongst all quantum theorists but it is one interpretation.
Well doesn't this article sort of allude to (or allege to vindicate) this very premise (i.e., that a wave function will collapse differently depending on the observer [or observational instrument], i.e., that a non-local collapse occurs [thus the change from potentiality to actuality happens] instantaneously because of measurement)?
I am not sure if it collapses differently but yes a nonlocal (instantaneous) collapse of the wave function.
Do not different state reductions, actualize or, come to be, because of different "observers" (or because of the influence of different observers)? but yes a nonlocal (instantaneous) collapse of the wave function. Is the collapsed object totally unalike the antecedent wave function? Is that like asking - is a particle totally unalike a wave?
I suppose you are right, i dont recall if that article mentioned it but i do recall from books ive read that if one measures the acceleration of an electron, they cannot know where it is, or they can measure its position but cannot know its acceleration. In regards to your second question, i am not sure how to properly think of this. I would think a particle is an emergent property of the wave function but again, im not too sure.
1.) Sounds like Heisenberg's principle. But I suppose that means different kinds of measurements or observations (rather than "measurers" or "observers") will influence different results. 2.) When they say this, "a single particle can be described by a wave function that spreads over arbitrarily large distances", in the article; how "far" do you think this spread or distance is taken to be (or actually is), prior to collapse?
I was wondering the same haha. Seems to me at the very least the wave function would spread in all directions at the speed of light (at least) but if we are operating in nonlocality... perhaps the entire universe? I also wonder if this directly ties into Bohm's implicate-explicate order. The wave function may in part reside in the implicate until observed, which unfolds the implicate into the explicate (particle).