The Biggest "Spooky" System Ever Seen: 4 Entangled Ions

By Eliza Strickland | June 4, 2009 7:07 am

entangled ionsIn the realm of quantum mechanics, atoms and subatomic particles just don’t follow the rules that we’re governed by in the larger world of classical mechanics. For example, the theory of quantum mechanics predicts that two or more particles can become “entangled” so that even after they are separated in space, when an action is performed on one particle, the other particle responds immediately. Scientists still don’t know how the particles send these instantaneous messages to each other, but somehow, once they are entwined, they retain a fundamental connection [LiveScience].

Now, a new study has dragged entanglement a little bit closer to our classical world. Researchers managed to entangle two pairs of vibrating ions so that when the motion of one pair of ions was changed, the other pair reflected the change as well. Previously, researchers have entangled particles in much more esoteric ways, coordinating the spin of electrons or the polarization of photons. With this study, says coauthor John Jost, “We’ve entangled something that has never been entangled before, and it’s the kind of physical, oscillating system you see in the classical world, just much smaller” [LiveScience].

In the study, published in Nature, the two ion pairs were held about a quarter of a millimeter apart in an ion trap, which is a significant separation for atoms. In each pair, a beryllium ion was partnered with a magnesium ion. “You can think of them like two balls connected by a spring that vibrate back and forth in unison,” says Jost. The first step to achieving these synchronized vibrations relied on standard techniques to entangle the spins of the beryllium ions in each pair. The trick was then to transfer this conventional form of entanglement into the vibration of the ion pairs, using lasers. “Depending on its internal spin state, the beryllium ions will absorb certain frequencies of laser light, which excites them and sets them vibrating,” explains Jost. The two entangled pairs of beryllium and magnesium ions then began to vibrate in lockstep [Nature News].

Christopher Monroe, a quantum physicist who wasn’t involved in the current study, says he finds the work enticing: “We all want to move quantum mechanics to the macroscopic world we live in.” … The separation between the quantum world and the macroscopic world is still unclear and interests many researchers. Now that entanglement has been demonstrated in a mechanical system, says Monroe, scientists may be able to apply the findings to larger and larger mechanical systems. Quantum mechanics shouldn’t care whether a system involves a couple atoms or trillions of atoms, Monroe says. “The quantum physics is exactly the same” [Science News].

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Image: John Jost and Jason Amini

CATEGORIZED UNDER: Physics & Math
  • Sunlamp

    What is an ‘ion’? Please define the jargon you use.

  • http://blogs.discovermagazine.com/80beats/ Eliza Strickland

    Sorry, I thought ions had common knowledge status. An ion is just an atom that has either a positive or negative electrical charge. It’s positive if it has more protons than electrons, and it’s negative if it has more electrons than protons.

  • Patimus

    If they could achieve the same results at opposite poles of the earth, then they’d be cooking. A quarter of a millimeter may be a lot by atomic standards but it’s not far for a signal to seem instantaneous. I’ve heard the same rules apply at extreme distances across space, or is that just theory?

    I’m sure I’m missing the point, but could someone clear it up? Maybe an analogy that would apply it to something on earth?

  • YouRang

    I’m not sure from this report that this is entanglement. Entanglement requires coherence of states between separated points in spacetime. They don’t seem to have shown that these two points are separated in spacetime rather than separated in space only but both being inside the light cone. IOW this report doesn’t say how this is different from the classical analog they mention–2 pairs of balls connected by a very tenuous spring. Say the large number of balls (atoms) in a mandolin string (or 12 string guitar) oscillating in coordination with the other mandolin string (12…). Because it is impossible to tune these strings perfectly, the system will oscillate. In that way it is different; the two “molecules” will oscillate at the same frequency, But like the mandolin (12..) pair, the 2 “molecules” are connected by EM. The EM for the mandolin is transmitted via sound waves/matter waves at the low speed of sound but the action is the same.

  • Nova Terata

    Sunlamp “ion” is not jargon its basic grade school chemistry / physics. 120 years ago it was jargon. And google/wikipedia a term if you don’t know it.

  • Jumblepudding

    A quarter of a millimeter is a gigantic distance when we’re talking about atoms. It almost seems like it needs an analogy in terms of visible objects. is this like two ships on opposite sides of the atlantic vibrating in tandem, two people on the top and bottom floors of a the empire state building, or what?

  • http://clubneko.net Nick

    A quarter of a milimeter is 250 micrometers. 1000 nanometers is in a micrometer. That’s 250,000 nanometers. An angstrom is 1/10th of a nanometer. Most atoms in a solid are on the order of Angstrom or sub-angstrom sizes. DNA is 2 nanometers wide.

    These ions are communicating as if they were side by side while 2,500,000 times farther apart than they would normally be when touching.

    2.5 million times further apart.

    By analogy, lets say you have two kids, both 1 meter tall. 1 meter x 1000 mm x 1000 um x 1000 nm x 10A / 2A(mm= millimeter um = micrometer nm= nanometer A=angstroms, and we’ll take 2A as the average ) That is 5 billion times larger than an atom. So, take that .25 MM x 5 billion, and that’s how many meters away you’d need to have your two children to imagine the distance between these two ions.

    About 1.25 billion meters. 1.25 million kilometers. It’s about 4 times the distance from Earth to the Moon.

    In other words, at the scale their working at, unimaginably huge.

    You can’t be separated in space but not time, at least not with any known techniques except quantum entaglement – which seems to separate objects in space, but not time, which allows for instantaneous communications.

    Einstein called it “spukhafte,” and it is, because it contradicts everything we know about the limitations of physics in this universe. This is the first time entanglement has been demonstrated on anything as large as an atom, let alone two. From a quantum-mechanical standpoint, this is break-through amazing. It’s shown that entanglement can work on objects larger than quanta. Now that we’ve done atoms, we can work our way up. Who knows what sort of implications this could have. Imagine two entangled doorways. We now know this is technically achievable, the only question is how much money we are willing to throw at it to accomplish it sooner rather than later.

    I tell you whut, the future’s gonna be crazy.

  • chris

    Why did they use Ions instead of magnetically nuetral particles?

  • MarkD

    Wow this is HUGE.
    If they can stay entangled at a distance, that’s faster than light communication on a continuous basis with a molecule that is actually big enough to be easily looked at. I hope the “looking at it” doesn’t mess it up though.

    Simple version:
    If they get this working and stable, you have an object that does the same thing as another object anywhere, instantly. Faster than light communication.

    So what is the current consensus on entangled particles? Do they thing that they are sharing the same “String” as far as string theory and tied together through an invisible hidden dimension?

  • Jumblepudding

    Thanks for the analogy. My mind be blown.

  • Patimus

    Thanks for the excellent analogy, I see the scale more clearly, yet, while I understand the idea of instant communication through quantum entanglement, it seems at a distance of a quarter of a millimeter sound travel would seem instantaneous. I’d like to see the machine they use to record such an event. Preciiiiiise!

  • Dr.What

    Does this remind anyone of the ansible from the Ender saga?

  • Russ

    The very theory and concept behind entanglement precludes communication. It just causes the results of random events separated by a distance to jive when later compared.

  • brotim

    So, if you build two doorways and sync them by entanglement, when you walk through one, would a copy of you exit the other?

  • broan

    @brotim.

    No. If you pushed one open though, the other one would be affected in some way. I think it depends on what you entangle. And an entanglement is easy to disrupt apparently.

  • honeybee

    Voodoo dolls!?

  • nosavynada

    My conversions may be off but… would not the equation actually yield 1.25 billion MM not M? and if so it eventually comes to around 770 miles I would think – still very impressive but not the interstellar distances talked about. All-in-All still very impressive and thank you never the less for the example it helps to get a grasp on this.

  • brotim

    Thank you for the answer!

    I s’pose what I’m really thinking about is entangling two areas of space/time as opposed to two bits of matter in different spaces, if that makes sense…

    The gist I get from the article is that more can be entangled than we thought. I’m just thinking about what might happen if the space/time itself were entangled and not just the matter. Ergo, a certain configuration of matter exits a portion of space/time that is entangled with another portion of space/time. Since matter is exiting the one, would identical (but different) matter exit the other?

    Again, thanks!

  • Avalons Child

    Seems to me that the particles are communicating on the cosmic internet, indiscernable and undectable by us, not for lack of technolgy but for lack of comprehension that it may be such. Yet we communicate wirelessly and instantly every day. How fascinating, what processess facilates their instant communication…….can we detect the same and to what end are the applications……and what is the source/intention…..?? Satyameva Jayate

  • brotim

    Actually, we are communicating at slightly less than light speed here on the Internet. The electrons are slowed over the wires/fibers by resistance and the radio waves only travel at light speed. So, though it may seem instantaneous, it really isn’t…

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