Quantum Tunneling and Entanglement

In summary, there is some scientific hype around the potential of quantum entanglement providing instantaneous communication, but this has not been demonstrated to date. Tunneling does occur instantly, but it is not possible to use this to transfer information or matter at FTL speeds.
  • #1
MattRob
211
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Alright, so there's definitely a lot of Sci-Fi hype about Entanglement. I'm sort of hoping the experts on the subject can set this straight.
Question: Could it actually be used to transfer information instantly from one point to another, seemingly providing FTL communication?

And second, does Quantum tunneling occur instantly? If so, could it be used somehow to transfer information/matter at FTL?

Long answer, sil'vu plait. :-)
I.e. Why or why not?
 
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  • #2
1) Nope. Imagine I randomly select a ball from a set of a blue ball and a red ball. I send one to A and one to B. When A gets his ball, he'll immediately know which one B got. Can A send information 'instantly' to B this way? No.

Entanglement is weirder than that, because the way quantum mechanics works, it's not a case of merely not-knowing if the ball is red or blue; the balls are in a truly undefined state until their color is 'measured', entangled such that one must be blue and the other then red, but without actually having any real but 'hidden' value. So this raises the strange question of how the ball at A 'knows' it's supposed to be blue once the ball at B has been measured to be red? It appears as if they're somehow 'communicating' (although it's not necessarily the case), and that communication (if it exists) would be instantaneous.

But from the standpoint of the people at A and B this makes no difference. They still can't use the entanglement for communication.

2) As for tunneling, it occurs instantaneously. But what tunneling is, is having a particle in a similarly undefined location, where there's probability of finding the particle in one region or another, even though there may be an exactly zero probability of finding the particle in the areas in-between. You can't really say the particle 'traveled' from point A to point B, since by definition, it doesn't have a location, just a probability of being in a location.

Once a particle has been measured at a particular location, though, this probability distribution evolves at a finite speed. So once it's been measured at point A, you will - to an extremely high degree of probability - not be able to measure it at B until after some time that doesn't exceed the speed of light.
 
  • #3
Wow. Thanks. Extremely helpful answer and very insightful. Nicely done.
For a Feynman-ish answer, light barrier's a darned bugger, isn't it?

EDIT: http://jamesmessig.wordpress.com/2009/10/07/quantum-tunneling-of-space-craft-step-by-step-for-effective-faster-than-light-travel-velocities-over-interstellar-distances/ an article I just found on the subject. Thoughts?
 
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1. What is Quantum Tunneling?

Quantum tunneling is a phenomenon in which a particle can pass through a potential barrier even though it does not have enough energy to overcome it. This is possible due to the probabilistic nature of quantum mechanics, where particles can exist in multiple states at once. As a result, there is a small chance that the particle can "tunnel" through the barrier and appear on the other side, defying classical physics.

2. How does Quantum Tunneling work?

Quantum tunneling occurs when a particle encounters a potential barrier with a height greater than its energy. In classical physics, this would mean the particle could not pass through the barrier. However, in quantum mechanics, the particle is described by a wave function, which allows it to exist in multiple positions simultaneously. This means that there is a small chance the particle can appear on the other side of the barrier, even though it does not have enough energy to do so.

3. What is Entanglement in Quantum Mechanics?

Entanglement is a phenomenon in quantum mechanics where two or more particles become connected in such a way that the state of one particle is dependent on the state of the other, regardless of the distance between them. This means that if the state of one particle is changed, the state of the other particle will also change instantaneously, even if they are light years apart.

4. How does Entanglement work?

Entanglement occurs when two particles interact in such a way that their quantum states become correlated. This means that the state of one particle cannot be described independently of the other particle. This correlation persists even if the particles are separated by large distances, and any change to one particle will immediately affect the other particle.

5. What are the practical applications of Quantum Tunneling and Entanglement?

Quantum tunneling and entanglement have many potential applications, especially in the field of quantum computing. Quantum tunneling can be used to create transistors that are smaller and more efficient than traditional transistors, leading to faster and more powerful computers. Entanglement can be used for secure communication, as any attempt to intercept the communication will be immediately detected due to the change in the entangled particles. Entanglement also has potential uses in quantum teleportation and quantum cryptography.

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