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Faster-than-light communication device?

MobiusPizza

Platinum Member
I heard that quantum entanglement can link two particle's properties so that modifying 1 of the entangled particle would alter the property of the other entangled particle instantaneously, over even light-year distnces.

If that's the case, we can of course make a secure communication device over any distances even to the other side of the universe but still have instantaneous communication. Radio waves takes severam minutes to reach Mars from Earth. If we have a faster than light communication device it's much more convenient.

I know that Heisenburg's uncertainty principle prevent obtaining information from particles without altering their state. However, although the state is altered, I am sure that we can still extract the information we want. As follows:

Let there be a communication device that encodes information on a pair of entangled protons. The information is stored as 1 when spin is greater than certain value while 0 when it is lower then certain value.

Of course if you fire a photon at it to determine it's spin it might disrupt the original information. But I don't understand why you can't fire 2 photons at the same time to cancel the effect. If the threshold for distinguishing 0 and 1 is large enough small errors created would be acceptable.

Frankly speaking I am not sure what properties are shared by two entangled particles apart from spin. And whether the spin means the angular velocity or something arbitary.
If it is angular velocity, since a proton is an 3D object, why cannot we arrange the detector so it only reads the proton in say 90 degrees from its original spin of which the information was encoded to avoid disrupting the information?
 
The problem (as I understand it) with quantum entanglement is that the particles are only entangled while their states are unknown. If you give the particles a known spin, then you can't use them to transmit information FTL, since the contents of the other particle are already fixed. IANAQP, though. 😛
 
Originally posted by: AnnihilatorX
I heard that quantum entanglement can link two particle's properties so that modifying 1 of the entangled particle would alter the property of the other entangled particle instantaneously, over even light-year distnces.

If that's the case, we can of course make a secure communication device over any distances even to the other side of the universe but still have instantaneous communication. Radio waves takes severam minutes to reach Mars from Earth. If we have a faster than light communication device it's much more convenient.

I know that Heisenburg's uncertainty principle prevent obtaining information from particles without altering their state. However, although the state is altered, I am sure that we can still extract the information we want. As follows:

Let there be a communication device that encodes information on a pair of entangled protons. The information is stored as 1 when spin is greater than certain value while 0 when it is lower then certain value.

Of course if you fire a photon at it to determine it's spin it might disrupt the original information. But I don't understand why you can't fire 2 photons at the same time to cancel the effect. If the threshold for distinguishing 0 and 1 is large enough small errors created would be acceptable.

Frankly speaking I am not sure what properties are shared by two entangled particles apart from spin. And whether the spin means the angular velocity or something arbitary.
If it is angular velocity, since a proton is an 3D object, why cannot we arrange the detector so it only reads the proton in say 90 degrees from its original spin of which the information was encoded to avoid disrupting the information?


How do you know the photons cancel the effects. The quantum decoherence operator is not linear.You cant just add one the subtract one.Your premise is flawed. I know some good papers on this....What is your level of math so that I can recommend some good ones.
 
erm I don't think my maths level is high enough to interpret quantum physics yet. Still waiting to go to University this year. But please do bring it on just for fun read
 
The math is actually not that difficult, but it helps if you know enough to understand the bra-ket notation. Basically you need to understand the basics on linear algebra.

Anyway, as has already pointed out there is no way to use entanglement to transfer information FTL. In order to "use" entanglement you always need to transfer classical information; this is how quantum cryptograhy works.
 
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