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Communications Shark Science

Temporal Cloak Erases Data From History 102

Posted by Soulskill
from the incognito-mode-on-steroids dept.
ananyo writes "Electrical engineers have used lasers to create a cloak that can hide communications in a 'time hole', so that it seems as if they were never sent. The method is the first that can cloak data streams sent at the rapid rates typically seen in telecommunications systems. It opens the door to ultra-secure transmission schemes, and may also provide a way to better shield information from noise corruption (abstract). The researchers manipulated laser light in time to create regular periods with zero light intensity (a Talbot carpet) in which to hide data. Unfortunately, the current set up erases the data-adding event entirely from history. Though they are confident that future modifications will allow them, or others, to send secret messages successfully, the more immediate use of the technology will be to cut down crosstalk when multiple data streams share the same fibre." Also at Slash Datacenter.
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Temporal Cloak Erases Data From History

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  • what (Score:5, Interesting)

    by Ragzouken (943900) on Wednesday June 05, 2013 @04:39PM (#43918447)

    Maybe it's just that it's late, but I have no idea what that summary was trying to say.

    • by Synerg1y (2169962)

      On that note, I'll believe it when I see it, why no video?

    • Re:what (Score:5, Interesting)

      by sosume (680416) on Wednesday June 05, 2013 @04:45PM (#43918553) Journal

      FTA: "Unfortunately, the current set up erases the data-adding event entirely from history. "
      So how do they know that they sent it in the first place?

      • "Trust us"
      • 1. Encode data in beam.
        2. Manipulate beam in funky ways so data is removed.
        3. ????
        4. Profit!

      • by Garridan (597129)
        For some reason, the researchers couldn't seem to remember the answer to that question when asked.
      • by jonfr (888673)

        If I explained to you, I am not sure if you would understand me. While I am not connected to this project that is written about in nature. I am going to try anyway, at least in the simple terms.

        This is however related to time, subject that I do understand. Since I think about it a lot.

        This is what I call a "D" event. A event "A" (sending the data) is created. That event exist in normal space time, the data sent "B" event is sent a long normal space time where light exist. Light travels along normal space ti

        • Re:what (Score:4, Informative)

          by TheCarp (96830) <sjc AT carpanet DOT net> on Wednesday June 05, 2013 @08:51PM (#43920623) Homepage

          I never did much time in college either but, that's besides the point. I found a couple of better articles and exploitations, by people who seem to actually understand it:
          http://www.technologyreview.com/view/424682/first-demonstration-of-time-cloaking/ [technologyreview.com]

          So, they are speeding up some photons, and slowing others, to create a "gap", passing something through that gap, and then, readjusting speeds. So, imagine the beam is..... Route 1 in Saugus MA. One of my favorite roads. Its not just 6 lanes of bumper to bumper traffic, that traffic is bumper to bumper at full speed.

          Like most beams of light, you have fuck all chance of passing through it without casting a shadow (this is the detected event being "hidden"). But imagine if all the cars were in communication by computer. A mile down the road about haldf the cars speed up, and bunch together, and the other half all slow down, then all resume normal speed, creating a traveling gap.

          Now, if you knew this gap was coming, you could scurry through it without traffic detecting you across the pavement.... after which, they perform the opposite operation, sealing the gap, as if nothing happened.

          Sounds like a really cool system doesn't it? Now lets imagine it has a limitation of a 100 foot gap, moving at 75 MPH, giving you less than a second to pass the 60 feet of tar before you get....detected

          I think part of the reason this sounds so weird is the terminology. It makes sense, there is no point in space where an object can be continuously and not be detected by the beam, however there are points which the beam intersects in space where the object can be, between the beam, and not interfere with the final beam...

          Or at least, that's what I get from it.

          • by cstacy (534252)

            So, imagine the beam is..... Route 1 in Saugus MA. One of my favorite roads. Its not just 6 lanes of bumper to bumper traffic, that traffic is bumper to bumper at full speed.

            Like most beams of light, you have fuck all chance of passing through it without casting a shadow (this is the detected event being "hidden"). But imagine if all the cars were in communication by computer. A mile down the road about haldf the cars speed up, and bunch together, and the other half all slow down, then all resume normal speed, creating a traveling gap.

            I am in the car that is stopping at Kelly's!

        • Re: (Score:1, Flamebait)

          by BitZtream (692029)

          Since I think about it a lot.

          Good thing thats all that is needed on slashdot to qualify you as an expert.

          I am however not so good with school, so I never did go up to the university level. I just never bothered to do so and I do not expect to do so any time soon.

          Right. Thats why your a genius but not in any field like this one.

          Instead I just do thought experiments.

          Clearly. One of those experiments seems to be thinking you have a clue.

          The reality is, you don't know enough to even realize its a scam. You believe in cold fusion and perpetual motion machines as well I'm sure.

      • Re:what (Score:4, Informative)

        by Shavano (2541114) on Wednesday June 05, 2013 @09:19PM (#43920771)

        Because the light pulses went into the pipe. Theoretically, if the build their modulators right and exactly undo what they did to make their "time holes" (which normal people would call dark intervals the original unmodulated light will be there on the fiber, superposed with a temporally spread version of the coded pulses they injected, which would be there, but hard to detect.

        At the other end of the obscured connection, the trick is to run the same modulation scheme again exactly and if you do it just right, the monochromatic component of the light will once again be spread into the gappy modulation pattern you had at the first modulator output, and the pulses you injected will be there in the otherwise dark intervals.

        The scheme depends on two things: (1) you have to time it exactly so that you don't lose the phasing between the original modulator pair and the modulator at the receiving end. If you miss the phase, your data will be in the bright intervals instead of the dark intervals and you won't be able to read it easily. That's what apparently happened in this experiment and why they're confident that what they did really happened even though they didn't get their data back out of the system. The other thing (2) it depends on is that the modulators have to be linear enough that when you modulate and remodulate the light, you don't mix the spectra of the data with the stream you're using to obscure the pulse sequence. If they mix, you won't get a clean signal out no matter how exactly you match the modulators.

        The second is a likely limitation on this scheme because they are using nonlinear modulators -- all electro-optically active materials are nonlinear. Linear materials don't modulate light. To do completely linear modulation, you would need to do the modulation mechanically, which is much to slow to create the kind of quite intervals they need to obscure their data.

      • Im glad Im not the only one who read that far. By the sound of it this would be like writing a secret message on a piece of paper. Then taking that paper and mushing it back into pulp, washing it and turning it back into paper. Yes there is "hidden data," but can we ever recover it? Lets then say that they determine how to reassemble the data from that near complete destruction, once one person knows how to do it, then everyone knows and the data can be captured and hacked just like any other technology.
    • by Bovius (1243040)

      My initial reaction to the summary: Okay, I know a lot of us in Slashdot crowd are gullible, but seriously? I demand a plausible lie.

      Reaction after reading the article: I suspect that the translation from an actual technical explanation to language intended for the layman was shaky at best. I don't think I've read an adequate explanation of how it actually works.

    • by geekoid (135745)

      Read the article. It will blow your mind.

      You can creata situation where all information stay in a bubble, when ther bubble collapse it's as if the informatiomnn had never exsited.

      So if normal destruciton of information was like burning a paper, even the informatiojn is still there, in the ash. Hard to get, but still it is there.

      This would be like being able to create a paper, use it, and then have it never have exisited.

      • by mark-t (151149)
        If it never existed, how could there be any memory of its use?
        • by geekoid (135745)

          Becasue the informtion is in it's own bubble of time.
          Also, time doesn't seem to work they way we precieve it. So anything dealing with time intuitivly feels wrong.

          It could be that the effect is no good becasue there is no way to retrieve it. If not, well. All kinds of wierd things become possible.

          In my very limited example the person who wrote the info ont he paper, and the person who read it would still remember the information.

          • by mark-t (151149)
            If something never happened, then there can't be any record of it.... that would *INCLUDE* human memory. To erase all record of something having existed would also entail erasing all human memory of its existence as well.
      • by game kid (805301)

        In the wake of this news, millions of teenagers anticipate a new version of Snapchat.

    • Maybe it's just that it's late, but I have no idea what that summary was trying to say.

      It's quite obvious, isn't it? Let me quote it again:

      The researchers manipulated laser light in time to create regular periods with zero light intensity (a Talbot carpet) in which to hide data.

      Basically, they're saying that even in our 21th century, the fabulous Age of Lasers (on Sharks), sweeping inconvenient stuff under the rug is still alive and well.

      • by geekoid (135745)

        What is alive and well is people who don't understand things so they use an logical fallacy to dismiss it. Yes, I am looking at you.

        • by BitZtream (692029)

          Look, this isn't hard.

          If something is erased from history, then you can not have knowledge of it. Its a paradox. If you have no knowledge of it, you can't even know its missing, nor could you have sent it in the first place.

          Common sense trumps sensationalist articles claiming to have accomplished something that contradicts itself.

        • by narcc (412956)

          What is alive and well is people who don't understand things so they use an logical fallacy to dismiss it. Yes, I am looking at you.

          You should probably look up the term "logical fallacy".

    • Um ... time travel? :\
    • Maybe it's just that it's late, but I have no idea what that summary was trying to say.

      When this article was posted yesterday, you understood it completely. Unfortunately, I can't seem to find the uri anymore to prove it to you....

    • by Anonymous Coward

      Whatever you do, don't cross the streams!

    • by Shavano (2541114)

      Take this into consideration, according to the quoted article:

      "Their work built on the principles behind invisibility cloaks, which hide objects in space by channelling light rays around them."

      ... or would if they could actually do that.

      • by BitZtream (692029)

        Invisibility cloaks exist that do exactly that. Do you live in a box? They aren't even new anymore. They also are currently so narrow band that they are pretty useless practically, but its got to start somewhere.

        • by Shavano (2541114)

          Invisibility cloaks exist that do exactly that. Do you live in a box? They aren't even new anymore. They also are currently so narrow band that they are pretty useless practically, but its got to start somewhere.

          My eyes have close to an octave of bandwidth. I'm not impressed by technology that can hide from monochromatic light. Also, the "invisibility" only applies at specific locations in space.

  • by Anonymous Coward on Wednesday June 05, 2013 @04:42PM (#43918513)

    Isn't that what happens when you touch the crack in the universe caused by an exploding Tardis?

  • by Arancaytar (966377) <arancaytar.ilyaran@gmail.com> on Wednesday June 05, 2013 @04:44PM (#43918549) Homepage

    How does the recipient get the message, if it's so thoroughly erased?

    • by drkim (1559875)

      How does the recipient get the message, if it's so thoroughly erased?

      Ahhh... what message?

    • by mark-t (151149)
      Even more, how does the sender know that they even sent it in the first place?
  • by Anonymous Coward

    I shall now hibernate until I can hop on a spaceship and mine asteroids.

  • by Millennium (2451) on Wednesday June 05, 2013 @04:49PM (#43918611) Homepage

    Does this mean they've proven the past is mutable?

    • by Black Parrot (19622) on Wednesday June 05, 2013 @04:53PM (#43918645)

      The funny part is that this technology has already been invented multiple times... they just keep erasing it.

    • by BitZtream (692029)

      No, because it has nothing to do with actually changing the past.

      Its just a modulation technique. Its actually almost identical to the same modulation a cable modem or cell phone uses.

      Its not a 'temporal cloak' its just a different form of modulation. The data is detectable by anyone who knows what modulation you're using and the timing for it. It doesn't get 'erased', its just not easily visible unless you happen to know what you're looking for ... exactly like hooking a volt meter up to your cable wall

    • by siddesu (698447)
      No, they just found a better way to send stuff to the NSA for analysis.
  • So, if a laser is used to send pulses of light that represents data, and they have developed a method to create "periods of zero light intensity" that hides data and *may* help prevent noise corruption... Does that mean they have figured out how to turn the laser off? Maybe I should go RTFA...

  • If they erase it from history, doesn't that mean the recipient forgets it too?

    • by Intropy (2009018)

      Yes. And I used to have already had told you that, but now I haven't yet not failed to have told you. That's why you now no longer know. You've now never known!

      • by Anonymous Coward

        So If they erase it from history, doesn't that mean the recipient forgets it too?

      • by oldhack (1037484)
        This is why we should never fuck with time - just not worth all the hassle that crop up.
  • Without having really understood the physics behind this, what I gather is that it basically would allow you to conceal optical signals from eavesdropping on the transmission line. But that's only on the transmission line. Obviously the transmitted data still needs to exist at the endpoints in one form or another... so eavesdrop on the endpoints instead? Unless you have a true point-to-point line, your data will also likely be routed over some sort of IP network, where it will have to exist in some other fo

    • by geekoid (135745)

      Imagine celll phones. Now no one in the middle would even know that information had been sent.
      Sure, you can watch the person with the phone and use a camera to see the text. But with glovbal communication, thats not the largest problem.

    • by BitZtream (692029)

      If I can't see it, neither can the receiver.

      Its either detectable or it isn't. If it isn't, no one can see it. If it is, then I can see it too.

  • by camperdave (969942) on Wednesday June 05, 2013 @05:21PM (#43918981) Journal
    Here's proof that it works. I used it to cloak my First Post. Go ahead and check. You won't see it there.
    • by geekoid (135745)

      Are you sayng Henery Phillips created the Phillips screw, but couldn't figure out how to use it?
      Personally I perfer the Fearson to the Phillips.

      • Are you sayng Henery Phillips created the Phillips screw, but couldn't figure out how to use it?.

        No. Thompson invented it, but couldn't get anyone to manufacture it. He sold the patents to his buddy Phillips, who made improvements to the design which made it easier to manufacture. Then he set up a company to actually manufacture them.

  • Is this just some researchers turning off a laser?

    • Yep, all that mumbo jumbo about time cloaks comes down to this:

      They found a way to turn a laser on and off really fast, and at the other end of the fiber undo it so it appears to have stayed on. The whole "cloak" thing is just the idea that while the laser is off, some other signal could be sent on the fiber. Yay, with more refinement they can use it to send two channels on one fiber. The current implementation isn't able to read the second channel.

      In theory, you could cut into a backbone provider's fib
  • Now that the spammers have finally been identified... is it possible to integrate the temporal cloak with a retroactive spam filtering device, to erase my spam in the past before the filters were able to detect it, so I will not have wasted time reading it?

    • by Daetrin (576516)
      It's already been done! The new spam cloaker is 90% effective at removing spam from history! You're now receiving one tenth the spam you were before! Unfortunately since the rest was erased from history you just don't remember how much spam you were actually getting before the machine was turned on, but believe us there was quite a lot of it! You may _think_ you're getting a lot now, but that's really practically nothing!

      You're welcome!
      • by mysidia (191772)

        It's already been done! The new spam cloaker is 90% effective at removing spam from history!

        Thank you... unfortunately, this 10% that got left over is a big PITA.

        Is there any way we can erase the spammers from history too -- as in erase their genetic material from being communicated during conception, so that the spammers were never born in the first place, or would that be too dangerous?

  • The output of the top secret printer feeds into a cross cut shredder and that dumps directly into the incinerator furnace. It is used all the time for extremely high sensitivity documents.

  • Sure, it might not look like it now, but that's only because I haven't activated my lasers.
  • reinventing color tv (Score:5, Interesting)

    by slew (2918) on Wednesday June 05, 2013 @06:52PM (#43919797)

    As far as I can tell, they are mostly just doing a twist on something that was known a long time ago: quadrature modulation.

    The way color TV transmission worked in the past (not anymore, it's all digital now, but I digress) was that they crammed 3 signals in the space original meant for black-and-white TV by basically converting RGB into Y (an approximation of the Black and White signal), and two color difference signals. These color difference signals were modulated to a high alternating frequency pattern (so that old B & W sets wouldn't see them very much) and then put into quadrature with each other (each signal getting about 1/2 the spatial frequency bandwidth, and essentially interleaving them in time). In some sense in quadrature modulation, you are hiding one signal in the "nulls" you create in the other signal.

    In this so-called "cloak" technique, the modulation is more complex and instead of trying to transmit two equal bandwidth signals together, they are exploiting the fact that their is no reason that the split has to be equal...

    The below example is overly simplified single-split case, but illustrates what is going on...

    Original: Signal ~ sin(wt+kx)
    Phase Modulated signal with simple small split phase shift "p": Psignal ~ 0.5*sin(wt+kx+p)+0.5*sin(wt+kx-p)
    And using the magic of trigonometry ... Psignal ~ sin(wt+kx)*cos(p)

    If the transmitter controls the phase just right, the "cosine" modulates the original signal and creates periods of time where the amplitude is really low (not really zero except at a point), yet back to their nominal amplitude at the receiver. Since the transmitter know when these "nulls" will be, it can put in short bursts of another covert signals that looks nominally like the original signal (same base frequency), but won't really be visible at the receiver (presumably the transmitter would pick the phase parameters of this covert signal so that they were "null" at the receiver).

    In practice, a single 50-50 split with complementary phase shift isn't really that great, you have to more harmonics approximate more interesting signal envelopes. Think about making a square wave out of harmonics and you can see how you might make the apparent "null" times much longer.

    Thus to the outside observer it looks mostly like the original signal (same nominal frequency for symbols being transmitted since the phase shifts are small, it would just look like jitter), but the transmitter was able to finesse the transmission so that it could transmit relatively normally so that the receiver would still pick out the signal. During the "null" times, the transmitter could transmit a covert signal which isn't picked up by the normal receiver but looks like a plausible innocuous signal, so a simple cursory observation of the channel looks as if only generic transmission is going on.

    We don't have to call this stuff using descriptions like temporal cloaks and erasing information from history. Except perhaps analog color tv transmission (may it RIP)

    • We don't have to call this stuff using descriptions like temporal cloaks and erasing information from history. Except perhaps analog color tv transmission (may it RIP)

      In other words the terminology used is a bit fuzzy and eccentric and we would do better reading about signals and probably getting a ham license =)

      Thanks for taking the time to explain. This is an effect I did not know about. Still don't understand fully. But at least I know its possible and a function of wave amplitude, power, and frequency.

  • I don't want to read this story. I've made up a story in my mind, based on just the headline, "Temporal Cloak Erases Data From History", and I'm 100% sure that mine is a better story than the actual one in the summary.

    And boy oh boy, do I ever want a "temporal cloak".

  • Make one that erases the passage of time then make a movie about it.

  • Great timing! Now, how soon can I get this for my Verizon phone?

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