As for as I understand (which is admittedly very little) particles that are created together become entangled. Currently, the experiments using entangled particles are over relatively short distances (the longest distance as of now is just over 15 miles).
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- there is no theoretical limit to the distance at which particles can remain entangled. 2. Quantum entanglement cannot be used for instant communication at a distance.
– Mar 15 '15 at 02:30 -
I guess I really should have left off why I was asking as everyone really got wrapped around the axle on that one. All I care about is the distance at which entanglement ends. Thanks all. It has been answered. – Curious Layman Mar 15 '15 at 04:11
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3if it has been answered you should check the answer you like best – anna v Mar 15 '15 at 05:41
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Once two particles are entangled, they remain so at any distance, so long as you do nothing which would push them to lose coherence with each other. Entanglement is independent of distance.
However, as a practical matter, it takes time to move the particles apart. Increasing distance increases how long it took to get them there. This means there's a higher probability of some event occurring which drives them out of coherence. This is merely a technical hurdle, not a theoretical one.
Cort Ammon
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Instant communication is still impossible because the transfer of information occurs when the sender measures the quantum state of their photon. That causes the receiver’s entangled photon to instantly change.
However, in order to understand the information, the receiver has to know what the original measurement was, along with some other instructions. Those instructions are sent via normal communications, which are limited to being no faster than the speed of light.
current maximum distance covered using entangled particles is 88 miles
Two good link on this are http://www.forbes.com/sites/alexknapp/2012/09/06/physicists-quantum-teleport-photons-over-88-miles/
