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Do-it-yourself quantum spooky action

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Qutools boothDRESDEN, Germany—How cool would it be not just to read about the craziness of quantum mechanics, but to see it—even better, do it—for yourself? Several years ago I asked virtuoso experimental physicist Paul Kwiat whether he could develop a simple demonstration anyone could do at home, and he and his undergraduate student Rachel Killmer came up with a "quantum eraser". This week I got to see another big step toward the era of quantum homebrewers. Tucked away in a booth in the exhibit tent at the German Physical Society conference, Munich-based start-up company qutools showed off the world’s cheapest kit for seeing quantum entanglement: spooky action at a distance. Though still out of reach of a DIYer (20,000 euros, or $28,000), the kit is cheap enough to become standard equipment in Physics 101 courses, and when you consider what physicists had to go through in the 1970s to see spooky action for the first time, it’s a marvel of miniaturization. "I’m so excited by what they’re doing,” says physics education innovator David Van Baak of Calvin College in Grand Rapids, Mich. "We’re past the stage where entanglement is a research-university-only affair. It’s getting out to the masses."

The main reason I came to the conference was for a symposium of some of the world’s leading quantum physicists and philosophers (pdf), organized by experimentalist Uwe Becker of the Fritz Haber Institute in Berlin. I got to meet, among others, Alain Aspect of the Institut d’Optique on the outskirts of Paris—one of the first ever to see spooky action for himself. Science writer Louisa Gilder dramatically describes what he and other pioneers had to go through in her book The Age of Entanglement. Their experiments filled entire basement labs, had to be largely custom-built, and looked almost steampunk. Aspect and others had to do all this against a backdrop of skepticism or even outright hostility among most of their colleagues.

Their contraptions produced pairs of particles that acted like magic coins: when flipped in unison on opposite sides of the lab, both coins always came up with the same side, either heads or tails. Aspect’s apparatus produced about 100 spooky coincidences per second. The qutools kit, which would fit on a living room end table, sees more than 10 times as many.

These contraptions can do the flipping in a way that rules out obvious explanations—for example, that the particles were somehow preprogrammed to behave as they did, or that some hidden signal passed between them. Through means that physicists have yet to grasp, the particles act as an indivisible unit despite the distance that separates them. Quantum pioneer Nicolas Gisin of the University of Geneva thinks understanding will come as physicists gain familiarity with the phenomenon. He says he already notices that his students feel more comfortable with entanglement than his generation does. "Young guys find it fascinating, but are not totally amazed," he says. "The kids here say, that’s just the way it is." So kits such as qutools’s hasten the day when we finally figure out what the theory really means, and the crazy becomes the quotidian.

Photo by George Musser

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  1. 1. Grasshopper1 10:13 pm 03/17/2011

    Nice! That’s going on my birthday wish-list.

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  2. 2. MisterA 6:52 am 03/18/2011

    Why has nobody produced an FTL entangled bit communications device?

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  3. 3. SkepticalKen 8:17 am 03/18/2011

    I read about the quantum eraser on wikipedia and it doesn’t exactly sound cheap, either.

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  4. 4. mysticzzz 10:30 am 03/18/2011

    in reply to- "Why has nobody produced an FTL entangled bit communications device?" Chinese have claimed FTL comm – see You can also look here- I don’t know if this is a legitimate report.

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  5. 5. EyesWideOpen 4:44 pm 03/18/2011

    I have a theory about how one could create the first "quantum communications" device. The article states: "Their contraptions produced pairs of particles that acted like magic coins: when flipped in unison on opposite sides of the lab, both coins always came up with the same side, either heads or tails."

    Instead of randomly "flipping" the particles (presuming the word "flipping" is used as a metaphor for "heads of tails" when "flipping" a coin), find a way to influence one of the particles in a "controlled flip" to either "heads" or "tails" (you know, 0 and 1 in binary?).

    Then, send a binary message using one particle. At the opposite side of the lab, read the binary message from the second particle.

    Now reverse this procedure, and voila: You can send and receive binary messages using two particles. If this is really quantum action, "opposite sides of the lab" could translate to remote locations (opposite sides of Earth). You somehow influence one particle to send sophisticated messages in binary (perhaps entire voice conversations that can be decoded and heard as audio).

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  6. 6. benwade 5:13 pm 03/18/2011

    For some reason, a quantum reason, information cannot be transmitted faster than light. I read the explanation, but to be honest, I didn’t understand it.

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  7. 7. EyesWideOpen 5:49 pm 03/18/2011

    To clarify my comment about how to adapt this experiment to quantum communication, by controlling the "flipping" from a binary state of zero (0) to one (1), the particle on the other side of the lab should "flip" to the same state… just as both particles randomly "flip" to the same state (defying laws of probability unless the particles are intertwined somehow).

    These particles are not traveling faster than light, because they are not traveling anywhere at all. The link between these particles in essence "tunnels" through the fabric of spacetime so there is effectively zero distance between the particles: they are connected as if they were right next to one another!

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  8. 8. hoamingin 9:32 pm 03/18/2011

    Don’t tell Creationists about this. They might use it as evidence that they do not need logic to claim that their explanations are "scientific".

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  9. 9. gokselm 11:41 pm 03/18/2011

    "Energy" cannot be transmitted faster than light, not the information!

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  10. 10. Wilhelmus de Wilde 10:08 am 03/19/2011

    Hi Eyes wide open (very good name)
    you say : "remote locations : the other side of the earth",
    let us go much further to 380.000 years after 10^-45sec after virtual point Zero (I don’t believe in BB), there also we (the observers) "see" photons, as we are baryonic creatures we only percieve baryonic paricles (photons) the photon at the origine so becomes baryonic n waaouw we created ourselves (no more problems with fine tuned constants etc).

    nest regards

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  11. 11. Daniel35 4:10 pm 03/19/2011

    I’d sure like to see if any such device can convince me that entanglement is real. First, are we talking about the "spin" on an electron or something else? If we really mean spin, wouldn’t flipping one be similar to flipping a gyroscope, which is said to take equivalent energy to stopping and starting it in the other direction? Assuming an electron, how does one "flip" a specific electron? How does one identify the electron being flipped, or how do they identify each other? Does the device perhaps show the 50% of electrons that flip the same way and ignore all that don’t? Can you flip maybe just one electron per second on each side of the room?

    On quantum FTL communications, first, will intentionally flipping an electron a certain way negate the effect? If not, then start flipping an electron in binary code and assume someone on another planet is doing the same experiment, but watching for a message. Then you watch for a reply. About 50% of the time you should be in sinc, properly entangled. :)

    Please copy any replies to

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  12. 12. verdai 5:09 pm 03/19/2011

    Do you Mind telling me What was done to achieve the entanglement?

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  13. 13. Quantique42 7:37 pm 03/20/2011

    No, information in quantum physics is energy, not a datalist as human sense. The interprétation of Eyeswideopen is right. Entrangled particles aren’t spacetimelly separate so light speed limit is respected.

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