How Entanglement-Generating Satellites Will Make the Quantum Internet Global(technologyreview.com)
technologyreview.com
How Entanglement-Generating Satellites Will Make the Quantum Internet Global
http://www.technologyreview.com/view/532216/how-entanglement-generating-satellites-will-make-the-quantum-internet-global/
3 comments
I'm curious: what exactly makes a photon lose its entanglement? Is it an interaction with an atom (electron or nucleus)? If so, how can entangled photons even propagate through matter (fiber glass or the atmosphere) without becoming de-tangled? Or is this a special kind of interaction?
Does this have any use besides encryption? Because strong encryption already exists without all this.
Quantum computers are devastating to a lot of encryption, maybe moreso than we can yet demonstrate. I think crypto will evolve, and what we consider secure today will be as compromised as WW2 crypto is today.
Not so much to symmetric encryption, effectively it halves the key length. And I don't think quantum links really substitute for public key encryption.
This has nothing to do with encryption. This is building an instantaneous global communication network using quantum entangled particles. One benefit, at least as far as we understand this phenomenon, is that the transfer of state between two entangled particles is untappable, making it the most secure communication medium we know of today without requiring any encryption at all.
That understanding could, of course, completely change at any time.
That understanding could, of course, completely change at any time.
> instantaneous global communication network
Unfortunately that is not true. The transportation of information is still limited by the speed of light as you cannot transmit causal information via the collapse and subsequent measurement of the states of entangled particles.
http://en.wikipedia.org/wiki/No-communication_theorem
Unfortunately that is not true. The transportation of information is still limited by the speed of light as you cannot transmit causal information via the collapse and subsequent measurement of the states of entangled particles.
http://en.wikipedia.org/wiki/No-communication_theorem
The wording of the article does not appear to support such a strong conclusion.
Allow me to change your understanding then. Quantum entanglement does not allow faster than light transmission of information.
Yep. Long story short, if I could send information instantaneously, thanks to relativity, if we're moving away at a fast enough speed, you could send me a message and I could reply to you before you sent it. ;)
I think you could get away with it without violating anything, if both parties are stationary to each other in time and space just in different locations in space.
For example, a ship travels to a nearby star, at near c. It gets there almost immediately in its time, and it takes 4 years in out time. But once it is there and is not moving relative to us, ftl communication doesn't violate anything. Or at least I can't image a scenario how could it as long as you can only transmit with that rule.
Unfortunately we can only test collapse in the same( practically ) reference frame. You know what would be interesting; measuring if the collapse is really instantaneous, if the two parties are moving away from each other at significant fractions of c. Maybe it isn't and that solves the problem. Or maybe collapse stops working if one party is moving very fast.
For example, a ship travels to a nearby star, at near c. It gets there almost immediately in its time, and it takes 4 years in out time. But once it is there and is not moving relative to us, ftl communication doesn't violate anything. Or at least I can't image a scenario how could it as long as you can only transmit with that rule.
Unfortunately we can only test collapse in the same( practically ) reference frame. You know what would be interesting; measuring if the collapse is really instantaneous, if the two parties are moving away from each other at significant fractions of c. Maybe it isn't and that solves the problem. Or maybe collapse stops working if one party is moving very fast.
If the ship flies out and comes back immediately, then stops, can it then send information back in time?
No. I don't see how. Be more specific if that wasn't a question.
Now, my idea works if you assume that the collapse is instantaneous, it doesn't travel at all. Therefore the logic that the equations show that the information ends in the past doesn't apply.
Now, my idea works if you assume that the collapse is instantaneous, it doesn't travel at all. Therefore the logic that the equations show that the information ends in the past doesn't apply.
[unsubstantiated armchair physics ahead]
One benefit of this approach I can see is that you don't, in theory, need transmitters and receivers to be in line of sight for a clear signal. If you are doing standard radio transmissions, it helps if there isn't a planet between you and the transmitter. With entanglement equipment on both ends, this is irrelevant.
You will also not be bothered by signal degradation. The real head-scratcher of quantum entanglement lies in that it works over any distance. The 'transfer' of state between particles is identical, whether the twin is sitting 1 meter or a million light years away.
But as the other commenters mentioned, you are still very much bound by the speed of light. So propagating state changes between entangled particles separated by 1 light year, will still take 1 year.
One benefit of this approach I can see is that you don't, in theory, need transmitters and receivers to be in line of sight for a clear signal. If you are doing standard radio transmissions, it helps if there isn't a planet between you and the transmitter. With entanglement equipment on both ends, this is irrelevant.
You will also not be bothered by signal degradation. The real head-scratcher of quantum entanglement lies in that it works over any distance. The 'transfer' of state between particles is identical, whether the twin is sitting 1 meter or a million light years away.
But as the other commenters mentioned, you are still very much bound by the speed of light. So propagating state changes between entangled particles separated by 1 light year, will still take 1 year.
[deleted]
now i know what will supplant bitcoin. Quantum ASIC entanglement miners - that is the future! Like with wine, the older the entangled ensemble, the more pricier it will be.