## Sunday, November 20, 2011

### Anton Zeilinger on quantum mechanics and games

Earlier this month, Austrian physicist Anton Zeilinger who is arguably the world's most prominent experimenter working on the foundations of quantum mechanics (if I avoid the term "recreational quantum entanglement physics") gave this rather entertaining 50-minute talk in Cape Town, South Africa.

Well, you can probably guess that your humble correspondent would agree with what he had to say (yes, I agree with every sentence) but I hope that the video may give you more than just some agreements or disagreements. Zeilinger shows a lot of cute historical pictures and quotes as well as gadgets that realize some of the bizarre quantum phenomena. He makes it clear that experiments, including those he masterminded, have ruled out hidden variables as well as sophisticated superluminal communication as the source of entanglement.

Then he presents a GHZM-like game with a pentagon of cups covering dices of two colors – and the neighbors always have a different color when you look even though 5 is an odd number. You may realize this in quantum mechanics (and in experiments) although it contradicts any "realist" or "classical" logic.

And so on: lots of fun no-go theorems for God, eavesdropping, shiny future for quantum computing, quantum library of Babel, quantum teleportation, quantum cars in a U.S. parking lot etc. Just watch it, it's cute.