Quantum teleportation is even weirder than you think

Philip Ball in Nature:

20170616_zaf_x99_056_webA BBC headline last week, ‘First object teleported to Earth’s orbit’, has to be one of the most fantastical you’ll see this year. For once, it seems the future that science fiction promised has arrived! Or has it?

The article was talking about reports by Chinese scientists that they had transmitted the quantum state of a photon on Earth to another photon on a satellite in low Earth orbit, some 1,400 kilometres away1. That kind of transmission — first demonstrated in a laboratory 20 years ago2 — is known as quantum teleportation.

It’s a label that can mislead the unwary, as the BBC headline demonstrates. A write-up of the work in Discover reports that the scientists “have successfully transmitted quantum entangled particles” — only to clarify, confusingly, that “unlike science fiction teleportation devices, nothing physical is being transported”.

But wait: didn’t someone once say information is physical? That was physicist Rolf Landauer3, a pioneer of information theory. So if you send nothing physical, how can you transmit anything at all from A to B?

This is one of the deep issues that quantum physicists and philosophers still argue about. We can debate whether ‘quantum teleportation’ as a term is a catchy way of conveying a scientific idea, or a misleading bit of hype. But the real question — what, exactly, is transmitted during quantum teleportation, and how — touches on issues much more profound.

More here.