
A single photon reveals quantum entanglement of 16M atoms - dnetesn
https://phys.org/news/2017-10-photon-reveals-quantum-entanglement-million.html
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jacknews
I find the popular descriptions of entanglement to be unenlightening. In this
case we go from "a pair of socks" to an "unsystematic phenomenon that occurs
simultaneously in two locations".

What? Where did the socks go?

My preferred analogy to show that the universe is weird is a pair of coins.
You throw one to your friend 10m away, and toss the other in the air for
yourself. Your's lands 'heads', while the coin to your friend is still
tumbling through the air. At that point you can be sure that your friend's
coin will land 'tails', even though it hasn't landed yet, since they are
correlated (to land opposite). Somehow the coins 'communicate' through space
and time, or act as though they're parts of a single entity. There's no
mechanistic explanation for how this happens, it's just the way the universe
appears to work. That's the mystery, and quantum mechanics at least allows you
to calculate it, if not really understand it.

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nerdponx
This is the best explanation of entanglement that I've read, and I think I
finally "get it".

It also makes me think that the problem is not in understanding "why is Coin1
correlated with Coin2", but in finding the latent variable that Coin1 and
Coin2 are both correlated with. Is that something being researched currently?

~~~
lawpoop
> Is that something being researched currently?

Sort of, but actually more no.

The way the equations in quantum physics work, this just happens, and there
isn't any accounting for distance or space. That's just how it is.

Now, that seems to contradict our intuitive understanding of physics. Things
can't be just linked like that without some force or information traveling
between them.

So there are a few different interpretations of that quantum weirdness:

1\. That's the way things really are, and our natural perception that things
don't work that way may have helped us evolve to this point, but is actually
wrong on the quantum scale

2\. There is a hidden variable (the communication part, like a pilot wave) and
we just haven't found it yet.

~~~
anonytrary
It has to do with the combinations of states in the observable you are
measuring (in the photon polarization example above, it would be spin or
angular momentum). You have to have some way of setting up the system in the
entangled state that you want.

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neom
Some good related learnings:

The Concept of Mass - with Jim Baggott (just watched this yesterday and it's
reeeaalllyy good although basic):
[https://www.youtube.com/watch?v=HfHjzomqbZc](https://www.youtube.com/watch?v=HfHjzomqbZc)

Quantum Entanglement and the Great Bohr-Einstein Debate | Space Time:
[https://www.youtube.com/watch?v=tafGL02EUOA](https://www.youtube.com/watch?v=tafGL02EUOA)

Measure for Measure: Quantum Physics and Reality (kinda old but still good):
[https://www.youtube.com/watch?v=GdqC2bVLesQ](https://www.youtube.com/watch?v=GdqC2bVLesQ)

Would recommend this order.

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DannyBee
Okay. TFA says "although recent advances have shown the entanglement of 2,900
atoms."

The related stories at the bottom of the page for me shows: "Quantum
entanglement between a single photon and a trillion rubidium atoms":
[https://phys.org/news/2017-03-quantum-entanglement-photon-
tr...](https://phys.org/news/2017-03-quantum-entanglement-photon-trillion-
rubidium.html#nRlv)

So, uh, yeah.

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z3t4
I wonder if quantum computing can some how be used in machine learning as a
short cut to train on massive arrays without exponential costs.

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SomeStupidPoint
Yes it can -- quantum ML is an active area of research for the MS QuArC group
and others. (Well, I'm not sure it's an _exponential_ speed up, but it's an
area of research.)

eg, [https://www.microsoft.com/en-
us/research/publication/quantum...](https://www.microsoft.com/en-
us/research/publication/quantum-deep-learning/)

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SubiculumCode
That is quite the number of atoms (although not even a mole's worth). It makes
me wonder if quantum entanglement in the brain is more likely.

~~~
eru
I think it's not so much that the brain's atoms wouldn't be entangled amongst
themselves, but that they are entangled with everything else. It's a warm and
wet environment.

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QAPereo
Is this article based on:
[https://www.nature.com/articles/s41467-017-00897-7](https://www.nature.com/articles/s41467-017-00897-7)
?

~~~
abysmalfitzg
No, it's based on this one:
[https://arxiv.org/abs/1703.04704](https://arxiv.org/abs/1703.04704)

~~~
QAPereo
Thanks very much!

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justifier
> In this way, the researchers succeeded in showing the entanglement of 16
> million atoms when previous observations had a ceiling of a few thousand.

It is my intended inference to show that all photons are 'entangled' weakly
though two individual photons can be entangled 'strongly'

