Posted on 08/08/2018 2:58:41 PM PDT by ETL
“Harnessing the mysterious property that Albert Einstein called ‘spooky action at a distance’ is a crucial step toward exploiting quantum quirks for technology such as new kinds of sensors or computers,” the physicists said.
“Entanglement is not just some academic curiosity; it’s also something you can harness as a basis for doing useful things with quantum mechanics,” Professor Clerk added.
Entangled states are typically extremely fragile — especially so when they involve large objects. So Professor Clerk and his colleague, Dr. Matt Woolley from the University of New South Wales, developed a theoretical proposal for how to keep the motion of large objects entangled.
Their approach involves involved coupling the objects to a specially designed circuit made out of a superconducting metal — a special material that can have zero electrical resistance, meaning that it conducts electricity perfectly.
This circuit acts to keep the two objects in the special entangled quantum state: when they are disturbed and threaten to fall out of alignment, the circuit nudges the two objects back into the entangled state. ..."
The physicists used a circuit to entangle the motion of two aluminum plates, each one vibrating like a tiny drumhead.
Not only did it work, but they were able to keep the plates entangled for times approaching an hour.
“The vibrating bodies are made to interact via a superconducting microwave circuit,” Dr. Sillanpää said.
“The electromagnetic fields in the circuit are used to absorb all thermal disturbances and to leave behind only the quantum mechanical vibrations.”
“In the future, we will attempt to teleport the mechanical vibrations,” added Dr. Caspar Ockeloen-Korppi, also from Aalto University.
“In quantum teleportation, properties of physical bodies can be transmitted across arbitrary distances using the channel of ‘spooky action at a distance’.”
(Excerpt) Read more at sci-news.com ...
One of the strangest aspects of quantum physics is entanglement: If you observe a particle in one place, another particle—even one light-years away—will instantly change its properties, as if the two are connected by a mysterious communication channel. Scientists have observed this phenomenon in tiny objects such as atoms and electrons. But in two new studies, researchers report seeing entanglement in devices nearly visible to the naked eye.
“There really is an interesting open question, which is: ‘How far can you go up in scale?’” says Andrew Armour, a physicist at the University of Nottingham in the United Kingdom who wasn’t involved in the work. The advance could also pave the way for ultrasensitive measurements of gravity and a hack-proof quantum internet.
Albert Einstein colorfully dismissed quantum entanglement—the ability of separated objects to share a condition or state—as “spooky action at a distance.” Over the past few decades, however, physicists have demonstrated the reality of spooky action over ever greater distances—even from Earth to a satellite in space. But the entangled particles have typically been tiny, which makes it easier to shield their delicate quantum states from the noisy world.
Two research groups have now scaled up entanglement to engineered objects barely visible to the naked eye. Simon Gröblacher, a physicist at Delft University of Technology in the Netherlands, and his colleagues etched beams about 10 micrometers long into silicon chips. The beams, roughly the size of a bacterium, could oscillate up and down like a plucked guitar string. The researchers connected the chips with an optical fiber and cooled the whole setup close to absolute zero to damp out vibrations. Then, using cleverly controlled laser pulses, the team added just enough energy to get one beam vibrating a bit more strongly than the other. By measuring light coming out of the apparatus, the researchers verified that the energy boost occurred but did not learn which beam got the energy, meaning that the added energy was shared by both beams—the hallmark of quantum entanglement. The delicate entangled state lasted just a fraction of a second, the group reports today in Nature.
Mika Sillanpää, a physicist at Aalto University in Finland, and his colleagues took a different approach, manufacturing pairs of aluminum drum heads, or vibrating disks, about the width of a human hair onto a silicon chip. After cooling the setup, the researchers used microwaves to nudge the drum heads into correlated motions—as one throbbed up and down, the other did the opposite. A second set of microwave pulses probed the motions, and an analysis of the signals showed the drum heads shared a single quantum state, the team reports in a second Nature paper. “When we took the data, we had no idea if we were entangled or not,” Sillanpää says. “It turns out the answer was ‘yes.’” The entanglement can last indefinitely, he says—as long as the drum heads stay immersed in their microwave bath.
The two setups have different potential applications. Gröblacher designed his beams to vibrate at the same rate as light sent through fiber-optics, to make them compatible with existing telecommunications systems. The setup is “completely engineerable,” Gröblacher says. If he can get the entangled states to last longer and increase the distance between chips, he envisions such devices serving as nodes in an eventual quantum internet that could transmit ultrasecure information between future quantum-enabled computers.
Sillanpää says his drumheads may be better suited to precision measurement. Because quantum sensors are so sensitive, they excel at picking up extremely weak signals such as gravitational waves, the space-time ripples that were recently detected for the first time. As the devices get larger, they could also test theories of gravity that extend Einstein’s general theory of relativity into the quantum realm, connecting two areas of physics that have remained stubbornly separate.
Both experiments have pros and cons, says John Teufel, a physicist at the National Institute of Standards and Technology in Boulder, Colorado. The entanglement of Gröblacher’s beams was short-lived, but it was detected with certainty. Sillanpää’s entanglement was longer-lasting, but his team needed a complicated chain of theoretical reasoning to infer that the drum heads’ motions were truly entangled. “Ideally what you’d want … is a little bit of both,” Teufel says. Regardless, he says, the results are “very exciting first steps.”
Albert Einstein:
The essence of the paradox is that particles can interact in such a way that it is possible to measure both their position and their momentum more accurately than Heisenberg’s uncertainty principle allows, unless measuring one particle instantaneously affects the other to prevent this accuracy, which would involve information being transmitted faster than light as forbidden by the theory of relativity (”spooky action at a distance”). This consequence had not previously been noticed and seemed unreasonable at the time; the phenomenon involved is now known as quantum entanglement.
Per EPR, the paradox demonstrated that quantum theory was incomplete, and needed to be extended with hidden variables. One modern resolution is as follows: for two “entangled” particles created at once (e.g. an electron-positron pair from a photon), measurable properties have well-defined meaning only for the ensemble system. Properties of constituent subsystems (e.g. the individual electron or positron), considered individually, remain undefined.
Therefore, if analogous measurements are performed on the two entangled subsystems, there will always be a correlation between the outcomes, and a well-defined global outcome for the ensemble. However, the outcomes for each subsystem, considered separately, at each repetition of the experiment, will not be well defined or predictable.
This correlation does not imply that measurements performed on one particle influence measurements on the other. This modern resolution eliminates the need for hidden variables, action at a distance, or other schemes introduced over time, in order to explain the phenomenon.
According to quantum mechanics, under some conditions, a pair of quantum systems may be described by a single wave function, which encodes the probabilities of the outcomes of experiments that may be performed on the two systems, whether jointly or individually.
At the time the EPR article discussed below was written, it was known from experiments that the outcome of an experiment sometimes cannot be uniquely predicted. An example of such indeterminacy can be seen when a beam of light is incident on a half-silvered mirror. One half of the beam will reflect, and the other will pass. If the intensity of the beam is reduced until only one photon is in transit at any time, whether that photon will reflect or transmit cannot be predicted quantum mechanically.
The routine explanation of this effect was, at that time, provided by Heisenberg’s uncertainty principle. Physical quantities come in pairs called conjugate quantities. Examples of such conjugate pairs are (Position, momentum), (Time, energy), and (Angular position, angular momentum). When one quantity was measured, and became determined, the conjugated quantity became indeterminate. Heisenberg explained this uncertainty as due to the quantization of the disturbance from measurement.
The EPR paper, written in 1935, was intended to illustrate that this explanation is inadequate. It considered two entangled particles, referred to as A and B, and pointed out that measuring a quantity of a particle A will cause the conjugated quantity of particle B to become undetermined, even if there was no contact, no classical disturbance. The basic idea was that the quantum states of two particles in a system cannot always be decomposed from the joint state of the two, as is the case for the Bell state...”
Heisenberg’s principle was an attempt to provide a classical explanation of a quantum effect sometimes called non-locality. According to EPR there were two possible explanations. Either there was some interaction between the particles (Even though they were separated) or the information about the outcome of all possible measurements was already present in both particles.
The EPR authors preferred the second explanation according to which that information was encoded in some ‘hidden parameters’. The first explanation of an effect propagating instantly across a distance is in conflict with the theory of relativity. They then concluded that quantum mechanics was incomplete since its formalism does not permit hidden parameters.
Violations of the conclusions of Bell’s theorem are generally understood to have demonstrated that the hypotheses of Bell’s theorem, also assumed by Einstein, Podolsky and Rosen, do not apply in our world.[2] Most physicists who have examined the issue concur that experiments, such as those of Alain Aspect and his group, have confirmed that physical probabilities, as predicted by quantum theory, do exhibit the phenomena of Bell-inequality violations that are considered to invalidate EPR’s preferred “local hidden-variables” type of explanation for the correlations to which EPR first drew attention.[3][4]
Quantum Entanglement
Quantum entanglement is a physical phenomenon which occurs when pairs or groups of particles are generated, interact, or share spatial proximity in ways such that the quantum state of each particle cannot be described independently of the state of the other(s), even when the particles are separated by a large distance—instead, a quantum state must be described for the system as a whole.
Measurements of physical properties such as position, momentum, spin, and polarization, performed on entangled particles are found to be correlated. For example, if a pair of particles is generated in such a way that their total spin is known to be zero, and one particle is found to have clockwise spin on a certain axis, the spin of the other particle, measured on the same axis, will be found to be counterclockwise, as is to be expected due to their entanglement.
However, this behavior gives rise to seemingly paradoxical effects: any measurement of a property of a particle performs an irreversible collapse on that particle and will change the original quantum state.
In the case of entangled particles, such a measurement will be on the entangled system as a whole. Given that the statistics of these measurements cannot be replicated by models in which each particle has its own state independent of the other, it appears that one particle of an entangled pair “knows” what measurement has been performed on the other, and with what outcome, even though there is no known means for such information to be communicated between the particles, which at the time of measurement may be separated by arbitrarily large distances.
Such phenomena were the subject of a 1935 paper by Albert Einstein, Boris Podolsky, and Nathan Rosen,[1] and several papers by Erwin Schrödinger shortly thereafter,[2][3] describing what came to be known as the EPR paradox. Einstein and others considered such behavior to be impossible, as it violated the local realist view of causality (Einstein referring to it as “spooky action at a distance”)[4] and argued that the accepted formulation of quantum mechanics must therefore be incomplete. Later, however, the counterintuitive predictions of quantum mechanics were verified experimentally[5] in tests where the polarization or spin of entangled particles were measured at separate locations, statistically violating Bell’s inequality, demonstrating that the classical conception of “local realism” cannot be correct.
In earlier tests it couldn’t be absolutely ruled out that the test result at one point (or which test was being performed) could have been subtly transmitted to the remote point, affecting the outcome at the second location.[6] However so-called “loophole-free” Bell tests have been performed in which the locations were separated such that communications at the speed of light would have taken longer—in one case 10,000 times longer—than the interval between the measurements.[7][8] Since faster-than-light signaling is impossible according to the special theory of relativity, any doubts about entanglement due to such a loophole have thereby been quashed.
According to some interpretations of quantum mechanics, the effect of one measurement occurs instantly. Other interpretations which don’t recognize wavefunction collapse, dispute that there is any “effect” at all. After all, if the separation between two events is spacelike, then observers in different inertial frames will disagree about the order of events.
Joe will see that the detection at point A occurred first, and could not have been caused by the measurement at point B, while Mary (moving at a different velocity) will be certain that the measurement at point B occurred first and could not have been caused by the A measurement. Of course both Joe and Mary are correct: there is no demonstrable cause and effect.
However all interpretations agree that entanglement produces correlation between the measurements, and that the mutual information between the entangled particles can be exploited, but that any transmission of information at faster-than-light speeds is impossible.[9][10]
In November 2016, researchers performed Bell test experiments in which further “loopholes” were closed.[11][12]
Entanglement is considered fundamental to quantum mechanics, even though it wasn’t recognized in the beginning. Quantum entanglement has been demonstrated experimentally with photons,[13][14][15][16] neutrinos,[17] electrons,[18][19] molecules as large as buckyballs,[20][21] and even small diamonds.[22][23] The utilization of entanglement in communication and computation is a very active area of research.
https://en.wikipedia.org/wiki/Quantum_entanglement
Subspace frequencies open, sir!
Pretty witchy, twichy technology. Does the NSA know about this? I'd hate to be entangled with them...
Fortunately I happen to have a macroscope.
The important thing is that observation ruins the entanglement. So it’s only a tip for understanding the way the quantum universe works, and therefore the way forces interact; it’s NOT useful for faster-than-light communication or, at least as I understand it, quantum computing.
Of course, when I say it’s not useful for faster-than-light communication, I refuse to disallow the possibility that it might just help us find a loophole in the laws of physics that would allow such communication.
A team of researchers in Switzerland has observed the quantum mechanical Einstein-Podolsky-Rosen paradox in a system of interacting ultracold atoms. Their work appears in the journal Science.
“How precisely can we predict the results of measurements on a physical system? In the world of tiny particles, which is governed by the laws of quantum physics, there is a fundamental limit to the precision of such predictions,” said team leader Professor Philipp Treutlein from the University of Basel and colleagues.
“This limit is expressed by the Heisenberg uncertainty relation, which states that it is impossible to simultaneously predict, for example, the measurements of a particle’s position and momentum, or of two components of a spin, with arbitrary precision.”
In 1935, however, Albert Einstein, Boris Podolsky, and Nathan Rosen published a paper in the journal Physical Review in which they showed that precise predictions are theoretically possible under certain circumstances.
“To do so, they considered two systems, A and B, in what is known as an ‘entangled’ state, in which their properties are strongly correlated,” the physicists explained.
“In this case, the results of measurements on system A can be used to predict the results of corresponding measurements on system B with, in principle, arbitrary precision. This is possible even if systems A and B are spatially separated.”
“The paradox is that an observer can use measurements on system A to make more precise statements about system B than an observer who has direct access to system B (but not to A).”
In the past, experiments have used light or individual atoms to study the Einstein-Podolsky-Rosen (EPR) paradox.
Now, Professor Treutlein and co-authors have successfully observed the paradox using a Bose-Einstein condensate — a many-particle system of several hundred interacting atoms — for the first time.
The team used lasers to cool atoms to just a few billionths of a degree above absolute zero.
In this ultracold cloud, the atoms constantly collide with one another, causing their spins to become entangled.
The physicists then took measurements of the spin in spatially separated regions of the condensate.
Thanks to high-resolution imaging, they were able to measure the spin correlations between the separate regions directly and, at the same time, to localize the atoms in precisely defined positions.
With their experiment, they succeeded in using measurements in a given region to predict the results for another region.
“The results of the measurements in the two regions were so strongly correlated that they allowed us to demonstrate the EPR paradox,” said Matteo Fadel, a Ph.D. student at the University of Basel. ...”
http://www.sci-news.com/physics/einstein-podolsky-rosen-paradox-bose-einstein-condensate-05958.html
Spoilsport. :D
Not useful for quantum computing?
They're well on their way to doing just that. Don't have much time at the moment to look up some stuff on it, but please feel free to do it yourself.
I'll see what I can do in what little time I have left...
“Not only did it work, but they were able to keep the plates entangled for times approaching an hour.”
WHAT ?!?!?
From IBM...
(much more at the link)
What is quantum computing?
Quantum computers are incredibly powerful machines that take a new approach to processing information.
Built on the principles of quantum mechanics, they exploit complex and fascinating laws of nature that are always there, but usually remain hidden from view.
By harnessing such natural behavior, quantum computing can run new types of algorithms to process information more holistically.
They may one day lead to revolutionary breakthroughs in materials and drug discovery, the optimization of complex manmade systems, and artificial intelligence.
We expect them to open doors that we once thought would remain locked indefinitely. Acquaint yourself with the strange and exciting world of quantum computing.
https://www.research.ibm.com/ibm-q/learn/what-is-quantum-computing/
Muhammad Ali was so fast that he could touch one particle and then touch another entangled particle over a light year away before it would start counterrevolving.
Perhaps they can somehow use the instantaneous "spooky action at a distance" (over arbitrarily long distances) quantum (now macro?) phenomenon to 'flip a switch' of sorts as a means of simple, but potentially powerful, communication.
Entanglements are supposed to be disrupted when some external influence is applied to them (the ‘observation’ thing that disrupts a quantum object and causes it to ‘collapse’ into a non-quantum reality.
This description sounds like this ‘circuit’ is the thing causing a false entangelment (holding the two macro-objects in the state that the experimenter thinks it should have.
Entangled objects are supposed to be isolated to retain a real entanglement.
I can hear you now!
(and SETI still hasn’t figured it out)
Musings. Things are not as they seem.
Entanglement and a lot of other quantum mechanics, relativity stuff hardly seem possible, they are so non-intuitive.
Dinesh DeSouza brought up the thinking of a philosopher who also advanced ideas that were not intuitive. He argued that we knew our perceptions, but not things in themselves. The best example I can give is a solid object - say a granite countertop. We experience it to be solid and many believe it to be solid. But if you consider the space between molecules, and the empty spaces within atoms, it seems that the countertop is mostly empty space.
The idea that there was no “before” the big bang is also counter-intuitive to many people. Jewish and Christian theologians concluded a long time ago that there was no time before creation.
It seems that many of us do not know as much as we think we do.
And if the universe itself is but one of a pair of entangled macro particles?
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