Quantum Teleportation, Not quite Beam me Scotty!

Scientists at The University of Geneva have successfully teleported a particle of light 25km. While it’s not exactly “Beam me up Scotty” material, Quantum Teleportation is still pretty cool. Computers are being built off this new technology, and they will shape the future of our communications.

I was quite a Star Trek fan as a kid. To be honest, it was just any science fiction. From Star Wars to Alex Mack, I loved it all. And while I’ve gotten taller, I haven’t really grown up. My inner-kid still gets super excited when any new scientific development resembles a gadget from my childhood. So when I heard about teleportation, I knew I had to find out more.

Quantum Mechanics is essentially the physics of the very very small. For example, it’s how electrons, protons as well as photons (particles of light) work. When you get down to this level, things don’t behave in a classical, or Newtonian, way.

To demonstrate this point, we have the “Schrodinger’s Cat Thought Experiment”. Erwin Schrodinger was an extremely prominent Quantum Physicist in the early 1900’s. He came up with this rather morbid thought experiment in 1935. A cat is put in a box where nobody can observe it. A contraption is set up which will let out a poisonous gas in the event that a particle decays. Quantum mechanics says that the particle is in a combination of states until an observation has been made. This means that the particle has both decayed and not-decayed at the same time. Which also means, that while the box is still closed, the cat is both dead and alive simultaneously. Like some dodgy, zombie apocalypse film.

Another area in quantum mechanics which is a little weird is called Entanglement. This is where two particles are connected in some unknown and spooky way. Think of two people on a seesaw. As one goes up, the other automatically goes down. Particles each have certain intrinsic properties which make them identifiable. For example, the charge is defined as positive (ie. a proton) or negative (an electron). Scientists also look at a property called spin, which describes the angular momentum of the particle. A particle is said to be either spin up or spin down. When two particles have become entangled, if one of them has spin up, the other must be spin down. The change of state of one automatically affects the state of the other, irrespective of distance. There is some unknown inner connection between the two.

The actual act of quantum teleportation is not what you would probably think. It’s almost more of a copy that is produced. Say you have a pair of entangled photons. Putting them in separate cardboard boxes, one is given to Alice, the other to Bob. Alice takes a peek at hers, and in doing so determines what state it is in. Bob then knows, without opening his lightweight delivery, exactly what is inside.

The new results in Geneva use a crystal as a type of storage device to teleport a photon. Rather than Alice and Bob, one of the entangled photons is sent to a crystal, while the other is sent along a rather long piece of optical fibre (25km to be exact). Yet another photon is sent after the second along the line of optical fibre, crashing into it and destroying both of them. The University of Geneva found that the information wasn’t destroyed on impact though, and was actually sent to the entangled pair in the crystal. The information is teleported instantaneously across this distance.

crystals
These crystals are home to the photonic information which is teleported. © GAP, University of Geneva (UNIGE). More info at Eurekalert.org

There is still a long way to go in quantum computing and communications, but this is an important step forward. A world of quantum computing would find us with ultrafast and extremely secure communications and networks.


The truth of Quantum Teleportation. Via XKCD. CC by 2.5

 


3 Responses to “Quantum Teleportation, Not quite Beam me Scotty!”

  1. Abe says:

    I just find anything and everything quantum just so intriguing, but yet at the same time i can never quite seem to get my head around it properly. But then i think back to this great (but rather lengthy) quote i read, and it helps placate me, because it seems that no one has a complete grasp on everything quantum just yet:

    “Take quantum theory, the laws of the subatomic world. Over the past century it has passed every single test with flying colours, with some predictions vindicated to 10 places of decimals. Not surprisingly, physicists claim quantum theory as one of their greatest triumphs. But behind their boasts lies a guilty secret: they haven’t the slightest idea why the laws work, or where they come from. All their vaunted equations are just mathematical lash-ups, made out of bits and pieces from other parts of physics whose main justification is that they seem to work. – Robert Matthews

  2. bryonies says:

    In the classical world, rather than the quantum one, Einstein showed that nothing can travel faster than the speed of light. This still holds true with quantum teleportation experiments. While it appears that any changes made to one entangled particle will instantaneously effect its pair, irrespective of distance, the classical information still travels at subluminal speeds. In the example used in my post, Alice would still need to give Bob a call on her phone to let him know what she found in her cardboard box.

    And yes, quantum is very very weird 🙂

  3. Peter Ge says:

    The quantum world is so weird! If I read this right, does this mean information is teleported rather than actual particles? Does that break the law that information cannot travel faster than light?