Quantum entanglement stronger than suspected

New Scientist ^ | July 17, 2002 | Ian Sample

[gcruse]

Pairs of photons linked by the weird quantum effect of entanglement can pass through sheets of metal without the entanglement being destroyed. The finding means the quantum linking of particles is far more robust than scientists thought and could help them develop new ways of making quantum computers.

Scientists think quantum computers could be hugely powerful because of their ability to perform many calculations at once, instead of doing one after another like regular computers.

When photons are entangled, the physical properties of one are intimately linked to the other. Measuring the properties of one will instantly tell you the properties of the other. But many scientists believed entanglement broke down if the photons ever interacted with anything.

Now, Erwin Altewischer and his team at Leiden University in the Netherlands have shown this is not true. They used a crystal to split photons into pairs of lower energy photons with different and entangled polarisations. They then fired these entangled photons at gold sheets thick enough to block light.

Surface waves

The sheets were peppered with holes 200 nanometres wide. Although the holes were too small for light to squeeze through, Altewischer found the photons created waves of electrons on the gold surface called plasmons that passed through the holes and re-emitted the photons on the other side. Measurements showed that the emitted photons were still entangled.

"It's a good omen, because it's saying quantum entanglement can survive when you might not expect it to," says Bill Barnes, a photonics expert at the University of Exeter. "If they can survive this, what else can they survive?"

Altewischer says the fact that the entanglement is preserved, even when the light is converted into electron waves, means it could be used to develop new types of quantum computer or quantum cryptography systems.

[yendu bwam]

What causes wave functions to collapse (if they do) - one of the big mysteries of physics!

[RightWhale]

They used a crystal to split photons into pairs of lower energy photons with different and entangled polarisations.

Is it possible that in the beginning there was one photon that split and resplit over and over until the present day and that all photons are entangled?

[Dick Vomer]

crystal blue persuasion??? It's a new sensation...

[snopercod]

ESP Explained!

[RightWhale]

I am linking the idea that some of these extra dimensions in the string theory might be large enough to be measured in the lab, large enough to be bigger than groups of neurons in the brain, and the idea that there can be only one photon. There can be only one. Highlander.

[snopercod]

Erwin Altewischer and his team at Leiden University in the Netherlands...

That explains it. They were smoking something while projecting Feynman Diagrams on the ceiling as a light show. Awesome, man! Far out!

[genefromjersey]

I hope you folks who design tinfoil protective hats are taking this information seriously !

[Senator Pardek]

On a related note, I believe it was Richard Feynman who theorized that the universe consists of only one particle, and that it zig-zagged around at a blinding rate all over, creating what seems to be matter consisting of many particles.

[RightWhale]

That is related. I suggested that in 1962 to my physics professors, but they were not amused. It might well be that there is one particle and we are somehow experiencing the one particle as many due to an as yet unknown factor.

[parsifal]

Yes, we are. The silly scientists simply do not know about the invisible ether, or they would not think that they are really onto something. Reynolds Wrap Forever! parsy.

[Some hope remaining.]

So if I could mess with the timing or the pattern of the single particle somehow then maybe I could suddenly swap that chicken sandwich you are about to bite into with the slug I saw in my backyard.

[Willie Green]

I am linking the idea that some of these extra dimensions in the string theory might be large enough to be measured in the lab, large enough to be bigger than groups of neurons in the brain, and the idea that there can be only one photon.

A guy in my college dorm had a similar theory.
He'd go into a trance staring at his laundry bag, fully believing that if he could focus his brainwaves his clothes would become clean.
I don't believe he ever graduated...

[RightWhale]

I don't believe he ever graduated

Some of us get ideas and are allowed to graduate anyway.

[Libertarianize the GOP]

.

[Duke Nukum]

I seem to remember reading somewhere that if ESP were real, then its explanation would lie in the realm of physics instead of psychology.

I think it was an idea attributed to Einstein in one of those popular books that mesh mysticism with quantum mechanics.

Whatever its source, I am unsure of its veracity.

[Dan Day]

I seem to remember reading somewhere that if ESP were real, then its explanation would lie in the realm of physics instead of psychology.

...except that it's not real.

To date, all claims of paranormal ability have failed to show results when submitted to proper controlled experimental conditions.

[Darth Hillary]

This is a little vague, Are they using a TEM00 Laser, creating a coherent beam of a single frequency, or are they using a non coherent light source which produces multiple spectral lines? A simple frequency doubling of a 404 NM laser diode gives a 202 NM beam, which can be doubled again to produce a 101 NM beam of light which would easily pass through a 200 NM opening. A beam with a wavelength below about 400 NM is Invisible to the human eye, but that doesn't stop it from being light.

[gcruse]

You might find more in Nature vol 318 p304.

[InterceptPoint]

Is it possible that in the beginning there was one photon that split and resplit over and over until the present day and that all photons are entangled?

I will up the bet.

Since photons travel at the speed of light time is slowed to zzzzzzzzzzzzero in the reference frame of the photon. As a result, photons don't have to concern themselves with time and they can be everywhere at once.

So you only need ONE PHOTON to populate the universe.