Quantum Entanglement of Macroscopic Diamonds

New submitter ananyo writes "A pair of diamond crystals has been linked by quantum entanglement — one of the first times that objects visible to the naked eye have been placed in a connected quantum state. 'This means that a vibration in the crystals could not be meaningfully assigned to one or other of them: both crystals were simultaneously vibrating and not vibrating (abstract). Quantum entanglement — interdependence of quantum states between particles not in physical contact — has been well established between quantum particles such as atoms at ultra-cold temperatures. But like most quantum effects, it doesn't tend to survive either at room temperature or in objects large enough to see with the naked eye.'"

Comments

weird.

[notgm]

this both gives me the chills, and doesn't.

www.quantum-vibrator.xxx

[Slugster]

great..... we dump all this money in some eggheads' laps, and all they can think of is to make fancy adult toys

Quantum First Post!

[Dutchmaan]

This is a first post, and yet it isn't!

next step in this study

[niw3]

should be an experiment with a cat & some poison

0.05 mm by .25 mm

[Anonymous Coward]

They say that each phonon involves the coherent vibration of about 1016 atoms, corresponding to a region of the crystal about 0.05 millimetres wide and 0.25 millimetres long â" large enough to see with the naked eye.

0.05 mm is roughly 1/4 the width of a human hair. Of course, I still can't see it, because it's just a patch of vibrations on a much larger diamond.

Harmony at last..

[RenHoek]

Neat... Now I can get a pair of diamond vibrators and please both my wife and mistress at the same time!

Re:Harmony at last..

[Baloroth]

Actually, no, because they are quantum entangled only one of them can vibrate at a time. So you can still only please one at at a time, you just don't know which one it will be until they tell you.

Re:Harmony at last..

[Baloroth]

No. The experiment took one photon, and sent it along two possible paths without recording which path it took, which causes a vibration in one (and only one) diamond. Since the path of the photon was random, and not recorded, you cannot say which diamond is vibrating. The way the researchers put it (better than the summary IMO) is "Neither the statement 'this diamond is vibrating' nor 'this diamond is not vibrating' is true.” You cannot selectively vibrate one. In fact knowing which one vibrates destroys the entanglement. It does, however, tell you the state of the other diamond (the opposite) without observing it directly, which creates a few paradoxes and is the source of the whole 'spooky action thing.'

Don't feel to bad if you don't understand it, even quantum physicists don't understand quantum physics very well. The mechanics behind what is really happening in entanglement is still unknown, there is only guesswork as to how it might happen.

Someone correct me if I'm wrong but...

[Shadow of Eternity]

As near as I can understand this they're entangled so that vibrations in one are indistinguishable from vibrations in another, they both do the same thing at the same time (or near it at least)... doesn't this imply the ability to entangle two whatevers and transit information via entanglement induced vibrations?

Re:Someone correct me if I'm wrong but...

[Baloroth]

No, since when you establish the vibrations you don't know in which one it occurs. So while you could establish vibrations in a distant diamond (or particle), at least theoretically, you never know when you do so which one is actually vibrating. When they set it up, they used 1 photon that could travel and strike either diamond, creating the vibrations. Without measuring the photon's path, they didn't know which one it hit and therefore which on would be vibrating. This caused the entanglement.

Two things: 1), the photon itself had to be able to strike both (so not FTL at all for this setup) and 2) no useful information was encoded in this experiment. One thing you could do, though, would be send one diamond one direction and the other another way. Either can know the other diamond's state by reading his own (the other is in the opposite), and no one else can, since anyone else reading it would collapse the state, and a second reading would have a different result (I believe this is more or less how quantum cryptography works). Quantum entanglement is useful for transferring information (in other cases), but the mechanics still don't allow FTL information transfer, they just allow you to encode more in less space by having two bits quantum entangled. I don't completely understand the physics of that.

Re:Is this again just a theory?

[Taibhsear]

Did you actually read the article? "Cheap words" make up all science and literature. They explained everything they did in the article. Or do you expect them to post all their experimental data on this brief web article?

"When we detect the Stokes photon we know we have created a phonon, but we can't know even in principle in which diamond it now resides," says Walmsley. "This is the entangled state, for which neither the statement 'this diamond is vibrating' nor 'this diamond is not vibrating' is true."

To verify that the state has been made, the researchers fire a second laser pulse into the two crystals to 'read out' the phonon, from which the laser photon draws extra energy.

Statistics not particles

[dak664]

Let us not lose sight of the fact that a photon is a statistical convenience, not a particle, and a phonon is even less a particle. You can't send "one photon" and detect "one phonon". These are statistical coincidence measurements that detect correlated behavior between the two diamonds after an electromagnetic interaction that can not transfer less than Planck's constant of action. Either diamond would show a 50% excitation in the absence of the signal from the other. Spooky action at a distance is inferred from correlation of the states over a large number of events. Which is why quantum computing is not going to be as fast as everyone thinks it will be.