Christopher Fuchs, Perimeter Institute, Toronto

Topic: "Quantum Theory from Quantum Information? (What would Feynman say?)"  (Video)

Abstract: How did the field of quantum information begin? To my mind, it was when John Wheeler formed his group of students and postdocs at the University of Texas in the early 1980s. David Deutsch (quantum Turing machines, quantum speed up), Benjamin Schumacher (qubits, quantum channel capacities), William Wootters (no-cloning, quantum teleportation), Wojciech Zurek (no-cloning, decoherence). Even Richard Feynman visited once. Those names now ring out to our field like the names of Bedford, Exeter, Warwick, and Talbot in King Henry's famous Saint Crispin's Day Speech.

To every student who walked into his office (even undergraduate freshmen), Wheeler would implore, "Give an information theoretic derivation of quantum theory!" He saw that as the only way to gain a real understanding of quantum theory. In this talk, I'll outline how Wheeler's old hope is still bearing fruit in my group at the Perimeter Institute. Particularly, taking his question seriously leads to the study of a mysterious structure called the Symmetric Informationally Complete (SIC) quantum measurement. When these structures exist (it seems they do for all finite dimensions, though no one has proved it), they give a very pretty way of writing Born's quantum probability rule in purely information-theoretic terms. This gives the hope that all the mathematical structure of quantum theory might be derivable from one very basic physical scenario. It's not the double-slit experiment, but one might chime in with Feynman and say, "In reality, [this scenario] contains the only mystery [of quantum mechanics]."