[math-fun] How to Recover a Qubit That Has Fallen Into a Black Hole

FYI -- http://arxiv.org/abs/1507.03592 Aidan Chatwin-Davies, Adam S. Jermyn, Sean M. Carroll We demonstrate an algorithm for the retrieval of a qubit, encoded in spin angular momentum, that has been dropped into a no-firewall unitary black hole. Retrieval is achieved analogously to quantum teleportation by collecting Hawking radiation and performing measurements on the black hole. Importantly, these methods only require the ability to perform measurements from outside the event horizon and to collect the Hawking radiation emitted after the state of interest is dropped into the black hole.