Researchers Entangle Two Millimeter-Sized Diamonds, A Huge Leap in the Scale of Quantum Entanglement
By Rebecca Boyle
Posted 12.01.2011 at 3:19 pm

As regular readers know, entanglement is the process of connecting two separate things, be they photons or nanoscale objects, so that they behave the same no matter their distance apart. What happens to one particle also happens to the other, even if they are separated by the entire universe.

Researchers at Oxford University took two small diamonds, about 3 millimeters square and 1 millimeter thick. They exposed them to incredibly short bursts — about 100 femtoseconds — of laser light, in a method called ultra fast pump probe spectroscopy. What happened next is complicated: The light induced some vibration in the lineup of the molecules in the diamond crystals. These inherent oscillations (present in all atoms, they’re just being taken advantage of here) are known as phonon modes. The pulse excited one phonon mode in both of the diamonds, and also produced two photons, which were scattered by the diamonds and which would be used to entangle the phonon states. Then the scattered photons were brought together, using a complicated setup involving a beam splitter and single-photon detectors.

The two diamonds were about half a foot apart, but when one of the photons was detected, the two diamonds were sharing a phonon. In other words, what happened to one diamond happened to the other. The researchers confirmed this by working backward, de-exciting the phonon and emitting another photon, which was itself detected. Entanglement lasted about 7 picoseconds, so it’s too short to be used in a quantum computer or other device — at least for now.

“The two diamond samples coherently shared one phonon, which is the hallmark of a quantum-entangled state,” explains L.-M. Duan, a physicist at the University of Michigan who wrote a perspective paper accompanying the Science paper. “These results provide a striking example that entanglement is not particular to microscopic particles but can manifest itself in the macroscopic world, where it could be used in future studies that make fundamental tests of quantum mechanics.”

Researchers Entangle Two Millimeter-Sized Diamonds, A Huge Leap in the Scale of Quantum Entanglement | Popular Science

The idea was used in SF to make instant communication across "great distances" (i.e. different solar systems) possible...

Is this research showing that's possible? Does that mean that 'communication' at least breaks speed of light?

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That's certainly still a possibility. In principle two entangled objects interact instantaneously; the question is how stable they can be, if there are any range limits etc. But yes, it might end up offering that.