# crowded quantum information

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On 12/3/2022 at 10:15 AM, bangstrom said:

"From the beginning"implies one of the 'hidden variables' ruled out by the Bell test.

Oh man, trying not to loose your face, you now even have lost sight of what entanglement is. We know that the particles are entangled from the beginning, because they are produced entangled. Do you suggest to show entanglement is real by using particles that are not entangled from the beginning? That is the crux of the 'singlet state': we know the wave function of both particles together, but not of the individual particles. That means we know the outcomes of the measurements must be (anti-)correlated.

On 12/3/2022 at 10:15 AM, bangstrom said:

Hidden variables are, “either (1) the description of reality given by the wave function in quantum mechanics is not complete or (2) two quantum operators cannot have simultaneous reality.”- John Bell

John Bell? Less so: that is from the EPR-article. And you said somewhere 'EPR is invalidated' (whatever that means...) But now it supports your viewpoint? Wow.

On 12/3/2022 at 10:15 AM, bangstrom said:

The only purpose for the classical signal is to set the polarizer to the correct position to receive the incoming signal. The incoming signal is already prepared and on the way by then.

The classical channel plays no role in the completed entanglement.

The 'only purpose'? That 'purpose' is central for quantum teleportation to succeed. The classical signal is necessary for teleportation. But I fully agree with Markus that when discussing entanglement in itself, you should not use more difficult setups that make use of entanglement.

On 12/3/2022 at 10:15 AM, bangstrom said:

Their correlation upon observation suggests some kind of a signal from the first observed to the second.

If you think classically, yes. But that is exactly what the Bell theorem says: the only way one could simulate entanglement with classical means would need an immediate interaction between the entangled particles. As you think classically, you think it needs an FTL signal.

Your arguments become worse and worse.

Oh my, page 25...

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5 hours ago, Eise said:

Your arguments become worse and worse.

They’re not arguments. They’re troll bait.

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On 12/4/2022 at 4:20 AM, Eise said:
On 12/3/2022 at 3:15 AM, bangstrom said:

Hidden variables are, “either (1) the description of reality given by the wave function in quantum mechanics is not complete or (2) two quantum operators cannot have simultaneous reality.”- John Bell

John Bell? Less so: that is from the EPR-article. And you said somewhere 'EPR is invalidated' (whatever that means...) But now it supports your viewpoint? Wow.

If you read the rest of the statement John Bell was listing in the quote the sort of things he considered “hidden variables’ in the EPR article and the hidden variables were what Aspect and Clauser ruled out as invalid fifty years ago.

I never claimed to concur with the EPR's hidden variables.

On 12/4/2022 at 4:20 AM, Eise said:

The 'only purpose'? That 'purpose' is central for quantum teleportation to succeed. The classical signal is necessary for teleportation.

What role does the classical channel play in the success of quantum teleportation? As I said, the classical channel only serves to prepare the receiving apparatus to receive the signal when it arrives.

On 12/4/2022 at 4:20 AM, Eise said:

If you think classically, yes. But that is exactly what the Bell theorem says: the only way one could simulate entanglement with classical means would need an immediate interaction between the entangled particles. As you think classically, you think it needs an FTL signal.

I understand the statement to say a classical signal lacks an “immediate interaction”, but if it had a FTL signal, it would no longer be a classical signal.

Is that your interpretation or something else?

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37 minutes ago, bangstrom said:

If you read the rest of the statement John Bell was listing in the quote...

Which statement you mean? Please give this 'rest of the statement' and a link to the article where it comes from.

38 minutes ago, bangstrom said:

What role does the classical channel play in the success of quantum teleportation? As I said, the classical channel only serves to prepare the receiving apparatus to receive the signal when it arrives.

Does teleportation work when you omit this preparation? If not, then the classical signal is essential.

40 minutes ago, bangstrom said:

I understand the statement to say a classical signal lacks an “immediate interaction”, but if it had a FTL signal, it would no longer be a classical signal.

Is that your interpretation or something else?

Nope. You must read it as 'quantum entanglement can only be understood by using quantum mechanics'. There is no FTL signal in the quantum mechanical explanation. QM entanglement cannot be simulated with classical means, unless you allow for FTL communication.

And you evaded my first point. Here it is again for you:

On 12/4/2022 at 11:20 AM, Eise said:
On 12/3/2022 at 10:15 AM, bangstrom said:

"From the beginning"implies one of the 'hidden variables' ruled out by the Bell test.

Oh man, trying not to loose your face, you now even have lost sight of what entanglement is. We know that the particles are entangled from the beginning, because they are produced entangled. Do you suggest to show entanglement is real by using particles that are not entangled from the beginning? That is the crux of the 'singlet state': we know the wave function of both particles together, but not of the individual particles. That means we know the outcomes of the measurements must be (anti-)correlated.

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On 12/5/2022 at 6:09 AM, Eise said:

Which statement you mean? Please give this 'rest of the statement' and a link to the article where it comes from.

The “rest of the statement” was my few words before and after the quote from Bell that you lifted out of text. I think the quote came from Bell’s “Bertlmann’s Socks”.

The quote wasn’t the one I was looking for and my reply wasn’t explicit enough. Anyhow, the quote was Bell’s comment about what he considered to be ‘hidden variables’ and ‘hidden variables’ were the things from the EPR article ruled out by Bell’s inequalities.

John Bell was not a supporter of hidden variables and his ‘inequalities’ ruled out their presence contrary to Einstein’s EPR article. Aspect and Clauser were the first to demonstrate experimentally that Bell's Inequalities violated the EPR effect. I explained this before

On 12/5/2022 at 6:09 AM, Eise said:

Does teleportation work when you omit this preparation? If not, then the classical signal is essential.

Teleportation works without the classical channel. The teleportation in the Danube experiment was accomplished within the time it took three entangled photons to traverse the optical bench and send one teleportation signal to a fourth photon on the way to the distant receiving station and also a radio signal to the same station to set the polarizer.

The teleportation signal had to be FTL to reach the photon on route through a fiber optic cable to the receiving station.

On 12/5/2022 at 6:09 AM, Eise said:

There is no FTL signal in the quantum mechanical explanation.

Can you explain how there is no FTL signal?

Here are two videos that explain different aspects of entanglement including the instantaneous transfer of information, hidden variables, and the violation of Bell's Inequalities.

On 12/5/2022 at 6:09 AM, Eise said:

And you evaded my first point. Here it is again for you:

On 12/4/2022 at 4:20 AM, Eise said:
On 12/3/2022 at 3:15 AM, bangstrom said:

"From the beginning"implies one of the 'hidden variables' ruled out by the Bell test.

Oh man, trying not to loose your face, you now even have lost sight of what entanglement is. We know that the particles are entangled from the beginning, because they are produced entangled. Do you suggest to show entanglement is real by using particles that are not entangled from the beginning?

I didn't answer the question because I thought a "good reader' like yourself would realize that their question made no sense so they must have read some nonsense into something I wrote and check to see what I really did say. If not the first time they asked, then before they asked the same question again.

Obviously, entangled particles are entangled from the beginning of entanglement to the end. They don't take a break in the middle and then resume.

I said  HIDDEN VARIABLES are not there at the beginning or at the end. Hidden variables are not the same as entanglement and the presence of hidden variables was ruled out by Bell et al..

To say that entangled particles are anti-coordinated at the end because they have been anti-coordinated since the beginning, that is one of the hidden variables that was ruled out by the Bell test.

On 12/4/2022 at 4:20 AM, Eise said:

That is the crux of the 'singlet state': we know the wave function of both particles together, but not of the individual particles. That means we know the outcomes of the measurements must be (anti-)correlated.

The particles are not in a singlet state when entangled. Not my favorite explanation, but the conventional explanation is that the particles are in a state of superposition while entangled. Anything that acts on one particle also acts on the other no matter how far apart they may be. The singlet states do not appear until entanglement is lost.

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6 minutes ago, bangstrom said:

Can you explain how there is no FTL signal?

Again: It is for you to explain, if there is such a signal, how come it doesn't contradict special relativity, which clearly forbids such signals?

If there is, but it is completely inconsequencial, how do you know there is such a signal?

What experiment do you propose to measure such a signal?

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1 hour ago, bangstrom said:

Teleportation works without the classical channel. The teleportation in the Danube experiment was accomplished within the time it took three entangled photons to traverse the optical bench and send one teleportation signal to a fourth photon on the way to the distant receiving station and also a radio signal to the same station to set the polarizer.

The teleportation signal had to be FTL to reach the photon on route through a fiber optic cable to the receiving station.

If this is the Danube experiment, there was a classical channel. Your “radio signal” was not FTL.

The classical signal was free-space, and the teleported photon went via an optical fiber.

“Because of the reduced velocity of light within the fibre-based quantum channel (two-thirds of that in vacuo), the classical signal arrives about 1.5 microseconds before the photon.”

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9 hours ago, joigus said:

Again: It is for you to explain, if there is such a signal, how come it doesn't contradict special relativity, which clearly forbids such signals?

Experimenters with entanglement and quantum computing have explained how their FTL transmissions are not in violation of relativity and I have repeated their explanations several times already.

Personally, I find their explanations a bit contrived and in violation of Einstein’s second postulate. If that is correct, I will paraphrase Einstein and say, “If there is a FTL signal, I feel sorry for Einstein because the dear Lord has a better way.”

9 hours ago, joigus said:

If there is, but it is completely inconsequencial, how do you know there is such a signal?

Such a signal is consequential and the signal itself can’t be observed but we see what appears to be evidence of a signal sent and signal received.

With quantum teleportation, some property of an entangled particle can be observed and instantly teleported to a remote entangled particle even if the other particle was generated by a previous entanglement. This demonstrates that the expected quantum property of an entangled particle can be changed in an instant.

9 hours ago, joigus said:

What experiment do you propose to measure such a signal?

The FTL nature of experiments with entanglement has been observed since the late sixties and serious attempts to measure the speed of entanglement have been performed over the past twenty years from Switzerland to China and places in between.  So far all of the attempts have found the speed too fast to measure.

Quantum "spooky action at a distance" travels at least 10,000 times faster than light

8 hours ago, swansont said:

If this is the Danube experiment, there was a classical channel. Your “radio signal” was not FTL.

There was a radio signal sent to prepare the receiver to receive the incoming signal from the teleportation. It had nothing to do with the generation or transmission of the teleported information.

The radio signal was plane old Hertzian all the way.

8 hours ago, swansont said:

The classical signal was free-space, and the teleported photon went via an optical fiber.

The photon sent through the optical fiber was one of four entangled photons and it was a photon from the first entanglement. The identity of the other free photon remaining behind from the second entanglement was observed which instantly broke the entanglement and established the identity of all four entangled photons including the one in the optical fiber.

The revealed identity of the photon in the fiber optic was teleported instantly to to the photon in the cable en route to the receiver. This is the part of the transmission that is instant and non-classical.

8 hours ago, swansont said:

“Because of the reduced velocity of light within the fibre-based quantum channel (two-thirds of that in vacuo), the classical signal arrives about 1.5 microseconds before the photon.”

The radio signal was sent to an electro-optical modulator EOM on the receiver end. An EOM is a bi-refringent crystal between two plates of a capacitor. An EOM can can be used as a variable polarizor. It has no moving parts and the polarization can be rotated electronically by applying the proper DC voltage. The polarization can be oriented to the proper position in nano seconds before the photon arrives in 1.5 microseconds.

Also, note the smaller square on the lower left side of the diagram. This is where the two entanglements are generated for the experiment.

A strong 150 femto second pulse of UV light from a laser is sent through a BBO crystal to hopefully generate a pair of entangled photons. The UV light that passes through unchanged is reflected back by a mirror to pass through the BBO crystal again to generate the second pair of entangled photons.

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5 hours ago, bangstrom said:

Experimenters with entanglement and quantum computing have explained how their FTL transmissions are not in violation of relativity and I have repeated their explanations several times already.

Nothing in what you've quoted implies FTL transmission. The papers you link below don't say anything about FTL transmissions. What the papers mention as "Alice's logic" or "Bob's logic" --across the Danube-- corresponds to representations of the wave function --polarisation directions-- that they must either agree upon beforehand, or --as is the case with this experiment-- by sending a classical signal --under the strictures of SR-- essentially informing about the chosen selected basis.

You, of course, misunderstand all of this, as you've been doing for 25-odd pages so far, and keep doing it, either because you don't care, you a vested interest in keeping up the hype about FTL, or some other reason. My guess about why you keep doing that is as good as anybody's.

A meaningful, intelligent, well-informed conversation about the topic is impossible with you. You keep adding these words that are not there, as well as many other words --or combinations of them-- that don't mean anything. Like your "particles that are in the same light cone."

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On 12/8/2022 at 5:40 AM, joigus said:

Nothing in what you've quoted implies FTL transmission.

The part of the experiment you are ignoring is the part where a photon from the first entanglement enters the fiber optic cable with an unknown polarization only predictable as random and emerges with a predictable polarization that was decided by the later observation of another photon from a second entanglement.

The information gathered from the observed photon was ‘teleported’ to the earlier photon while in flight which is only possible if the transmission was far faster than light.

The photon in the cable was delayed by its transmission through fiber glass just long enough for the predicted polarization of its newly teleported condition to be transmitted by radio to the receiving station across the river. This enabled the receiving station to verify that the teleported condition of the incoming photon had been successfully completed.

The radio transmission to the receiving station was automatically transmitted after the teleportation but before the reception across the river. This is the timing of events that makes the experiment so remarkable in that it demonstrates the successful transmission of a quantum property from the identity of a photon left behind to a photon ‘in flight’ away from the source.

This is not possible in classical physics and it supports Bell’s conclusion that the quantum properties of entangled particles observed at the end of an entanglement are not fixed or unchangeable from those at the start and that they can be altered instantly and ‘at a distance’. This rules out the main points of EPR article.

Entanglement has long been known to be superluminal so there no need to mention this with along with every description.

You appear to be saying there is nothing superluminal taking place with quantum entanglement or with quantum teleportation but the Danube experiment and similar experiments by Zeilinger and others around the world do not support that view.

On 12/8/2022 at 5:40 AM, joigus said:

You, of course, misunderstand all of this, as you've been doing for 25-odd pages so far, and keep doing it, either because you don't care, you a vested interest in keeping up the hype about FTL, or some other reason.

The reason is that I have an unbiased interest following advances in quantum experiments for the past forty years. So far, you have demonstrated almost no understanding of the experimental side of things and your unsupported personal opinions are fifty years out of touch with the revolution in thinking has taken place with and around this years three Nobel prize winners.

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3 hours ago, bangstrom said:

The information gathered from the observed photon was ‘teleported’ to the earlier photon while in flight which is only possible if the transmission was far faster than light.

Here's a riddle for you. If they've sent FTL information, how come it can't be used to send an FTL signal? You haven't described any protocol that does that, and you haven't described the physics. And I'm certain that it can't be done for reasons abundantly explained.

4 hours ago, bangstrom said:

The reason is that I have an unbiased interest following advances in quantum experiments for the past forty years. So far, you have demonstrated almost no understanding of the experimental side of things and your unsupported personal opinions are fifty years out of touch with the revolution in thinking has taken place with and around this years three Nobel prize winners.

I couldn't care less what you think about I'm in touch with this or that, or whether I understand this or that.

The principles they've used in the Danube experiments have been known for nearly a hundred years. Quantum mechanics is a local theory and has no FTL transmission of anything, or of any kind, as proved and explained repeatedly. It wasn't only by myself, but also by many others, some of whom are more in touch than you or I will ever be with "the experimental side of things." Quantum systems have this feature of keeping "indefinition in classical data" for long distances. That's everything at play here.

No new physical principles have been discovered in the Vienna experiments. It's all good-old-reliable QM, known since the '20s-'30s. It was Schrödinger who first pointed those out. It's only that the experiments have been possible to conduct only very recently. And hats off to that.

The problem with QM is it's so unintuitive --even so late in the game as today-- that people who don't understand the conceptual and mathematical framework well enough, and start drawing conclusions from popular-science books and YT videos, like you seem to do, easily get in the habit of repeating this kind of poorly thought concepts to no end. I'm very familiar with this social phenomenon, and Gell-Mann shrewdly prevented against it in the snap of an interview that I posted at the start. Feynman, of course, had similar views, as expressed by Gell-Mann in other fragment of the same interview. Bell was very ambivalent about the consequences of his theorem, and sometimes preferred to declare that "it only proves quantum mechanics is right." You can find a testimony to that from Susskind on his lectures about entanglement.

You seem to be only interested in wearing down other members by mumbling over and over the same misconceptions. That they are misconceptions has been shown very clearly. You haven't answered to Swansont's arguments about the signal; you haven't answered to MigL's and mine on the formalism, you haven't answered to Eise's review of the literature, and finally, you haven't answered to Markus Hanke's laconic --but mathematically precise-- account of what entanglement is all about, pretty much clarifying or insisting on points raised by MigL, Eise, Ghideon, Swansont, and myself.

In order to keep living in this imaginary world of yours, you appeal to whatever fringe interpretation there is, embracing one theory --no matter how speculative-- and dropping another --no matter how fundamental-- as you see fit, only as long as it seems to support your claims. Sometimes it is the TIQM we have to believe, other times it's the WF of radiation with absorbers at spatial infinity, which is a theory of classical electrons and classical radiation... Other times it's Copenhagen's interpretation --the last one without you even realising you're implying it. And still other times you declare SR is not relevant to this discussion, or Zurek's discussion of the measurement is not relevant to these measurements --for some mysterious reason.

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12 hours ago, joigus said:

Here's a riddle for you. If they've sent FTL information, how come it can't be used to send an FTL signal?

I have answered this several times despite your numerous claims that I never answer a question.

It is impossible to send more than one qubit of information at a time via quantum entanglement and this is too little information to be intelligible at the macro level. The signal sent is necessarily random on both ends so a sender can not know what they sent and a receiver can not interpret the results.

Also, the sender and receiver of a FTL signal are beyond reach of a light speed signal so neither can know if the other has sent or received the signal until a later consultation.

Just because sending instant signaling at a distance is impossible at the Alice and Bob macro level doesn’t mean it is impossible at the quantum particle level.

12 hours ago, joigus said:

You haven't described any protocol that does that, and you haven't described the physics. And I'm certain that it can't be done for reasons abundantly explained.

FTL communication is impossible at the macro level. I have repeated that many times.

FTL signaling is experimentally demonstrable at the particle level. Quantum particles appear to be able to exchange information instantly and at any distance as if they are side-by-side and they don’t require our explanations or Einstein’s permission to do so.

12 hours ago, joigus said:

The principles they've used in the Danube experiments have been known for nearly a hundred years. Quantum mechanics is a local theory and has no FTL transmission of anything, or of any kind, as proved and explained repeatedly. It wasn't only by myself, but also by many others, some of whom are more in touch than you or I will ever be with "the experimental side of things."

This is why I find so many of the views expressed here as impossible to accept. You and others may claim the EPR article has never been invalidated therefore hidden variables are still in effect.

You claim Bell doubted that his inequalities ruled out hidden variables so we can ignore Bell and there is no instant action at a distance since quantum experiments of the last fifty years have never demonstrated any kind of FTL transmission because that violates relativity.

Your views appear to be fifty years out of date.

12 hours ago, joigus said:

Quantum systems have this feature of keeping "indefinition in classical data" for long distances. That's everything at play here.

This has been demonstrated as false by experiments involving Bell’s inequalities. The idea of quantum systems having definite and unchanging quantum properties while entangled is one of the 'hidden variables' ruled out by the Bell test.  Zeilinger among others have demonstrated that a quantum property can be teleported in an instant to a series of entangled particles. Quantum properties are not definite from start to finish and can even be altered by later outside events.

13 hours ago, joigus said:

No new physical principles have been discovered in the Vienna experiments. It's all good-old-reliable QM, known since the '20s-'30s. It was Schrödinger who first pointed those out. It's only that the experiments have been possible to conduct only very recently. And hats off to that.

As I say, yours is old time physics.

13 hours ago, joigus said:

You seem to be only interested in wearing down other members by mumbling over and over the same misconceptions. That they are misconceptions has been shown very clearly. You haven't answered to Swansont's arguments about the signal; you haven't answered to MigL's and mine on the formalism, you haven't answered to Eise's review of the literature, and finally, you haven't answered to Markus Hanke's laconic --but mathematically precise-- account of what entanglement is all about, pretty much clarifying or insisting on points raised by MigL, Eise, Ghideon, Swansont, and myself.

I have answered the questions, just not to your satisfaction and perhaps not to theirs, and my "misconceptions' have have been "shown very clearly" out of line with the 1935 EPR article so I'm not buying.

I did agree with Markus with the exception of his comment about quantum properties remaining unchanged from the start. That is one of those hidden variables ruled out by the Bell test.

13 hours ago, joigus said:

In order to keep living in this imaginary world of yours, you appeal to whatever fringe interpretation there is, embracing one theory --no matter how speculative-- and dropping another --no matter how fundamental-- as you see fit, only as long as it seems to support your claims. Sometimes it is the TIQM we have to believe, other times it's the WF of radiation with absorbers at spatial infinity, which is a theory of classical electrons and classical radiation... Other times it's Copenhagen's interpretation --the last one without you even realising you're implying it. And still other times you declare SR is not relevant to this discussion, or Zurek's discussion of the measurement is not relevant to these measurements --for some mysterious reason.

It is possible to discuss SR without mentioning entanglement or entanglement without mentioning SR as Markus did. They are two different topics and the discussion about SR was getting circular far off topic in this thread about entanglement.

In this "imaginary world" of mine, it appears that one quantum particle can ‘know’ the states of other quantum particles even at great distances and two or more particles can instantly coordinate their behaviors.  And lab experiments demonstrating quantum entanglement support this view.

John Clauser and Alain Aspect, in the seventies and eighties, demonstrated in separate experiments that quantum entanglement was real, that it acted instantly and that no local effect could be responsible for the coordination between the particles so the entanglement was non-local.

Their experiments and those of others have shown that entanglement is characterized by non-locality with the two particles sharing a common wave function such that, when you measure a quantum property of one entangled particle, you instantly know something about the other particle, even if they are a great distance apart- theoretically even galaxies apart.

If you look outside your bubble, you should find that this is not just my view but it has become the mainstream common consensus.

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1 hour ago, bangstrom said:

You claim Bell doubted that his inequalities ruled out hidden variables so we can ignore Bell and there is no instant action at a distance since quantum experiments of the last fifty years have never demonstrated any kind of FTL transmission because that violates relativity.

Your views appear to be fifty years out of date.

This is only because you can't read appropriately. It's been explained before. I suggest you go back and do your homework.

You've said many more silly things, but one silly thing at a time, please.

You say this because you don't understand quantum mechanics. Quantum states have a space-time factor and a spin factor. These are very different Hilbert subspaces of the overall state. Einstein's original argument was about particle trajectories, which "live" in the space-time factor of the state. Particle trajectories have to do with a highly singular space of states. A model of hidden variables for particle trajectories does exist however insatisfactory it may be for heuristic reasons. It's called the De Broglie-Bohm pilot wave. Bell considered this model very closely, and wondered why, if his theorem forbids hidden variables, the explicit building of a model implementing particle trajectories is possible. Here, my dear ignoramus:

From:

Bell was puzzled by this: How is it possible, when swarms of impossibility theorems concerning the completion of QM with hidden variables were known at the time, that a model of hidden variables was flying in the face of those? Is there something wrong with our theorems?

You see? History of ideas is more intricate than what you'd have it be.

The answer is very simple, although in no way obvious: Einstein's original argument is about particle trajectories, while the argument of hidden variables post-Bohm, is only about spin. It's not that I haven't told you, is it?

Because QM, in its entirety, needs to be factored out into space and spin, the whole of QM will never be possible to expand in terms of hidden variables that give you all that the theory gives you. Period.

But the commutation rules for the space algebra and the commutation rules for the spin algebra are very, very different. One can be given a discrete parameter representation, while the other cannot. One requires non-compact operators --unbounded-- while the other doesn't.

And another important difference: While, for space variables, you can pick the x-representation for all of it and expand the whole space factor of the state in mutually commuting variables, for spin OTOH, you must be content with only one projection. IOW, space admits a totally-commuting representation for its variables. This doesn't happen for spin.

There's a mathematical frustration for spin. There are no c-numeric functions of (sx,sy,sz) even though all these components "live" in the same subspace of the overall state. You must pick one, plus the total square of all of them to expand the basis: (sz, sx2+sy2+sz2), as you should know. Otherwise, you have no business discussing anything here.

OK. I will leave the argument there for the time being. Try to see if you can digest that, and I'll try to explain more as I can.

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On 12/5/2022 at 12:22 PM, bangstrom said:
On 12/4/2022 at 11:20 AM, Eise said:
On 12/3/2022 at 10:15 AM, bangstrom said:

Hidden variables are, “either (1) the description of reality given by the wave function in quantum mechanics is not complete or (2) two quantum operators cannot have simultaneous reality.”- John Bell

John Bell? Less so: that is from the EPR-article. And you said somewhere 'EPR is invalidated' (whatever that means...) But now it supports your viewpoint? Wow.

If you read the rest of the statement John Bell was listing in the quote the sort of things he considered “hidden variables’ in the EPR article and the hidden variables were what Aspect and Clauser ruled out as invalid fifty years ago.

Seems you did not understand my remark. Your citation is from the original article by Einstein, Podolsky and Rosen. (That you claim is 'invalidated', whatever that means). It is not mentioned in Bell's 'Bertlmann's Socks'. And I fully agree that hidden local variables are ruled out.

On 12/7/2022 at 9:27 PM, bangstrom said:

Anyhow, the quote was Bell’s comment about what he considered to be ‘hidden variables’ and ‘hidden variables’ were the things from the EPR article ruled out by Bell’s inequalities.

Right. Except that it was E, P and R's comment, not Bell's. But the absence of local hidden variables does not mean that the only alternative is an FTL signal. An FTL signal:

• does not appear in the QM that explains the correlation between the measurements, so you cannot build your argument for an FTL signal on QM. Markus explained this clearly in his post on page 22
• is forbidden by SR in principle
• cannot physically exist because for observers in different inertial frames the direction of the signal can differ. That means they differ about the direction of the causal relationship between the measurements. But in SR all inertial observers agree in the direction of causal relationships.

On 12/7/2022 at 9:27 PM, bangstrom said:

Teleportation works without the classical channel.

Really? You said:

On 12/9/2022 at 1:50 PM, bangstrom said:

The radio transmission to the receiving station was automatically transmitted after the teleportation but before the reception across the river. This is the timing of events that makes the experiment so remarkable in that it demonstrates the successful transmission of a quantum property from the identity of a photon left behind to a photon ‘in flight’ away from the source.

Italics by me. So the timing of the classical signal and the measurement are essential. Ask Zeilinger to do his 'teleportation' without classical signal. If you say it is not essential, then you can do without. (But why should the timing be so important...?)

On 12/7/2022 at 9:27 PM, bangstrom said:

To say that entangled particles are anti-coordinated at the end because they have been anti-coordinated since the beginning, that is one of the hidden variables that was ruled out by the Bell test.

Nope. Complete false picture of entanglement. The particles are anti-correlated per definition of what entanglement is. We know the particles are entangled, so that they are anti-correlated. That is exactly what entanglement means:

• the particles are (anti-)correlated
• no measurement was done on the particles yet

We just don't know what the measurements will result to, but if we have a pure singlet state, and we know the spin is up in one direction, then the other particle, measured in the same direction, will be down. But this is based on the correlation between the particles. And in QM this correlation is stronger than we can understand classically. So if you think classically, where such entanglement does not exist, we must conclude that there is a FTL signal. So your way of thinking is already more than 90 years outdated.

On 12/7/2022 at 9:27 PM, bangstrom said:

The particles are not in a singlet state when entangled.

Exactly the opposite: the singlet state is the fully entangled state. Exactly as Markus described.

On 12/10/2022 at 12:00 PM, bangstrom said:

I did agree with Markus with the exception of his comment about quantum properties remaining unchanged from the start. That is one of those hidden variables ruled out by the Bell test.

Please give an exact citation where Markus said that. You even agree:

On 12/7/2022 at 9:27 PM, bangstrom said:

Obviously, entangled particles are entangled from the beginning of entanglement to the end. They don't take a break in the middle and then resume.

Now what is this 'hidden variable ruled out by the Bell test'? That the particles are entangled? Or is a hidden variable an attribute of the particles from the beginning, that determine which particle will show which spin?

On 12/9/2022 at 1:50 PM, bangstrom said:

The reason is that I have an unbiased interest following advances in quantum experiments for the past forty years. So far, you have demonstrated almost no understanding of the experimental side of things and your unsupported personal opinions are fifty years out of touch with the revolution in thinking has taken place with and around this years three Nobel prize winners.

🤣

Edited by Eise
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18 hours ago, Eise said:

Seems you did not understand my remark. Your citation is from the original article by Einstein, Podolsky and Rosen. (That you claim is 'invalidated', whatever that means). It is not mentioned in Bell's 'Bertlmann's Socks'. And I fully agree that hidden local variables are ruled out.

Apparently, Bell was quoting from the EPR article when he listed what he considered to be 'hidden variables.

I agree that local hidden variables have been ruled out by the Bell test. The ruling out of hidden variables by the Bell test is what 'invalidated' the EPR article.

18 hours ago, Eise said:

But the absence of local hidden variables does not mean that the only alternative is an FTL signal.

No hidden variables means there no hidden variables therefore hidden variables have no speed because they don't exist.

I don't see the connection with FTL.

18 hours ago, Eise said:

An FTL signal:

• does not appear in the QM that explains the correlation between the measurements, so you cannot build your argument for an FTL signal on QM.

The FTL signal is a measured value not necessarily a predicted value from QM.

18 hours ago, Eise said:

An FTL signal: is forbidden by SR in principle

The cosmos doesn't care.

18 hours ago, Eise said:

An FTL signal: cannot physically exist because for observers in different inertial frames the direction of the signal can differ. That means they differ about the direction of the causal relationship between the measurements. But in SR all inertial observers agree in the direction of causal relationships.

All speeds and directions are relative but somehow they manage to exist.

Also, the cosmos doesn't care about SR.

18 hours ago, Eise said:

So the timing of the classical signal and the measurement are essential. Ask Zeilinger to do his 'teleportation' without classical signal. If you say it is not essential, then you can do without. (But why should the timing be so important...?)

The classical channel is for measuring the predicted polarity of the teleported signal. It has nothing to do with the preparation and sending of the signal for teleportation. It is for measurement purposes only.

The polarity of the teleported signal can not be predicted until the polarity of the particle from the second entanglement has been measured. When the polarity has been observed, then the receiving end can be informed by radio of what polarity needs to be measured and the receiver is set to record the predicted polarity of the incoming signal to verify that the teleportation was successful.

Zeilinger can successfully teleport without the classical signal but he needs a measurement at the other end to verify that his teleportations were successful. Otherwise, he is like a target shooter shooting blind and without a target.

The classical signal must be sent AFTER the teleportation has taken place to make a prediction and the receiver must be prepared to receive the signal BEFORE the teleported signal arrives. This is an extremely short window of opportunity but it can be done by high speed electronics.

Edited by bangstrom
removed a duplicate entry
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19 hours ago, Eise said:

So if you think classically, where such entanglement does not exist, we must conclude that there is a FTL signal. So your way of thinking is already more than 90 years outdated.

No one is thinking classically and no one is saying entanglement does not exist so your presumptions are 90 degrees off

base.

19 hours ago, Eise said:

Exactly the opposite: the singlet state is the fully entangled state. Exactly as Markus described.

The singlet state is:  In quantum mechanics, a singlet state usually refers to a system in which all electrons are paired. The term 'singlet' originally meant a linked set of particles whose net angular momentum is zero, that is, whose overall spin quantum number s = 0 {\displaystyle s=0} . From wiki.

This is not the same as entanglement where the particle states are indeterminate and the particles frequently far apart.

I don't recall that Markus ever equated the two.

19 hours ago, Eise said:

Please give an exact citation where Markus said that. You even agree:

"Quantum entanglement is also a series of local events, starting from the instant when the entanglement was first created - joigus was quite right in bringing up this (classical) analogy. The difference between them is simply counterfactual definiteness." Markus from p. 22

My objection was to the, "Quantum entanglement is also a series of local events, starting from the instant when the entanglement was first created."

This sounded a lot like a 'hidden variable' theory where the entangled particles are anti-coordinated and unchanging in their properties from  the beginning  especially since this applies to the analogies "joigus" presented which involved EPR style hidden variables.

Upon review, I see Markus later explained that his remarks were about the duration of the entanglement and not spin states, in which case, I stand corrected. And we are in agreement about quantum properties not being in fixed positions from start to finish in an entanglement.

20 hours ago, Eise said:

Now what is this 'hidden variable ruled out by the Bell test'? That the particles are entangled? Or is a hidden variable an attribute of the particles from the beginning, that determine which particle will show which spin?

The particles being entangled is not a hidden variable.

The latter involves a hidden variable where the particle spins are established from the beginning and remain unchanged until entanglement is lost.

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5 hours ago, bangstrom said:

Apparently, Bell was quoting from the EPR article when he listed what he considered to be 'hidden variables.

In which article of Bell? You made the citation, you should know. I did not find it, until now.

5 hours ago, bangstrom said:

No hidden variables means there no hidden variables therefore hidden variables have no speed because they don't exist.

I don't see the connection with FTL.

You don't? If there were local hidden variables, there is no need for any signal. The electrons or photons would carry an attribute that would locally determine the measurement outcomes.

5 hours ago, bangstrom said:

Also, the cosmos doesn't care about SR.

SR is one of the best proven theories in physics, and essential in QFT, Electro-Magnetism, E = mc^2, and a hell of a lot more. It is intrinsic to the metric of spacetime.

5 hours ago, bangstrom said:

The classical channel is for measuring the predicted polarity of the teleported signal. It has nothing to do with the preparation and sending of the signal for teleportation. It is for measurement purposes only.

BS:

From Wikipedia.

4 hours ago, bangstrom said:

No one is thinking classically and no one is saying entanglement does not exist so your presumptions are 90 degrees off base.

Yes, no one is denying entanglement, but it only exists 'in the quantum world', and in QM there is no need for an FTL signal. Just a correlation that is greater than classically possible. Trying to understand this correlation classically, one would need an FTL signal.

4 hours ago, bangstrom said:

The singlet state is:  In quantum mechanics, a singlet state usually refers to a system in which all electrons are paired. The term 'singlet' originally meant a linked set of particles whose net angular momentum is zero, that is, whose overall spin quantum number s = 0 {\displaystyle s=0} . From wiki.

Ah, nearly forgot that you have reading problems. From the same article:

Quote

Singlets and entangled states
It is important to realize that particles in singlet states need not be locally bound to each other. For example, when the spin states of two electrons are correlated by their emission from a single quantum event that conserves angular momentum, the resulting electrons remain in a shared singlet state even as their separation in space increases indefinitely over time, provided only that their angular momentum states remain unperturbed. In Dirac notation this distance-indifferent singlet state is usually represented as:

The possibility of spatially extended unbound singlet states has considerable historical and even philosophical importance, since considering such states contributed importantly to the theoretical and experimental exploration and verification of what is now called quantum entanglement. Along with Podolsky and Rosen, Einstein proposed the EPR paradox thought experiment to help define his concerns with what he viewed as the non-locality of spatially separated entangled particles, using it in an argument that quantum mechanics was incomplete. In 1951 David Bohm formulated a version of the paradox" using spin singlet states.

The difficulty captured by the EPR-Bohm thought experiment was that by measuring a spatial component of the angular momentum of either of two particles that have been prepared in a spatially distributed singlet state, the quantum state of the remaining particle, conditioned on the measurement result obtained, appears to be "instantaneously" altered, even if the two particles have over time become separated by light years of distance. Decades later John Stewart Bell, who was a strong advocate of Einstein's locality-first perspective, proved Bell's theorem and showed that it could be used to assess the existence or non-existence of singlet entanglement experimentally. The irony was that instead of disproving entanglement, which was Bell's hope, subsequent experiments instead established the reality of entanglement. In fact, there now exist commercial quantum encryption devices whose operation depends fundamentally on the existence and behavior of spatially extended singlets.

A weaker form of Einstein's locality principle remains intact, which is this: Classical information cannot be transmitted faster than the speed of light c, not even by using quantum entanglement events. This form of locality is weaker than the notion of Einstein locality" or `local realism" used in the EPR and Bell's Theorem papers, but sufficient to prevent the emergence of causality paradoxes.

4 hours ago, bangstrom said:

This is not the same as entanglement where the particle states are indeterminate and the particles frequently far apart.

Except the distance it is the same. Also in bound states the spin states are not determined, until measured, and they are just as well anti-correlated.

4 hours ago, bangstrom said:

Upon review, I see Markus later explained that his remarks were about the duration of the entanglement and not spin states, in which case, I stand corrected. And we are in agreement about quantum properties not being in fixed positions from start to finish in an entanglement.

Good. So now where do you still have problems with Markus' explanation? It must be somewhere, because it is clear his conclusion is that there is no FTL signal.

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18 hours ago, Eise said:

You don't? If there were local hidden variables, there is no need for any signal. The electrons or photons would carry an attribute that would locally determine the measurement outcomes.

If the given particles carry an attribute that locally determines the outcomes, there would be no need for a signal. This is the most intuitively obvious explanation but it was one of the first hidden variables ruled out by the Bell test so it is not supported by experimental evidence.

I suspect the wave like connection between entangled particles and its instant loss on both ends could serve as a non-local signal that establishes the correlation.

18 hours ago, Eise said:
On 12/12/2022 at 3:49 AM, bangstrom said:

The classical channel is for measuring the predicted polarity of the teleported signal. It has nothing to do with the preparation and sending of the signal for teleportation. It is for measurement purposes only.

BS:

I' m familiar with the setup of the classical channel but you haven't explained how the classical channel is necessary for the quantum channel or how it can have an affect on the quantum channel.

18 hours ago, Eise said:

Good. So now where do you still have problems with Markus' explanation? It must be somewhere, because it is clear his conclusion is that there is no FTL signal.

I don’t recall where Markus said there was no FTL signal. If he did, then I don’t agree.

19 hours ago, Eise said:

Ah, nearly forgot that you have reading problems. From the same article:

You are right. Singlet states include entanglement. I learned something.

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On 12/12/2022 at 11:59 AM, bangstrom said:

The singlet state is:  In quantum mechanics, a singlet state usually refers to a system in which all electrons are paired. The term 'singlet' originally meant a linked set of particles whose net angular momentum is zero, that is, whose overall spin quantum number s = 0 {\displaystyle s=0} . From wiki.

This is not the same as entanglement where the particle states are indeterminate and the particles frequently far apart.

No. The term singlet comes from group theory. A singlet under SO(3) --rotations-- is essentially unique --mod projective representations--, and it is,

$\frac{1}{\sqrt{2}}\left(\left|\uparrow\downarrow\right\rangle -\left|\downarrow\uparrow\right\rangle \right)$

The triplet representation is 3-dimensional,

$\left|\uparrow\uparrow\right\rangle$

$\frac{1}{\sqrt{2}}\left(\left|\uparrow\downarrow\right\rangle +\left|\downarrow\uparrow\right\rangle \right)$

$\left|\downarrow\downarrow\right\rangle$

It's made up of 2 non-entangled states and one entangled state. But the middle one --even though it's entangled-- is not nearly as "badly" entangled as the singlet one.

The singlet state is an entangled state, but not all entangled states --in spin-- are singlets. The singlet state is peculiar for special reasons. One of them is that it's a scalar under unitary representations of the rotation group, which physically means it looks as having 0 spin angular momentum in every direction you look. The other reason is that it has maximal Von Neumann entropy. So it's maximally undetermined, so to speak. Both reasons are intimately related, but are not equivalent.

Keeping maximal entanglement entropy and maximal indetermination for bipartite states is a considerable technological feat. It's the opposite of what you said. Far-apart systems are tipically non-entangled. Entanglement generally comes from particles interacting close to each other.

It's hard to find a phrase in what you say that's not badly wrong in one sense or another.

Stop saying things you know next-to-nothing about. It's bad for you, and it's bad for the discussion.

As I said, one silly --or incorrect-- statement at a time...

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!

Moderator Note

Since this is going nowhere and discussion keeps circling back over the same ground, I’m closing it.

bangstrom, do not bring the subject up again. Speculation requires more than repeated insistence.

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