Faster than light communication and breaking entanglement

If the spin is established for both particles at the moment of entanglement, what is the mystery? When one observes the spin of one of the particles, they know the spin of the other. The spin of the other doesn't change; it remains as it was when it was entangled. We simply know now what it is. What am I missing? Isn't it like flipping a coin? If it comes up heads, we instantly know it isn't tails?

If your talking about fast computing well we are already doing it with quantum computers.
If your talking about FTL communication to cover great distances then we have a problem.

Lets say you do for arguments sake manage to entangle particles , and with a great break through you manage to create a communication code with the different spins allowing for ftl communication.
If you want ftl communication for just earth and solar system you might save a few minutes here and there but communication we already have is very fast as it is.

What do you think this would achieve? if you want to send communications great distances. ie light years away .. you have to fly 1 of the particles out their first. by the time that particle gets to its destination so many years have passed on earth that your revolutionary form of communication would be outdated and probably in a museum some where on Earth.

Catch 22

Q

originally posted by: grey580
a reply to: neoholographic

I'll just leave this here.


astroengineer.wordpress.com...

An interesting story.

Dammit, you beat me to it!!! Well done sir.

Has anyone read the astroengineers blog linked to the black triangle thread? I seems like they have had FTL communication in operation for some time. The story about the mars rover communicating at FTL speeds seemed so legit but I guess it could be a hoax.

originally posted by: okamitengu
I actually think bob would send alice the D... especially if she is in a bikini...

You win the internets today!

a reply to: noeltrotsky

Oh, I know about entanglement as defined in the studies going on at the moment - it's the OP I was questioning as he said "break entanglement".

My understanding of it is that to entangle things, they need to be in very close proximity, therefore by "breaking entanglement" in two remote photons, how would you "re-entangle" them to be able to use them again?

originally posted by: neoholographic
a reply to: dragonridr

Nope, you don't need to measure spin to break entanglement.

I suggest you go and read up on things like entanglement breaking and signal to noise ratios when dealing with information channels.

When you add energy to a closed system such as an entangled particle your changing it and breaking entanglement. The only way we can tell what a particle is doing a measurement. Sorry you spend years shipping them apart and you can even give them a meaning. But no information travels faster than light.

No matter what you do the information can only travel as fast as light. Think of it as a delayed transfer of information. You know what it's going to say just not when.

a reply to: dragonridr

That's what I thought.. So, as the OP has it defined, this is a one shot deal.

a reply to: Jonjonj

oh and this one as well

www.abovetopsecret.com...

Quantum Gravitational Antennas for instantaneous communications across the Universe

a reply to: dragonridr

Again, I suggest you read up on breaking entanglement and signal to noise ratio when dealing with information channels. What you're talking about has nothing to do with what I'm saying.

Whether a particle is spin up or spin down doesn't matter.

When you break entanglement, the signal to noise ratio is weakened. You can measure the strength of this signal and it's called the signal to noise ratio.

If you have an entangled particle pair where entanglement hasn't been broken, you will have a stronger signal to noise ratio. You're not measuring whether a particle is spin up or spin down, you're measuring how much noise is in the channel.

originally posted by: grey580
a reply to: Jonjonj

oh and this one as well

www.abovetopsecret.com...

Quantum Gravitational Antennas for instantaneous communications across the Universe

That one I had NOT seen, thank you for the link.

a reply to: neoholographic

I am not sure I am getting this. I still think of it as one message on every information channel (bit) when the bit have been used when you break entanglement. I think of it as instant regardless of distance but not reusable when entanglement broken so many entangled particles needed to continue communication.

originally posted by: BogieSmiles
If the spin is established for both particles at the moment of entanglement, what is the mystery? When one observes the spin of one of the particles, they know the spin of the other. The spin of the other doesn't change; it remains as it was when it was entangled. We simply know now what it is. What am I missing? Isn't it like flipping a coin? If it comes up heads, we instantly know it isn't tails?

There is sufficient theory that suggests that the particles are "undefined" until one or the other is observed. At that point one is fixed at one spin (random) , and the other one instantly adopts the opposite spin.

a reply to: Jonjonj

Yes but if it was a quantum signal it wouldn't need sunrise or a Martian dawn, to transmit. It should theoretically be able to transmit from the other side of the sun. With a very small power drain.

They knew about twenty years ago that live cells taken from a mouth swab, were entangled with the donor. So all cells grown, from a sample, would be entangled, at close distance or the other side of the galaxy.

originally posted by: neoholographic
a reply to: noeltrotsky

You have it all wrong. Nobody is talking about spin. It's really simple and most people know that you can measure the strength of correlation as signal to noise. Stronger correlation means you have a stronger signal to noise ratio. Here's a recent experiment that was done.

Viewpoint: Don’t Cry over Broken Entanglement

The simplest example of how this can work involves two entangled pulses of light, each containing just one photon. “Alice” (the sender) keeps one pulse and sends the other one towards her target, “Bob.” When Bob sends back the pulse, Alice interferometrically recombines it with the light she kept. Here is where the difference between classical and quantum signals becomes important: With classical light, time and frequency can’t both be simultaneously localized, as the Fourier transform of a pulse that is sharply localized in time is spread out over all frequencies. In contrast, if the sent and retained signals are truly entangled, they will be simultaneously strongly correlated in both arrival time and frequency. The much stronger initial correlation of the entangled beams allows reflected photons to be distinguished from background photons with a much higher signal to noise when they are “decoded” by recombining them with the retained signal. (The decoder is basically the reverse of the original entangler—a sort of “disentangler”—which only lets through the tiny residual correlation that matches the original entanglement.) Even though the entanglement doesn’t survive, a classical correlation survives that is stronger than would exist in the absence of entanglement in the first place. The enhancement in signal to noise is by a factor d, where d is the number of optical modes involved in the entanglement. In this way, the presence (or absence) of an object can be determined with far less light than a classical experiment would require.

physics.aps.org...

Again, it has nothing to do with spin, it's about the strength of correlations between entangled pairs. If you have an entangled particle pair and you expose one of the pairs to the environment, you break entanglement and increase the noise which will weaken the signal to noise ratio. So again, it's not a measure of polarization but of correlation based on the signal to noise ratio.

Your NOT talking about faster than light information transfer. The article you posted and are referencing is talking about secure communications. The part that says, “Alice” (the sender) keeps one pulse and sends the other one towards her target, “Bob.” When Bob sends back the pulse..." clearly talks about a signal being sent back and forth between them.

The article you referenced is about building an unbreakable communications system. Nothing to do with FTL information transfer which is how you tried to apply it. I was discussing FTL as you never posted any sources in your OP.

Your entire discussion of communicating with the past is wholly unsupported. Feel free to clarify how that would be possible including sources.

You need to read up on entanglement experiments much better. It's extremely complex.

originally posted by: charlyv
There is sufficient theory that suggests that the particles are "undefined" until one or the other is observed. At that point one is fixed at one spin (random) , and the other one instantly adopts the opposite spin.

My understanding is that when the observation takes place the experiment is doing so in a way to ensure the spin will be a specific way that they want. This causes the entangled particle to have the opposite spin. Because you 'forced' the spin on one you have 'sent information' to the entangled partner...namely the opposite spin.

originally posted by: BogieSmiles
If the spin is established for both particles at the moment of entanglement, what is the mystery? When one observes the spin of one of the particles, they know the spin of the other. The spin of the other doesn't change; it remains as it was when it was entangled. We simply know now what it is. What am I missing? Isn't it like flipping a coin? If it comes up heads, we instantly know it isn't tails?

Because the individual spin is not determined precisely (meaning in a pure state of the spin operator of individual particle) for each of the particles, only the composite state is determined.

What happens is that if you measure one of the pairs, by having it interact with macroscopic equipment which result in the relaxation and evolution to a fixed and definite spin state on one particle, the other particle, despite being distant in regular is automatically effected in some way.

en.wikipedia.org...

en.wikipedia.org...

More than enough to chew on....

originally posted by: charlyv

originally posted by: BogieSmiles
If the spin is established for both particles at the moment of entanglement, what is the mystery? When one observes the spin of one of the particles, they know the spin of the other. The spin of the other doesn't change; it remains as it was when it was entangled. We simply know now what it is. What am I missing? Isn't it like flipping a coin? If it comes up heads, we instantly know it isn't tails?

There is sufficient theory that suggests that the particles are "undefined" until one or the other is observed. At that point one is fixed at one spin (random) , and the other one instantly adopts the opposite spin.

Not quite 'undefined' previously but in a mixed state, like (1/sqrt(2), 1/sqrt(2)) can, after measurement be (1,0) or (0,1).

a reply to: noeltrotsky

Again, you don't understand what you're talking about. It's talking about how even when entanglement is broken there's still a benefit because you can detect a signal to noise ratio unlike particle pairs that haven't been entangled.

Here's the paper that was being discussed.

Entanglement's Benefit Survives an Entanglement-Breaking Channel

Entanglement is essential to many quantum information applications, but it is easily destroyed by quantum decoherence arising from interaction with the environment. We report the first experimental demonstration of an entanglement-based protocol that is resilient to loss and noise which destroy entanglement. Specifically, despite channel noise 8.3 dB beyond the threshold for entanglement breaking, eavesdropping-immune communication is achieved between Alice and Bob when an entangled source is used, but no such immunity is obtainable when their source is classical. The results prove that entanglement can be utilized beneficially in lossy and noisy situations, i.e., in practical scenarios.

arxiv.org...

Again, it shows that when particle pairs are entangled, there's still a signal that can be detected even in increased noise after breaking entanglement. Exactly what I've been saying.

Again, if you break entanglement in your first channel but not in subsequent channels in a five channel system, the signal to noise ratio in the first channel will be weaker than the other channels.

It's basic common sense if you take the time and study things like breaking entanglement, information channels and signal to noise ratios.