Weird quantum effects stretch across hundreds of miles

MINOS
The MINOS detector

In the world of quantum, infinitesimally small particles, weird and often logic-defying behaviors abound. Perhaps the strangest of these is the idea of superposition, in which objects can exist simultaneously in two or more seemingly counterintuitive states. For example, according to the laws of quantum mechanics, electrons may spin both clockwise and counter-clockwise, or be both at rest and excited, at the same time.

The physicist Erwin Schrödinger highlighted some strange consequences of the idea of superposition more than 80 years ago, with a thought experiment that posed that a cat trapped in a box with a radioactive source could be in a , considered both alive and dead, according to the laws of quantum mechanics. Since then, scientists have proven that particles can indeed be in superposition, at quantum, subatomic scales. But whether such weird phenomena can be observed in our larger, everyday world is an open, actively pursued question.

Now, MIT physicists have found that subatomic particles called can be in superposition, without individual identities, when traveling hundreds of miles. Their results, to be published later this month in Physical Review Letters, represent the longest distance over which quantum mechanics has been tested to date.

A subatomic journey across state lines

The team analyzed data on the oscillations of neutrinos—subatomic particles that interact extremely weakly with matter, passing through our bodies by the billions per second without any effect. Neutrinos can oscillate, or change between several distinct "flavors," as they travel through the universe at close to the speed of light.

The researchers obtained data from Fermilab's Main Injector Neutrino Oscillation Search, or MINOS, an experiment in which neutrinos are produced from the scattering of other accelerated, high-energy particles in a facility near Chicago and beamed to a detector in Soudan, Minnesota, 735 kilometers (456 miles) away. Although the neutrinos leave Illinois as one flavor, they may oscillate along their journey, arriving in Minnesota as a completely different flavor.

The MIT team studied the distribution of neutrino flavors generated in Illinois, versus those detected in Minnesota, and found that these distributions can be explained most readily by quantum phenomena: As neutrinos sped between the reactor and detector, they were statistically most likely to be in a state of superposition, with no definite flavor or identity.

What's more, the researchers found that the data was "in high tension" with more classical descriptions of how matter should behave. In particular, it was statistically unlikely that the data could be explained by any model of the sort that Einstein sought, in which objects would always embody definite properties rather than exist in superpositions.

"What's fascinating is, many of us tend to think of quantum mechanics applying on small scales," says David Kaiser, the Germeshausen Professor of the History of Science and professor of physics at MIT. "But it turns out that we can't escape quantum mechanics, even when we describe processes that happen over large distances. We can't stop our quantum mechanical description even when these things leave one state and enter another, traveling hundreds of miles. I think that's breathtaking."

Kaiser is a co-author on the paper, which includes MIT physics professor Joseph Formaggio, junior Talia Weiss, and former graduate student Mykola Murskyj.

Weird quantum effects stretch across hundreds of miles
MIT physicists have found that subatomic particles called neutrinos can be in superposition, without individual identities, when traveling hundreds of miles, and not just at quantum, subatomic scales. Credit: Christine Daniloff/MIT
A flipped inequality

The team analyzed the MINOS data by applying a slightly altered version of the Leggett-Garg inequality, a mathematical expression named after physicists Anthony Leggett and Anupam Garg, who derived the expression to test whether a system with two or more distinct states acts in a quantum or classical fashion.

Leggett and Garg realized that the measurements of such a system, and the statistical correlations between those measurements, should be different if the system behaves according to classical versus quantum mechanical laws.

"They realized you get different predictions for correlations of measurements of a single system over time, if you assume superposition versus realism," Kaiser explains, where "realism" refers to models of the Einstein type, in which particles should always exist in some definite state.

Formaggio had the idea to flip the expression slightly, to apply not to repeated measurements over time but to measurements at a range of neutrino energies. In the MINOS experiment, huge numbers of neutrinos are created at various energies, where Kaiser says they then "careen through the Earth, through solid rock, and a tiny drizzle of them will be detected" 735 kilometers away.

According to Formaggio's reworking of the Leggett-Garg inequality, the distribution of neutrino flavors—the type of neutrino that finally arrives at the detector—should depend on the energies at which the neutrinos were created. Furthermore, those flavor distributions should look very different if the neutrinos assumed a definite identity throughout their journey, versus if they were in superposition, with no distinct flavor.

"The big world we live in"

Applying their modified version of the Leggett-Garg expression to neutrino oscillations, the group predicted the distribution of neutrino flavors arriving at the detector, both if the neutrinos were behaving classically, according to an Einstein-like theory, and if they were acting in a quantum state, in . When they compared both predicted distributions, they found there was virtually no overlap.

More importantly, when they compared these predictions with the actual distribution of neutrino flavors observed from the MINOS experiment, they found that the data fit squarely within the predicted distribution for a quantum system, meaning that the neutrinos very likely did not have individual identities while traveling over hundreds of miles between detectors.

But what if these particles truly embodied distinct flavors at each moment in time, rather than being some ghostly, neither-here-nor-there phantoms of quantum physics? What if these neutrinos behaved according to Einstein's realism-based view of the world? After all, there could be statistical flukes due to defects in instrumentation, that might still generate a distribution of neutrinos that the researchers observed. Kaiser says if that were the case and "the world truly obeyed Einstein's intuitions," the chances of such a model accounting for the observed data would be "something like one in a billion."

"What gives people pause is, quantum mechanics is quantitatively precise and yet it comes with all this conceptual baggage," Kaiser says. "That's why I like tests like this: Let's let these things travel further than most people will drive on a family road trip, and watch them zoom through the big world we live in, not just the strange world of quantum mechanics, for hundreds of miles. And even then, we can't stop using . We really see quantum effects persist across macroscopic distances."


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Journal information: Physical Review Letters

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cps
Jul 19, 2016
Does this show that the Penrose interpretation (gravity causes wave function collapse) is false?

Jul 19, 2016
Quote from article: "Applying their modified version of the Leggett-Garg expression to neutrino oscillations, the group predicted the distribution of neutrino flavors arriving at the detector, both if the neutrinos were behaving classically, according to an Einstein-like theory, and if they were acting in a quantum state, in superposition. When they compared both predicted distributions, they found there was virtually no overlap."

What I would like to know is what is the average energies of the neutrinos detected in Minnesota compared to the average energies of the neutrinos created at the source?

Jul 19, 2016
I haven't seen anyone mention it in research articles but wouldn't superposition give us the ability to communicate over vast differences, like here to Europa? Anyone but me believe that is on the horizon?

Jul 19, 2016
this idea of large superpositions is fascinating, sounds like the novel Quantumnition by Benjamin Owen

Jul 19, 2016
I'm used to complex systems but I'm not an expert on these concepts. I'm trying to make sense of them and I'd like to know if my understanding is clear.
Dark Matter is the building blocks of matter.
Dark matter interactions, with itself and matter, are Quantum effects.
We have difficulty measuring Quantum effects/interactions because we and our tools are made of matter and therefore affect the outcome of the measurements.

Jul 19, 2016
@BrettC Common consensus is that:
a) Dark Matter is commonly hypothesised to be a separate type of matter distinct from normal matter such as electrons, quarks and neutrinos. It could be described as the building block of large scale structure in the universe though (Galaxy filaments, spiral galaxies). There are some who think that Dark Matter may even be normal matter objects like primordial black holes that exert gravitational force but are hard to detect otherwise
b) There are various hypotheses for Dark Matter interactions with baryonic matter and with itself, all of which by definition include interaction through gravity, however it may have more interactions with itself or with normal matter. Some models include WIMPs, MACHOs, RAMBOs or axions
c) All things considered we are pretty good at quantum effects/interactions, we've put it to use for many practical purposes: lasers, transistors, LEDs, MRI, etc. The difficulties stems from the small/'delicate' nature of quantum systems

Jul 19, 2016
So Dark matter is still considered matter but made up of material less substantial than normal matter? Like a fragment of matter. Everything can be broken down to sub components. You can't get something from nothing, even if you don't have enough information about it to define it.
So I try to break things down to concepts that I already understand.
Gravity, for instance, could be a polarization of sub-matter that creates a directional friction that parts of normal matter are subjected to.

Jul 19, 2016
@JamesG, my understanding is if you could reliably entangle a set of particles at that distance, the answer would be yes.

Jul 20, 2016
This comment has been removed by a moderator.

Jul 20, 2016
@BrettC I'm not really sure what you mean by 'substantial'. In terms of mass and interactions, the neutrino could be said to be pretty insubstantial, but this isn't a very productive way to look at things. Not everything can be broken down into smaller components, we have very good evidence for example that the electron is such a fundamental particle. There are of course theories such as String Theory, or M Theory advocating small vibrating strings or branes that make up all particles, but many scientists reject these theories on the basis of a lack of testable predictions and a lack of evidence from particle colliders like the LHC.

Again, I'm not really sure what you mean about polarization of sub-matter and directional friction. However if you are referring to friction because it exerts a force then this would be the wrong kind as it always slows down moving objects: gravity when viewed classically as a force can cause particles to gain momentum if heading towards a star, say.

KBK
Jul 22, 2016
Start digging into the works of Gabriel Kron for evidence of the connective tissue.

You will have a very difficult time finding his full mathematical works, though.

Almost as if it went into hiding into black ops, or something. Ie, just a bit too revealing and functional, too telling, too leading, too hot for the world of open science. Especially if one wants to keep technological leaps and advances under wraps.

After we hit the 1950's...it's almost as if Gabriel Kron never existed......

Jul 22, 2016
I haven't seen anyone mention it in research articles but wouldn't superposition give us the ability to communicate over vast differences, like here to Europa? Anyone but me believe that is on the horizon?

Vast 'differences'? That's an issue with semantics - not transmission technology ;)

But if you mean vast 'distances': While one could, theoretically, use a neutrino beam for communications 'through' the planet you need to realize that the vast majority of sent neutrinos pass the receiver without interacting. Not very efficient.

As for superposition: That doesn't help at all in terms of distance. It helps in terms of bandwith. Superposition is used in all fiber optics lines the world over. It's extremely likely that the post you typed was transmitted using superposition during most part of it's path to the server.
So superposition in information transmission is not 'on the horizon'. It's here - and has been for quite a few decades.

Jul 22, 2016
my understanding is if you could reliably entangle a set of particles at that distance, the answer would be yes.

Entanglement does not allow for information transmission (e.g. passing a message like this text). Entanglement allows for *quantum* information transmission - which is NOT the same thing and cannot be used for passing a message (like this text)

Google for the difference between "information transmission" and "quantum information transmission" (or look it up on wikipedia) to understand why.

The speed limit for classical messages (like this text) is the speed of light. IRRESPECTIVE of the method used. It looks like that is one of those fundamentals (like Heisenberg Uncertainty) that are independent of the actual technology used.

Jul 22, 2016
Entanglement does not allow for information transmission (e.g. passing a message like this text). Entanglement allows for *quantum* information transmission
Aa enjoys ad libbing but I prefer to use references as they are more informative and less pretentious
https://en.wikipe...nication

Jul 23, 2016
Entanglement does not allow for information transmission (e.g. passing a message like this text). Entanglement allows for *quantum* information transmission - which is NOT the same thing and cannot be used for passing a message (like this text)
This is correct and easily demonstrated.

The entanglement cannot be detected without classical information to determine how (i.e. on what parameter- real physicists would say on what basis) the particles are entangled, and this information cannot be sent faster than light.

And there's another hitch: the entangled particles cannot be separated faster than light, so without waiting at least one speed-of-light delay there is nothing to detect.

Jul 23, 2016
LOL how did they account for the curvature of the earth? Or were the beams pointed down locally?

Jul 24, 2016
JamesG wrote:
I haven't seen anyone mention it in research articles but wouldn't superposition give us the ability to communicate over vast differences, like here to Europa? Anyone but me believe that is on the horizon?


James, quantum superposition is a different phenomena than quantum entanglement.

Quantum entanglement is like ability to carry some specific characteristic over distance. Quantum superposition from the other hand is basically "indecision" /or at least "postponed decision"/. And basically communication as we know it, and especially digital comm., is based on "ensured decision", ensured result. Basically it's meaningless /at least from the point of view of comm. and inform. theory/ to perform an operation if you can't predict it's result /at least statistically/. Every unpredictability creates noise, increased entropy /and thus considered "bad"/. Even quantum computing is based on predictable results /although such emerging from q. behavior/.

Jul 24, 2016
A couple of things worth mentioning:
@indio, most neutrinos go through most matter like it's empty space. They only interact through the weak force, and very weakly in gravity (they have a very small mass). The weak force is slow, and neutrinos move at the speed of light (or very close to it). The curve of the Earth is no barrier; in fact, it's helpful because it weeds out all the other particles from the beam.

@pepe, one of the things that gives a quantum computer its power is superposition. It's rather difficult to explain, but the idea is that the addition of the uncertain state lets a whole bunch of states that are mixed up in a tangle of indeterminacy be represented at once so that calculations that depend on such states can be done in one operation instead of many. The entropy, in other words, can be used to our advantage instead of creating a problem.

Jul 24, 2016
There's a very serious implication of this result however.
Some time ago, based on watching solar neutrino, and specifically the fact, that different compositions of such n. were detected at different distances from the Sun, it was decided, that they should change their flavor while traveling, hence they should travel with a speed, lower than that of light, so also they should have some rest mass /diff. from 0/. If this exper. and it's conclusions are right, that pretty much invalidates this previous chain of thought as according to it all neutrino travel in just one condition - that of superposition and "decide their flavor in the moment of detection, so they never change while traveling.

Jul 24, 2016
@pepe, the entire point of superposition is that at detection there is a probability they will come out this, that, or the other, rather than a certainty of outcome; that's not to say the probability can't oscillate over spacetime interval.

Jul 24, 2016
Da Schneib - did I said, that q. superposition doesn't play in q. computing? :)
I see I only said results should be predictable even if they emerge from q. effects. Which is right.
Unpredictability means impossibility to test the device and to extract any meaningful /from the point of view of info. theory/ results.

Jul 24, 2016
Da Schneib - simple question: do they /neutrinos/ change while traveling, or not?
/if you say they do you are contradicting the whole idea of q. superposition/

Jul 24, 2016
Da Schneib - simple question: do they /neutrinos/ change while traveling, or not?
/if you say they do you are contradicting the whole idea of q. superposition/
Change how, exactly? Does the wave equation of their flavor probability outcome at measurement change over spacetime interval? Yes. Does that mean they intrinsically change? No; it just means if you measure them now over here, you will find a different probability of getting one flavor or another than if you measure them then over there. That is all that can be said. We can't show that this is an intrinsic "change of a neutrino." This view is a consequence of accepting the Born Rule as an inherent feature of quantum reality.

Jul 24, 2016
Da Schneib - did I said, that q. superposition doesn't play in q. computing? :)
I wasn't sure and sought to encourage you to clarify your view.

I see I only said results should be predictable even if they emerge from q. effects. Which is right.
Yes, I saw that. By "predictable" in this sense, then, you mean of definite stochastic probability in the ensemble. But this seemed in tension with your prior statement. Thus I sought clarification.

Unpredictability means impossibility to test the device and to extract any meaningful /from the point of view of info. theory/ results.
Depends what you mean by "unpredictability." In any single measurement the actual outcome on a superposed parameter is uncertain; it is stochastic, that is, random in the event and probabilistic in the ensemble.

Jul 24, 2016
" Does the wave equation of their flavor probability outcome at measurement change over spacetime interval? Yes. Does that mean they intrinsically change? No"

Exactly, which invalidates the idea that the fact, that solar neutrino detection is different at different distances from the Sun means that these neutrino change while traveling /from one type to another/.

I think I already said in my first comment that statistical predictability is viable. Actually this is the situ. with the classical electronics - you can't ever predict the behavior of every single electron, and q. effects as tunneling are common. In reality QM works at full everywhere and all the time and so any predictability is statistical in nature, and predictable, "classical" results come from numbers /always/.


Jul 24, 2016
" Does the wave equation of their flavor probability outcome at measurement change over spacetime interval? Yes. Does that mean they intrinsically change? No"

Exactly, which invalidates the idea that the fact, that solar neutrino detection is different at different distances from the Sun means that these neutrino change while traveling /from one type to another/.
I'm still not quite clear what you mean here. One possible interpretation of "change from one type to another" is that the probability of detecting this type now over here is different from the probability of detecting it then over there; now over here the probability of this type is highest, but then over there the probability of that type is highest. Does this mean the neutrino changed? That depends on what you mean by "changed."

Jul 24, 2016
This is an "idea", if you like. But the thing is - this difference in detection and supposed change in the neutrino nature WHILE they ware traveling were the reason the way of thinking about them to change from mostly /most probably/ massles /mass in rest/ particle traveling with the speed of light to "should travel slowly, so they should have some mass". The key is in the word "while", because acc. to SRT you have no "while" if you travel with the speed of light. If they travel in superpos. they don't necessary have "while".

Jul 25, 2016
Does this show that the Penrose interpretation (gravity causes wave function collapse) is false?


Theorists argue that warped space-time prevents quantum superpositions of large-scale objects, but researchers have blurred the line between classical and quantum physics by connecting chaos and entanglement.

If it did, would you be able to tell?

Jul 25, 2016
@pepe So far the speed of neutrinos measured in our best experiments is within the margin of error of the experiments the speed of light. However, that said, according to our best estimates of the mass of neutrinos, that is consistent; they are on the close order of 500,000 times lighter than an electron, and so they should be within that margin of error. So they could be moving very slightly less than c and we couldn't detect the difference with our best experiments now.

In that case, they would experience time, and such a fluctuation as proposed could therefore take place.

Now, you will note that I am accepting your premise that time stops for massless particles; I do not necessarily agree with it, but that is another conversation.

Jul 25, 2016
If it did, would you be able to tell?
An excellent question, @Spaced.

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