Light from ancient quasars helps confirm quantum entanglement

August 20, 2018 by Jennifer Chu, Massachusetts Institute of Technology
The quasar dates back to less than one billion years after the big bang. Credit: NASA/ESA/G.Bacon, STScI

Last year, physicists at MIT, the University of Vienna, and elsewhere provided strong support for quantum entanglement, the seemingly far-out idea that two particles, no matter how distant from each other in space and time, can be inextricably linked, in a way that defies the rules of classical physics.

Take, for instance, two particles sitting on opposite edges of the universe. If they are truly entangled, then according to the theory of quantum mechanics their physical properties should be related in such a way that any measurement made on one particle should instantly convey information about any future measurement outcome of the other particle—correlations that Einstein skeptically saw as "spooky action at a distance."

In the 1960s, the physicist John Bell calculated a theoretical limit beyond which such correlations must have a quantum, rather than a classical, explanation.

But what if such correlations were the result not of , but of some other hidden, classical explanation? Such "what-ifs" are known to physicists as loopholes to tests of Bell's inequality, the most stubborn of which is the "freedom-of-choice" loophole: the possibility that some hidden, classical variable may influence the measurement that an experimenter chooses to perform on an entangled particle, making the outcome look quantumly correlated when in fact it isn't.

Last February, the MIT team and their colleagues significantly constrained the freedom-of-choice loophole, by using 600-year-old starlight to decide what properties of two to measure. Their experiment proved that, if a classical mechanism caused the correlations they observed, it would have to have been set in motion more than 600 years ago, before the stars' light was first emitted and long before the actual experiment was even conceived.

Now, in a paper published today in Physical Review Letters, the same team has vastly extended the case for quantum entanglement and further restricted the options for the freedom-of-choice loophole. The researchers used distant quasars, one of which emitted its light 7.8 billion years ago and the other 12.2 billion years ago, to determine the measurements to be made on pairs of entangled photons. They found correlations among more than 30,000 pairs of photons, to a degree that far exceeded the limit that Bell originally calculated for a classically based mechanism.

"If some conspiracy is happening to simulate quantum mechanics by a mechanism that is actually classical, that mechanism would have had to begin its operations—somehow knowing exactly when, where, and how this experiment was going to be done—at least 7.8 billion years ago. That seems incredibly implausible, so we have very strong evidence that quantum mechanics is the right explanation," says co-author Alan Guth, the Victor F. Weisskopf Professor of Physics at MIT.

"The Earth is about 4.5 billion years old, so any alternative mechanism—different from quantum mechanics—that might have produced our results by exploiting this loophole would've had to be in place long before even there was a planet Earth, let alone an MIT," adds David Kaiser, the Germeshausen Professor of the History of Science and professor of physics at MIT. "So we've pushed any alternative explanations back to very early in cosmic history."

Guth and Kaiser's co-authors include Anton Zeilinger and members of his group at the Austrian Academy of Sciences and the University of Vienna, as well as physicists at Harvey Mudd College and the University of California at San Diego.

A decision, made billions of years ago

In 2014, Kaiser and two members of the current team, Jason Gallicchio and Andrew Friedman, proposed an experiment to produce entangled photons on Earth—a process that is fairly standard in studies of quantum mechanics. They planned to shoot each member of the entangled pair in opposite directions, toward light detectors that would also make a measurement of each photon using a polarizer. Researchers would measure the polarization, or orientation, of each incoming photon's electric field, by setting the polarizer at various angles and observing whether the photons passed through—an outcome for each photon that researchers could compare to determine whether the particles showed the hallmark correlations predicted by quantum mechanics.

The team added a unique step to the proposed experiment, which was to use light from ancient, distant astronomical sources, such as stars and quasars, to determine the angle at which to set each respective polarizer. As each was in flight, heading toward its detector at the speed of light, researchers would use a telescope located at each detector site to measure the wavelength of a quasar's incoming light. If that light was redder than some reference wavelength, the polarizer would tilt at a certain angle to make a specific measurement of the incoming entangled photon—a measurement choice that was determined by the quasar. If the quasar's light was bluer than the reference wavelength, the polarizer would tilt at a different angle, performing a different measurement of the entangled photon.

Credit: Massachusetts Institute of Technology

In their previous experiment, the team used small backyard telescopes to measure the light from stars as close as 600 light years away. In their new study, the researchers used much larger, more powerful telescopes to catch the incoming light from even more ancient, distant astrophysical sources: quasars whose light has been traveling toward the Earth for at least 7.8 billion years—objects that are incredibly far away and yet are so luminous that their can be observed from Earth.

Tricky timing

On Jan. 11, 2018, "the clock had just ticked past midnight local time," as Kaiser recalls, when about a dozen members of the team gathered on a mountaintop in the Canary Islands and began collecting data from two large, 4-meter-wide telescopes: the William Herschel Telescope and the Telescopio Nazionale Galileo, both situated on the same mountain and separated by about a kilometer.

One telescope focused on a particular quasar, while the other telescope looked at another quasar in a different patch of the night sky. Meanwhile, researchers at a station located between the two telescopes created pairs of entangled photons and beamed particles from each pair in opposite directions toward each telescope.

In the fraction of a second before each entangled photon reached its detector, the instrumentation determined whether a single photon arriving from the quasar was more red or blue, a measurement that then automatically adjusted the angle of a polarizer that ultimately received and detected the incoming entangled photon.

"The timing is very tricky," Kaiser says. "Everything has to happen within very tight windows, updating every microsecond or so."

Demystifying a mirage

The researchers ran their experiment twice, each for around 15 minutes and with two different pairs of quasars. For each run, they measured 17,663 and 12,420 pairs of entangled photons, respectively. Within hours of closing the telescope domes and looking through preliminary data, the team could tell there were strong correlations among the pairs, beyond the limit that Bell calculated, indicating that the photons were correlated in a quantum-mechanical manner.

Guth led a more detailed analysis to calculate the chance, however slight, that a classical mechanism might have produced the correlations the team observed.

He calculated that, for the best of the two runs, the probability that a mechanism based on classical physics could have achieved the observed correlation was about 10 to the minus 20—that is, about one part in one hundred billion billion, "outrageously small," Guth says. For comparison, researchers have estimated the probability that the discovery of the Higgs boson was just a chance fluke to be about one in a billion.

"We certainly made it unbelievably implausible that a local realistic theory could be underlying the physics of the universe," Guth says.

And yet, there is still a small opening for the freedom-of-choice loophole. To limit it even further, the team is entertaining ideas of looking even further back in time, to use sources such as cosmic microwave background photons that were emitted as leftover radiation immediately following the Big Bang, though such experiments would present a host of new technical challenges.

"It is fun to think about new types of experiments we can design in the future, but for now, we are very pleased that we were able to address this particular loophole so dramatically. Our experiment with quasars puts extremely tight constraints on various alternatives to quantum mechanics. As strange as may seem, it continues to match every experimental test we can devise," Kaiser says.

Explore further: Tracking down the mystery of entangled particles of light

More information: Dominik Rauch et al, Cosmic Bell Test Using Random Measurement Settings from High-Redshift Quasars, Physical Review Letters (2018). DOI: 10.1103/PhysRevLett.121.080403 , dx.doi.org/10.1103/PhysRevLett.121.080403

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48 comments

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elevyn_11_
not rated yet Aug 20, 2018
Wowzers! Yikes!
danR
5 / 5 (3) Aug 20, 2018
I'm missing it altogether. The only entangled photons I'm seeing in the text and picture are terrestrial. Red/blue photons from the quasar... what role are they playing? Unless somehow they are capturing pairs that were generated simultaneously from the same orbital change (or whatever simultaneous-photon-generating-process of the same ion. At the same quasar.

If a picture is worth a thousand words, a video is worth a thousand pictures. I'll await youTube's contribution.
antialias_physorg
4.4 / 5 (14) Aug 20, 2018
The only entangled photons I'm seeing in the text and picture are terrestrial.

Correct.
Red/blue photons from the quasar... what role are they playing?

They are determining which type of measurement to make on the (terrestrial) entangled photons.
A loophole in the Bell inequality states that there may be some systemic bias in the machine you use so that locally you always measure in a certain way that causes correlation.

By using a sources for setting the measurenment that are so far apart that they cannot have influenced each other when their respective light was emitted that bias is eliminated (or at least made very, very, very unlikely - because the light from the two quasars would have to be correlated)

The trick is to make this decision in a way that not even light can travel between the two measuring points in the time between the two measurements (this is why they have just such a tight timing window)
danR
5 / 5 (6) Aug 20, 2018
antialias
That's a bit clearer, yes.
Whart1984
Aug 20, 2018
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Whart1984
Aug 20, 2018
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Whart1984
Aug 20, 2018
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holoman
1 / 5 (2) Aug 20, 2018
Maybe, more than photons can be entangled.

https://drive.goo...Vw5fBiVq

Surveillance_Egg_Unit
3.8 / 5 (5) Aug 20, 2018
@Whart
Exactly what IS this "dense aether" that you seem to hold so dear? Does it have anything to do with the proven CMBR?
Surveillance_Egg_Unit
2.6 / 5 (5) Aug 20, 2018
Somewhere in the knowable Universe, millions of light years away, there is a Solar System that is an exact replica of our Solar System. And within that Solar System there is a planet which is the third planet from that Star. And on this planet there are hominid creatures who have holes in their head with which to see, hear, smell and communicate. These creatures also have 2 legs, 2 arms, and all the physical attributes by which we are known for. And in the top universities of that planet, there are scientists who have made the decision to study and experiment with entangled photons with just the precise measurements derived from 2 powerful telescopes on the mountaintop of an island. Those scientists performed their experiments at the precise moment that Terran scientists performed theirs. Thus proving that Classical Physics is just as valid as Quantum in the Universe.
dirk_bruere
3 / 5 (1) Aug 21, 2018
"... the seemingly far-out idea"
Can we avoid that kind of dumbed down language please.
Entanglement is a concept almost 85 years old
Whart1984
Aug 21, 2018
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davmi
not rated yet Aug 21, 2018
2 entangled photons begin their flight from the source and correlation being measured at approximately the same distance (or time) away from the source.

Could the above quantum behavior be explained by below classical behavior?

2 strings with one end tie to the same point (called source) and their other end tie to 2 different point (called detector A & B respectively). If a hammer is hitting at the source, thus an identical waveform (ie. properties) would have traveled down to both strings. When measurement is made at the detector A & B would probably give a correlated result too.

I am wondering what if the measure of one photon is made at 0.1 meter from the source and the other at thousands of meter away from the source. Would this quantum correlation still hold?
humy
5 / 5 (7) Aug 21, 2018
In dense aether model
Whart1984

Stop right there; the very old aether theory was (and still is) disproven by relativity and has been dead for a very long time now.
Science has long moved on.
Stop talking crackpot nonsense.
the entanglement is pilot wave thing only
Einstein's pilot wave theory doesn't even support the old disproven aether theory in particular and the fact you mention it in the context of the aether theory is a clear sign you don't understand what these concepts are actually about.
humy
5 / 5 (6) Aug 21, 2018
Exactly what IS this "dense aether" that you seem to hold so dear? Does it have anything to do with the proven CMBR?
The CMBR is Brownian motion of aether
.Whart1984

Oh dear. He asks a perfectly reasonable question and you respond with your usual nonsense assertions that cannot make any sense even with the old disproven aether theory hypothetically being correct.
"Brownian motion" has NOTHING to do with either "CMBR" or "aether" (even if it existed) and "aether" (even if it existed) has NOTHING to do with "CMBR". These three concepts are totally unrelated. So, unlike me, you don't even understand the disproven aether theory you are so keen on promoting. I don't get why you want to promote it anyway; Something to do with your religion?
humy
5 / 5 (7) Aug 21, 2018
. Einstein's pilot wave theory ...
Sorry, my missedit; That should have been "Einstein's pilot wave hypothesis"; NOT "theory". Mustn't confuse "theory" with "hypothesis" in science.
Phyllis Harmonic
4.3 / 5 (3) Aug 21, 2018
. . . I am wondering what if the measure of one photon is made at 0.1 meter from the source and the other at thousands of meter away from the source. Would this quantum correlation still hold?


Yes. The distance between the photons is irrelevant as is distance from the source. Entangled photons (or any quantum entangled objects) "depend" on each other for a complete description of their quantum states. This is very different than the classical test you described. A vibration on one string can be described wholly without reference to the vibration on the other string. For instance, you can dampen the vibration on one string and the other will still vibrate.
Whart1984
Aug 21, 2018
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Whart1984
Aug 21, 2018
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antialias_physorg
3.9 / 5 (7) Aug 21, 2018
Could the above quantum behavior be explained by below classical behavior?

No. That's the entire point of the experiment. Particularly this experiment is closing one loophole (other experiments have closed others)

If a hammer is hitting at the source, thus an identical waveform (ie. properties) would have traveled down to both strings. When measurement is made at the detector A & B would probably give a correlated result too.

We're not dealing with string here. The fastest anything could travel between the entangled photons would be with the speed of light (c is not just the speed of light. It's much more. It is the universal speed limit of *information* ). The measurement is explicitly set up so that the two photons are measured within such a short time window and so far apart from each other that information transmission between them is not possible within that interval.

1 picometer or a billion parsec to the source. Makes no difference.
TorbjornLarsson
3.4 / 5 (5) Aug 21, 2018
Talk about extreme experiments ... well, it worked.

Could the above quantum behavior be explained by below classical behavior? ,,,

If a hammer is hitting at the source, thus an identical waveform (ie. properties) would have traveled down to both strings. When measurement is made at the detector A & B would probably give a correlated result too.


No, the measurement conditions and so the result is decided later. The measured property does not exist meanwhile (though the correlation does), and it would require an infinite set of simultaneous polarizations - the photons can carry one. The experiment exclude all hidden variables.

Now you can also understand


We cannot understand without fact, you are relating known erroneous ideas. And frankly, the balderdash is also hard to interpret in the first place.

Why not start educating yourself about relativity? It is high school stuff, I believe, not too hard to grasp. Quantum mechanics usually comes later.
humy
5 / 5 (5) Aug 22, 2018
...Therefore the vibrating vacuum ...
Whart1984

You talk no end of crackpot nonsense this above statement being just one example of many that shows this.
So vacuum itself can 'vibrate'? Err, no, that's nonsense.
You obviously don't know the first thing about modern physics.
In fact, not even according to the old disproven aether theory does vacuum 'vibrate' thus you show you haven't EVEN understood the aether theory!
humy
5 / 5 (3) Aug 22, 2018
To clarify;

When I talk about the "aether theory" here, I am referring to only the OLD type, which is the type Whart is presumably talking about, that says that space and time are absolute and speed of light is relative in the sense it is relative to the current arbitrary direction of what is called the "aether wind" (a now completely discredited hypothesis) and this puts it in direct conflict with relativity and is disproven by relatively.

There is also a less old type (for some reason normally spelt as "ether") that isn't in conflict with relativity because it says that space and time are relative and speed of light is absolute, i.e. NOT relative to anything so in that narrow way it says almost the exact opposite of the older aether theory.
Even Einstein thought of this less old 'ether' theory as still being perfectly credible.
However, even THIS 'ether' theory is largely rejected by modern physicists as being totally superfluous (via Occam's razor) and even very unhelpful.
humy
5 / 5 (3) Aug 22, 2018
--continued---

In fact, that less old 'ether' theory is much more abstract in meaning from the older aether theory and is also SO different from the older one that I assert it is a highly misleading misnomer and it shouldn't be called by a name that sounds like the word "aether" as that would inevitably, as it does, cause much confusion.
They really should come up with a totally different name for it.
DDayanov
1 / 5 (2) Aug 22, 2018
Once I was discussing current work that laser scientist doing with one scientist and he told me that Russians working on using this technology to detect submarines on 15000 feet deeps using satellites in 1990th. Don't know what they achieved. At least this one can be used for communication with colonies on Mars and further with 0 sec latency. And just another prove that everything in this universe is interconnected
humy
5 / 5 (4) Aug 22, 2018
At least this one can be used for communication with colonies on Mars and further with 0 sec latency.

I am afraid not, or at least not if I understand the physics of this correctly; If I understand this correctly, you cannot 'choose' which state one of the two entangled photons WILL be observed to have by the photon detector BEFORE sending it from the photon emitter.
Can a real quantum physicist here confirm that?
antialias_physorg
3.7 / 5 (6) Aug 22, 2018
At least this one can be used for communication with colonies on Mars and further with 0 sec latency.

Nope. Speed of light is the limit. Entanglement does not allow for faster than light communication.

Reason: For information transmission you have to
- Set (at the origin)
- Transmit
- Read (at the target location)

While entaglement allows for the "transmit" and "read" parts it doesn't allow for the "set" part. That breaks entanglement.

Meaning that if you create a pair of entangled photons and keep one here while transmitting one to Mars...and then "set" the photon property of the photon you kept here (to encode a message) then that act of setting does not affect the state of the target photon in the least.
Kron
5 / 5 (2) Aug 22, 2018
if you create a pair of entangled photons and keep one here while transmitting one to Mars...and then "set" the photon property of the photon you kept here (to encode a message) then that act of setting...
...destroys the state of entanglement.
DDayanov
5 / 5 (1) Aug 22, 2018
you cannot 'choose' which state one of the two entangled photons WILL be observed to have by the photon detector BEFORE sending it from the photon emitter.

If I understand something about lasers not only pair (all photons) instantly emitted from one source ideally should have quantum entanglement. And as soon as changes phase of one (using phase modulation) all others should change they phases too
DDayanov
2.3 / 5 (3) Aug 22, 2018


Reason: For information transmission you have to
- Set (at the origin)
- Transmit
- Read (at the target location)

What about:
- Devide
- Transmit
- Set (at the target location)
- Read (at the origin)
? ;))
antialias_physorg
3 / 5 (6) Aug 22, 2018
What about:
- Devide

Nope.

No-cloning theorem:
https://en.wikipe..._theorem

If I understand something about lasers not only pair (all photons) instantly emitted from one source ideally should have quantum entanglement.

Whatever gave you that idea?
DDayanov
3 / 5 (2) Aug 23, 2018
What about:
- Devide

Nope.

No-cloning theorem:
https://en.wikipe..._theorem



Did you read and analyze Bell experiment above? It looks like the only things you can do is Bla-Bla-Blah
antialias_physorg
3.7 / 5 (6) Aug 23, 2018
Just because something is a laser doesn't automatically mean all photons are entangled. Entanglement means correlation - but correlation doesn't necessarily mean entanglement. (Saying that all photons emitted from a laser are entangled is like saying "all 8-balls are black...therefore all black things must be 8-balls")

The no cloning theorem (and by extension the no broadcast theorem) is at the heart of quantum crypto security. You can't just 'duplicate' (or "divide") an entangled entity and have all the entanglement still present in all parts.

Even if you could it wouldn't help you any. Because if you forcibly set any of the entangled entities at one end to some state it wouldn't affect the outcome of the measurement at the other and at all. That measurement would still reflect the entangled state - now destroyed by the set operation - of the original)

the only things you can do is Bla-Bla-Blah

Yeah. Math is loads of blah, blah. But who cares about math, right?
DDayanov
5 / 5 (1) Aug 24, 2018

Yeah. Math is loads of blah, blah. But who cares about math, right?


Wrong. I'm doing ML for life. And currently meditating on problem of so many math models that even professional mathematician who work in creation of models for same fields in different teams cannot understand each other on conferences. Solution as I see it: math is science of approximation. As soon as enough data collected for choosing model from existing models algorithm give a list of suitable for approximation. And human mathematicians can approximate Bla-Bla-Blah ;))
antialias_physorg
3.7 / 5 (6) Aug 25, 2018
I'm pretty sure you have something lese in mind. What you are describing is certainly not math

...and 'meditating' on anything doesn't get you anywhere - particularly not in science.
It's bascally the opposite of 'impressive'.
Whart1984
Aug 26, 2018
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Whart1984
Aug 26, 2018
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antialias_physorg
3 / 5 (6) Aug 26, 2018
On the contrary, entanglement is itself hyperdimensional effect and it runs with superluminal speed

Entanglement is not information. You do not seem to be aware of what information actually is. For a quick synopsis read my third post in this thread.

And what does 'hyperdimensional' even mean. You're just throwing sciency sounding words around that you don't understand.

Here's a hint:
This just makes you seem really, really dumb. Not just 'uneducated dumb' (which is excusable), but 'trying to pass himself off as being educated by plugging in random words he's heard on Star Trek dumb' (which is not).
Whart1984
Aug 26, 2018
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Whart1984
Aug 26, 2018
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Whart1984
Aug 26, 2018
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Whart1984
Aug 26, 2018
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Whart1984
Aug 26, 2018
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Whart1984
Aug 26, 2018
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Whart1984
Aug 26, 2018
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granville583762
5 / 5 (3) Aug 26, 2018
Seeing into the past and Nessy lives in Loch Ness
phys.org> two particles sitting on opposite edges of the universe. If they are truly entangled, then according to the theory of quantum mechanics their physical properties should be related in such a way that any measurement made on one particle should instantly convey information about any future measurement outcome of the other particle

Based on this theory the two particles such that particle A stays on earth for 4billion years where as particle B travels 4billion Lyrs and send it data of the beginning of life 4billion years ago to particle A that stayed on earth for 4billion Lys - we can see into the past
If we are to believe in this entanglement, we can see into the past
or Nessy doesn't live in Loch Ness!
jonesdave
3.9 / 5 (7) Aug 26, 2018
@Whart
Exactly what IS this "dense aether" that you seem to hold so dear? Does it have anything to do with the proven CMBR?


It follows on from Aether theory, which has been shown to be wrong. This version requires its adherents to be particularly dense. Hence, 'Dense Aether Theory.' Simples :)
granville583762
5 / 5 (3) Aug 26, 2018
The dense Aether model question is like Ground Hog Day - were always waiting for that change in the weather!
The dense Aether model is the dead giveaway Whart1984, each incarnation gets asked the same question "what is the dense Aether model" with less and less success on each emergence from the quantum fluctuations, may be next time will have more success

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