Quantum Tunnels Show How Particles Can Break the Speed of L

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Quantum Tunnels Show How Particles Can Break the Speed of L

Postby socrat44 on October 21st, 2020, 1:43 pm 

Quantum Tunnels Show How Particles Can Break the Speed of Light
Recent experiments show that particles should be able to go faster than light when they quantum mechanically “tunnel” through walls.
Natalie Wolchover, Senior Writer/Editor,
October 20, 2020

''In short, quantum tunneling seemed to allow faster-than-light travel, a supposed physical impossibility.''
''Tunneling seems to be incurably, robustly superluminal.''
“How is it possible for [a tunneling particle] to travel faster than light?”
Quantum tunneling: “There’s a mystery there, not a paradox.”
'' Researchers stress that superluminal tunneling is not a problem as long as it doesn’t allow superluminal signaling. It’s similar in this way to the “spooky action at a distance” that so bothered Einstein. ''

https://www.quantamagazine.org/quantum- ... 65xY6HlgKs
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Re: A Drop in the Quantum Bucket

Postby Faradave on October 21st, 2020, 2:26 pm 

Suppose you have a little pan of boiling water that turns into a cloud of steam. The spreading cloud encounters a needle upon which a drop of water condenses. Where was the drop before it condensed? It was distributed over some volume, which might be described statistically but not definitely for the H2O molecules. So, it becomes meaningless to estimate how long the "drop" took to get from the pan or any one location in the cloud to the needle. Indefinite prior location is the problem.

Similarly, the wave nature of a fundamental particle gives it an indefinite location, including (with correspondingly low probability) locations far from the central region of distribution. Wherever the particle is found, it changes from a distributed state to a detected (or measured) state. Such changes in quantum state can be (as far as we know) instantaneous. In this scenario, a change in state is not "moving", it's "becoming" (i.e. becoming "detected"). If it's not moving then "speed" does not really apply.

As you note, the investigators discount communication by tunneling.
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Re: A Drop in the Quantum Bucket

Postby socrat44 on October 22nd, 2020, 4:36 am 

Faradave » October 21st, 2020, 2:26 pm wrote: Such changes in quantum state can be (as far as we know) instantaneous.


Such investigation similar to instantaneous (faster than speed of light) tunneling solution
(instantaneous action is possible when the action is faster than the constant speed of light)
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Re: A Drop in the Quantum Bucket

Postby bangstrom on October 25th, 2020, 4:41 am 

Faradave » October 21st, 2020, 1:26 pm wrote:
Similarly, the wave nature of a fundamental particle gives it an indefinite location, including (with correspondingly low probability) locations far from the central region of distribution. Wherever the particle is found, it changes from a distributed state to a detected (or measured) state. Such changes in quantum state can be (as far as we know) instantaneous. In this scenario, a change in state is not "moving", it's "becoming" (i.e. becoming "detected"). If it's not moving then "speed" does not really apply.

As you note, the investigators discount communication by tunneling.


https://www.quantamagazine.org/quantum- ... 65xY6HlgKs

Should the same principle of a distributed state apply when the “particles” are rubidium atoms?

Also, what effect might the magnetic barrier have on communication by tunneling?
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Re: Beating Light to the end of the Tunnel

Postby Faradave on October 28th, 2020, 2:09 pm 

bangstrom wrote:Should the same principle of a distributed state apply when the “particles” are rubidium atoms?
I remember the article. I believe the answer is yes. The larger the particle and the wider the barrier the less likely the ability to tunnel. So, large rubidium atoms are indeed an achievement. However, if they widen the magnetic barrier to document faster than light tunneling, the probability will become much lower. Still it's possible in principle.

"The smaller the mass of the particle, the more its wave function wants to spread..." - Feynman p.255

The more spread out the particle's probability amplitude (in space) the more likely that particle will be to precipitate (collapse its wave function) outside a given barrier.

bangstrom wrote:Also, what effect might the magnetic barrier have on communication by tunneling?
I don't think anything changes (though I might wish otherwise). The authors are careful to note:

"In a paper published in the New Journal of Physics in September, Pollak and two colleagues argued that superluminal tunneling doesn’t allow superluminal signaling for a statistical reason: Even though tunneling through an extremely thick barrier happens very fast, the chance of a tunneling event happening through such a barrier is extraordinarily low." - bold added

Separately, I'm reminded:
"…in quantum mechanics correlations jump instantly but information does not." - Styer p.94
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