I've Said It Before and I'll Say It Again

Science fact is more fantastical than science fiction. This is why I ever had the idea to write Sci-FU, so any time I see some science news concerning something I wrote about, I get particularly excited. In this case though, I actually haven't written it yet, but I've been planning to.

Quantum physics at a distance

Physicists at the University of Vienna and the Austrian Academy of Sciences have achieved quantum teleportation over a record distance of 143 km. The experiment is a major step towards satellite-based quantum communication.

One of the events in the sequel I've yet to start formally writing (I've been writing bits and pieces as I have ideas) for Sci-FU is the development and launching of a satellite network that uses quantum mechanical phenomena, like quantum teleportation, to communicate. Looks like we may have such satellites much sooner than the roughly 50 years Sci-FU is in the future. Read on to find my analogy for explaining quantum teleportation.

The Schrodinger's Cat thought experiment demonstrates a way to put something into a superposition. In that specific example, it is a cat being made both alive and dead by some device. This device could be unstable explosives, a radiation source, poison, and I think I've heard of others as well. The point is, there is a probability the cat will be killed by them.

Now, let's change the scenario a little and put two cats in the box, but the lethal device can only kill one of them. Let's just say it's poison that spills and only one cat can lick up enough to kill it. This scenario actually puts both cats into a superposition of alive and dead, and entangles their state. If cat A is dead, then cat B must be alive and if you separate the cats without disturbing them somehow, this will still be true. (You cut the box in half and seal the two halves to make two boxes.)

Now we have two entangled cats that are both alive and dead. To explain quantum teleportation we actually need a third cat (cat C) that is definitely alive and a can of cat food, that can only feed one cat. Place the cat food into on of the two boxes containing the original cats. Doesn't matter which one, but let's say you put it into cat B's box. Now you remove the cat food can from that box and give it to cat C, without actually disturbing any of the boxes or spilling any of the food. (There are reasons it is called a 'thought experiment' beyond humanitarian purposes.)

This scenario actually demonstrates quantum teleportation because the state of cat A is teleported to cat C. Here are the two possibilities:

1. Cat A died of the poison and cat B is alive. When you give cat B the food, it eats it, so there is no food for cat C, which then dies. Now both cat A and cat C share the state of being dead.
2. Cat A is alive and cat B died of the poison. When you give cat B the food, it cannot eat any of it, so when you then move the food to cat C's box, it eats it and lives. Now both cat A and cat C share the state of being alive.

(Of course it is more complicated than that as these two possibilities act out at the same time because they are the two superpositions. Only when you observe the cats will the choice be made of which possibility is viewed, but until then, they are both true.)

That is, essentially, how quantum teleportation works. Cat A and cat C are completely separate cats, but the state of one has been pushed onto the other by way of cat B and the food. You are not teleporting the particle or the cat but its quantum state, to another place.