Quantum Entanglement: Exploring Its Uses in Tech

[NetMage]

Hello, I'm new to the community here at Physics Forums. I am an undergrad double majoring in mathematics/computer science. I will soon be enrolled in a double masters for both math and comp sci...and eventually would like to enroll in a physics PhD program. Well then, enough about me...here are my thoughts.

From what I've researched on quantum entanglement it seems that the pair of electrons or particles entangled will be instantly changing spin according to its entangled partner. Now, the idea of sending information by the entangled particles has been refuted it seems by much of the academic community. It seems as though people suggest that no information is sent, rather the communication between the particles is instant...few suggest that IF there is information being sent, it must be traveling over 10,000 times faster than light.

Now, to the point...does it even matter if quantum entanglement is sending information or not? Let me give an example:

Lets say two photons are entangled. One is in New York and the other in LA. Now, regardless if any information is being sent between the particles, could we not just utilize the 'spin' of the electrons to communicate with servers? For instance, a spin will be 'up' or 'down'. Well, in binary (machine language) the options that a computer understands is either 0 or 1. So could we not just find arbitrary points in time and say one electron spin is up while its entangle partner's spin is down...and have the computer understand this? Thus, sending information instantly or perhaps to some, 10,000 times faster than light. One could write an operating system that understood this, thus revolutionizing information being sent by large distances, and more efficiently. Please, give me your thoughts.

 

[NetMage]

Oh, one last thing, to make it more practical of an idea, one could control the spins using magnetism no? Thus, when changing the spin of one, you have changed the spin of the other, and when this happens, you have successfully communicated from New York to LA, assuming there is a way to make a computer understand the spins.

 

[DrChinese]

So could we not just find arbitrary points in time and say one electron spin is up while its entangle partner's spin is down...and have the computer understand this? Thus, sending information instantly or perhaps to some, 10,000 times faster than light.

Welcome to PhysicsForums, NetMage!

My I ask how you intend to set the bit as up or down?

The point being that changing one does NOT change the other instantaneously. OBSERVING one tells you the value of the other instantly, but that is simply redundant information.

 

[NetMage]

Well, I have not gotten that far yet :) However, it simply seems as though this idea is feasible, and I will continue to put thoughts toward it as I further myself into my academic endeavors. I think we will find that this can and will be done.

 

[etamorphmagus]

Well, I have not gotten that far yet :) However, it simply seems as though this idea is feasible, and I will continue to put thoughts toward it as I further myself into my academic endeavors. I think we will find that this can and will be done.

It's pretty established that information does not travel faster than light.

 

[JK423]

does it even matter if quantum entanglement is sending information or not?

Let's say two photons are entangled. One is in New York and the other in LA. Now, regardless if any information is being sent between the particles,

Here you don't care about "information sending" via entanglement, but below your idea is based on information sending

could we not just utilize the 'spin' of the electrons to communicate with servers? For instance, a spin will be 'up' or 'down'. Well, in binary (machine language) the options that a computer understands is either 0 or 1. So could we not just find arbitrary points in time and say one electron spin is up while its entangle partner's spin is down...and have the computer understand this? Thus, sending information instantly or perhaps to some, 10,000 times faster than light. One could write an operating system that understood this, thus revolutionizing information being sent by large distances, and more efficiently

This idea is all about information sending and this is shown to be impossible. Check other similar threads for the *why*

 

[NetMage]

Hm, I think you may be misreading what I was trying to say. What I'm trying to convey here is that regardless of there actually being any signal or 'information being sent from one entangled particle to the next', we can know one thing about each particle. If one is spin up, then the other is spin down. That seems like all the information WE need in order to establish communications. Dr.Chinese raised the best question, how will we organize the bit for the computers that are to interact with the spins. I am by no means claiming to be an expert here, it just seems as though we are overlooking perhaps a few things when deriving meaning from quantum entanglement (ive only read a book and a few lecture series over it). An interesting question is, if we observe the spin of an entangled particle, we know the sping of its counterpart...as Dr.Chinese stated, redundant information. However, perhaps what we need to be working on first in order to begin thinking of organizing the bit or other methods of communication, we must first find if there perhaps is a way to control spins in entangled particles. It is a relatively new phenomena that we poorly understand.

 

[nismaratwork]

Hm, I think you may be misreading what I was trying to say. What I'm trying to convey here is that regardless of there actually being any signal or 'information being sent from one entangled particle to the next', we can know one thing about each particle. If one is spin up, then the other is spin down. That seems like all the information WE need in order to establish communications. Dr.Chinese raised the best question, how will we organize the bit for the computers that are to interact with the spins. I am by no means claiming to be an expert here, it just seems as though we are overlooking perhaps a few things when deriving meaning from quantum entanglement (ive only read a book and a few lecture series over it). An interesting question is, if we observe the spin of an entangled particle, we know the sping of its counterpart...as Dr.Chinese stated, redundant information. However, perhaps what we need to be working on first in order to begin thinking of organizing the bit or other methods of communication, we must first find if there perhaps is a way to control spins in entangled particles. It is a relatively new phenomena that we poorly understand.

I just want to be sure here: you understand that without classical means (read: lightspeed or less) you can't communicate INFORMATION that the other party will understand? You are still limited to light or sub-light communication with this method, even if the spin-flip occurs at 10,000x or more c?

 

[DrChinese]

However, perhaps what we need to be working on first in order to begin thinking of organizing the bit or other methods of communication, we must first find if there perhaps is a way to control spins in entangled particles. It is a relatively new phenomena that we poorly understand.

The phenomena of entanglement was named as such circa 1935. So if you call 75 years old "new", then I would agree with you. It is true that the technology to readily entangle particles is only about 20 years old - that being Parametric Down Conversion. However, there is a lot of theory going back further than that.

The theoretical issues surrounding entanglement are better understood than you may have been led to believe. There have been perhaps 20,000 papers written on the subject including probably 5000+ different experiments.

In general, there are 2 elements needed for entanglement: a) some kind of conserved system (such as total spin or momentum); and b) 2 or more particles in some kind of superposition of states. Using quantum mechanics, it is possible to predict and test a variety of exotic effects. To date, nothing has been seen which is not consistent with the predictions of QM. That includes delayed choice experiments, quantum erasers, as well as the kinds of seemingly non-local behavior you cite.

There is absolutely nothing in all of this that has ever given a hint that superluminal (FTL) communication is possible. You may as well speculate that warp drives are possible too. Not meaning to sound sarcastic, I am simply pointing out that there is no science behind your idea. I encourage you to ask questions and read more about this fascinating subject.

 

[NetMage]

Well, before I got on, help me better understand this, as I stated, I'm no expert, just an undergrad about to go to grad school. I just have extraordinary interests in subjects such as these, hence why I plan to extend my grad studies after my math and CS dual masters program, into a physics grad program. Now, if there are two entangled particles, and we know the spin of one, that tells us information about the other as I understand. If we KNOW (which we would not have to, because you could just pick and arbitrary point and time and call it up or down) the spin of one particle, we KNOW things about the entangled partner. In an abstract way, information has already been sent. Maybe not through the particles themselves, but information through us. Because we know one, we know the other, so not necessarily sending information, but hopefully you understand what I'm getting at. Now as far as communicating information faster than light, you are misunderstanding my intentions. In my first post I stated that for reasons I'm trying to get across, there doesn't have to be any information being sent. Let me reinvent my scenario and try to better explain myself and you may critique it as necessary.

Ok, So we have two entangled particles, one let's say in New York, and one let's say in LA. Now, ASSUMING (and here is where it is all hypothetical and the main point of this thread) *we can figure out how to control the spins on the electrons*, for my elementary brains purpose, I will say magnetism. Using magnetism, the servers only have to know when the magnets change to communicate. Spin up = 0 let's say, and spin down = 1. you could design around this idea. And yes, I understand this is hypothetical and was hoping maybe someone could fill me in if i am misrepresenting the phenomena of entanglement.

 

[NetMage]

Thank you Dr.Chinese for your hospitality :)

 

[JK423]

Now, ASSUMING (and here is where it is all hypothetical and the main point of this thread) *we can figure out how to control the spins on the electrons*

That's the point! We can't control their spins. When you make a measurement on your electron's spin, the outcome is random! If we could control the outcome, then yes we would be able to send information instantly. The fact that we can't makes it impossible.
For example, say that '1' is spin up and '0' spin down. In order to send the message 100111101 etc you should be able to control which value the spin would take, and that's determinism. Quantum mechanics do not allow this. So, you would send something like 100111010101, but i wouldn't mean anything because it would be just random bits with no meaning.

 

[DevilsAvocado]

Hm, I think you may be misreading what I was trying to say. What I'm trying to convey here is that regardless of there actually being any signal or 'information being sent from one entangled particle to the next', we can know one thing about each particle. If one is spin up, then the other is spin down. That seems like all the information WE need in order to establish communications.

I don’t want to tear down any "newborn interest", but there is one crucial fact about entanglement that you’ve seems to have missed. Yes, if we arrange the measuring equipment in a certain way (aligned parallel) then a "YES" (or 1) at one site will certainly be "NO" (or 0) at the other site.

But there is no way to force one of two states out of a QM system with a 50% probability! If it was, there would not be any QM probability, which is the very basis of QM. Most of today’s technology with computers and cell phones and other cool gadgets all build on the fact that QM is correct.

Let’s say you want to send the letter "A" from New York to LA with entanglement. Letter "A" in binary (computer) format is:

100 0001​

How are you going to control this so this is the sequence that is measured in LA? There are 128 combinations in 7 binary digits, and the receiver in LA might just get any random binary value:

101 0101​

This is translated to the letter "U". Sure, in LA they will know that New York now will have:

010 1010​

But this is translated to the character "*", and this is not much of a meaningful 'conversation', right?

This just doesn’t work...


EDIT: Oops, JK423 is basically saying the same thing...

 

[NetMage]

I see, interesting indeed

 

[NetMage]

Now, see there...we have already made some progress. We went from quantum entanglement not being able to send information...to sending meaningless information...just because it hasnt been done, does not mean it cannot. I'm no physicist yet, however I do believe there is so much we don't know. And in the span of a few comments on a thread we have figured 1 thing out.

 

[nismaratwork]

Now, see there...we have already made some progress. We went from quantum entanglement not being able to send information...to sending meaningless information...just because it hasnt been done, does not mean it cannot. I'm no physicist yet, however I do believe there is so much we don't know. And in the span of a few comments on a thread we have figured 1 thing out.

No one has "figured" anything out in this thread, what we have are people explaining the basics of QM probability distributions and the need for classical means of verification using entangled pairs. Let's get be grandiose about this... there are at least half a dozen threads like this which you could read and have your questions answered.

To be brief: the speed of light in vacuum (c) is the limit for communication... when you start to suggest that people establish codes ahead of time, we'll point out that as "Alice" and "Bob" have to travel sub-c, then communicate, you're just changing the order of when the classical means are inserted.

I could go on...

 

[NetMage]

Would someone go into more depth as to WHY we cannot control the spins on the particles? As I am understanding this, we CAN infact know the spin of a particle and thus determine the spin of the other...? Or am I once again misunderstanding? It seems to me if one had several entangled particles, enough to ALREADY set up the bit, then there would be no problem with this, regardless of changing spin. For instance, say we have enough entangled particles in a system that essentially codes for binary. I understand this will be millions or more different combinations. But SAY we have this established (Once again I understand this is not very practical, more about the principal), would this not allow for communication? To repeat myself: Say we have millions of, or whatever arbitrary number it would take, entangled particles to set up the combinations for let's say...basic text...the binary...without even having to change spins, is this still not feasible. From everything that has been explained and that I have researched...this does not violate any QM.

 

[nismaratwork]

Would someone go into more depth as to WHY we cannot control the spins on the particles? As I am understanding this, we CAN infact know the spin of a particle and thus determine the spin of the other...? Or am I once again misunderstanding? It seems to me if one had several entangled particles, enough to ALREADY set up the bit, then there would be no problem with this, regardless of changing spin. For instance, say we have enough entangled particles in a system that essentially codes for binary. I understand this will be millions or more different combinations. But SAY we have this established (Once again I understand this is not very practical, more about the principal), would this not allow for communication? To repeat myself: Say we have millions of, or whatever arbitrary number it would take, entangled particles to set up the combinations for let's say...basic text...the binary...without even having to change spins, is this still not feasible. From everything that has been explained and that I have researched...this does not violate any QM.

You CAN communicate information using quantum methods, you just can't do it faster than c. The principle you've articulated is behind the hopes for a quantum computer in many ways, without the emphasis on speed at least. Once you say, "we have this established", you require that two or more people be in CLASSICAL communication (face to face, radio, or other) to set the ground rules for each change of state. You're not really using the entangled pairs to send the information then, but rather as a way of securing information over great distances, or a means of signaling... still the information itself propagates at c or slower.

 

[NetMage]

nismaratwork, I am not simply asking a question. I am getting to know the scientific community better, learning, and hopefully if not now, soon be contributing to it. This just so happens to be a topic of interest, and that as I learn more about it, may perhaps do research in it and write my dissertation on. I'm 20 years old, and far ahead of most of my peers. Cut me some slack ;)

 

[NetMage]

Right, I understand this. I just wanted to establish whether or not entanglement communications is a feasible method. that's all haha.

 

[nismaratwork]

Right, I understand this. I just wanted to establish whether or not entanglement communications is a feasible method. that's all haha.

It definitely is. Let's pretend that you're going back in time and for some crazy reason you want to make sure that the Nazis win WWII. You remember that one of the biggest coups for the Allied forces was intercepting the code device on a U-Boat. You don't care about faster than light comms, but you want it to be instant, and SECURE. So, you bring the technology to use entangled photons to send information, but to keep it secure you can't verify by radio. You make sure that the captain and first officer of each U-Boat knows what "signal 1" "signal 2" and so forth means with their entangled photons. It doesn't matter if they get a 0 or 1, because each time there is a spin flip, they call to memory a conversation they had with their commanding officers at base. They now have completely secure signaling devices, even if they can't send so much as the message "hello" via direct means.

This is the simplest use of a single entangled pair, but there is such a thing as using quantum means of communication at less than c, which would be altered by any spying (or any perturbation). In this case, it's not the speed, but the security that's so desirable. In essence, the benefits of QM comms are many, but FTL isn't one of those benefits.

 

[DevilsAvocado]

just because it hasnt been done, does not mean it cannot.

Never say never, right?

You should know what you’re up against, namely a violation of causality, allowing an effect to occur before its cause. Also called http://en.wikipedia.org/wiki/Retrocausality" : Can the future affect the present, and can the present affect the past? Is time travel possible?

The http://en.wikipedia.org/wiki/No_communication_theorem" clearly says NO.

But you are not alone. http://en.wikipedia.org/wiki/John_G._Cramer" without coincidence counting, to achieve "spooky communication".

And in the span of a few comments on a thread we have figured 1 thing out.

It’s great that you’ve learned a new thing. We have spent 5 months and 1500 posts discussing http://en.wikipedia.org/wiki/EPR_paradox" , but I’m not sure we’ve learned anything...!? (:rofl:)

 

[NetMage]

HAHA, and thank you very much for that...this is what I was really looking for the whole time...I just had a difficult time of expressing it I suppose. I was not looking for INSTANT communication, although that would have been a neat thing ^^. Simply that it COULD be done :P. Using classical means to interpret QM, and sending the information.

 

[nismaratwork]

HAHA, and thank you very much for that...this is what I was really looking for the whole time...I just had a difficult time of expressing it I suppose. I was not looking for INSTANT communication, although that would have been a neat thing ^^. Simply that it COULD be done :P. Using classical means to interpret QM, and sending the information.

In that case, you're barking up the right tree, but understand, here and elsewhere when most hear "entanglement... communication" we start to think people are trying to do what DevilsAvocado is talking about, and violate causality. I'm glad you're not, but people at PF get jaded like anyone else.

DA: Yeah well, part of that is the complexity of the question and rich new perspectives from people like RUTA... and part is the cyclical hell of a couple of clowns who can't let a few pages of discourse develop without "refuting" it.

 

[DevilsAvocado]

Would someone go into more depth as to WHY we cannot control the spins on the particles?

Elementary my dear Watson - just think of flipping coins.

(In QM there is no way of knowing the outcome, even if you had all the initial data on every atom in the whole universe.)

 

[DevilsAvocado]

and part is the cyclical hell of a couple of clowns who can't let a few pages of discourse develop without "refuting" it.

HAHAH LOOOL! :rofl: :rofl: :rofl: RIGHT ON SPOT!

And yes, of course RUTA and DrChinese et al. has learned me a lot! Thanks guys!

 

[nismaratwork]

HAHAH LOOOL! :rofl: :rofl: :rofl: RIGHT ON SPOT!

And yes, of course RUTA and DrChinese et al. has learned me a lot! Thanks guys!

I hear you; it took me a lot of time to really research and catch up with the thread when I started reading it, but I know more about interpretations of QM now, and the concept of reality as defined by EPR or non-realists, and the issue of non-locality than I ever did. Dr. C's immense knowledge is priceless, and I had never really explored RUTA's specialty in RBW interpretation. It's literally food for my thoughts.

NetMage: It may not be what you were originally looking for, but the thread in question is: about "action at a distance" aka Non-Locality aka entanglement et al in the context of Bell's work, and the Einstein Podolsky Rosen paper (EPR). You might enjoy the read, although it's going on 90 pages now, I would start from the beginning and work through it. No doubt it will raise all kinds of questions, but there are tons of links to relevant resources, and it's... well... it's really fun.

 

[NetMage]

Ah no, I was simply trying to find out if it was feasible using quantum entanglement to ULTIMATELY send information. Of course I meant through classical means though ;). Sorry for the long drawn out mix up. My computer knowledge has quite some depth to it. I was considering eventually setting up communications using this method. That was the main idea, and was curious as if it could be done. As complex as this may be, I think it could have some very significant implications such as stated before, information and data security. With computers interacting via entanglement, it would be difficult for third parties to intercept information :). This would be a useful thing along with quantum cryptogrophy. Once again, sorry for the mix up and hopefully I was not too overbearing :P. I will continue to do my research and share my exploits with the community. If any of you have more ideas regarding this, I'd love to hear them!

 

[NetMage]

I hear you; it took me a lot of time to really research and catch up with the thread when I started reading it, but I know more about interpretations of QM now, and the concept of reality as defined by EPR or non-realists, and the issue of non-locality than I ever did. Dr. C's immense knowledge is priceless, and I had never really explored RUTA's specialty in RBW interpretation. It's literally food for my thoughts.

NetMage: It may not be what you were originally looking for, but the thread in question is: about "action at a distance" aka Non-Locality aka entanglement et al in the context of Bell's work, and the Einstein Podolsky Rosen paper (EPR). You might enjoy the read, although it's going on 90 pages now, I would start from the beginning and work through it. No doubt it will raise all kinds of questions, but there are tons of links to relevant resources, and it's... well... it's really fun.

Will do, can you send a link as to where I can find this?

 

[nismaratwork]

Will do, can you send a link as to where I can find this?

Yes of course, I'm sorry that's a rather silly oversight on my part: https://www.physicsforums.com/showthread.php?t=395509&highlight=Is+action+at+a+distance+possible

Enjoy!

 

[NetMage]

Thanks again, I'm sure I'll be speaking with you on here again in the future :). Next time I'll do my best to be less confusing