‘Ghost’ Photos through Quantum Physics

toysoldierScientists funded by the Air Force have used quantum entanglement — in which pairs of particles continue to interact even after they are spatially separated — to snap this picture of a tin solider without aiming a camera directly at the object.  The technique, called “ghost imaging,” has potential military or space applications, such as using aerial drones to survey of battlefields obscured by clouds, or the smoke that follows airstrikes.  Yanhua Shih, who has been experimenting with entangled photons since 1995, says:

“…[T]he image is not formed from light that hits the object and bounces back. The camera collects photons from the light sources that did not hit the object, but are paired through a quantum effect with others that did. An image of the toy begins to appear after approximately a thousand pairs of photons are recorded.”

These are exciting times on the frontiers of physics. Researchers in Copenhagen took a step towards producing a quantum bit. And scientists at Arizona State are trying to figure out how electrons interact. Both are necessary steps towards building superfast quantum computers.

[Image: University of Maryland]

30 thoughts on “‘Ghost’ Photos through Quantum Physics”

  1. What could have been some interesting science is prostituted into creating some fancy sounding toy for the military, which will no doubt make the consultants very rich, and further the American fantasy of conquering the world, all evidence to the contrary be damned.

  2. What’s this you say? Scientific research being used for military applications!? This is the first I’ve heard of such things. How dare the scientists who are being funded by a branch of the military use their discoveries for the benefit of their backers! I can’t believe they would do such a thing.

  3. Science is great and everything, but they still haven’t answered the question of what floats, other than a witch. I say it’s a really tiny rock.

    Seriously though, that is pretty strange. Hooray for quantum physics! Soon we’ll be able to create matter. I’m going to create lots of gold and oxygen

  4. Seriously though, this is bogus. But what the heck, entertaining.

    Consider this – the “tin soldier” is seen from a point-of-view. How do you selectively receive only those photons whose entangled mates all pass through this point-of-view? Answer – either you don’t, or you are essentially pointing a lens or sensing device at the “tin soldier” itself. Bogus. And the “battlefield clouds” idea? No. My work here is done.

  5. “website design”,

    The internet was originally a toy created for the military. You owe your career to such “prostitution of science”.

  6. Entanglement has mind blowing applications. Imagine having data rates at nearly infinite speed in real time. You could achieve that by entangling the information source where you want to get the information from to your receiving client. Distance, cabling, connections, etc. would no longer be an issue. You could practically be on another planet and still receive the information you want as it happens. Bye bye telecom infrastructure, hello entanglment.

  7. Anyone remember David Bowie in the ‘Man who Fell to Earth’? He had patented a camera that could take pictures with an alternative point of reference than from where the camera was located. This seems to be similar in the way it’s described.

  8. Anon, you should check out the source article in the air force times (it’s the first link in the article above). There seems to be a little bit more to it then the above article suggests, but it looks legit to me.

  9. @5 Anon. I’m glad your young no research mind has all of the answers. I’m sure they never tackled any of these hardships when doing this. Good thing you cleared it up on a comment page in a couple seconds. They can stop their progress now.

  10. This is the stuff Einstein called “spooky action at a distance.” He didn’t like it either. Doesn’t mean it doesn’t happen.

    As for the military aspect — well, at least it’s not black ops. If you look at it, it continues to exist… 🙂

  11. th nly ghst tht xsts s th hly ghst nd y wll ll ndy s tht h s lrd f lrds nd kng f kngs nd h rgns!:D


  12. M nd th Tlk Shw Hst nd brd n th snd, cm Hly Ghst nd jn s s w srch fr th nxt Plt. Scnc nd Mltry r strng bdfllws bt w w ll f r ccmplshmnts thr thn plwng flds t th 2 f thm.

    GD s Myth t sbd th Hmns nt thnkng thy r mr thn psnts. Hmns r t d th bddng f th Rch nd Pwrfl lt.

  13. Witch! Witch! (well, I should actually say that this is beyond me. My brain is too small to understand this D: how can you take a picture without aiming the camera?)

  14. This story is bogus. please read this http://en.wikipedia.org/wiki/Photon_entanglement . This may be possible in the future but right now we don’t have the technology to actually do this. This story is total bullshit.

    You mean the article that hasn’t been updated since 2/2008, and has “this article needs additional citations for verification? That article?

    Wikipedia is really nice, but I would hardly count it as the end all/be all of current information.

    Feel free, however, to read http://www.airforcetimes.com/news/2008/06/airforce_ghost_imagery_062908/ and http://www.airforcetimes.com/news/2008/06/airforce_ghost_imagery_062908/ (both already linked in the article) before you give us your expert opinion again.

    BTW, this is outstanding. While the technology may be in its infancy, we’re seeing some incredible applications of quantum physics.

  15. Interesting that this post has inspired so much controversy. At the very least, I would say that if researchers from respected academic institutions, funded by U.S. taxpayers and publishing in a peer-reviewed journal, are making this claim, that in and of itself is newsworthy. If this claim isn’t true, like bogus missile-defense tests, then I want my money back.

  16. Quantum Teleportation was my Degree Seminar Topic. I had studied a lot about Quantum Entanglement then.

    But, upto my knowledge, this is unbelievable.

    The theory is that, there is a pair of electrons which are entangled together at creation. Both particles share properties, even if they are at a distance. The camera captures each of the photons of the pair. One photon hits the object and the other photon in the pair having similar properties hits the camera. It is Quantum Physics 🙂


  17. Jeffrey Bub, of Stanford, wrote: “Formally, the amount of classical information we gain, on average, when we learn the value of a random variable (or, equivalently, the amount of uncertainty in the value of a random variable before we learn its value) is represented by a quantity called the Shannon entropy, measured in bits (Shannon and Weaver, 1949). A random variable is defined by a probability distribution over a set of values. In the case of a binary random variable, with equal probability for each of the two possibilities, the Shannon entropy is 1 bit, representing maximal uncertainty. For all other probabilities

  18. Complete rubbish. We don’t have the technology to actually be able to figure out the particular connected photons that are required for this. If each photon is connected to the other, how can you tell which is which?

  19. Again, all I can say for sure is that the Air Force has made the claim.

    That said, maybe somebody who knows more about this than me can comment on the notion that it’s necessary (or even possible) to pick a particular photon out of the crowd for this tech to work.

  20. No the internet was created by scientists for scientists. It was not created for military purposes but I’m sure the military will find it useful.

    It’s really to bad that we always need to sign off on military applications. America never stops bringing war to the forefront. Let’s enjoy science and forget about the military applications for a change.

  21. I’ll start with an apology: Haven’t got time to read the article, but what they are likely to be talking about is not having discrete “pairs” of particles that transmit information to each other (like split electron or neutron spin), but rather, where a photon can be directed to hit either the camera or the item, until the photon hits the camera, it is en route to both locations at once. With the inclusion of polarised lenses to enable the identifying of particles that take one route, they can force all of the photons that would pass around the soldier (if they took that direction) to show up on the camera first, allowing the sensor to build up a negative picture of the item.

    Its rather difficult to explain in detail, but with some background knowledge in the field of quantum erasers, you should be able to follow this explanation.

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