Spukhafte Fernwirkung

Spooky action at a distance.

That’s what Albert Einstein called quantum entanglement, the phenomenon in which entangled particles act as if they are a single object (what happens to one automatically affects the other), no matter the distance. He derided the notion, citing it as proof that quantum theory was flawed and incomplete, positing that mathematicians would eventually discover that entanglement was nothing more than an error in their calculations.

Let it be known that Albert Einstein, while brilliant, was only human. Remember that whole adage about how human it is “to err?” Here’s proof of the validity of that little phrase.

Because quantum entanglement has been observed. No mere mathematical error, but an honest-to-Feynman physics oddity.

Sorry, Al.

But what exactly is so important about some particles acting couple-y?

No, not porn. Well… maybe a little porn. But, that’s secondary to the main reasons quantum entanglement is important.

When you think of THE FUTURE, what do you imagine? Towering skyscrapers? Moving walkways instead of sidewalks? Women in skimpy outfits made of leather and plastic and anything with a metallic sheen? Floating cars? Floating car chases?

I just really wanted to put a clip from The Fifth Element in here, because I love that movie.

Moving on. Do you picture space travel? Phasers? Replicators? Teleportation?

Yeah, teleportation was where I was trying to go with this.

Quantum entanglement is the base of the idea of quantum teleportation. But before you start yelling “ENERGIZE!” at random Scottish blokes on the street (seriously, you should be snogging them instead… shit, I’ve got to stop watching so much British television), I should probably tell you that, at present, quantum teleportation is not the stuff of science fiction stories.

Teleportation has long eluded physicists because it seems to violate the uncertainty principle- by taking a measurement on an atom, you disturb the state of the atom and an exact copy cannot be made.

Enter quantum entanglement.

This is a tough one to explain. Imagine there’s an explosion, blowing two electrons in opposite directions. These electrons have correlated spins- if one is spinning up, the other is spinning down, so the total spin is zero (if you don’t really understand what I’m talking about, just roll with me here). Without taking a measurement, though, we have no idea which way either electron is spinning.

After a while, the electrons will be light-years apart. So, we take a measurement of the spin of one electron. We find it has an up spin. We now immediately know that the other electron has a down spin. Yes, we instantly know information about something light-years away. And successive measurements made on one pair of entangled electrons could violate the uncertainty principle. That is what was so “spooky” to Einstein- that nonlocal, uncertainty-violating insanity that is quantum entanglement.

And because quantum entanglement can violate the uncertainty principle, we’ve shattered the primary hurdle standing between physicists and teleportation.

Physicists have been experimenting on information exchange/teleportation between entangled particles since it was first proposed in 1993. In 1997/98, scientists at Cal Tech, Aarhus University in Denmark, and the University of Wales experimentally demonstrated quantum teleportation when they teleported a single photon across a tabletop.

Here’s how that works: Quantum teleportation requires three components. A and B are entangled particles. C is the particle to be teleported. So, C comes in contact with A. A then “scans” C, giving A the complete information about C. The information is then immediately transferred to B, who then becomes an exact replica of C.

And that’s quantum teleportation. But it’s not all fun and games. There are some problems with it. See, the original object (C, in our example) is destroyed in the teleporting process. That means you can only make one copy of the original object. And teleporting a human being? Currently, the idea is laughable. The amount of information involved is enormous, and it would take the age of the universe to transfer all the information using the best communication channels we can think of right now.

Anyway, experiments in quantum teleportation have just been getting grander. In 2004, scientists at the National Institute of Standards and Technology teleported more than a photon- they teleported an entire atom. In 2008, scientists in Rome found a way to clone an entangled photon in such a way as to preserve the entanglement. A large bunch of these clones, treated as a single quantum state, can all be entangled with the original partner photon. And recently (thus this post), scientists at the University of Science and Technology of China and Tsinghua University in Beijing teleported a photon nearly 10 miles, the farthest information transfer to date.

Because of this long-distance teleportation, scientists have started to see the possible communication applications of this science. Next-generation satellite communication networks could be based on quantum teleportation, which would make the teleported phone call impenetrable. Nobody could possibly eavesdrop on the call in any way- the rules of quantum teleportation don’t allow that, because the two particles are entangled with themselves and no other particle.

Plus, quantum teleportation could speed up computing power. Quantum computing is one of the wet dreams that plague the land of physics, and this recent Chinese study is a big step toward making that wet dream a sexy, sexy reality.

Another recent study involving quantum entanglement has found that human eyes can detect entanglement. It requires shooting a lot of photons at the human eye, though, because it takes about 7 photons before the eye will even register the photons and lots of photons get lost in the gelatinous swamp of the vitreous humor, so it takes hundreds (or thousands) of photons before a human can become a reliable photon detector.

Still, it’s interesting that the human eye can help detect entanglement. I mean, sure, the experiment also involved a standard detector, and all the humans actually saw were little points of light on one side of their field of view or the other, and the only way to tell photons were entangled was to compare the human data with the standard detector data…

Actually, this whole experiment seems really weird, practically useless, and an utter waste of time for the land of science. I have no defense for it.

Still, quantum entanglement itself is awesome. I’ve always thought it was the most romantic notion in physics. I mean, think about it. These particles are bound to each other in a way they aren’t to any other particle in the universe. And when something happens to one, it immediately affects the other. It’s a beautiful concept. I actually wrote an oddly sweet short story about it my freshman year of college because I found the idea of entanglement so lovely.

I’m not the only one who thinks that way, either. Samuel Braunstein from the University of Wales once compared entangled particles to lovers “who know each other so well that they could answer for their lover even if separated by long distances.”

And they say romance is dead. It’s not dead- it’s just hiding where you least expect it.

***

While writing this, I was struck by a similar concept used in The Dark Crystal (the only reason I can make this connection is because I literally just watched this movie this afternoon, so it’s fresh in my mind… I really do adore that film, by the by- it was such a strong part of my childhood). When the Crystal cracked, the urSkeks (a race of beings) were split into two new races, the Skeksis and the Mystics. And these two races are intricately bound. Each pair of Skeksis and Mystics were once a whole being. And when one of them gets injured or killed, the other half of the pair is injured in the same place or dies in the same way, even though they now live far from one another.

Spooky action in a Jim Henson flick. Good times.

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