Like a long-distance romance, quantum entanglement is a fragile interaction; one moment, two particles can be sharing that special bond in which they are essentially one and the same, even when separated by vast distances. Then, just like that, the link can be broken. So the fact that Chinese researchers have set a new record by entangling eight photons at the same time--and then manipulating and observing them--is nothing short of amazing.
As Technology Review’s KFC cleverly points out, “getting eight photons exactly where you want them at the same time is the quantum mechanical equivalent of herding cats (clearly of the Schrodinger variety).” Manipulating individual particles at this level is difficult enough, and that’s before you create that quantum link. Once you’ve entangled two or more particles, manipulating the entangled system without breaking the link is even more daunting.
How do you entangle this many photons? You start with one photon from a high energy beam, and you split it with a nonlinear crystal. You now have two weaker photons that are entangled--any exertion on one will affect the other. You put one photon aside in an apparatus and you then split the other, put one of those aside and split the other, etc.But each split weakens the beam, and previously it was difficult--and time consuming--to produce to a manipulable eight-photon entangled system, so difficult that it hadn’t been achieved. The Chinese team, from the University of Science and Technology of China in Hefei, used a much brighter UV laser capable of churning out more entangled pairs much faster than smaller lasers. Then they figured out how to manipulate them.
That’s significant on a variety of fronts, not least of which is quantum computing. An eight-photon system would allow researchers to probe the quantum world at higher resolutions than was previously possible, demonstrating key pieces of the technology puzzle that should someday enable quantum computers to work as we’ve envisioned them.
For more, check the arXiv.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.


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Impressive, I wonder if we will soon find a way to generate entangled particles without spending so much energy doing so. The energy required to create 8 pseudo-stable entangled photons seems to be pretty high, I wonder if the energy required to create 6 billion of them is linearly difficult? I'm sure the usage for 8 entangled photons far exceeds my understanding of the subject, but I can extrapolate even crudely implications of billions of stable entangled pairs. Such as exact holography or possibly even instantaneous transportation and cloning if we could ever entangle particles other than photons lol
This makes me wonder if their are seas of stability in quantum mechanics. Where certain numbers of entangled particles and energies will be stable and act more like one. Reminds me of reading about artificial molecules being built from other molecules or quantum dots, that took on the characteristics of the modeled type they created an aluminum analog if I remember correctly.
In light of recent finds that electromagnetic radiation causes cancer quantum entanglement is a communication savior. In some years the wireless towers will disappear as each and every mobile phone will be entangled with a base or between themselves.