Thought Experiment on Quantum Entanglement Communications

[Old Guy In Stanton]

I thought about putting this in the pseudoscience forum, but I am pretty sure this is based on a decent lay understanding of quantum theory basics. I have a thought experiment on quantum entanglement and communication that I would like to present and get some feedback on.

- Imagine a "transmitter" that consists of a bank or row of 27 boxes.
- Think of these boxes as keys on a keyboard.
- Each box contains a tiny linear accelerator, with a single particle in it, going around and around.
- Each box is labeled for a letter of the alphabet, with the last box labeled "space."

- Now imagine a "receiver" which consists of another row of 27 boxes.
- Again, each box has a tiny linear accelerator, with a single particle in it, going around and around.
- Each of these particles is entangled with it's counterpart particle in the "transmitter" bank.
- Again, each box is labeled for a letter of the alphabet, with the last box labeled "space."

So you have two banks of accelerators. You move the two banks an inch (or a lightyear) away from each other:

Transmitter: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [space]
^
|
| Some Distance
|
V
Receiver: A B C D E F G H I J K L M N O P Q R S T U V W X Y Z [space]

 

- The particle in the transmitter's "A" accelerator is entangled with the particle in the receiver's "A" accelerator.

- Same applies for B, C, D.... [space] accelerators.

- Action:
1) On the transmitter end, I press, or otherwise disturb or "look at" the third key.
2) This collapses the wave state of the particle in that accelerator.
3) This breaks entanglement between that particle and the one in the other "C" box on the receiver.
4) The receiver-end particle does something other than its continuous circling, and creates a macro event.

5) Note: I don't care WHAT it does, merely that it does something... and that the other 26 boxes do nothing.
6) This macro event is labeled "C"

I have just communicated a piece of information. I do the same three more times, collapsing the wave states of the "A", "T" and "space" keys. I have now instantly transmitted the word "CAT" over a distance of an inch (or a light year).

I note that I cannot re-use these two banks of accelerators, to re-transmit new C's, A's, T's, or spaces, as entanglement is broken for these four keys. But if each row of each bank has many such "ranks" of matched accelerators (say in a grid 27 wide X 100 deep), I can discard the "empties" and use the next accelerator in line for that particular piece of encoded data.

Here is the principle: For each of the boxes, I do not care what each of the entangled particles does. All I care about is WHICH BOX in the receiver bank creates a macro event of some sort. The number of the box tells me what the data is.

OK, can someone tell me in plain, specific English why this will not work?

[uncool]

You have made the assumption that "breaking entanglement" will cause a "macro event". Why should that be?

[Old Guy In Stanton]

You have made the assumption that "breaking entanglement" will cause a "macro event". Why should that be?

 

Isn't that the assumption with Schrodinger's Cat? The particle sets off an event that kills the cat. Or not. You don't know, because you don't (and cannot) know what the particle will do. But in this scenario, you don't CARE whether the event kills the cat or not. An event merely has to happen with that particular "box."

 

One possibility would be that: that the collapse causes the receiver particle to do something else other than quietly go around the accelerator. Say it hits a wall of the accelerator, which sets off a detector. Again, you don't care where it hits (left, right, up, down) merely that it does something other than what it is doing.

 

Break the overall scenario down into specific issues: are you telling me that it is impossible for a quantum event of unknown effect to trigger a detector? Happens all the time at CERN. Again, you don't care WHAT detector in a particular accelerator is triggered, merely that one is triggered in the "A" or the "B", etc. receiver box. Imagine 27 cats, and one of them is either killed or released. All you need to know is which cat.

Edited March 21, 2016 by Old Guy In Stanton

[swansont]

No it won't work. The only issue is where your idea breaks down.

 

If the sender breaks the entanglement, how is the receiver supposed to know this? The particles are in a superposition of states until the entanglement is broken, but you can't tell this state until you measure the particle. And even then, you don't know if it was entangled or not. You might be able to determine that, but only after getting the sender to tell you what s/he measured. And that information can't travel faster than c.

 

Isn't that the assumption with Schrodinger's Cat? The particle sets off an event that kills the cat. Or not. You don't know, because you don't (and cannot) know what the particle will do. But in this scenario, you don't CARE whether the event kills the cat or not. An event merely has to happen with that particular "box."

 

One possibility would be that: that the collapse causes the receiver particle to do something else other than quietly go around the accelerator. Say it hits a wall, which sets off a detector. Again, you don't care where it hits (left, right, up, down) merely that it does something other than what it is doing.

 

Break the overall scenario down into specific issues: are you telling me that it is impossible for a quantum event of unknown effect to trigger a detector? Happens all the time at CERN. Again, you don't care WHAT detector in a particular accelerator is triggered, merely that one is triggered in the "A" or the "B", etc. receiver box. Imagine 27 cats, and one of them is either killed or released. All you need to know is which cat.

 

 

But you don't know if your cat is dead because you did the measurement or because the other person did the measurement first. All you see is a dead cat. The other person sees a live cat, but only after opening the box. How do they know to open the box? And what does "live cat" mean? You don't know beforehand it would be alive.

 

And real QM is even more subtle. If you measure a spin you could both measure e.g. spin down if your apparatus isn't set up the same way (similarly with polarization), even though the entanglement required opposite spins. Basically, you are assuming you know things you can't know.

[Old Guy In Stanton]

No it won't work. The only issue is where your idea breaks down.

 

If the sender breaks the entanglement, how is the receiver supposed to know this? The particles are in a superposition of states until the entanglement is broken, but you can't tell this state until you measure the particle. And even then, you don't know if it was entangled or not. You might be able to determine that, but only after getting the sender to tell you what s/he measured. And that information can't travel faster than c.

Again, you don't care what happens. You don't need to measure anything as far as that box is concerned. All you need to know is that THIS box, or THAT box changed.

 

- Look at box C

- Waveform of the particle in box C collapses

- Previously-established entanglement with the particle in the other box C collapses

- The particle in the other box does something other that what it was doing (you don't care what).

- NONE of the other boxes have changed.

- Therefore, because THIS box changed, and THIS box is labeled "C" on both ends, you have communicated the letter "C."

 

Nothing else needs to be sent to the receiver. You don't need to know what the person who is transmitting measured.

[Strange]

 

Isn't that the assumption with Schrodinger's Cat? T

 

I think you are confusing "superposition" and "entanglement". Not the same thing (although related). The cat thought experiment relies purely on superposition, it does not require entanglement.

Again, you don't care what happens. You don't need to measure anything as far as that box is concerned. All you need to know is that THIS box, or THAT box changed.

 

Nothing changes. (Except that the person at the transmitter end knows what entangled value you will read, if/when you read it. But they can only transmit that information to you at light speed.)

Edited March 21, 2016 by Strange

[swansont]

Again, you don't care what happens. You don't need to measure anything as far as that box is concerned. All you need to know is that THIS box, or THAT box changed.

 

- Look at box C

- Waveform of the particle in box C collapses

- Previously-established entanglement with the particle in the other box C collapses

- The particle in the other box does something other that what it was doing (you don't care what).

- NONE of the other boxes have changed.

- Therefore, because THIS box changed, and THIS box is labeled "C" on both ends, you have communicated the letter "C."

 

Nothing else needs to be sent to the receiver. You don't need to know what the person who is transmitting measured.

 

 

But you can't tell that the other box is doing anything different.

[Old Guy In Stanton]

 

I think you are confusing "superposition" and "entanglement". Not the same thing (although related). The cat thought experiment relies purely on superposition, it does not require entanglement.

 

Nothing changes. (Except that the person at the transmitter end knows what entangled value you will read, if/when you read it. But they can only transmit that information to you at light speed.)

 

Why do I have to know what the entangled value is? I am not "reading" the entangled value, just which box reacts to the loss of entanglement.

 

It's like a voltage spike. You have a circuit that has a current value of, say, zero volts DC. As long as the DC current is 10 volts, there is no activation of an alarm device that is attached to it. Now hook up another device, which will insert a random DC voltage into the circuit. You don't care what the voltage reads... merely that it changed (and set off the alarm).

 

Similarly, you don't care what the entanglement result is; all you care about is which box changed.

 

 

But you can't tell that the other box is doing anything different.

Is there no way for an unknown change in a quantum particle to effect a change on the macro level? When an electron stops going around and around an accelerator, it hits a target of some kind that sets off an alarm.

 

Change in activity of quantum particle >>>>> change in macro state of alarm. Isn't this what they do at CERN?

[Strange]

There is no change in the other entangled particle. The only thing that changes is (knowledge about) the value of a property that you will measure. As you don't know what the value is going to be until you measure it, you can't tell that anything has happened.

 

Why do I have to know what the entangled value is? I am not "reading" the entangled value, just which box reacts to the loss of entanglement.

 

No box reacts. Because nothing changes.

[swansont]

There is no change in the other entangled particle. The only thing that changes is (knowledge about) the value of a property that you will measure. As you don't know what the value is going to be until you measure it, you can't tell that anything has happened.

 

No box reacts. Because nothing changes.

 

 

The superposition collapses, but there's no way to detect this in the way that's being described.

[Delta1212]

Quantum entanglement doesn't do anything weird except in light of some other quantum weirdness.

 

If you split a quarter in half so that you have a heads side and a tails side, drop them in two envelopes and send them to opposite sides of the globe, as soon as you open one envelope, you will know exactly which half someone opening the other envelope will find, regardless of whether they have checked their envelope yet or not.

 

That's how quantum entanglement works, except that we know for other reasons that each envelope contains half a quarter that is both heads and tails simultaneously until someone checks. Once you check, it collapses to one or the other, and you know which one someone will find in the other envelope. But you have no way of knowing whether they checked theirs before you, and checking doesn't induce any detectable change in the other one, because the only thing you can detect is whether you got heads or tails.

 

You can't tell whether the superposition has collapsed until you check it, but if you check it, you collapse the superposition. There's simply no way to tell unless someone sends you a message saying "Hey, I checked mine and if you check yours, you'll get heads" but then you're still not going to get any new information by checking it yourself except to confirm information that was already sent to you via traditional means.

[Old Guy In Stanton]

No it won't work. The only issue is where your idea breaks down.

 

If the sender breaks the entanglement, how is the receiver supposed to know this? The particles are in a superposition of states until the entanglement is broken, but you can't tell this state until you measure the particle. And even then, you don't know if it was entangled or not. You might be able to determine that, but only after getting the sender to tell you what s/he measured. And that information can't travel faster than c.

But you don't know if your cat is dead because you did the measurement or because the other person did the measurement first. All you see is a dead cat. The other person sees a live cat, but only after opening the box. How do they know to open the box? And what does "live cat" mean? You don't know beforehand it would be alive.

 

And real QM is even more subtle. If you measure a spin you could both measure e.g. spin down if your apparatus isn't set up the same way (similarly with polarization), even though the entanglement required opposite spins. Basically, you are assuming you know things you can't know.

 

So what you are saying is that there is no way to know what is in the box without opening it, but you don't know which of the 27 boxes to open because you don't know what is in the box. And when you open them, you don't know the significance of what you find in each, because you don't know that this is the box that changed.

 

Is that a fair restatement?

Quantum entanglement doesn't do anything weird except in light of some other quantum weirdness.

 

If you split a quarter in half so that you have a heads side and a tails side, drop them in two envelopes and send them to opposite sides of the globe, as soon as you open one envelope, you will know exactly which half someone opening the other envelope will find, regardless of whether they have checked their envelope yet or not.

 

That's how quantum entanglement works, except that we know for other reasons that each envelope contains half a quarter that is both heads and tails simultaneously until someone checks. Once you check, it collapses to one or the other, and you know which one someone will find in the other envelope. But you have no way of knowing whether they checked theirs before you, and checking doesn't induce any detectable change in the other one, because the only thing you can detect is whether you got heads or tails.

 

You can't tell whether the superposition has collapsed until you check it, but if you check it, you collapse the superposition. There's simply no way to tell unless someone sends you a message saying "Hey, I checked mine and if you check yours, you'll get heads" but then you're still not going to get any new information by checking it yourself except to confirm information that was already sent to you via traditional means.

 

OK, I think I understand that.

 

The problem is that you are checking the "identity" or contents of the box.

 

Is there a way for a quantum event to create a macro event?

[swansont]

So what you are saying is that there is no way to know what is in the box without opening it, but you don't know which of the 27 boxes to open because you don't know what is in the box. And when you open them, you don't know the significance of what you find in each, because you don't know that this is the box that changed.

 

Is that a fair restatement?

 

Pretty fair.

 

The problem is that you are checking the "identity" or contents of the box.

 

Is there a way for a quantum event to create a macro event?

Not without triggering the "checking the box" issue.

[Old Guy In Stanton]

Pretty fair.

 

 

Not without triggering the "checking the box" issue.

 

Is there any way that a quantum-level event could trigger a macro-level event?

 

Is the previous sentence a good summary of what happens at CERN when an electron hits a target?

 

I think I'm clear on what I am asking, now:

(1) Is there a way for a quantum-level event to trigger a macro-level event?

AND

(2) Is it possible to entangle two quantum particles in such a way that affecting one causes the other to change its behavior

(i.e.: BE some macro-measurable event.

 

These are the two key points. If (and ONLY if) both of the above are possible, then a system of four boxes, arranged as in my OP example (but with just two boxes instead of 27), should be able to instantaneously communicate information over a distance.

 

- The transmitting person triggers box A, but leaves box B alone.

- The receiving box A quantum event (change in whatever quantum behavior it has) rings a bell.

- The receiving box B does NOT have a quantum event, because the transmitting box A was not touched.

- The receiving person sees that the box that rang it's alarm bell is labeled A, and therefore knows that this is what the other person sent.

 

Can you show that either (1) or (2) above is impossible?

 

Addendum: I googled "can a quantum event trigger a macro event" and found this:

https://books.google.com/books?id=a4JhVFaUOjgC&pg=PA839&lpg=PA839&dq=can+a+quantum+event+trigger+a+macro+event&source=bl&ots=aC5RziV0Yv&sig=03Wo1T3pvir09MktDmB-u-4Dbco&hl=en&sa=X&ved=0ahUKEwjP9oK3sNXLAhVO2mMKHayUANIQ6AEIIDAB#v=onepage&q=can%20a%20quantum%20event%20trigger%20a%20macro%20event&f=false

 

And that jogged my memory. In microbiology, proton pumps are doing stuff with quantum-level particles. That article mentions quantum events triggering point mutations.

Here's an article on how to entangle electrons. Apparently, it can now be done on demand.

 

https://erc.europa.eu/succes-stories/how-entangle-two-electrons-%E2%80%93-and-do-it-again-and-again

 

So what kind of stable behaviors could these electrons be induced to have, that collapsing the wave could cause the "receiver" electron to change it's stable behavior?

Edited March 22, 2016 by Old Guy In Stanton

[Strange]

I think I'm clear on what I am asking, now:

(1) Is there a way for a quantum-level event to trigger a macro-level event?

AND

(2) Is it possible to entangle two quantum particles in such a way that affecting one causes the other to change its behavior

(i.e.: BE some macro-measurable event.

 

(1) Yes. For example, a quantum event (atomic decay) causes the audible clicks from a Geiger counter.

 

(2) No. The only thing that changes is that the state of a particle goes from undetermined to unknown. (The superposition collapses, as swansont puts it.)

[Delta1212]

Yes, I think it's important to note that, in fact, all macro-level events are the result of quantum-level events, but not in the way you are proposing. There's no system that you can set up that will be able to detect "oh, something quantum happened" and react to it.

 

The system can react to the result of quantum events, but not the fact of their taking place. You can only react to direct interactions and any direct interaction causes the very collapse you're wanting to detect.

[swansont]

Is there any way that a quantum-level event could trigger a macro-level event?

 

The answer is not going to change. yes, but not in any way that gets you around this issue. This will be the same as looking at the particle. You're essentially asking that you both interact and not interact with the particle. You gotta pick one or the other.

[Old Guy In Stanton]

This article appears to state that quantum action can be communicated. what am I not understanding here?

 

http://www.livescience.com/5499-einsteins-spooky-physics-entangled.html

 

"Using electric fields and lasers, the researchers herded the ions into separate pairs and then entangled their motion. Then they separated the pairs by 240 micrometers (millionths of a meter), which is actually quite a span for an atom. Even at this distance, when the researchers changed the motion of one pair — stopped or started the vibrations — the other responded immediately, stopping or starting in kind."

 

If this is correct, I do not see why my scheme would not work.

[Strange]

This article appears to state that quantum action can be communicated. what am I not understanding here?

 

The difference between journalism and science.

 

For example, nothing like this bit you quote from the article appears to be in the paper:

"Even at this distance, when the researchers changed the motion of one pair — stopped or started the vibrations — the other responded immediately, stopping or starting in kind."

 

The oscillations are synchronised but they cannot be started and stopped to cause an effect on the other.

 

A more accurate article can be found here: http://www.nature.com/news/2009/090603/full/news.2009.540.html (there is a short video on that page which explains it quite well)

And here: http://www.nist.gov/pml/div688/jost_060309.cfm

And the paper itself here: http://arxiv.org/abs/0901.4779