New Type of Entanglement - Time

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Main Question or Discussion Point

I read this article in the Technology Review published by MIT:

http://www.technologyreview.com/blog/arxiv/26270/?p1=A3

First let me say that this is a very interesting development. But unfortunately the article has a "dumbed down" analogy for the layman, which I wish I could understand a little better. Here's the quote:

""If the past detector was active at a quarter to 12:00, then the future detector must wait to become active at precisely a quarter past 12:00 in order to achieve entanglement," they say. For that reason, they call this process "teleportation in time"."

Of course, this analogy is ridiculous for all the obvious reasons (physics doesn't care what kind of clock we use, for starters). But I am hoping someone here can explain it in a way that is not ridiculous but still intuitive enough to grasp.

Thank you,

Krombacher
 

Answers and Replies

  • #2
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I did a quick look at the original research paper and the report article is way oversimplified and confused/inaccurate. I think I got a hint of understanding of what the experimenters were saying--I'll check back with you later-- have to go work on my airplane while the weather is warm. Maybe someone else can explain/comment sooner.
DC
 
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  • #3
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Thanks DarioC, would appreciate your thoughts when you get back.

Krombacher
 
  • #4
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There are indications, from what I can derive from the original paper, that the reference to zero time (t=0) is in Minkowski time. The zero time is at the origin of a light cone spreading out from an "event" as plotted on a 2 space/1 time dimension graph/chart.

I've spent 2 hours on this paper and am just starting to see the light (I hope.) I have picked up a lot from the paper, but I'm not saying anything until I can tie it together to make some sense, if ever.

I'm after this now for my own curiosity to see if I can comprehend what the paper is saying rather than whether I believe it is anything more than---words escape me.

By the way, this "research" is paid for out of our taxes, courtesy of the U.S. Military. Go figure.

DC
 
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  • #5
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Well, I'm glad I could bring something to this board which stokes the curiosity of its members. I would love to hear what others have to say. Is this really a new way to look at entanglement as the article states, or is it the classical entanglement but with a different perspective? Has this phenomena of "Entanglement - Time" vs. "Entanglement - Space" been predicted theoretically already or does this discovery make entanglement "spookier" as Einstein once described entanglement?

But the real question percolating in my head is, is sending information into the future via Entanglement - Time anything special, as the article seems to indicate? I mean how is it different from putting some information in a time capsule, burying it and in the future digging it back up? The information "traveled to the future" that way too. But the article is saying that with time entanglement, the qubit (information) does not travel through the intermediate time, it just goes straight to the future. How is this significant or special? Is the information traveling superluminally through time (as opposed to through space), like often depicted in a Minkowski space-time triangle? Does that make sense or is that gibberish?

This is all so new to me, so I appreciate your thoughts.

Krombacher
 
  • #6
DrChinese
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There have been a number of fascinating developments in entanglement in recent years, including a greater understanding of how entanglement seems to operate outside the bounds of Minkowski spacetime. For example, it is possible to entangle particles which have never existed in the same lightcone. Further, the particles need not have existed at the same time.

So the point is that whether or not you call this an entirely new type of entanglement is more semantic. I did read the arxiv article abstract, and here is its link:

http://arxiv.org/abs/1101.2565

"Recently, it has been shown that the massless quantum vacuum state contains entanglement between timelike separated regions of spacetime, in addition to the entanglement between the spacelike separated regions usually considered. Here, we show that timelike entanglement can be extracted from the Minkowski vacuum and converted into ordinary entanglement between two inertial, two-state detectors at the same spatial location -- one coupled to the field in the past and the other coupled to the field in the future. The procedure used here demonstrates a clear time correlation as a requirement for extraction, e.g. if the past detector was active at a quarter to 12:00, then the future detector must wait to become active at precisely a quarter past 12:00 in order to achieve entanglement. "
 
  • #7
DevilsAvocado
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Yes, this is very interesting, but the 'smell of canard' is overwhelming when PCWorld announce it like this:

http://www.pcworld.com/article/216946/great_scott_scientists_claim_time_travel_is_possible.html" [Broken]

[PLAIN]http://www.rockdiscography.com/thecrypt/pickids/canard.gif [Broken]

:biggrin:

What I understand from this, is that they are using Unruh-DeWitt detectors that can extract entanglement from the vacuum in empty space. Now if you place these detectors outside each other light cones (past/present), and then generate the entanglement, I guess you can put like the authors do: "teleportation in time"

It’s a real interesting future out there... I just wish my whole brain could be entangled to it... :rolleyes:
 
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  • #8
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"As the window functions are shifted away from the t = 0 origin, the detectors must remain
active for far longer, in order to achieve the same degree of entanglement. This supports the intuition that most of the field entanglement is concentrated in the region close to the edges of the light cone."

I must take this into consideration. Chuckle.

DC
 
  • #9
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Thank you Dr. Chinese for digging up the link of the original work. I see they still use the same analogy of quarter to 12 and quarter after 12. I think, my conclusion on that analogy is that it is just not very effective.

I do agree with DevilsAvocado, it is "an interesting future out there...I just wish my whole brain could be entangled to it."

One question that I have is that do the detectors need to be in the same point in space, but at a later time, and how does one achieve that? That's got to be impossible, with the earth rotating and revolving around the sun, finding the same point in space cannot be what they mean.

So, if that premise is wrong, then does that mean that you can position the detectors anywhere right now say at point X at time A and then sometime in the future, say at point Y at time B? And are these points arbitrary?

If so, then that would mean to me that the qubit at point XA say in Paris can be "read" at point YB in San Francisco at a later time. But if for some reason I didn't want to read it in San Francisco, then I can change my mind and read it in NY.

In any case, it has to be one or the other right? Either you find the exact point in space to intercept the message or that premise is wrong, and any point in space at a later time will do.

Thanks for your comments in helping me to understand the ramifications of this thing.

Krombacher
 
  • #10
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I also wonder whether the application of this is not so much time travel as it is more about communicating over long distances.

If my prior post is the correct interpretation of this (and I don't know if it is), but IF, does that mean that a satellite say near pluto or beyond sends images to earth using this technology, all you have to do is wait from a quarter to 12 when the image is sent from the satellite to a quarter after 12 when the image is received on earth?

Krombacher
 
  • #11
DevilsAvocado
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I also wonder whether the application of this is not so much time travel as it is more about communicating over long distances.
Without understanding every detail in the paper, I can promise you one thing – time travel is completely out of the question (via entanglement). Causality is preserved in quantum mechanics (a rigorous result in modern quantum field theories) and therefore modern theories do not allow for time travel or FTL communication, see the http://en.wikipedia.org/wiki/No-communication_theorem" [Broken].

When we talk about entanglement and teleportation, it’s http://en.wikipedia.org/wiki/Quantum_teleportation" [Broken], not "Star Trek Teleportation", and the difference is 'substantial'... :wink:
[PLAIN said:
http://en.wikipedia.org/wiki/Quantum_teleportation]Quantum[/PLAIN] [Broken] teleportation, or entanglement-assisted teleportation, is a technique used to transfer quantum information from one quantum system to another. It does not transport the system itself, nor does it allow communication of information at superluminal (faster than light) speed. Neither does it concern rearranging the particles of a macroscopic object to copy the form of another object. Its distinguishing feature is that it can transmit the information present in a quantum superposition, useful for quantum communication and computation.
 
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  • #12
Well my grasp on quantum physics is still faint but im trying very hard to wrap my mind around the whole idea. However this does kind of relate to an idea that spurred my interest in quantum physics in the first place. Quantum Communication. Using quantum physics and the entanglement theory to be more specific to make long distance communication possible. Basically using the spin up or spin down of an electron as 1's and 0's to transmit data.
 
  • #13
DrChinese
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Well my grasp on quantum physics is still faint but im trying very hard to wrap my mind around the whole idea. However this does kind of relate to an idea that spurred my interest in quantum physics in the first place. Quantum Communication. Using quantum physics and the entanglement theory to be more specific to make long distance communication possible. Basically using the spin up or spin down of an electron as 1's and 0's to transmit data.
Welcome to PhysicsForums, recurveman!

The main thing is to remember that the spin results are always random for entangled particles. So you end up with a stream of random 1s and 0s, and no useful message.
 
  • #14
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Recurveman,
There is, or was, a "secure" com. link( in Switzerland, between banks?) that used a quantum photon link of sorts. The bottom line was if someone intercepted the information in route it would change/destroy/wipe out some characteristic of the photon(s) and the end user would be aware that the data was compromised. I'm not keeping up on this so I don't have a link.

Back to time--
I wonder if there might be some connection between photons coming from one source when they behave so strangely in multi-path experiments. Also in the basic 2 split experiment with single, sequenced electrons. Could electrons from one source be entangled in some way (time) that each one is linked to the others behavior?

Think I have to read more on entanglement. Is there such a thing (even undiscovered) as single-source group entanglement?

I think I have a lot more reading and thinking to do. Chuckle.

DC
 
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  • #15
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Please forgive my puny grasp of the subject, but are these implying that we can now transmit data through time?

For example, can we presently create an entangled photon in the year 2013 year along with a set of instructions. "Ok future us, if the Red Sox win the world series in 2012, please alter the state of the 2011 photon?"
 
  • #16
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No, I was comment on two different subjects. The data link was a practical hardware test to use, I think, photon status (spin?) to communicate in real time for passing secure data. It used fiber optics, several kilometers long as I remember. I'll look it up.

The time part is just theoretical from the paper linked above. No one has done it. I was speculating that if it did work perhaps it had effects on other quantum experiments such as the ones with strange "prediction" results.

DC
 
  • #17
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AFAIK there is nothing to stop us breaking weak causality. So when a particle begins superposition at t1 and ends by decoherence at t2 the difference t2-t1 can be zero.
BUT it must still be sequential to maintain strong causality.
 

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