Quantum Entanglement Observed on Macroscopic Scale

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Quantum Entanglement Observed on Macroscopic Scale

Postby AvatarIII » Fri Dec 02, 2011 10:27 am UTC

http://www.livescience.com/17264-quantu ... monds.html

Spoiler:
Scientists have linked two diamonds in a mysterious process called entanglement that is normally only seen on the quantum scale.

Entanglement is so weird that Einstein dubbed it "spooky action at a distance." It's a strange effect where one object gets connected to another so that even if they are separated by large distances, an action performed on one will affect the other. Entanglement usually occurs with subatomic particles, and was predicted by the theory of quantum mechanics, which governs the realm of the very small.

But now physicists have succeeded in entangling two macroscopic diamonds, demonstrating that quantum mechanical effects are not limited to the microscopic scale.

"I think it's an important step into a new regime of thinking about quantum phenomena," physicist Ian Walmsley of England's University of Oxford said."That is, in this regime of the bigger world, room temperatures, ambient conditions. Although the phenomenon was expected to exist, actually being able to observe it in such a system we think is quite exciting."

Another study recently used quantum entanglement to teleport bits of light from one place to another. And other researchers have succeeded in entangling macroscopic objects before, but they have generally been under special circumstances, prepared in special ways, and cooled to cryogenic temperatures. In the new achievement, the diamonds were large and not prepared in any special way, the researchers said.

"It's big enough you can see it," Walmsley told LiveScience of the diamonds."They're sitting on the table, out in plain view. The laboratory isn't particularly cold or particularly hot, it's just your everyday room."

Walmsley, along with a team of physicists led by Oxford graduate student Ka Chung Lee, accomplished this feat by entangling the vibration of two diamond crystals. To do so, the researchers set up an apparatus to send a laser pulse at both diamonds simultaneously. Sometimes, the laser light changed color, to a lower frequency, after hitting the diamonds. That told the scientists it had lost a bit of energy.

Because energy must be conserved in closed systems (where there's no input of outside energy), the researchers knew that the "lost" energy had been used in some way. In fact, the energy had been converted into vibrational motion for one of the diamonds (albeit motion that is too small to observe visually). However, the scientists had no way of knowing which diamond was vibrating.

Then, the researchers sent a second pulse of laser light through the now-vibrating system. This time, if the light emerged with a color of higher frequency, it meant it had gained the energy back by absorbing it from the diamond, stopping its vibration.

The scientists had set up two separate detectors to measure the laser light — one for each diamond.

If the two diamonds weren't entangled, the researchers would expect each detector to register a changed laser beam about 50 percent of the time. It's similar to tossing a coin, where random chance would lead to heads about half the time and tails the other half the time on average.

Instead, because the two diamonds were linked, they found that one detector measured the change every time, and the other detector never fired. The two diamonds, it seemed, were so connected they reacted as a single entity, rather than two individual objects.

The scientists report their results in the Dec. 2 issue of the journal Science.

"Recent advances in quantum control techniques have allowed entanglement to be observed for physical systems with increasing complexity and separation distance," University of Michigan physicist Luming Duan, who was not involved in the study, wrote in an accompanying essay in the same issue of Science."Lee et al. take an important step in this direction by demonstrating entanglement between oscillation patterns of atoms—phonon modes—of two diamond samples of millimeter size at room temperature, separated by a macroscopic distance of about 15 cm."

In addition to furthering scientists' understanding of entanglement, the research could help develop faster computers called photonic processors, relying on quantum effects, said Oxford physicist Michael Sprague, another team member on the project.

"The long-term goal is that if you can harness the power of quantum phenomena, you can potentially do things more efficiently than is currently possible," Sprague said.


Fixed the spelling in the title. -Hawk

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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby Carlington » Fri Dec 02, 2011 11:38 am UTC

Reasonably happy with the accuracy in this article - I'm not familiar with livescience.com as a science news source, but it seems as though they do a better job than Wired, for example.
Does anyone know what the bit about "teleporting bits of light from one place to another" was? Surely if we'd developed something describable as teleportation, it would've been discussed by now?
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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby Qaanol » Fri Dec 02, 2011 12:25 pm UTC

The scientific article was published in Science under the title Entangling Macroscopic Diamonds at Room Temperature, but it’s behind a paywall*.

I expect the actual result is far more mundane than the media account makes it out to be.

Carlington: Quantum teleportation involves transferring a quantum state from one particle to another, using information transferred at or below light speed. It is not faster than light, it does not teleport physical objects, and no information is transferred faster than light.

*Scientific articles should not be behind paywalls. Journals do not pay authors for the articles, most journals do not pay the peer reviewers, the actual research behind the articles is funded by a university, government, or other agency that is not the journal publisher, and the cost of distributing a copy of an article via the internet is essentially zero. All paywalling does is make scientific knowledge less available.
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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby Levi » Fri Dec 02, 2011 12:44 pm UTC

How did they entangle the diamonds?

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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby Kulantan » Fri Dec 02, 2011 1:35 pm UTC

Magic Sufficiently advanced technology.
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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby KnightExemplar » Tue Dec 06, 2011 3:30 am UTC

So... to build a quantum computer with 128 q-bits... we'll need 256 equally sized diamonds.

Why does this sound prohibitively expensive still?
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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby Dauric » Tue Dec 06, 2011 3:25 pm UTC

KnightExemplar wrote:So... to build a quantum computer with 128 q-bits... we'll need 256 equally sized diamonds.

Why does this sound prohibitively expensive still?


Probably not actually, industrial diamonds are quite cheap, and we have the technology to artificially create jewelry grade diamonds in the lab as well.
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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby Xeio » Tue Dec 06, 2011 3:45 pm UTC

Wait, Einstein dubbed it "Spooky action at a distance" and we still continue to call it quantum entanglement? What is wrong with us?

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Re: Quantum Entanglement Observed on Macroscopic Scale

Postby Ulc » Tue Dec 06, 2011 3:56 pm UTC

Qaanol wrote:*Scientific articles should not be behind paywalls. Journals do not pay authors for the articles, most journals do not pay the peer reviewers, the actual research behind the articles is funded by a university, government, or other agency that is not the journal publisher, and the cost of distributing a copy of an article via the internet is essentially zero. All paywalling does is make scientific knowledge less available.


You apparently have no idea about the process. There's a huge editing, bureaucratic and logistical system associated with each journal, and even the best of them have relatively few readers.

Your average article goes through several cycles of editing and resubmitting (each time requiring someone working for the journal to go through the article) before it even gets to the peer reviewer - then the journal staff has to keep an eye on the peer reviewers and remind them to review it, then when the peer review comes they have to deal with the submitter and practically all peer reviewers disagreeing with each other, and sort out who's talking bullshit, which of the reviewers have actually read the article in details and how to deal with this. If rejected on minor things, this usually start over.

Paywalling isn't a good solution, but unless the journals got huge outside funds, it's the only one solution at all.
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