8 ms·

Qubits 30 meters apart used to confirm Einstein was wrong about quantum

43 points by dev_tty01 3y ago

Khelavaster 3y ago
What's unintuitive that when one complementary oscillation state is measured in one qparticle, we know the other complementary oscillation state in the other qparticle? "Influence at distance" is different than "shows information about distant particles".
- wiml 3y ago
  If it were merely "showing information about a distant particle" it would be some variety of a hidden variables theory. Hidden variables theories can be distinguished from others by Bell's inequality. The Aspect experiments demonstrated that Bell's inequality holds in real life.
  - zmgsabst 3y ago
    Bell’s inequality only rules out local hidden variables. But entanglement and related things like anyons are fundamentally non-local. Anyonic braiding in particular suggests that reality is non-local. AdS/CFT suggests that non-locality (rather than non-determinism) may be the correct solution to resolving the behavior of QM; and more neatly fits with relativity than non-deterministic theories. The article itself starts off correctly saying local realism, but then makes an extraneous assumption that realism rather than locality is incorrect — but that’s not supported by evidence.
    - kgwgk 3y ago
      > Bell’s inequality only rules out local hidden variables. Depending on what are the assumptions and the alternatives. If one goes full determinist everything could have a common (local) cause.
lgrebe 3y ago
Can someone explain like I’m in non AP high school physics? This is demonstrating information "traveling" faster than light by using entangled qbits. Correct?
- saagarjha 3y ago
  If we keep “traveling” in quotes then yes.
- zmgsabst 3y ago
  This shows that information about the measurement didn’t travel from one particle to the other. Either: - the information was always spread out (non-local) - the two particles aren’t really separated, they just appear to be (non-Euclidean) - the information was made up on the spot (non-real) Scientists often don’t talk about the first two options; this article omits them, because it’s hard to think about (and violates an assumption scientists make — that you can study bits of reality in isolation). Personally, I don’t think option #3 makes much sense — I think it was a calculation trick that has outlived its usefulness. But that would mean admitting Einstein was right, which doesn’t let you write pithy article titles.
  - stouset 3y ago
    > Scientists often don’t talk about the first two options; this article omits them, because it’s hard to think about (and violates an assumption scientists make — that you can study bits of reality in isolation). As far as I know, the first option (hidden variable theory) has been soundly disproven by experiment.
    - kgwgk 3y ago
      Not when everything is held together by a non-local glue - which I assume is what your parent comment meant with the parenthesis.
      - rtpg 3y ago
        IIRC based on my reading of this a while back: the non-local glue is some sort of mega-deterministic theory where everything about the universe is encoded in some function meaning non-local stuff happens because in the end everything is in the universe. There is some state function that takes the universe… which was my understanding of the theory and ultimately very unsatisfying.
m463 3y ago
So if I understand this correctly, two qubits can be measured independently 30m apart. Can I use this as secret information to send a message from one to the other? check the qubits at known intervals both places, then send a message from one to the other, using the measured values as a one-time-pad?
- hexane360 3y ago
  Yes, this is a big part of quantum telecommunication. But you always need a classical side-channel. You can even copy a quantum state using 2 entangled qubits and a classical channel. This is called quantum teleportation.
- lisper 3y ago
  Congratulations, you have just (re-)discovered quantum cryptography :-) (Note that while you can use this to securely establish a shared secret, you can't use it to transmit information faster than light.)
  - onesphere 3y ago
    Quantum... blockchain?
- psychphysic 3y ago
  Kind of but not really. https://www.technologyreview.com/2019/02/14/103409/what-is-quantum-communications/ https://www.technologyreview.com/2019/02/14/103409/what-is-q...
psychphysic 3y ago
It's kind of hilarious that the current culture understanding of science is that it's worth pointing out Einstein was "wrong" nearly 70 years after he died. I get it, it's click-baity and it gets the plebs to read. But still makes me chuckle. Louis CK has a bit about where in Jerusalem Jesus reportedly stumbled on the way to his crucifixion and how there was an orthodox Christian "screaming this is where he fell" two thousand and twenty three years later.
- tommiegannert 3y ago
  It's also interesting that, if you become a symbolic leader, it doesn't matter if you're right or wrong: you're inspiring others to continue your work either way. What matters is that he had an idea/opinion, and shared it. Is this what Musk tried to do with Hyperloop?
  - hammyhavoc 3y ago
    If Musk did indeed try to do that, did he succeed?
  - friendzis 3y ago
    > Is this what Musk tried to do with Hyperloop? No, it was just grift. Hyperloop was "debunked" many times, as in fundamental shortcomings of the proposed idea were discussed.
    - o0banky0o 3y ago
      I feel the point there is that you can propose all day, until you try you never know, and it would have been a damn cool thing to pull off. He hedged a bet
- marginalia_nu 3y ago
  I get that it's difficult to educate the public about this, but the Bohr-Einstein debate is about as settled as Galileo's leaning tower of Pisa experiment. It's kind of unfortunate that the public perception of quantum physics is very much a hundred years out of date, and is concerned with questions that have been largely settled and are a complete non-controversy in physics.
transfire 3y ago
There is another possible explanation… time as we experience it is entropic but at the fundamental level is like space and quanta can move in either direction. This is known as Retrocausality.
ta93754829 3y ago
ok so super laymen dumb question, because I have very little understanding of the physics... but could the entanglement process itself be "encoding" the behavior on each of the entangled qubits? if i spin something, and split it in half and move one half away from the other, it's still going to be appear "entangled"
ashildr 3y ago
„…wrong about quantum“? What a stupid headline.

43 points by dev_tty01 3y ago

What's unintuitive that when one complementary oscillation state is measured in one qparticle, we know the other complementary oscillation state in the other qparticle? "Influence at distance" is different than "shows information about distant particles".

wiml 3y ago
If it were merely "showing information about a distant particle" it would be some variety of a hidden variables theory. Hidden variables theories can be distinguished from others by Bell's inequality. The Aspect experiments demonstrated that Bell's inequality holds in real life.
- zmgsabst 3y ago
  Bell’s inequality only rules out local hidden variables. But entanglement and related things like anyons are fundamentally non-local. Anyonic braiding in particular suggests that reality is non-local. AdS/CFT suggests that non-locality (rather than non-determinism) may be the correct solution to resolving the behavior of QM; and more neatly fits with relativity than non-deterministic theories. The article itself starts off correctly saying local realism, but then makes an extraneous assumption that realism rather than locality is incorrect — but that’s not supported by evidence.
  - kgwgk 3y ago
    > Bell’s inequality only rules out local hidden variables. Depending on what are the assumptions and the alternatives. If one goes full determinist everything could have a common (local) cause.

lgrebe 3y ago

Can someone explain like I’m in non AP high school physics? This is demonstrating information "traveling" faster than light by using entangled qbits. Correct?

saagarjha 3y ago
If we keep “traveling” in quotes then yes.
zmgsabst 3y ago
This shows that information about the measurement didn’t travel from one particle to the other. Either: - the information was always spread out (non-local) - the two particles aren’t really separated, they just appear to be (non-Euclidean) - the information was made up on the spot (non-real) Scientists often don’t talk about the first two options; this article omits them, because it’s hard to think about (and violates an assumption scientists make — that you can study bits of reality in isolation). Personally, I don’t think option #3 makes much sense — I think it was a calculation trick that has outlived its usefulness. But that would mean admitting Einstein was right, which doesn’t let you write pithy article titles.
- stouset 3y ago
  > Scientists often don’t talk about the first two options; this article omits them, because it’s hard to think about (and violates an assumption scientists make — that you can study bits of reality in isolation). As far as I know, the first option (hidden variable theory) has been soundly disproven by experiment.
  - kgwgk 3y ago
    Not when everything is held together by a non-local glue - which I assume is what your parent comment meant with the parenthesis.
    - rtpg 3y ago
      IIRC based on my reading of this a while back: the non-local glue is some sort of mega-deterministic theory where everything about the universe is encoded in some function meaning non-local stuff happens because in the end everything is in the universe. There is some state function that takes the universe… which was my understanding of the theory and ultimately very unsatisfying.

m463 3y ago

So if I understand this correctly, two qubits can be measured independently 30m apart. Can I use this as secret information to send a message from one to the other? check the qubits at known intervals both places, then send a message from one to the other, using the measured values as a one-time-pad?

hexane360 3y ago
Yes, this is a big part of quantum telecommunication. But you always need a classical side-channel. You can even copy a quantum state using 2 entangled qubits and a classical channel. This is called quantum teleportation.
lisper 3y ago
Congratulations, you have just (re-)discovered quantum cryptography :-) (Note that while you can use this to securely establish a shared secret, you can't use it to transmit information faster than light.)
- onesphere 3y ago
  Quantum... blockchain?
psychphysic 3y ago
Kind of but not really. https://www.technologyreview.com/2019/02/14/103409/what-is-quantum-communications/ https://www.technologyreview.com/2019/02/14/103409/what-is-q...

psychphysic 3y ago

It's kind of hilarious that the current culture understanding of science is that it's worth pointing out Einstein was "wrong" nearly 70 years after he died. I get it, it's click-baity and it gets the plebs to read. But still makes me chuckle. Louis CK has a bit about where in Jerusalem Jesus reportedly stumbled on the way to his crucifixion and how there was an orthodox Christian "screaming this is where he fell" two thousand and twenty three years later.

tommiegannert 3y ago
It's also interesting that, if you become a symbolic leader, it doesn't matter if you're right or wrong: you're inspiring others to continue your work either way. What matters is that he had an idea/opinion, and shared it. Is this what Musk tried to do with Hyperloop?
- hammyhavoc 3y ago
  If Musk did indeed try to do that, did he succeed?
- friendzis 3y ago
  > Is this what Musk tried to do with Hyperloop? No, it was just grift. Hyperloop was "debunked" many times, as in fundamental shortcomings of the proposed idea were discussed.
  - o0banky0o 3y ago
    I feel the point there is that you can propose all day, until you try you never know, and it would have been a damn cool thing to pull off. He hedged a bet
marginalia_nu 3y ago
I get that it's difficult to educate the public about this, but the Bohr-Einstein debate is about as settled as Galileo's leaning tower of Pisa experiment. It's kind of unfortunate that the public perception of quantum physics is very much a hundred years out of date, and is concerned with questions that have been largely settled and are a complete non-controversy in physics.

transfire 3y ago

There is another possible explanation… time as we experience it is entropic but at the fundamental level is like space and quanta can move in either direction. This is known as Retrocausality.

ta93754829 3y ago

ok so super laymen dumb question, because I have very little understanding of the physics... but could the entanglement process itself be "encoding" the behavior on each of the entangled qubits? if i spin something, and split it in half and move one half away from the other, it's still going to be appear "entangled"

ashildr 3y ago

„…wrong about quantum“? What a stupid headline.